OT1 Proposals

HCl, HF and H2O+ in comets : probing solar nebula and coma chemistry

Proposal ID: OT1_dbockele_1

Principal Investigator: Dominique Bockelee-Morvan

Time: 25.1 hours priority 1

Category: Comets

Summary:

The composition of comets provides a record of the chemistry of the primitive solar nebula, in the region and at the time of their formation. The presence of interstellar-like organics and other exotic gases in cometary nuclei gives the definite impression that comets preserve a record of the interstellar composition characteristic of the presolar cloud, or that cometary and interstellar molecules formed by similar processes. We propose to take benefit of the unique capacities of Herschel in the sub-millimeter domain and the high sensitivity of HIFI to search for cometary molecules of cosmogonic interest that cannot be observed from the ground, namely HCl (both (35)Cl and (37)Cl isotopes) and HF. These species are the main reservoirs of fluorine and chlorine in the ISM, as measured from Herschel, and are locked onto grains in dense molecular clouds. Their survival during the collapse of the presolar cloud is uncertain, but both HCl and HF should have reformed readily from the released atomic Cl and F in the proto-planetary disk. We expect that these molecules condensed onto pre-cometary grains during the cooling phase of the Solar Nebula. In addition, observations of H2O+ are proposed to constrain the H2O chemistry in cometary atmospheres and to measure accurately the frequency of its 111-000 and 202-111 ortho transitions near 1115 and 742 GHz, respectively, for best interpretation of H2O+ interstellar data.

Detecting the Largest Rings in the Solar System--Dust Rings from the Irregular Satellites

Proposal ID: OT1_ddan01_1

Principal Investigator: Daniel Tamayo

Time: 12.8 hours priority 1

Category: Solar System Other

Summary:

We propose to extend observations of Saturn's newly discovered Phoebe ring (Verbiscer et al. 2009) to new wavelengths and greater radial range to better characterize the dust properties and constrain the dynamics and particle size distribution of the ring. We will seek similar rings around both Uranus and Neptune. This work is important to understanding the transfer of material from the irregular satellites to the inner regular satellites, the outermost of which can have their surfaces completely transformed by this process. Furthermore, this dust represents an important analogue to the dust observed in debris disks around other stars.

The discovery of the Phoebe ring, as well as work by Turrini et al. (2009), Bottke et al. (2010), and Buratti et al. (1991), among others, suggests that the other giant planets should also possess rings supplied by their irregular satellites. We therefore propose searches for such rings at both Uranus and Neptune. Our proposal is aimed to return important science results for a modest time investment (12.8 hours)

Probing the Enceladus torus with Herschel

Proposal ID: OT1_elellouc_1

Principal Investigator: Emmanuel Lellouch

Time: 27.2 hours priority 2

Category: Planets

Summary:

Observations of Saturn with HIFI, performed initially in June 2009 and in more details in June 2010 within the framework of the KP-GT ``Water and related chemistry in the Solar System", have revealed unexpected absorptions in the core of several emission lines of water from Saturn's atmosphere (557 GHz, 987 GHz, 1113 GHz and 1670 GHz). These absorptions cannot occur in Saturn itself; rather we show that they are due to absorption from water in the ``Enceladus torus", i.e. a cloud of material originating from Enceladus' active plumes, spreading around Saturn and forming a broad toroidal structure centered around Enceladus' orbit at 4 Saturn radii. Based on a comet-like fluorescent excitation model, our preliminary analysis of these data indicate line-of-sight water column densities of (1-3)x10^13 cm-2 and a radial extent of about 2.5 Saturn radii. This discovery provides an entirely new method to probe physical conditions (density, structure, and composition) in the Enceladus torus. Here we propose a detailed follow-up on these observations. The goals are (i) to monitor the variation of these absorptions with viewing geometry, taking advantage thatthe change of aspect in the Saturn system (with the satellite and ring system becoming progressively more ``open") over the upcoming years (ii) to search for H2O emission directly originating from the torus (iii) to search for several additional compounds such as NH3 (known to be produced by Enceladus' plumes), OH (seen in the UV from HST) and several ionized species (H3O+, H2O+, OH+, expected from torus ionization). The ensemble of data will hopefully provide us with (i) an improved understanding of the excitation conditions in the torus (e.g. on the role of electrons) (ii) an improved understanding of its composition and chemistry (iii) a detailed 3-dimensional view (radial, vertical and longitudinal) of the torus and the ability to directly test physically-based model torus models.

Probing the extremes of the outer Solar System: short-term variability of the largest, the densest and the most distant TNOs from PACS photometry

Proposal ID: OT1_evileniu_1

Principal Investigator: Esa Vilenius

Time: 29.2 hours priority 1

Category: Kuiper Belt bodies

Summary:

Pluto was believed to be the outermost object in the Solar System until, at the end of the last Millenium, a number of similar objects were found on orbits beyond Neptune. These objects are now being designated as Trans-Neptunian Objects (TNOs) and are believed to be a reminder of a primordial population. The TNO population comprises a wide range of orbital types and spectral features, many of which are of icy nature. Their origin and evolution are still an open question and subject to debate. We propose repeated high-SNR PACS photometry observations of three extreme specimen of the TNO population: (136199) Eris, the largest dwarf planet, (90377) Sedna, the most distant body in the Solar System and (50000) Quaoar, the densest TNO observed so far. We request a total of 51.7 hours of Herschel observing time using different channels, aiming a SNR of 10 or higher. We intend to perform time-series photometry in order to refine physical properties, which have often been determined using coarse thermal models and single-band data in the past, to find hints of thermal IR lightcurves of Eris and Sedna and to make a high SNR observation of the entire lightcurve of Quaoar. Together with available optical lightcurves we can distinguish whether flux variations are due to shape effects or inhomogeneities of the object's surface. We will make use of existing thermal and thermophysical models to refine physical properties, which may be used to recompute density estimations for Eris and Quaoar and to model surface compositions. Herschel is highly suitable for this task, since it offers the highest sensitivity available to date in the far-IR regime, in which TNO emission peaks due their low surface temperatures. Our results will put constraints on some of the important questions concerning the Trans-Neptunian region and will therefore be of vital importance for observers and modelers in Solar System sciences.

Properties of Jupiter Trojans from far-IR spectroscopy and photometry

Proposal ID: OT1_evileniu_2

Principal Investigator: Esa Vilenius

Time: 44.1 hours priority 2

Category: Asteroids

Summary:

The two swarms of Jovian Trojan asteroids, which librate around Jupiter's Lagrangian points L4 and L5, occupy an intriguing place between the predominantly rocky inner Solar System and its icy outer regions. Their dynamical and physical properties provide crucial constraints on our understanding of the origin and early evolution of the Solar System. When Spitzer enabled the first spectroscopic observations of these objects at mid-IR wavelengths, the spectral signature of fine-grained silicates was found on a number of bright Trojans (Emery et al., 2006; Mueller et al., 2010). This provided a surprising piece of observational evidence between the hypothesized genetic connection between Trojans and cometary nuclei. Thanks to the spectroscopic capabilities of PACS, a completely unexplored wavelength range is now opening up that contains diagnostic features of elusive materials such as crystalline water, hydrous silicates, or organic irradiation residues.

We here propose PACS spectroscopy observations of 4 Jupiter Trojans, the respectively two brightest objects in the L4 and L5 swarms: Hektor, Agamemnon, Patroclus, and Aneas. We also propose a small amount of time for PACS photometric observations in support of spectroscopy. Our sample is sufficiently large to provide our results credibility, but small enough to keep our observing time request modest. Our observations will provide new constraints on the amount of water ice on the surface (if any) and will shed light on the hypothesized previous cometary activity of these objects.

An Irregular Dust Cloud around Uranus

Proposal ID: OT1_gkennedy_1

Principal Investigator: Grant Kennedy

Time: 16.5 hours priority 2

Category: Satellites

Summary:

The Solar System's irregular satellites have been grinding themselves to oblivion since their capture by the Giant planets billions of years ago. We have developed an evolutionary model of this collisional evolution that matches the known irregular populations and predicts that the cloud of small icy fragments created could be detectable. These circumplanetary clouds may also be detectable around extrasolar planets. We propose to use the SPIRE instrument on Herschel for 16.5 hours to observe a ~1 degree square region around Uranus in search of this cloud of icy particles. Because we expect the surface brightness to be fainter than the Zodiacal, galactic, and cosmic background this observation requires subtraction of two images taken one year apart. The first image is centered on Uranus, but a year later the planet has moved by 4 degrees and the same background is imaged the second time. Discovery of this cloud will be concrete evidence that the irregulars are collisionally evolved and allow a much better estimate of the size distribution between micron size grains and the largest irregulars. Dust cloud structure and asymmetry will provide information on grain properties and their fate, many of which are thought to coat the surfaces of outer regular satellites. The knowledge gained of the irregular satellite populations will allow more informed models of extrasolar circumplanetary swarms and pave the way for their discovery. It would be particularly apt that dust around Uranus is discovered by Herschel, as Uranus itself was discovered by William Herschel in 1781.

Variability in Ice Giant Stratospheres: Implications for Radiative, Chemical and Dynamical Processes

Proposal ID: OT1_gorton01_1

Principal Investigator: Glenn Orton

Time: 17.1 hours priority 1

Category: Planets

Summary:

We will assess the rotational variability in the stratospheres of the ice giants, Uranus and Neptune, to understand the dynamical and chemical variability of the atmospheric structure of both planets as a function of longitude. This effort follows up observations by the Spitzer IRS that shows consistent evidence for rotational variability of stratospheric hydrocarbons in Uranus and intermediate-term variability in Neptune's emissions, neither of whose origins are not well understood. Herschel provides an opportunity to follow up these observations with its unparalleled sensitivity. Over the 17-hour periods characterizing the equatorial rotation periods of both planets a series of eight PACS dedicated line scans will be made of strategic lines of HD, methane and water vapor. An efficient scheme takes advantage of the simultaneous availability of Uranus and Neptune in Herschel's visibility window. These will assess the variability of hydrocarbons vs temperatures in both atmospheres to an unprecedented accuracy. The results will be analyzed by a team consisting of many members of the Key Project on ``Water and Related Chemistry in the Solar System'' who will apply their expertise with the data and its analysis, as well as researchers who discovered the Spitzer variability and ground-based inhomogeneity. The data will be examined in the context of models by team members who are experts in radiative transfer, photochemistry, and dynamical modeling of circulation and zonal thermal wave structure. By refining quantitative models for interactions between radiative, dynamical and chemical processes in these two cold but radiatively and dynamically diverse planets, a baseline will be created that will be useful in the interpretation of variability in the spectra of giant exoplanets. This work will also be programmatically useful in the evaluation of the variability of radiation from Uranus and Neptune, both which are key members of the Herschel flux calibration system.

Nitrogen, Phosphorus and Sulphur Chemistry in Saturn's Atmosphere: Internal and External Origins for HCN, HCP and CS

Proposal ID: OT1_lfletche_1

Principal Investigator: Leigh N. Fletcher

Time: 8 hours priority 1

Category: Planets

Summary:

Our understanding of some of the fundamental physiochemical processes at work within Saturn's gaseous atmosphere is presently limited by the difficulties associated with detection of a number of atmospheric species. Based on our new understanding of Saturn's bulk composition and chemistry from the Cassini mission, Herschel/HIFI offers an unprecedented opportunity to detect these species for the first time, and to place constraints on their origins. Radiative transfer calculations have been used in tandem with chemical modelling to select optimal transitions of HCN, HCP and CS for study by HIFI. These species have never been detected before, but are expected to be important secondary repositories for nitrogen, phosphorus and sulphur in Saturn's atmosphere. Furthermore, the superb spectral resolution of heterodyne spectroscopy is ideal for distinguishing between broad tropospheric absorptions and narrow stratospheric emissions, allowing us to distinguish between internal and external origins for each species. Tropospheric abundances will be compared to expectations from state of the art thermochemical and photochemical models, in addition to predictions of lightning-induced shock chemistry. Stratospheric abundances will be interpreted in terms of external supply of N, P and S-bearing materials, either from large asteroidal/cometary impacts (where shock chemistry in impact plumes is also important) or influx of material from Enceladus, the rings or interplanetary dust particles. As a result, the HIFI search for the first signatures of Saturn's HCN, HCP and CS abundances will serve as vital constraints on internal chemistry and the coupling between Saturn's cold atmosphere and external environment, revealing the fundamental processes at work in the cold outer reaches of our Solar System.

Analysis of OPRs and D/Hs of hydrogen sulfide in comets: Understanding their natal origin and constraining their place of formation in the protoplanetary disk.

Proposal ID: OT1_lpaganin_1

Principal Investigator: Lucas Paganini

Time: 20 hours priority 2

Category: Comets

Summary:

Measuring the relative amounts of individual species present in the nucleus of a comet can provide information on their formation mechanism, and thus on cometary origins. We propose to investigate ortho-to-para ratios (OPRs) of hydrogen sulfide and further survey its isotopologues (e.g. HDS) to evaluate deuterium-to-hydrogen ratios (D/Hs) of all suitable comets that become available over the performance period of this OT1. We seek to obtain a quantitative analysis of production rates of sulfur species, isotopic fractionation in H2S (HDS/H2S), and the ratio of nuclear spin species for H2S. This can provide a measure of the temperature at which the nuclear spins were last set prior to being incorporated into the nucleus. Comparison of these measurements in comets with those found in interstellar cloud cores, aided with predictions of nebular chemistry, will test the presence of legacy ice from the natal cloud core and the degree of processing experienced by pre-cometary ices.

The chlorine cycle on Jupiter and Saturn

Proposal ID: OT1_nteanby_2

Principal Investigator: Nicholas Teanby

Time: 6.4 hours priority 2

Category: Planets

Summary:

Hydrogen halides provide key insights into giant planet atmospheres but their detection has so far remained elusive. Herschel/HIFI's low noise and high spectral resolution provides a unique opportunity to detect these species for the first time - with an estimated sensitivity at the sub part per trillion level - an improvement of over three orders of magnitude on the best measurements currently available.

Observing hydrogen halide species provides an exciting new avenue for studying chemical and dynamical processes at work on the giant planets. This proposal will focus on HCl - the halide with the highest predicted abundance and detectablity. HCl could have an internal or external origin - although models predict that an external origin from influx of extraplanetary material is the most likely.

The observed HCl abundances will be used to: (1) Determine the magnitude of external Cl sources and compare exogenic flux environments and physiochemical processes between Jupiter and Saturn. (2) For Jupiter, by comparing the Cl flux to the O flux (from H2O), we can determine the excess Cl flux and measure the proportion of Io's plasma torus that enters the top of the jovian atmosphere. This unique measurement would have implications for the whole Jupiter system. (3) Use the gradient of the vertical profile to determine the efficiency of HCl scavenging by NH3 in the stratosphere and constrain the stratospheric chlorine cycle. (4) Provide the most stringent test of interior thermochemical models to date, by determining limits on the abundance of HCl in the troposphere. This will help constrain the speed at which internal material is dredged up and the efficiency of HCl depletion by formation of ammonia salts. Comparing HCl abundances between Jupiter and Saturn will allow us to probe these processes under different internal and external environments, providing further insight.

Confirmation of the first detection of HNC on Titan

Proposal ID: OT1_rmoreno_1

Principal Investigator: Raphael Moreno

Time: 12.4 hours priority 1

Category: Satellites

Summary:

Observations of Titan were performed on June 14, 2010 with Herschel/HIFI, as part of the Herschel guaranteed time key programme "Water and related chemistry in the Solar System" (PI: P. Hartogh). These measurements, targetted to the H2O 556.935 GHz line, have shown in addition an unanticipated line at 543.897 GHz. We attribute this emission to HNC(6-5), which would represent the first detection of HNC in Titan's atmosphere. Preliminary interpretation of the data suggests that HNC is confined to the upper atmosphere (above at least 300 km, and may be even higher). HNC is a plausible species in Titan's atmosphere, expected to be produced by dissociative recombination reaction of the ionospheric ion HCNH+ at altitudes above 1000 km. The loss process considered is HNC protonation by reaction with H-bearing ions and H atoms, yielding HCN. An accurate knowledge of the vertical distribution of HNC and HCN at altitudes above 800 km would provide a major constraint for the photochemical formation scheme of HNC. The goal of this proposal are (i) to spectroscopically confirm the presence of HNC in the upper atmosphere of Titan by observing another transition at 906 GHz (ii) to measure the narrow component of HCN at 532 GHz, in order to retrieve its abundance abundance profile over 400-800 km. The so-constrained HNC/HCN ratio in the upper atmosphere will permit us to discriminate between the different possible formation/loss schemes of HNC.

Probing the atmospheres of Uranus, Neptune and Titan with CH4 lines

Proposal ID: OT1_rmoreno_2

Principal Investigator: Raphael Moreno

Time: 26.3 hours priority 1

Category: Planets

Summary:

Methane is a key species in the Outer Planets. It is the third most abundant molecule in all four Giant Planets, with an abundance of about 2 % in Uranus and Neptune, and reaching 5% (of N2) at the surface of Titan. Because of its large abundance, methane plays a dominant role in governing the atmospheric chemistry of all these planets. Indeed, the photolysis of methane by solar photons initiates a complex chemistry, giving rise to a wealth of hydrocarbons. In the case of Titan, the photochemistry of methane is even more complex, because of the coupled CH4-N2 chemistry taking place in Titan's upper atmosphere. Initial observations of Neptune and Titan, performed in the framework of the GT-KP ``Water and related chemistry in the Solar System'' (PI: P. Hartogh) have allowed the detection of CH4 emission at 119.6 micron and in several other lines, but with a low spectral resolution. These measurements have constrained the stratospheric abundance of CH4. In the case of Uranus, the PACS measurements of the CH4 line at 159 microns shows only tropospheric absorption, and with a low signal-to-noise ratio. The goal of this proposal is to use the high spectral resolution of HIFI in order to resolve the 1882 GHz methane lines on Neptune and Titan. These optically thick lines will allow to constrain the vertical temperature profiles in their stratospheres, and in Neptune's case, the vertical distribution of methane. For Uranus, we propose to observe again the methane line at 159 micron with PACS, but with a gain of a factor 3 in sensitivity, in order to confirm the detection and better constrain its abundance.

Herschel portrait of Pluto: measuring the thermal lighcurve and the emissivity of volatile ices

Proposal ID: OT1_sprotopa_1

Principal Investigator: Silvia Protopapa

Time: 31.3 hours priority 2

Category: Kuiper Belt bodies

Summary:

Beyond the orbit of Neptune there exists a population of remnant bodies from the formation of the Solar System; i.e. the Transneptunian objects (TNOs) in the Kuiper belt. Scientific interest in these bodies arises because they are considered to retain the most pristine and least altered material of the Solar System. Improving the knowledge of these distant bodies thus extends the understanding of the origin and evolution of the Solar System. The Pluto/Charon system plays a key role in the study of the Transneptunian region. Much of what we understand of the physical constitution, composition and evolution of the objects in the Kuiper Belt is put into context by studies of Pluto. Herschel is the only facility which gives the opportunity to draw a portrait of the Pluto/Charon system using the thermal wavelength region. In particular we propose to measure Pluto/Charon thermal lightcurve and perform spectroscopic measurements of the system in the range (50-220) micron. These combined measurements will constrain thermal properties (thermal inertia) and emissivities (spectral and bolometric) of the different terrains on Pluto. The observations will provide constraints on the composition, the physical character (grain sizes, mixing characteristics, texture) and the temperature profile within the near-surface layers of Pluto. We intend also to search for signatures of yet unknown surface ices. Furthermore these observations give us the possibility to answer some open questions like: (i) is Pluto's surface changing? (ii) are nitriles and carbon dioxide ices present on the surface of Pluto as predicted? Answering these questions will provide a benchmark for understanding Pluto and all the large TNOs in the Kuiper Belt. Herschel gives the unique opportunity to complement NASA's New Horizons mission to Pluto, expected to arrive in 2015.

The latitudinal and seasonal variations of D/H and O2 on Mars

Proposal ID: OT1_thencren_1

Principal Investigator: Therese Encrenaz

Time: 26.3 hours priority 1

Category: Planets

Summary:

We propose to use HIFI to determine latitudinal and seasonal variations of HDO, H2-18O, O2 and CO on Mars. The water data will be used to retrieve the D/H ratio and study its variations with latitude and season. The martian D/H ratio, presently poorly known, is a an important parameter as its excess on Mars (about 5 times the terrestrial value) is interpreted as the signature of an early outgassing of the martian atmosphere. In addition, models predict a possible variation of D/H with latitude and season, as an effect of condensation processes and surface/atmosphere interactions. The O2 and CO data will be used to study the cycle of these two non-condensible species as a function of the solar longitude. Results will be compared with climate models which predict significant variations of all these species. Our data will provide important constraints to photochemical models. H2O is known to be maximum at high northern latitudes during northern summer, while CO and O2 are expected to be maximum at high southern latitudes at the same time. Some CO variations have been observed in the infrared but not in the millimeter/submillimeter range so far. No information is presently known about the possibile variations of O2. Herschel is unique in its capability to observe O2 and H2O. We propose to observe Mars in three positions (North, Center and South) at two different seasons, with Ls close to 50 deg. and 120 deg. respectively. We will use AOT II-2 mode (raster scan with DBS) limited to 3 points. We have chosen high-frequency transitions to get the maximum spatial resolution. We propose to observe 3 settings: (1) H218O and HDO around 1630 GHz, (2) O2 and HDO around 1815 GHz and (3) 13CO and C18O around 1867 GHz. The total observing time is 26.3 hours.

Unveiling the kinematics of the MWC49A's ionized disk and outflow with H-recombination line masers.

Proposal ID: OT1_abaezrub_2

Principal Investigator: Alejandro Baez Rubio

Time: 7.2 hours priority 1

Category: Circumstellar/Debris disks

Summary:

% MWC349A, the unique H-maser source observed so far, is a massive star with an ionized outflow believed to be generated in its photoevaporating rotating circumstellar disk. We plan to use the unique spectral capabilities provided by HIFI to perform observations of basically all of the H$\alpha$ recombination lines (from $H26\alpha$ to $H15\alpha$) covered by this instrument. Spectral resolved profiles will reveal essential kinematics inormation of the inner regions of the ionized outflow and the rotating disk. The observed line profile will be compared with the prediction of our non-LTE 3D radiative transfer model to constrain key parameters of the disk-outflow system. From the model's prediction we will stablish if the inner disk is rotating with a Keplerian law, the rotation of the outflow and likely the presence of radial motions (accretion/excretion) in the disk and the location of the lunching point of the outflow. These parameters will help to discriminate between the models proposed for the origin of the outflows and the evolutionary state (pre-main sequence or evolved B[e] stars) of the central star.

Search for a correlation between planets and debris discs around retired A stars

Proposal ID: OT1_abonsor_1

Principal Investigator: Amy Bonsor

Time: 20.3 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Planet formation leads to two detectable outcomes - planets and debris disks. No correlation between these outcomes has been found for main sequence FGK stars. However, planet formation outcome depends on spectral type. Furthermore, the higher incidence of both planets and debris for A stars makes correlations easier to detect. We propose to test for a debris-planet correlation around A stars, by observing 36 subgiants (retired A stars) with PACS to search for debris disk emission. All of these stars have been searched for planets, and 18 have detections. Our population models, calibrated to main sequence disk evolution statistics, predict that we should detect disks toward 23% of our sample. Comparison of debris incidences in the planet and control samples will quantify any debris-planet correlation, which would provide valuable constraints for planet formation models. Even without such a correlation, we expect to find 4 debris-planet systems, adding to the 10 currently known, which would provide a significant advance in our understanding of the dynamics of planet-disk interactions, and so of how these systems could have formed. Also, since the post-main sequence debris disk population is currently poorly known, any disk discovery (or lack of it) will provide important new constraints on the evolution of debris in this phase.

Solving the beta Pictoris carbon puzzle by HIFI observations of CII

Proposal ID: OT1_abrandek_1

Principal Investigator: Alexis Brandeker

Time: 8.4 hours priority 1

Category: Circumstellar/Debris disks

Summary:

The nearby young A-star beta Pictoris is well known for its large circumstellar dust disk. The disk is also known to contain gas, which from absorption lines in the UV is found to be overabundant in carbon by a factor ~20. Recently, Herschel/PACS observed very strong emission from the CII line which seems to indicate that the disk is even more abundant in carbon than previously thought, up to a factor of 100 above other elements. This is unexpected, and we propose to investigate this with HIFI high-resolution spectroscopy of the CII 157um line profile. From the known Keplerian velocity field and the line profile, we will be able to constrain the spatial location of the carbon and thus the total carbon mass. The spatial location of the carbon gas will also give clues to its origin, in particular if it is related to the recently discovered planet in a ~10 AU orbit around beta Pic.

Warm HCN in the planet-formation zone (R<50 AU) of GV Tau

Proposal ID: OT1_afuente_2

Principal Investigator: Asuncion Fuente

Time: 4.6 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Spitzer NIR observations revealed the presence of warm C2H2 and HCN with large gas phase abundances in the disk around GV Tau N. The emission of these molecules has been interpreted as originated in the disk at R<50 AU, i.e., in the planet formation zone. Recent observations by our team of the HCN 1-0 and 3-2 lines using the IRAM 30m telescope and the Plateau de Bure Interferometer give further support to this interpretation. We propose to complete the mm and NIR observations by observing the HCN 7-6, 11-6 and 13-12 lines with the instrument HIFI on board Herschel. These detections will allow us to carry out a complete study of the HCN excitation, and to estimate the physical conditions (gas temperature and density), the radius and the kinematics of the emitting region. In addition, we will observe key CO and H2O lines in order to determine the amount of warm gas and derive the HCN and H2O abundance in the inner region of this young disk. To determine the physical conditions and chemical composition of this inner disk gas is the key to understand the evolution of the volatile material that becomes incorporated into the planet-forming regions.

Herschel observations of solar−type stars with planets, planetesimals and dust

Proposal ID: OT1_amoromar_1

Principal Investigator: Amaya Moro-Martin

Time: 11.6 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Similar to the Solar system, there are only 18 planetary systems known to harbor planets and planetesimals. This small sample is of unique value to our understanding of the diversity, dynamical history, and formation mechanisms of extra-solar planetary systems. Here we propose to observe seven of these systems, with spectral types F7-K2 and ages from 0.5-6.4 Gyr. They all show excess emission at 70 um but not at 24 um, implying the presence of an inner region depleted of warm dust, resembling the Solar System in its Jovian planets + Kuiper belt configuration. It is possible to characterize their planetesimal belts from the study of their dust disks. However, the disks SEDs are not known beyond 70 um. Long wavelength observations are of fundamental importance to determine the presence of cold grains, the only tracer of the outer edge of the dust-producing planetesimal belts. Because the latter is a critical parameter to understand the dynamical history and formation of these systems, we propose to carry out PACS 70/160 and SPIRE observations with the main goal of constraining the SEDs at long wavelengths. We have selected PACS 70 to take full advantage of the Herschel’s improved spatial resolution at 70 um compared to Spitzer, opening the opportunity to resolve the cold dust component that traces the planetesimal belt (which extent could be related to the dynamical history of the planetary system), and to detect extended halos (thought to arise from small dust grains on highly eccentric or hyperbolic orbits, that likely relate to the level of dynamical activity in the planetesimal belt). This proposal requires a total of 11.6 hours. The results will increase our understanding of the diversity of planetary systems, helping us place our Solar system into context. Herschel is the only observatory that can carry out the observation required for this study because of its high sensitivity in the wavelength range where the peak of the dust emission may be located.

Dust and gas in brown dwarf disks: A multi-wavelength survey with Herschel

Proposal ID: OT1_ascholz_1

Principal Investigator: Alexander Scholz

Time: 13.6 hours priority 2

Category: Brown Dwarfs/Very Low-Mass Stars

Summary:

Disks around young brown dwarfs are a valuable test regime for our current understanding of star and planet formation. The disk sizes and masses are key indicators to assess the significance of dynamical encounters for the formation of very low mass objects. The disk mass, together with the properties of the dust, also constrains the potential for planet formation around brown dwarfs, which can be used to evaluate the diversity and ubiquity of planetary systems.

To tackle these science goals, we need constraints on the global characteristics of brown dwarf disks. This requires multi-wavelength observations of the far-infrared/submm continuum to trace the distribution and properties of the dust in the disk, as well as line spectroscopy to probe for the presence and amount of gas in the disk. Herschel is uniquely suited for such a project.

Here we propose to observe a well-characterised and carefully selected sample of 16 brown dwarfs with PACS and SPIRE photometry, complemented by PACS line spectroscopy for the 3 brightest objects. We expect to provide the first robust assessments of the masses and sizes of disks in the substellar regime. For the first time, we will be able to probe the dust opacity and the amount of gas in the brown dwarf regime, crucial parameters for the understanding of the disk physics. These observations will gain further value in synergy with planned submm interferometry campaigns with SMA and ALMA in the next year. Our project constitutes a significant step towards a solid characterisation of brown dwarf disks.

Tracing global protoplanetary disk dispersal and evolution in Cep OB2

Proposal ID: OT1_asicilia_1

Principal Investigator: Aurora Sicilia-Aguilar

Time: 23 hours priority 2

Category: Circumstellar/Debris disks

Summary:

We propose to use Herschel PACS photometry observations at 70 and 160 microns to study the global structure of protoplanetary disks in different stages of evolution. Our goal is to determine the contribution of the various physical disk dispersal mechanisms (grain growth/settling, planet formation, photoevaporation) for a uniform sample of disks with different ages and stellar masses. Far-IR observations are extremely sensitive to the global disk properties (flaring, small dust grain depletion, total disk mass). The data will constrain the disk structure as well as the way evolution proceeds (inside-out evolution versus homologous depletion), revealing the effects of the different dispersal mechanisms and their interplay depending on the age and mass of the systems. We will study a large sample of disks in the Cep OB2 region, which contains three populations with ages 1, 4, and 12 Myr. Cep OB2 has been extensively studied at optical and IR(Spitzer) wavelengths, so the properties of these stars and their inner disks (including the presence of gas and accretion)have been determined. Millimeter observations are also available for 32 objects. The sample contains 59 disks (observed with IRS) plus ~120 additional cluster members for which we have optical, IRAC and MIPS data. The disks span a wide range of SED types, from flared, primordial disks with small grains to flattened objects without silicate features and transition objects with cleared or optically thin inner disks, and also show differences in the gas content and accretion. By combining the PACS photometry with our available multiwavelength data and our RADMC radiative transfer code for disk modeling, we will be able to trace the global disk structure/dust content of the objects. We will then examine the global trends of disk structure and evolutionary status within the full sample, checking its dependency of age and stellar mass in order to understand the effect of the different physical processes on disk dispersal.

Physical conditions in PDRs

Proposal ID: OT1_atielens_1

Principal Investigator: Alexander Tielens

Time: 21.1 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Luminous stars have a profound influence on their environment as their far-UV (6-13.6 eV) photons dissociate and ionize surrounding gas. The gas in these so-called PhotoDissociation Regions (PDRs) is heated by the photo-electric effect on polycyclic aromatic hydrocarbon (PAH) molecules and very small grains (VSG) and cools through emission in atomic fine-structure ([OI], [CII], [SiII]) and molecular rotational (H2, CO) lines. PDR models are known to have intrinsic problems and have moreover only been tested using observations with very large beams on complex regions. Herschel's high sensitivity, high spatial resolution, and wide wavelength coverage allows for the first time a study of the far-IR spectra of spatially resolved PDRs. We propose to map the key diagnostic, far-IR and sub-mm, atomic ([CII] 158μm, [OI] 63, 145μm) and molecular (CO) lines using PACS and SPIRE in a sample of edge-on, spatially resolved Galactic PDRs. The sources in this sample are all well-studied over a wide-wavelength range and have all been mapped by IRS/Spitzer in the rotational H2 lines, the [SiII] 34μm line, the PAH features and the VSG continuum. The goals of our combined Herschel/Spitzer study are to determine the density and temperature structure of the region, to quantify the gas energetics (cooling/heating efficiency), and to compare the gas (heating) characteristics with the emission characteristics of the (neutral & cationic) PAHs and VSGs. This will provide deep insight in the photo-electric heating of atomic gas which is central to the structure of PDRs, the phases of the ISM, and the structure of protoplanetary disks. In addition, these well-known Galactic PDRs provide natural laboratories for studies of the interaction of massive stars with their environment and a semi-empirical way of calibrating the infrared characteristics of regions of massive star formation and, thus, the observational characteristics of galaxies out to the early Universe.

Testing Planetary Dynamics and Evolutionary History in the HR 8799 Planet/Disc System

Proposal ID: OT1_bmatthew_4

Principal Investigator: Brenda Matthews

Time: 9.8 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to map the debris disc associated with the multi-planet system HR 8799 in order to constrain the current dynamical state of the planetary system and refine models for dust production in the disc, thereby testing models for the origins of the three known giant planets. Herschel's sensitivity and resolution make it possible to image both the cold planetesimal disc (posited to lie between radii of 90-300 AU) as well as the fainter extended halo (300 - 1000 AU radius) at multiple wavelengths. Direct detection of the edges of the cold belt of dust and an independent measure of the system's inclination will provide critical constraints on models of the planetary orbits within the system, particularly for the outer-most planet for which mass and orbit information can be constrained by simultaneous fits to the planet and disc.

The combination of three massive, coeval, and spectroscopically characterizable planets, together with the dust disc, makes this system a "Rosetta Stone" for planet formation studies. The disc is also important for differentiating between planet formation scenarios. Models predict variations in resonance structure for migration versus in situ formation, and multi-wavelength variations in observed structure within Herschel's wavelength range in the case of planetary migration. This proposal is at the very heart of Herschel's top science goal of understanding the mechanisms involved in the formation of stars and planetary bodies. The resolution, sensitivity and multi-wavelength imaging of Herschel are crucial to this program.

Probing the physics and dynamics of the hidden warm gas in the youngest protostellar outflows

Proposal ID: OT1_bnisini_1

Principal Investigator: Brunella Nisini

Time: 53.7 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to obtain PACS and HIFI spectroscopic maps of five outflows driven by young and heavily embedded "Class 0" protostars, in selected transitions of [OI], CO and H2O. These species represent the main coolants of the warm (T ~ 100-2000 K) and dense (10^4 cm^{-3}-10^6 cm^{-3}) shocked gas that gives rise to most of the radiative luminosity of these systems. The immediate objectives of the proposed observations will be: 1) to detect, through a map of the [OI]63um line, the embedded atomic primary jet that should be responsible for the acceleration of the outflow; 2) to map the excitation structure of the molecular warm gas component and understand its role in the dynamics of the system; 3)to derive the spatial variations, as a function of the central source, of the H2O abundance and O/H2O abundance ratio, that will be tracing time-dependent chemical changes during the flow life-time. In order to maximize the scientific return from this program, we have selected sources that will be already mapped in the H2O 557 GHz line within the WISH Key Program. If added to the ground-based and space-borne spectral maps already available for the selected objects, the proposed Herschel observations will represent the first multi-wavelength spatial study of protostellar outflows covering the complete spectral domain of emission (from NIR to mm) of these objects. Such a data-base has a strong legacy value for both future missions and development of theoretical models and numerical simulations of shocks and outflows.

Disk masses for ~10 Myr old brown dwarf disks

Proposal ID: OT1_briaz_4

Principal Investigator: Basmah Riaz

Time: 3 hours priority 1

Category: Brown Dwarfs/Very Low-Mass Stars

Summary:

We request SPIRE 200-500mu observations for two brown dwarf disks, 2MASSW J1207334-393254 (2M1207) and SSSPM J1102-3431 (SSSPM 1102), in the TW Hydrae Association (TWA). From our previous Spitzer observations, we had confirmed excess emission at wavelengths of ~5-38mu for both of these sources. With the SPIRE observations, we can probe the optically thin dust in the outer cooler regions of these disks. We have performed radiative transfer modeling for these systems. With the available mid-infrared observations, we find high degeneracies for the disk mass and outer disk radius estimates. Observations at far-infrared wavelengths can help constrain the model fits and obtain better estimates for the disk mass and outer radius for these disks. At an age of ~10 Myr, 2M1207 and SSSPM1102 are the oldest known brown dwarf disks. It is thus important to estimate the disk masses for these older disks, and to understand, in comparison with the younger Taurus systems, if brown dwarf disk masses show any decline with the age of the system.

We also request PACS 70mu photometry for another candidate brown dwarf disk in the TWA, 2MASSW J1139511-315921 (2M1139). This object shows an excess emission at 24mu, but none at shorter wavelengths. With 70mu observations, we can confirm if the disk flares up at longer wavelengths. If the presence of such a disk is confirmed for 2M1139, then this would be the first transition disk detected among the sub-stellar members of TWA.

Do stars with rocky terrestrial planets also have Edgeworth-Kuiper Belts?

Proposal ID: OT1_bzuckerm_1

Principal Investigator: Ben Zuckerman

Time: 4.9 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to measure with PACS the broadband far-infrared spectrum of some young A- and F-type main sequence stars with known, exceptionally luminous, mid-infrared emission. Such stars are uncommon but are of special interest because they point to and delineate the era of rocky terrestrial planet formation. Herschel observations will establish whether cool dusty regions analogous to the Sun's Kuiper Belt region accompany inner regions where terrestrial planet formation is occurring.

A Search for Water Ice in Exo-Kuiper Belts

Proposal ID: OT1_cchen01_2

Principal Investigator: Christine Chen

Time: 20 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to obtain PACS full range spectra of 6 bright debris disks (with 70 micron fluxes >0.5 Jy) that have been spatially resolved in scattered light. We plan to search for far-infrared emission features due to water ice and other species. Herschel PACS is expected to be the premier tool for characterizing dust around debris disks because the grains in debris disks are believed to be (1) large (with minimum blow-out sizes great than one a few microns) and (2) cold (with typical grain temperatures less than 70 K). Our proposed sources possess high albedos, suggestive of water ice. A Herschel detection of water ice would be the first definitive detection of water ice in an external Kuiper Belt.

Peering into the protostellar shocks: NH3 emission at high-velocities

Proposal ID: OT1_ccodella_1

Principal Investigator: Claudio Codella

Time: 15.8 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Ammonia and water are key molecules for determining the physical and chemical structure of star forming regions because of their large abundance variations. In shocked regions where jets driven by low-mass protostars impact the surrounding medium, the NH3 and H2O abundances undergo a dramatic enhancement due to ice grain mantle sublimation. Thanks to the very recent HIFI (CHESS KPs) observations performed towards the prototype L1157 outflow, we compared the line profiles due to the NH3(1_0-0_0) and H2O(1_10-1_01) transitions in the HIFI-band 1b. The high-spectral resolution provided by HIFI allowed us to observe a striking difference in profile between water and ammonia, with H2O emitting at definitely higher velocities. In Codella et al. (2010) we propose that such difference reflects different formation mechanisms: while NH3 is believed to be a direct product of grain surface reactions, water is enhanced by the release of the icy mantles as well as by endothermic reactions occurring in the warm (> 220 K) shocked gas, which convert all gaseous atomic oxygen into water.

We propose here the obvious next step, i.e. to observe the NH3(1_0-0_0) line at 572.5 GHz in a sample of 8 bright low-mass outflow spots already observed in the H2O(1_10-1_01) line within the WISH KP. The analysis of the profiles in such sample will allow us to: (i) determine whether the difference in profiles is unique to L1157 or a common characteristic of chemically rich outflows; (ii) provide clues to the physical characteristics of the shock and of the pre-existing material. Such analysis will be performed by using a suite of chemical, PDR, radiative transfer and shocks models which our team has developed.

The present proposal can be considered as a WISH+CHESS KPs synergy and indeed it gathers components of the teams leading the investigations of protostellar outflows in both CHESS and WISH Herschel GT-KPs.

A Clearer View of Dust Evolution in Protoplanetary Disks

Proposal ID: OT1_cespaill_1

Principal Investigator: Catherine Espaillat

Time: 30 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to quantify dust evolution in protoplanetary disks around low-mass pre-main sequence stars, the precursors of our own Sun. To this end, we will measure grain growth and settling, the first two steps towards planet formation, in disks located within the star-forming clouds of Taurus, Chamaeleon, and Ophiuchus. In addition to studying "full" disks we will also target objects which are in the process of clearing gaps in their disks, a phenomena which is most likely due to newly formed planets. By combining spectral energy distributions that employ mid-infrared Spitzer and submillimeter Herschel data with spatial brightness distributions obtained with interferometers in the millimeter (SMA, ALMA), we will provide a self-consistent analysis of the amount of dust growth, settling, and clearing in disks, which will also serve as a guide for future disk studies with JWST. The systematic, semi-empirical evidence obtained through this proposed study will provide needed insight and constraints to aid in theoretical modeling of dust evolution and planet formation, bringing us a few steps closer to understanding the origin of our own solar system.

Settling an Icy Issue: Using Dust and Ice in Young Disks to Constrain Theoretical Models

Proposal ID: OT1_cespaill_2

Principal Investigator: Catherine Espaillat

Time: 20.8 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to obtain PACS range spectroscopy to measure the amount of water ice and dust evolution in protoplanetary disks located within the ~1-2 Myr old Taurus, Chamaeleon, and Ophiuchus clouds. Theoretical works show that grain growth and dust settling are critical first steps in forming planets and that the ice content of disks plays an influential role in the coagulation process. However, the amount of dust evolution actually experienced by disks and their real ice content is largely unconstrained. To provide a quantitative link between theory and observations we will target 40 disks, many of which show signs of planet formation as inferred from gaps and holes in their dust distribution. We will use irradiated accretion disk models to do a self-consistent analysis of their spectral energy distributions utilizing multi-wavelength data from Spitzer and Herschel. This study will determine the degree of dust evolution experienced by the disks and their ice abundances which can serve as constraints for theoretical models of disk evolution and planet formation.

Physics of gas evaporation at PDR edges

Proposal ID: OT1_cjoblin_1

Principal Investigator: Christine Joblin

Time: 9.8 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Far-ultraviolet (FUV) photons in massive OB star-forming regions have a major impact on the structure, dynamics, chemistry and thermal balance of their associated molecular cloud. We propose to study the photoevaporation under FUV irradiation of dense filaments in prototype photodissociation regions (PDR) by mapping with the HIFI spectrometer the [CII] 158 micron line associated with the evaporating gas and high-J CO lines tracing the warm dense structures. The combination of the spectral range covered by Herschel and the very high spectral resolution of HIFI is unique to get insight into the process of mixing of cold molecular gas into warm atomic gas. This process governs the evolution of dense gas submitted to FUV photons in a wide variety of astronomical objects including protostellar and protoplanetary disks but is best studied in PDRs. We ask for 9.8 hours of observations in two PDRs, NGC7023 and the Horsehead nebula. NGC7023 is illuminated by a B2Ve star and hosts very diluted atomic gas and dense filaments. The Horsehead nebula is a PDR viewed nearly edge-on with a high gas density gradient at the edge that is illuminated by a O9.5V star and is immersed in an HII region. In these objects, there is evidence for dynamical processes that create a mixing layer between molecular and atomic gas, both from gas kinematics (first results with HIFI on the [CII] line) and chemistry. The first HIFI [CII] results clearly call for a larger spatial coverage of the region using OTF mapping mode with HIFI to obtain a more complete picture of the PDR morphology and dynamics. The 12^CO(8-7) and 13^CO(8-7) lines will be also targeted to trace the warm interfaces of the dense filaments/edges. The team gathers together specialists of the studied regions and of the Herschel instruments: HIFI (this proposal), SPIRE and PACS (complementary data). The team has strong expertise in the study of the physics and chemistry of PDRs, both in terms of data analysis and modelling using and developing the Meudon PDR code.

Exploring the gaseous component of debris disks of high fractional luminosity : a deep [O I] 63.2 micron survey with Herschel.

Proposal ID: OT1_ckiss_1

Principal Investigator: Csaba Kiss

Time: 17.2 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. However, there is a very small interesting group of stars in our neighbourhood (49 Ceti, and our discovery HD 21997), which may represent the missing link between these phases as indicated by the unexpected presence of debris-like dust content and measurable CO gas component. With the aim of discovering and characterizing more of these spectacular objects here we propose to obtain [O I] 63 micron observations of a sample of carefully selected young (<50Myr) debris disks of high fractional luminosity with Herschel/PACS. Our objectives are to 1) discover and determine the incidence of 49 Ceti-like gaseous debris disks; 2) characterize disk structure; 3) determine the timescale of gas dispersal; 4) perform a detailed investigation of HD 21997. New discoveries would lead to the definition of a new subclass of circumstellar disks, the gaseous debris disks. We required 17.2h of Herschel time for the observations.

Herschel characterization of the new class of dusty first-ascent giant stars

Proposal ID: OT1_cmelis_1

Principal Investigator: Carl Melis

Time: 13.1 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We have recently discovered a new class of first-ascent giants surrounded by substantial dusty and gaseous disks that are sometimes accreting onto the central star. These old stars, who are nearing the end of their lives, are experiencing a rebirth into characteristics typically associated with newborn stars. As such we dub them "Phoenix Giants". As a critical step to understanding these unique systems and the origin of their circumstellar material, we propose Herschel PACS and SPIRE imaging observations to characterize their dusty disks. We expect that Herschel observations of Phoenix Giant disks will establish a benchmark characterization of the outer disk regions of this recently discovered class of first-ascent giant stars.

Investigation of the nitrogen chemistry in diffuse and dense interstellar gas

Proposal ID: OT1_cpersson_1

Principal Investigator: Carina Persson

Time: 18 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We propose to investigate the interstellar chemistry and physics of nitrogen through Herschel/HIFI observations of simple nitrogen-hydride molecules including NH, NH2, NH3, and related ions. The nitrogen chemistry is still rather uncertain and we therefore propose to compare and contrast the abundances and ortho/para ratios of nitrogen hydrides in the diffuse interstellar gas to the dense cores of molecular clouds. This comparison can be done very efficiently by observing excited-state transitions in selected cores that have previously been used in the PRISMAS program as background sources for absorption measurements in the ground-state transitions. In this way, we will determine whether nitrogen chemistry is dominated by gas-phase reactions or by processes on surfaces of dust grains, and whether the dominant chemistry is different in different parts of the interstellar medium. In summary, we propose HIFI observations of 5 transitions of simple nitrogen-bearing molecules in 8 sources, and 3 transitions in 2 sources. The total requested observing time is 26.2 hours.

The neutral disk of MWC349

Proposal ID: OT1_cthum_1

Principal Investigator: Clements Thum

Time: 5.7 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We wish to study the circumstellar disk of the bright radiostar MWC349 with the aim to infer the evolutionary state of this prominent but enigmatic massive stellar object. We propose to make a full wavelength range scan with PACS and with the SPIRE spectrometer in order to determine the continuum spectrum of the disk, especially in the ill determined or unexplored wavelength region centered on 200-300 microns where the emission from the ionized wind and the warm circumstellar dust are comparably strong.

These spectral scans are at least 10x more sensitive than our ISO data, and permit a deep search for molecules like water and CO. The presence of water which is being found by Herschel in a range of accretion disks young stellar objects would be strong evidence for the nature of the MWC349 disk as due to accretion, whereas the absence of water is most easily explained if the disk results from mass loss in a strong stellar wind or ejection event. Our proposed investigation has thus the potential to resolve the half--century old question about the evolutionary state of MWC349.

Deuterated water chemistry towards high-mass star-forming regions.

Proposal ID: OT1_cvastel_2

Principal Investigator: Charlotte Vastel

Time: 15.3 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Observations of the HDO molecules are an important complement for studies of water, since they give strong constraints on the formation processes: grain surfaces versus gas-phase chemistry through energetic process as shocks. HIFI observations of multiple transitions of HDO in SgrB2(M) combined with ground-based observations allowed for the first time the determination of its abundance throughout the envelope. In the framework of the PRISMAS Key Program, a large sample of high-mass star-forming regions have been observed with the detection of many species in their line of sight. The HDO (111-000) fundamental transition has also been detected in absorption at the velocity of the hot core towards the 2 sources that have been observed so far, probably tracing the colder envelope in its surrounding.

We propose to observe higher energy level HDO transitions towards a sample of three compact HII regions that will be targeted by the PRISMAS Key Program (G34.3+0.1, W33A, W49N) in order to perform a full modeling from the hot core through the envelope using a spherical Monte Carlo radiative transfer code, RATRAN, which takes into account radiative pumping by continuum emission from dust. We will use for an optimum accuracy of the modeling the HDO and D2O collision rates with H2, recently computed within our group, that are not available in the public so far.

This study will hopefully give strong constrains on the formation processes of water, combining the proposed observations with published or soon to be published high resolution H2O observations with HIFI towards the same sources.

Hot Dust within HII Regions

Proposal ID: OT1_cwatso01_1

Principal Investigator: Christer Watson

Time: 5.6 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We propose observing thermal dust emission inside two wind blown bubbles identified by their PAH emission (N90 and N56 from a Churchwell et al., 2006) in all SPIRE and PACS bands. These bands sample emission from all dust grain sizes and temperatures thought to exist behind the post shocked gas. By measuring the emission across the face of the bubble and comparing with numerical simulations, we will determine how the grain size distribution changes with distance from exciting source. These results will help determine what dominant physics, sputtering or gas-dust friction, dominates grain processing within these sources. We will also measure emission from the cold, dense cloudlets proposed by Everett & Churchwell (2010) as the source of dust within these bubbles. By better characterizing these physical properties of dust grains, we will be able to better predict how dust grains affect the energetics of wind blown bubbles.

The Conditions of Isolated Dark Clouds with Signs of On Going H2 Formation

Proposal ID: OT1_dli_2

Principal Investigator: Di Li

Time: 1.3 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We propose to map three nearby isolated dark clouds, CB 45, B227, and L1574 with SPIRE. They are carefully selected based on their intriguing morphology of displacement between CO, 2MASS extinction, atomic gas traced HI Narrow self-absorption (HINSA),which is a unique tracer of cold atomic gas INSIDE molecular clouds. SPIRE maps will provide crucial dust emission information for quantifying dust column density, dust temperature and dust properties. SPIRE will provide much higher resolution than 2MASS extinction and is capable of tracing relatively diffuse dust structure missed by 2MASS. Combining HINSA, molecular gas, extinction, and dust emission data, we will have an unprecedented comprehensive data set for understanding the transition from atomic to molecular ISM. The spacial information and high sensitivity provided by SPIRE will enable us to construct time dependent H2 formation model for realistic clouds. Such a model will provide quantitive answers, for the first time, to fundamental questions in star formation, such as "How molecular are molecular clouds?" and "What is the age of a dark cloud?".

Ammonia as a Tracer of the Earliest Stages of Star Formation

Proposal ID: OT1_dlis_2

Principal Investigator: Dariusz Lis

Time: 26.3 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Stars form in molecular cloud cores, cold and dense regions enshrouded by dust. The initiation of this process is among the least understood steps of star formation. High-resolution heterodyne spectroscopy provides invaluable information about the physical conditions (density, temperature), kinematics (infall, outflows), and chemistry of these regions. Classical molecular tracers, such CO, CS, and many other abundant gas-phase species, have been shown to freeze out onto dust grain mantles in pre-stellar cores. However, N-bearing species, in particular ammonia, are much less affected by depletion and are observed to stay in the gas phase at densities in excess of 1e6 cm^-3. The molecular freeze-out has important consequences for the chemistry of dense gas. In particular, the depletion of abundant gas-phase species with heavy atoms drives up abundances of deuterated H3+ isotopologues, which in turn results in spectacular deuteration levels of molecules that do remain in the gas phase. Consequently, lines of deuterated N-bearing species, in particular the fundamental lines of ammonia isotopologues, having very high critical densities, are optimum tracers of innermost regions of dense cores.

We propose to study the morphology, density structure and kinematics of cold and dense cloud cores, by mapping the spatial distribution of ammonia isotopologues in isolated dense pre-stellar cores using Herschel/HIFI. These observations provide optimum probes of the onset of star formation, as well as the physical processes that control gas-grain interaction, freeze-out, mantle ejection and deuteration. The sensitive, high-resolution spectra acquired within this program will be analyzed using sophisticated radiative transfer models and compared with outputs of state-of-the-art 3D MHD simulations and chemical models developed by the members of our team.

Studying diffuse interstellar clouds with observations of hydrides

Proposal ID: OT1_dneufeld_1

Principal Investigator: David Neufeld

Time: 34.8 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

With the use of the HIFI instrument, we propose to observe four simple hydride molecules - HF, OH+, H2O+, and H2Cl+ - in absorption towards five bright submillimeter continuum sources. The target sources, all located in the Galactic plane with sight-lines that intersect multiple interstellar clouds, are the massive star-forming regions W49N, W51, G29.96-0.02, W3(OH), and G330.95-0.17. This selection of sources samples sight-lines in the 1st and 4th quadrants of the Galaxy and in the outer Galaxy. The proposed observations will have integration times sufficient to obtain signal-to-noise ratios in the range 100 - 400 in a single spectral channel, providing great sensitivity to absorption by foreground material. We will thereby determine the molecular column densities in foreground clouds located in spiral arms that lie along the sight-lines to these continuum sources. The four molecules we will observe, all detected previously in the ISM in early Herschel observations, will provide critical information about the diffuse interstellar medium. In particular, HF will permit the identification and study of clouds with a very small H2 column density that may be virtually undetectable in the spectra of other molecules; OH+ and H2O+ will allow us to study clouds with a small molecular fraction (revealed by a large OH+/H2O+ ratio), and to determine the cosmic ray ionization rate as a function of Galactocentric radius; and H2Cl+ will probe the photoionization rate and its variation with position in the Galaxy.

An accurate mass measurement for prestellar cores

Proposal ID: OT1_dnutter_1

Principal Investigator: David Nutter

Time: 11 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Prestellar cores are crucial to our understanding of star formation. It is at this evolutionary stage that the stellar mass is set. If we are to understand the origin of the stellar IMF, we must therefore study the masses of the prestellar cores from which the stars are formed. There is currently a large uncertainty in the measured prestellar core mass that we obtain from far-IR and submillimetre observations. This uncertainty is caused by our inability to simultaneously determine the column density, temperature and dust emissivity index from photometric observations. Physical processes such as grain growth, or ice-mantle formation, which are affected by changes in density and temperature, will change the dust emissivity index. By simply taking a canonical value for the emissivity index, we cannot determine the correct mass for prestellar cores.

The SPIRE FTS allows us to break this degeneracy for the first time, and simultaneously measure the column density, temperature and dust emissivity index, and therefore determine accurate masses. We propose to map 16 prestellar cores with the SPIRE FTS, and hence generate accurate maps of their column density. We will map each core using the full FTS field of view. We will be able to determine the absolute value of the dust emissivity index, and also see whether it varies across each of the cores. We have selected cores in different environments in order to study the core-to-core, and cloud-to-cloud variations in the dust properties. We will be able use this information about the relation between the three measured parameters, to more accurately determine masses for a much larger sample of cores for which only photometric data are available.

PACS Photometry of Nearby Warm Debris Disk Systems from the WISE All-Sky Survey

Proposal ID: OT1_dpadgett_1

Principal Investigator: Deborah Padgett

Time: 52.8 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Debris disks trace the collisional breakdown of asteroid and comet parent bodies orbiting nearby main sequence stars. They are detectable in ~16% of FGK stars, nearly twice as often in A stars, and are almost unknown around M stars. The debris disks of sunlike stars are typically cold analogs of our Kuiper belt with emission peaking near 70 microns wavelength. However, a relatively small number of warm disks are known with emission at 24 microns. These systems are especially interesting because they trace dust in the region likely to host terrestrial planets, where the dust has a short dynamical lifetimes. They also tend to be young systems aged < 1 Gyr. This knowledge of warm debris disks - extrasolar analogs to our solar system's Zodiacal cloud - is based on the 25 year old IRAS survey and observations of selected targets with ISO and Spitzer.

The Wide-Field Infrared Survey Explorer (WISE) has just completed new, sensitive all-sky mapping in the 3.3, 4.6, 12, and 22 micron bands. Association of the WISE sources to Hipparcos and Tycho stars has led to the identification of 99 nearby main sequence stars with robustly detected warm 22 micron excesses not previously known. To determine whether these systems represent outbursts of asteroidal dust production (such as in the HD 69830 system), or simply the Wien side of emission from a cold outer dust belt, photometry at longer wavelengths is needed. We propose Herschel/PACS 70 and 160 micron photometry of this unbiased sample. These data will allow us to fully characterize the dust temperature and infrared luminosity of these systems, allowing them to be understood in the context of other debris disks and disk evolution theory. The sample includes field M stars as close as 12 pc, the first objects of this class seen to have warm dust emission. The results will strongly constrain our picture of the collisional history of inner planetary systems.

A New Method to Determine the Gas Mass in Protoplanetary Disks

Proposal ID: OT1_ebergin_4

Principal Investigator: Edwin Bergin

Time: 21.1 hours priority 1

Category: Circumstellar/Debris disks

Summary:

The mass of planet-forming disks is one of its most fundanmental quantities and can determine the primary mode of planet formation. Because the dominant constituent, H2, is undetectable, we are forced to adopt indirect methods to trace the total gas content. The primary method used is to observe thermal dust continuum emission at submm/mm wavelengths where the dust emission is optically thin. However, mass estimates are highly uncertain because grain evolution can substantially alter the dust opacity coefficient and the gas-to-dust ratio, which are required to convert total flux to mass. We propose here a dedicated program to use PACS spectroscopy to search for the emission of HD J=1-0 at 112 microns and derive the gas mass from a tracer that uniquely probes H2. HD will co-exist with H2 in the gas phase and is the dominant reservoir of deuterium, carrying the cosmic D atom abundance. Our program is a comprehensive effort where observations will be combined with chemical theory and excitation modeling to enable the conversion of integrated emission to mass. This program offers a unique opportunity to derive disk gas masses via an independent method with important implications for the formation of planetary systems.

A Systematic Survery of the Water D to H Ratio in Hot Molecular Cores

Proposal ID: OT1_ebergin_5

Principal Investigator: Edwin Bergin

Time: 18 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

The D/H ratio of water and the enrichment of HDO relative to H2O in comets, oceans, and interstellar water vapor, has been posited as one of the primary links between chemistry in the cold (T = 10-20 K) dense interstellar medium (ISM) and chemistry in the Solar Nebula. However, there are only ~10 measurements of HDO/H2O, even in hot (T > 100 K) molecular cores, which have the most favorable chemistry (due to fossil evaporation of D-enriched ices) and excitation. In addition the existing measurements have a wide range of uncertainty, making it impossible to discern the presence of source-to-source variations, which could hint at the origin of deuterium enrichments in the dense ISM. We propose here to change this statistic with a systematic survey of HDO and H2O in a sample of 20 hot molecular cores spanning a two order of magnitude range in mass and luminosity. This will increase the number of known water D/H ratios by ~200%. This program is unique in scope for Herschel and requires the uniformity in calibration and high spectral resolution offered by the HIFI instrument. With the stability of HIFI we will be able to derive D/H ratios with significantly less uncertainty. Our observations will be combined with theoretical chemical models to explore the statistics offered by this sample. By looking at a large number of objects with a range of conditions we aim to unlock the secrets of water deuteration in the interstellar space.

Low gas to dust ratio in proto-planetary disks: the Carbon content of CQ Tau, MWC 758 and MWC 480

Proposal ID: OT1_echapill_1

Principal Investigator: Edwige chapillon

Time: 6.4 hours priority 2

Category: Circumstellar/Debris disks

Summary:

The study of the transition from gas-rich protoplanetary disk to gas-poor debris disk is crucial to constrain the planetary formation mechanisms. Although it is a key parameter for big gaseous planet formation, the evolution of the gas-to-dust ratio with time and star properties is not yet known. One of the first steps to observationally constrain it is to determine independently the gas mass and the dust mass of disks. The dust content, determined from continuum emission, is better known than the gas content. As molecular hydrogen is not observable at the low temperatures of disks, the gas mass is usually derived from CO observation. However, CO may not be always the main carbon reservoir: it should freeze on grain mantles in the cold mid-plane of T Tauri disks, and be photodissociated in the upper layers by the UV field, leading to CI and CII, especially in disks surrounding A stars. We propose here to characterize the gaseous Carbon content in three disks (CQ Tau, MWC 758 and MWC 480) using the three main C carriers: CO, CI and C+. Previous CO observations indicates warm disks (the temperature being well above the CO freeze-out temperature). Two of them, CQ Tau and MWC 758, have very low CO content and may be in the transition stage between gas-rich and gas poor disks. A low CI content was also found for CQ Tau using APEX. We propose to take advantage of sensitivity of Hershel at 1900 GHz (157 um) and high spectral resolution provided by the HIFI instrument to observe C+ in these disks.

The Herschel/HIFI insight on the CH+ puzzle

Proposal ID: OT1_efalgaro_1

Principal Investigator: Edith Falgarone

Time: 38.7 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

Seventy years after its discovery in the diffuse interstellar medium, the origin of the CH+ cation is still elusive. Herschel/HIFI offers a unique opportunity to disclose the underlying gas dynamics at the origin of CH+ in the diffuse medium by allowing high sensitivity and high spectral resolution observations of the CH+ (J=1-0) transition, unreachable from the ground: it will be the leading and only instrument and the observations will bring a completely new look at this resilient puzzle.

The abundant CH+ ion is not only a sensitive tracer of the most tenuous phases of the interstellar medium but it is likely a specific tracer of turbulent dissipation, because its formation route is highly endoenergic. We propose absorption spectroscopy observations of mainly the CH+ J=1-0 line, against 10 background dust continuum sources, bright enough to allow us to sample a broad variety of galactic environments. The lines-of-sight will probe the outskirts of star-forming regions, including one InfraRed Dark Cloud, where turbulent dissipation is most intense, and diffuse gas at high galactic latitude where turbulence is milder. The primarily goal of this project is the comparison of the CH+ abundances with model predictions of turbulent dissipation regions, in which dissipation proceeds either in low-velocity shocks or intense velocity-shears. Another goal is testing the possibility that CH+ forms at the turbulent interface between the two thermally stable phases of the interstellar medium.

As HF, CH+ is a potential sensitive tracer of diffuse matter in the early universe. Understanding its origin and the dissipative processes that it traces will shed a new light on galaxy formation and evolution.

Characterization of the long wavelength features of interstellar Polycyclic Aromatic Hydrocarbons

Proposal ID: OT1_epeeters_1

Principal Investigator: Els Peeters

Time: 9.4 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Strong emission features at 3.3, 6.2, 7.7, and 11.2 um dominate the mid-infrared spectra of most interstellar objects. These IR features are due to vibrational fluorescence of large (50-150 C-atom) Polycyclic Aromatic Hydrocarbon molecules pumped by UV photons. These species will also have bands at far-infrared wavelength, notably due to 'drum-head' modes. We have performed experimental and theoretical studies that demonstrate that these bands carry unique information, particularly on the size of the emitting species that cannot be obtained from the shorter wavelength bands.

We propose to measure the far-IR spectra of a sample of well-studied PAH sources using PACS and SPIRE. The sample has been carefully selected to show strong mid-IR PAH bands, and a relatively weak dust continuum at the Herschel wavelengths to maximize the line-to-continuum ratio for far-IR PAH bands. These observations are designed to measure infrared bands to a level of 1% of the dust continuum. Together with the Spitzer/ISO studies, the full spectrum of the IR emission features from 3 to 600 um can be determined. In order to determine the implications for the emitting PAHs, we will compare these bands to the PAH database that we have compiled over the last 15 years and analyze the emission using the realistic PAH emission model that we have developed over the years.

Investigating the origin of the far-infrared emission of the microquasar Cygnus X-1

Proposal ID: OT1_frahoui_1

Principal Investigator: Farid Rahoui

Time: 6.2 hours priority 2

Category: Galactic Other

Summary:

Microquasars are Galactic X-ray binaries exhibiting collimated outflows commonly called jets. In particular, the so-called compact jets are detected almost simultaneously in all the spectral domains, and are characterised by the existence of a spectral break at which they change their emission regime from optically thick to optically thin synchrotron. The determination of this cut-off frequency is fundamental for the understanding of the accretion-ejection processes as it is related to the black hole spin and mass, as well as to the accretion rate. In a previous Spitzer spectroscopic study of Cygnus X-1, we assessed the contribution of the compact jets to the mid-infrared continuum as well as their spectral break. Nevertheless, its accurate value appears to be dependent on the model used to describe the continuum of the companion star, which is the blue supergiant HD226868. Indeed, it changes whether we consider bremsstrahlung from the stellar winds or thermal emission from a circumstellar dust component. We therefore require photometric observations of Cygnus X-1 with PACS, in the blue, green, and red filters, in order to assess the flux density level of the source at 70, 100, and 160 microns. These measurements, combined with our Spitzer spectra, will allow us to discriminate between bremsstrahlung and dust, which will eventually lead us to the accurate determination of the spectral break of the compact jets exhibited by Cygnus X-1.

Debris Disks around Planet-Bearing Stars

Proposal ID: OT1_gbryden_1

Principal Investigator: Geoffrey Bryden

Time: 67.2 hours priority 1

Category: Circumstellar/Debris disks

Summary:

The relationship between planets and debris disks is unclear. On one hand the direct imaging of planets in three systems with prominent debris disks (beta Pic, HR 8799, and Fomalhaut) suggests a direct link between the two phenomena. Indeed, the eccentric shape of the Fomalhaut dust ring is clearly driven by its shepherding planet, whose existence and eccentricity were correctly predicted based on the disk asymmetry. On the other hand, Spitzer surveys fail to find any correlation between cold debris at 10's of AUs and radial-velocity-detected planets in the inner system. Motivated by Herschel's advantages over Spitzer, we propose to further explore the planet-debris relationship by observing 67 stars known to have planets. For the 9 targets that are already known to have orbiting debris, we will resolve the disks, determining the location of the dust-producing planetesimals and measuring disk asymmetries that may be induced by neighboring planets. For the remainder of the targets we will search for new debris disks and then look within the overall sample for any correlations with planet properties.

A Disk Census for New Low-Mass Members of TWA

Proposal ID: OT1_gherczeg_1

Principal Investigator: Greg Herczeg

Time: 9.2 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to conduct a protoplanetary and debris disk survey of 14 recently-identified members of the benchmark (10 Myr) TW Hya Association (TWA). Our new sample expands the member census by tripling of the low-mass population (>M5; <0.2 M_sun). TWA represents a critical age where the longest-lived protoplanetary disks and the youngest debris disks overlap in the same population, so it offers a critical window into the formation and evolution of planetary systems. We specifically propose a PACS 70/160 micron photometric census to identify new disks, and followed by SPIRE 200/250/350 micron photometric observations of all newly-identified disk systems to characterize their SEDs and determine the nature of their circumstellar disks (protoplanetary or debris). Based on the disk fraction among known late-type members (3/6 = 50%), we estimate that 6-7 of our targets are likely to host circumstellar disks; these disks have been incredibly rare until now, so each will be a prime target for future studies of accretion, disk evolution, and planet formation.

Using PACS and SPIRE photometry and spectroscopy to characterise the discs of Herbig Be stars: structure, gas content and cold crystalline dust composition.

Proposal ID: OT1_gmeeus_1

Principal Investigator: Gwendolyn Meeus

Time: 33.4 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Herbig Be stars are the link between massive protostars and the intermediate-mass Herbig Ae stars. While for this last group the disc has been characterised in terms of flaring/flat geometries in which dust grains grow and settle towards the midplane, and the bulk of the gas dissipates after 5 Myr, the picture of a disc around a more massive star is less clear. Therefore, we propose to observe a sample of 40 Herbig Be stars, in an effort to determine their disc properties. In particular, we aim at answering the following questions: 1) How do these discs dissipate?, 2) Does grain growth and settling occur? 3) Can gas giant planets still form, and what is the stellar upper mass limit for their formation?, and finally 4) How do the Herbig Be discs differ the lower mass Herbig Ae and T Tauri discs? To answer these questions, we propose to use PACS and SPIRE in photometric mode for the whole sample, and in spectroscopic mode for a subset of the 6 brightest - most promising targets. We will complement the proposed observations with existing optical to mid-IR photometry, as well as mid-IR spectroscopy, to construct spectral energy distributions (SED). These SEDs trace the dust continuum and will be analysed with the aid of radiative transfer modelling. For part of the sample, we also have mid-IR images or interferometry, revealing the spatial extend at those wavelengths. In a next step we will relate the derived disc properties with stellar properties. In addition, for the 6 spectroscopic targets we will be able to make a detailed case study of their cold dust and gas content: the forsterite feature at 69 micron reveals the iron content in the crystalline dust, and gas lines of e.g. OI and CO will allow us to constrain the amount of gas still present in the disc, using both radiative transfer modelling as well as thermo-chemical models. The proposed observations will provide a valuable database for a better understanding of the disc structure and evolution in the more massive Herbig Be type stars.

Water Formation and Destruction Processes in Molecular Clouds

Proposal ID: OT1_gmelnick_1

Principal Investigator: G.J. Melnick

Time: 10 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

The study of water is one of the most compelling and unique science goals of the Herschel mission. Unfortunately, our understanding of water may not be limited by the quality of the data so much as by remaining uncertainties regarding the processes that govern the formation and destruction of water. We propose a set of focused observations designed to measure the depth-dependent distribution of water vapor, which is sensitive to a set of processes (e.g., photodissociation, photodesorption, grain surface reactions) that not only determines the distribution of water, but affects the abundance and distribution of many other gas-phase molecules. The knowledge gained will not only improve chemical models for which these processes are important, but will greatly improve our estimates of the true water-vapor abundance derived from all Herschel measurements. We propose a set of HIFI and PACS water maps, pointed observations, and strip scans toward three objects whose face-on or edge-on appearance makes them ideal laboratories for this study: Orion, Cepheus B, and DC 267.4-7.5. Our prior SWAS observations provide confidence in the presence of the water emission we seek to detect as well as proof that the proposed study is feasible. We also make use of ground-based molecular line maps that have already been obtained. This study is not a part of the WISH program, nor can it be carried out with WISH data. The choice of HIFI instead of SPIRE for this study is driven by the need for both sensitivity and velocity resolution - it would require > 2000 hours for SPIRE to obtain a sparsely-sampled map of the same area (23.5'x40') and sensitivity (9.E-18 W/m2, 10-sigma) as the fully-sampled 557 GHz map we propose toward Orion alone and, with HIFI, the water lines will be velocity resolved, which is key to the success of this study. Finally, a by-product of this study will be one of the largest velocity-resolved water maps to be made by Herschel. The total time required for this Herschel-unique program is 38.5 hours.

Characterizing the evolved, planet-forming disks orbiting the old classical T Tauri systems V4046 Sgr and MP Mus

Proposal ID: OT1_gsacco_1

Principal Investigator: Germano Sacco

Time: 14.4 hours priority 1

Category: Circumstellar/Debris disks

Summary:

V4046 Sgr and MP Mus are the second and the third closest known classical (actively accreting) T Tauri systems, respectively (the intensively studied TW Hya being the closest). We have recently established that, like TW Hya, both systems are orbited by dusty, molecular disks. Given their proximity (d<100 pc), ages (~10 Myr), and masses (0.7-1.2 solar masses), these three systems represent readily-studied analogs of the young sun during the crucial, late phases of the star formation process, when the circumstellar disk still retains a significant gaseous component and giant planets likely are forming or have recently formed. Furthermore, the close binary V4046 Sgr affords an unusual opportunity to investigate planet formation within circumbinary disks. We propose to observe the V4046 Sgr and MP Mus disks using Herschel's PACS and SPIRE spectrometers with the complementary aims of (1) measuring the detailed spectral energy distribution of the continuum dust emission between 55 and 670 micron and (2) detecting the brightest atomic emission lines. These data, together with the comprehensive suite of X-ray, mid-infrared and radio observations we are already collecting for these two systems, will allow us to fully characterize the physical properties of both the dust and the gas components of their circumstellar disks and to investigate the effects of high energy emission from the central star on the evolution of the circumstellar, planet-forming environment.

A Herschel Study of Star Formation Feedback on Cloud Scales

Proposal ID: OT1_harce_1

Principal Investigator: Hector G. Arce

Time: 51.5 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to conduct a study of the impact of radiative and mechanical stellar feedback on the surrounding medium of a cluster-forming cloud. Outflows and UV radiation from young stars affect the dynamics and the chemistry of the gaseous environment, thereby influencing the star formation process in the cloud. Herschel offers an extraordinary opportunity to observe unique tracers of these important physical and chemical processes. Our observations will mostly consist of unbiased HIFI, PACS, and SPIRE spectral maps of NGC1333, a nearby cloud, that harbors a cluster of protostars, many outflows and a couple of B stars, and it is commonly used as the prototypical cluster to model clustered star formation. These maps will allow us to conduct a study of an unbiased sample of shocks from outflows at different evolutionary stages within one cloud. We will use important shock tracers and coolants that typically cannot be observed from the ground to investigate the chemistry and physics of the outflow phenomenon in order to fully understand their impact on the natal cloud. Our study will provide the most complete estimate of the outflow energy and momentum input budget in a cluster. In addition, we will investigate how stellar UV radiation affect the water abundance, its formation and destruction, and the chemistry of the gaseous environment. Our proposed Herschel observations (and complementary ground-based data) will provide the best estimate of the water mass reservoir for star formation at the scales of the cloud. The resulting data sets for this cluster-forming region will surely provide a long term observational basis against which to test current and future models of cloud chemistry, stellar feedback and shocks.

A Study of the Small Negative Molecular Ions CN-, CCH-, and OH- in the Interstellar Gas

Proposal ID: OT1_hgupta_1

Principal Investigator: Harshal Gupta

Time: 37.2 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

The HIFI instrument on Herschel provides a unique opportunity to undertake an astronomical study of light negative molecular ions in the interstellar gas, as these are difficult or impossible to observe from ground based observatories. A sensitive search for the negative ions CN-, CCH-, and OH- with HIFI toward 6 galactic molecular sources is proposed. Three successive rotational transitions (J=6, 7, 8) of CN- and CCH- in HIFI bands 1 - 3, and the lowest rotational transition of OH- near 1.12 THz will be observed. The goals of this study are: i. to enlarge the number of known sources of light negative molecular ions; ii. to determine the abundances of the anions, as well as the anion-to-neutral ratios to assess theoretical models of the fractional ionization of molecular clouds; and iii. to assess the chemical environment of anions through parallel observations of neutral molecules (H13CN and HNC) and positive molecular ions (CO+ and H13CO).

Planets, Debris Disks, and the Lambda Bootis Stars

Proposal ID: OT1_hmaness_1

Principal Investigator: Holly Maness

Time: 7.1 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to explore the link between lambda Bootis stars, debris disks, and planetesimal formation and evolution. The lambda Boo stars are a rare type of peculiar A star (2%), which are Population 1 and metal poor. Planet bearing systems and debris disk stars appear unusually well represented in the lambda Boo class: for example, beta Pic, Vega, and HR 8799 are all lambda Boo candidates.

A small sample of 14 lambda Boo stars observed by Spitzer suggests an occurrence of infrared excess approaching 100%. Only two lambda Boo stars are included in the DEBRIS/DUNES Herschel key program debris disk surveys. We will use PACS/Herschel to make sensitive, high-resolution maps of 27 new lambda Boo stars. Like DEBRIS/DUNES, we will reach the stellar photosphere for all targets, enabling a measurement of the true rate of excess infrared emission among lambda Boo stars compared to normal A stars.

The depletion pattern of heavy elements in the atmospheres of lambda Boo stars suggests they may have accreted gas from which dust grains have condensed and been removed: this gas may be circumstellar gas that has formed planetesimals or dusty interstellar gas. While the circumstellar disk scenario predicts sizes of a few hundred AU, the cloud accretion scenario predicts 1000-2000 AU bow structures oriented in the direction of the relative motion of the cloud and star. With target distances of < 140 pc, these bow structures are expected to be resolved for all targets. These will be the first mid-infrared observations of lambda Boo stars outside of the low density Local Bubble: if interstellar medium interactions dominate the lambda Boo phenomenon then systematic variations in excess strength and morphology may occur with distance.

Taming the Invisible Monster: The Disk of Epsilon Aurigae in the Far-Infrared

Proposal ID: OT1_hoard_1

Principal Investigator: D. W. Hoard

Time: 3.6 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to obtain photometric flux density measurements of the remarkable binary star Epsilon Aurigae in all six of the PACS and SPIRE imaging bands. Epsilon Aur is seen close to edge on, and has long (2 yr) eclipses every 27.1 yr. The last eclipse, during 1982–1984, received world-wide attention from astronomers. During 2009–2011, the system is again in eclipse and is the focus of a world-wide observing campaign enlisting both professional and amateur astronomers. Epsilon Aur consists of a high luminosity post-AGB F0 star with a much less luminous stellar companion. The latter is newly proven by us to be surrounded by a solar system-sized disk of cool dust. This disk is a rare example of an evolved disk, composed of the remnants of the endgame of stellar evolution, rather than a "primordial" disk as found in T Tauri stars and A stars like Beta Pic. Gaps in the Epsilon Aur disk, reminiscent of the structure of the rings of Saturn, were recently inferred from ground-based time-series spectroscopic observations. By analogy to the role of shepherd moons in the rings of Saturn, this suggests that there could be planetesimals, dwarf planets, or even full-size terrestrial planets in the Epsilon Aur disk. The spectral energy distribution of Epsilon Aur is well-sampled from the far-UV to the mid-IR (0.1-70 microns), with one radio measurement at 1200 microns. However, it is currently unconstrained in the wavelength region spanned by PACS and SPIRE, which is dominated by the dust disk. These Herschel instruments are uniquely configured to provide high S/N photometry bridging the gaps between the mid-IR and radio regimes. These SED points are crucial to confirm if a non-blackbody slope is present, relating to dust grain emissivity, and if potentially bright emission features from molecular species might dominate. These observations will contribute to understanding stellar evolution in binary stars, as well as the formation, evolution, and rejuvenation of planetary systems.

Understanding the Origin of Transition Disks via Disk Mass Measurements

Proposal ID: OT1_ipascucc_1

Principal Investigator: Ilaria Pascucci

Time: 43.8 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Transition disks are a distinguished group of few Myr-old systems caught in the phase of dispersing their inner dust disk. Three different processes have been proposed to explain this inside-out clearing: grain growth, photoevaporation driven by the central star, and dynamical clearing by a forming giant planet. Which of these processes lead to a transition disk? Distinguishing between them requires the combined knowledge of stellar accretion rates and disk masses.

We propose here to use 43.8 hours of PACS spectroscopy to detect the [OI] 63 micron emission line from a sample of 21 well-known transition disks with measured mass accretion rates. We will use this line, in combination with ancillary CO millimeter lines, to measure their gas disk mass. Because gas dominates the mass of protoplanetary disks our approach and choice of lines will enable us to trace the bulk of the disk mass that resides beyond tens of AU from young stars. Our program will quadruple the number of transition disks currently observed with Herschel in this setting and for which disk masses can be measured. We will then place the transition and the ~100 classical/non-transition disks of similar age (from the Herschel KP "Gas in Protoplanetary Systems") in the mass accretion rate-disk mass diagram with two main goals: 1) reveal which gaps have been created by grain growth, photoevaporation, or giant planet formation and 2) from the statistics, determine the main disk dispersal mechanism leading to a transition disk.

Massive Young Stars in W43: PACS/SPIRE SED Spectral Scans of MM1 to MM4

Proposal ID: OT1_jbally_2

Principal Investigator: John Bally

Time: 6.7 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to acquire complete spectral-scans of the four most luminous and massive young stellar objects (MYSOs) in the giant W43 giant HII region complex located at a distance of 5.5 kpc in the Galactic Molecular Ring. The SED modes of the PACS spectrometer and the high-resolution mode of the SPIRE FTS will be used to trace variations in chemical abundances, excitation conditions, and structure in the SEDs as functions of the evolutionary states of these four massive objects. While the central pixels record the spectra of the target MYSOs, the adjacent pixels will probe the spectral properties of the surrounding dense molecular clumps, additional massive YSOs that happen to fall within the aperture, PDRs, and adjacent ionized regions. W43 is one of the most luminous star forming regions in the Galaxy. It has undergone a `mini-starburst' within the last few Myr. Massive star formation continues in at least 50 clumps spread over a 20 pc diameter region. The proposed observations will test evolutionary models for MYSOs.

EPICS: Evolution of Protostellar Ices, Carbonates and Silicates

Proposal ID: OT1_jchiar_1

Principal Investigator: Jean Chiar

Time: 31.9 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Dynamical and energetic processes that occur during the evolution of a protostar have a strong influence on composition and other characteristics of the dust and these can be well probed with far-IR spectroscopy using Herschel's PACS instrument. Physical evolution of protostars, driven by gravity, is accompanied by a dramatic evolution of the dust, driven by condensation and coagulation, thermal processing by the central star, and shocks driven by protostellar jets. Mid-IR spectroscopic studies of dust in protostellar environments reveal a wide diversity of dust components ranging from volatile ices, to carbonates to refractory crystalline silicates. However, the relationship between the dust evolution and the evolution of the protostar itself has not yet been studied. The evidence suggests that ices are connected to the deepest embedded phase, while crystalline silicates may trace the presence of disks. Carbonates may be either connected to processing of ices in the envelope of YSOs or result from disk processes. In order to probe this dust evolution that accompanies protostellar evolution, we have carefully selected a sample of well-characterized protostars spanning a wide range in evolutionary age and protostellar characteristics from the deeply embedded class 0 stage through the accretion disk (class I) and protoplanetary disk (class II) phases. We will employ PACS in SED mode to study the lattice vibration phonon modes of the ices, silicates and carbonates that occur in the 51 to 220 micron region. Our proposed study will allow us to address at what stage of protostellar evolution different dust signatures become apparent. In this way, we can address the (inter)relationship of these different compounds and the processes involved in their formation. Our study directly addresses Herschel's top-level goal of studying the ingredients in the dust throughout the evolution of a protostar that will then become part of the planetesimal and planet-forming process.

Close Binaries with Infrared Excess: Destroyers of Worlds?

Proposal ID: OT1_jdrake01_1

Principal Investigator: Jeremy Drake

Time: 16.4 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We have recently used Spitzer to confirm that large IR excesses seen in about 20-30% of old close binary stars by IRAS correspond to very warm close-in dust that appears to originate from recent collisions of planets or planetesimals (Matranga et al. 2010). Somehow, close binaries seem to be destabilizing their planetary progeny, perhaps through secular shrinkage of the stellar separation caused by magnetically-driven angular momentum loss. The aim of this proposal is to use Herschel to search for excesses characteristic of Kuiper-belt-like cold dust or planetesimals in a sample of 88 close binaries from an approved Spitzer IRAC survey. Probing these larger radii in such systems will provide a robust sample of broad SEDs to understand debris disks in close binaries, provide insight into the possibly origin of the Earth mass or more of dust required, and give us a unique handle in understanding planetary formation in circumbinary disks.

A 3-Dimensional view of the ionized and the warm neutral gas in Orion

Proposal ID: OT1_jgoicoec_4

Principal Investigator: Javier R. Goicoechea

Time: 27.7 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

While bolometric images provide a ``snapshot'' of the impact of high-mass star formation over entire molecular cloud complexes, it is only by pursuing large scale maps of different spectrally-resolved line tracers of the ionized and the warm neutral gas that we can probe and study the cloud dynamics and kinematics in detail.

We propose to use HIFI to carry out large scale mapping of the core of the Orion GMC (7.5'x11.5'), the closest high-mass SFR in the disk of the galaxy. Our goal is to study the impact and feedback of the high-mass star formation process on the parental molecular cloud by following the ionized, the warm neutral gas and the dense molecular gas over large scales and at high spatial resolutions. The global cloud dynamics, the kinematic interplay of the different gas phase components and their influence on the environment will be revealed by a series of velocity-resolved [NII], [CII], CH+, CH, high-J CO, HCO+ and HCN line maps that cannot not be observed from the ground.

FOOSH: FU Orionis Objects Surveyed with Herschel

Proposal ID: OT1_jgreen02_2

Principal Investigator: Joel Green

Time: 21 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to utilize the unprecedented spatial resolution and sensitivity of Herschel at far-infrared and submm wavelengths to observe nearly all known FU Orionis objects, the dramatic result of burst accretion events in protostellar disks. The known FUors represent a vital window into a key process of star formation rather than a rare and peculiar event in the lives of a few stars. In addition, FUors provide a natural laboratory that probes the effect on enhanced heating on disk composition and structure. Our objectives are to (1) Study the structure of known envelopes and constrain the amount of remnant envelope material around the remainder; (2) characterize the physical and chemical properties of the disks and envelope, the parameters that set the initial conditions for planet formation in T Tauri disks; (3) observe solid-state, atomic, and molecular spectral features toward FUors in order to determine the effects of increased luminosity on mineralogy, disk chemistry, and envelope material. In order to do this we will use all three instruments onboard Herschel, providing a comprehensive survey of FUors.

Low efficiency clouds and the minimum conditions for star formation

Proposal ID: OT1_jhatchel_1

Principal Investigator: Jennifer Hatchell

Time: 20.4 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

To understand the conditions required for star formation, the best regions to observe are regions where those criteria are only just fulfilled - molecular clouds with low star formation efficiencies (SFE). The Scorpius molecular complex contains 4000 solar masses of molecular gas, yet Spitzer observations show it contains only 11 young stellar objects hence an extreme SFE of less than 0.3%. Its low SFE can be contrasted with the rich L1688 protostellar cluster in nearby Ophiuchus and intermediate SFEs in Lupus, with which it shares a similar environment on the boundary of the Lupus-Sco-Cen OB association. We aim to map the Scorpius clouds with SPIRE and PACS to locate and characterise the dense cores, identifying gravitationally unbound, bound and protostellar cores. We aim to determine why regions such as this have such low SFE, the evolutionary path(s) for starless cores, and the minimum conditions for star formation. At 130 pc, Scorpius is among the closest star forming regions hence one of the best Herschel targets for this work.

Very Large Debris Disks from the PLANCK submillimeter All-Sky Survey

Proposal ID: OT1_jlestrad_1

Principal Investigator: Jean-Francois Lestrade

Time: 5.6 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Debris disks are analogs of our Kuiper Belt in the periphery of the Solar System, but are surrounding other main sequence stars. Comets in the Kuiper Belt, and more generally planetesimals in a debris disk, are left over from the early phase of planet formation according to the ''core-accretion" theory and are connected to a planetary system orbiting closer in. Differently, an alternative theory for the formation of giant planets distant from their star invokes ''gravitational instabilities'' in young, large, and massive protoplanetary disks, and predicts no left over planetesimal in a peripheral disk at the end this fast process. Hence, existence and sizes of debris disks are a central question in planet formation theory.

The PLANCK in-orbit observatory is conducting the first all-sky survey in the submillimeter and offers the first opportunity for an unbiased survey of very large, and cold debris disks. We have used the existing PLANCK data to identify debris disk candidates spatially unresolved with the PLANCK beam (4.2'). We propose to confirm their nature by spatially resolving them with the Herschel SPIRE camera, and to determine their sizes by imaging and dust temperature by sampling their SED at 250, 350 and 500$\mu$m. If successful, we would have identified a new population of very large, and cold debris disks characterized by distant planetesimals from their central star, supporting the ''core-accretion'' theory for giant planet formation.

Cooling and chemistry in the most embedded massive protostars in the Magellanic Clouds

Proposal ID: OT1_joliveir_1

Principal Investigator: Joana Oliveira

Time: 34.6 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Stars form from contracting molecular cloud cores, but this process relies heavily on the ability of the core to cool and to overcome the magnetic barrier; this, in turn, depends on the chemical composition and could therefore lead to drastically different outcomes at low metallicity. However, most of what we know about star formation is derived from studies of solar-metallicity YSOs in the Milky Way. To investigate the role of metallicity on the star-formation process we propose to observe a sample of early-stage massive young stellar objects in the metal-poor Small and Large Magellanic Clouds. These were selected from among sources with spectroscopic evidence of ice and/or maser emission, and comprise a range in luminosity. We propose to use PACS and SPIRE FTS to measure the strengths of key atomic and molecular lines, in order to measure the temperature, density, ionization state and abundances of the main cooling species in these objects. By comparing the SMC and LMC samples, and Galactic samples of YSOs, we will assess the effect of the reduced metallicity on the formation process of massive stars.

How to produce warm dust around warm debris disks? - Testing the outer Planetesimal Belt Scenario

Proposal ID: OT1_jolofsso_1

Principal Investigator: Johan Olofsson

Time: 7.3 hours priority 1

Category: Circumstellar/Debris disks

Summary:

During the last decade, some peculiar objects emerged from mid-infrared observation campaigns: warm debris disks. These unique and rare objects have the same properties as "classical" debris disks, except that they display emission features in the mid-infrared, that are associated with warm micron-sized silicate grains. The origin of the warm dust component is still subject to discussion. According to the most recent studies, this dust population may be the consequence of two scenarios. The first explanation would be that a recent catastrophic collision took place in the inner regions of the disks, producing a large amount of micron-sized grains. The second possibility is that a cold outer planetesimal belt is feeding the inner regions, in a similar way as the Late Heavy Bombardment that took place in the Solar System. Such dynamical instability can possibly be triggered by giant planet's migration. We propose to use the PACS photometer, combined with SED modeling, for a unique set of 6 warm debris disks, than may host on-going planetary formation, in order to search for emission in excess at long wavelengths, that may reveal the presence of outer planetesimal belts.

A Herschel Survey of Disks across the Stellar/Substellar Boundary in Taurus

Proposal ID: OT1_jpatienc_1

Principal Investigator: Jenny Patience

Time: 35 hours priority 1

Category: Brown Dwarfs/Very Low-Mass Stars

Summary:

With the exceptional sensitivity of the  Herschel Space Observatory, we propose to map a complete sample of 124 low mass members of the Taurus star-forming region, spanning the transition from low mass stars to brown dwarfs. Taurus is the ideal population for this investigation since the low stellar density enables the detailed study of individual objects without contamination from nearby sources. The sensitive PACS 70um and 160um maps of all sources will provide a census of disks, ranging from primordial gas rich disks to transition disks and debris disks, and define a benchmark population study for comparison with objects of higher mass, older ages, and in different environments.  For the 59 targets with evidence of disk excesses from Spitzer 24um images, we also propose to obtain SPIRE 250-500um scans to further characterize the disk properties. The Herschel data for all sources will be combined with existing photometry to construct SEDs over the optical to submm range, and we will fit the SEDs with a comprehensive grid of models developed with the state-of-the-art radiative transfer code MCFOST. The proposed Herschel data cover wavelengths inaccessible from the ground and over the important range associated with the transition from optically thick to optically thin emission. By comparing the well-sampled SEDs with an extensive grid of models, we will estimate key structural parameters such as radius, mass, scale height, and evidence of flaring or dust settling. These properties represent important observational constraints on models for brown dwarf formation and the viability of these disks as sites for future planet formation.

Characterizing the life cycle of interstellar matter in the Magellanic Clouds with CII and CI

Proposal ID: OT1_jpineda_1

Principal Investigator: Jorge Pineda

Time: 59.6 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

The understanding of the processes governing the formation of interstellar clouds and subsequent star formation is key for our understanding of how galaxies evolve in our Universe. Special interest is given to the study of low-metallicity interstellar matter as it is thought to be representative of the environment where stars formed at earlier cosmological time. Unique targets for this study are the Large and Small Magellanic clouds, which are the closest low-metallicity star forming systems. We propose deep, velocity--resolved observations of the [CII] 158 um, [CI] 609um, and [CI] 370um lines towards 54 representative positions in the Large and Small Magellanic clouds with the HIFI instrument on board of Herschel. These will be combined with our MAGMA CO data to obtain a complete inventory of carbon in the Magellanic clouds. We selected positions to represent different ISM environments, based on whether they show: a) HI peaks with little or no 160um dust emission and no CO, b) HI and 160um peaks but still no CO, and c) CO peaks. We also include a sample of lines-of--sight observed by FUSE which have known H2 column densities, which will allow us to calibrate our use of [CII] as a tracer of HI and H2 column densities. Our sample therefore includes clouds in different stages of evolution going from diffuse atomic to diffuse molecular and to dense molecular clouds. We will use an excitation/radiative transfer code and a PDR model to derive the physical conditions of the line-emitting gas. Our observations have the potential to discover large quantities of dark H2 gas traced by [CII] and perhaps [CI] emission, as recently observed in [CII] emission in the galactic plane (Langer et al. 2010 and Velusamy et al. 2010).

Protostellar Envelopes Resolved Inside and Out: A Close Look in the Far-IR

Proposal ID: OT1_jtobin_1

Principal Investigator: John Tobin

Time: 3 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to use Herschel PACS and SPIRE observations to develop a detailed characterization of the envelope temperature and density structure in four nearby (d ~ 200-300 pc) protostars. This will enable us to understand how the non-axisymmetric structure in the surrounding dusty envelopes affects the infall process and the structure of the inner envelope. The goal of this proposal is to take advantage of the superb spatial resolution in the far-IR and sub-millimeter to constrain envelope densities and temperatures over the wide range of spatial scales involved in protostar formation. The proposed observations will resolve the warm inner envelope around these protostars with PACS and map the cold outer envelope with PACS and SPIRE with unparalleled sensitivity and resolution. The multi-band Herschel data enable us to construct dust temperature and density maps which we will combine with our existing Spitzer/near-IR dust extinction maps and measurements of envelope mass and morphology. We will interpret our observations using radiative transfer models to provide the most comprehensive characterizations of protostellar envelope density and temperature structures with which to confront theory.

Polycyclic aromatic hydrocarbons (PAHs) in protoplanetary disks around late-type T Tau stars in Orion Nebular Cluster

Proposal ID: OT1_kkim_1

Principal Investigator: Kyoung Hee Kim

Time: 31.3 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose a search for far-infrared features from polycyclic aromatic hydrocarbon molecules (PAHs) in a small sample of protoplanetary disks around late-type T Tau stars. These objects were identified in the course of our large Spitzer-IRS survey of the Orion A cloud to have mid-infrared PAH features with unusual profiles, which are far too bright to explain by photoexcitation by their host stars; they must be excited by ultraviolet light from their more massive neighbors. Recent laboratory spectra of PAHs demonstrate the variation of wavelength and strength with molecule size for the far-infrared features of PAHs, a sensitivity that is lacking in the mid-infrared features. The observation of such features in disks around low-mass stars, in which we frequently see the effects of coagulation and growth among the silicate-grain population, represents an opportunity to search for size variation among the PAH population, a congruence with the PAH molecules found in the primitive meteorites, and perhaps hints of the role played by carbonaceous molecules in the assembly of solid bodies in disks.

Cool Herschel/Hot Spitzer: The distribution of water in protoplanetary disks

Proposal ID: OT1_kponto01_1

Principal Investigator: Klaus Pontoppidan

Time: 39 hours priority 1

Category: Circumstellar/Debris disks

Summary:

One of the key mission objectives of Herschel is to observe water in various environments, but in protoplanetary disks in particular. Water has an immediate relevance to the formation of planets and to our own origin. We propose to obtain deep PACS/SPIRE line spectra of water, OH and CO in protoplanetary disks already known to have strong rotational water vapor emission at mid-infrared (10-36 micron) wavelengths, as detected by Spitzer (the newly discovered mid-infrared molecular forest). The mid-infrared lines trace warm to hot gas formed within a few AU from the central star. The proposed observations will relate the oxygen chemistry and transport of water in the inner few AU with that of the cooler outer disk - 1-100 AU - as traced by the PACS water lines. The line ratios of water in the Spitzer spectral range suggest that water vapor may be strongly depleted in the disk surface beyond 1 AU although gas and dust temperatures are high enough to maintain abundant water out to at least 10 AU. It was suggested by Meijerink et al. 2009 that this depletion of water could be due to a ``cold finger effect'', in which the surface water vapor is carried downwards into colder regions of the disk where it freezes out and is bound in the disk mid-plane as part of the general dust growth and settling. If so, the surface abundance structure of water is a direct tracer of the mid-plane snow-line. Based on model fits to the mid-infrared lines, we predict very strong differences in the 50-200 micron water lines, depending on the distribution of water in the outer disk surface. Our program is unique in that 1) we specifically target disks known to have strong water emission from the inner disk and 2) we go significantly deeper than others ensuring that we can constrain the abundance of water vapor down to 10^-10 per hydrogen in the outer disk, thus putting very strong constraints of the efficacy of the proposed cold finger effect.

Dusty Disks around Hot White Dwarfs: Debris Disks or Remnant of post-AGB Binary Disks?

Proposal ID: OT1_ksu_2

Principal Investigator: Kate Su

Time: 7.6 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Dusty disks around hot (Teff > 100,000 K) white dwarfs are a new phenomenon discovered by Spitzer. The origin of such a disk is still in debate. We propose to obtain far-infrared photometry for 6 dusty disks around hot WDs identified from our Spitzer 24 micron survey. The Herschel far-infrared measurements will provide strong constraints on the outer boundary of the disk and its total dust mass in the system, crucial information necessary to differentiate the origin of the disks.

Outflows from evolved Class II sources: an Herschel/HIFI insight into the kinematical/physical properties of the atomic and molecular component.

Proposal ID: OT1_lpodio_1

Principal Investigator: Linda Podio

Time: 26 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Stellar jets are known to play a key role in the overall star formation process as they can remove angular momentum from the disk and disperse the parental envelope. A characteristic emission lines spectrum is produced by the shocks caused by the interaction of the ejected material with the surrounding medium. The collimated, fast and hot gas (T~2000-1e4 K) is traced by atomic and H2 lines, while the slow and cold swept-up material (T~10-20 K) can be probed through millimeter lines. Herschel opens a window on the "warm" component at 100-2000 K, which hold crucial information on the understanding of the connection between the outflow atomic and molecular components and the transfer of energy to the surrounding medium.

Preliminary results obtained from the analysis of GASPS/PACS data of Class II sources associated to jets detected at optical/NIR wavelengths show extended and velocity shifted emission in atomic ([OI]63um, [CII]157um) and molecular (CO, H2O) lines, suggesting that these lines are originating in the outflowing gas. However, also emission from the surrounding accretion disk may contribute to the emission in the unresolved star-disk region (PACS resolution ~9.4").

We propose to complement the GASPS/PACS data with HIFI observations of the [CII]157um, CO 10-9, and H2O at 556.9 GHz lines in a small sample of GASPS targets associated to outflowing gas sigantures. HIFI high spectral resolution (fraction of km/s) will allow us to observe line profiles and separate emission from the disk and the outflows. The [CII]157um line, with the [OI] lines detected by PACS, will probe the jet atomic component, while HIFI and PACS CO and H2O lines will allow us to derive kinematical/physical properties of the molecular component. The characterization of molecular gas component, as well as the estimates of the mass loss rate associated to the different component is crucial to test the magneto-hydrodinamical jet models and understand the interplay between accretion and ejection.

An in-depth Herschel study of gas, dust, and ices in FU Orionis objects

Proposal ID: OT1_maudar01_1

Principal Investigator: Marc Audard

Time: 31.3 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose to obtain the broad-band medium-resolution spectra of 15 known outbursting sources with Herschel PACS and SPIRE to cover the 50-650 micron range and to study both the continuum (and the spectral features of ices and dust) and the emission lines. Additional photometry with PACS and SPIRE will be obtained to better characterize the direct environment of the FU Orionis objects. The main goals are 1) to place the FU Ori objects in the context of young stellar evolution by looking for differences in infrared spectral diagnostics between FU Ori objects and regular young stars. To this end we plan 2) to study the composition and evolution of dust grains in FU Ori objects, 3) to look for the presence of ices, 4) to identify atomic lines, in particular faint lines not previously or barely identified with ISO and to use line ratios to constrain the emission mechanism, 5) to search for molecular lines of hydroxyl and water, and of high transition states of (J=13-30) of CO. The CO lines will be used to constrain the origin of the lines (outflow, disk), 6) to use the Herschel spectra and photometry with ground-based and Spitzer data to fit the spectral energy distributions with radiative transfer codes to derive the disk and envelope properties. The Herschel observations of our sample of outbursting sources will probe an important phase in the life of young stellar objects with the aim to better understand their differences and their common properties, and to better place them into the evolutionary sequence from Class I star to Class II stars.

Understanding the Protostellar Mass Accretion Process: Herschel 100-500 micron Photometry of Low Luminosity Embedded Protostars

Proposal ID: OT1_mdunham_1

Principal Investigator: Michael Dunham

Time: 6 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Spitzer Space Telescope surveys of nearby, low-mass star-forming regions have discovered a new class of very low luminosity objects (VeLLOs), protostars embedded within dense cores with luminosities less than or equal to 0.1 Lsun. VeLLOs represent the extreme low end of the protostellar luminosity distribution, which is comprised mainly of sources below about 1 Lsun. The standard model of star formation, which predicts a mass accretion rate constant with time, is inconsistent with such a large population of low luminosity embedded protostars, leading numerous recent authors to suggest that mass accretion is variable and/or episodic in nature. Further constraints on this mass accretion process require far-IR and submm data to fill in the gap between existing Spitzer mid-IR and ground-based millimeter continuum data. We propose to obtain Herschel PACS and SPIRE 100-500 micron photometry of 24 confirmed and candidate embedded protostars with L < 1.0 Lsun. With these data, we will: (1) calculate accurate evolutionary indicators, (2) provide essential inputs for source models that seek to constrain the properties of both the protostars and the dense cores in which they are embedded, and (3) confirm or reject candidates that have not been conclusively shown to be embedded protostars. The proposed observations will provide crucial data for further understanding the protostellar luminosity distribution and mass accretion process for a very modest (6.0 hours) allocation of observing time.

Diffuse ISM phases in the inner Galaxy

Proposal ID: OT1_mgerin_4

Principal Investigator: Maryvonne Gerin

Time: 13 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

First HIFI and PACS observations obtained in the framework of the PRISMAS and HEXOS key programs have demonstrated the advantage of using absorption spectroscopy for studying the diffuse interstellar medium in the inner Galaxy. Detections of HF, OH+, H2O+, CH+, CH and the N-hydrides have significantly improved the knowledge of the diffuse molecular gas and started to open windows on the diffuse atomic gas. However the information on the diffuse ionized gas remains fragmentary. We propose to take advantage of the Herschel spectroscopic capabilities and further characterize the diffuse neutral and ionized interstellar medium along lines of sight already selected in the PRISMAS and HEXOS programs. We target the fine structure lines of ionized nitrogen and carbon, [NII] 1.46 THz, CII] 1.9 THz,and the ground state and first excited lines of neutral carbon at 492 GHz & 809 GHz. [NII] is tracing is diffuse ionized gas, while the neutral carbon lines reveal the diffuse neutral gas and probe the gas pressure and [CII] traces both the neutral and ionized matter . Towards strong far infrared sources such as our targets, we expect that the [CII] line profile will present a superposition of emission and absorption features, that can only be resolved by the high spectral resolution provided by HIFI. Even for [NII] and [CI], the profiles may show superpositions of absorption and emission features, justifying our request for HIFI spectra, since the gas and electron densities in the foreground material are much lower than in the background sources. We propose to take advantage of the sensitivity offered by absorption spectroscopy to determine the ionized carbon abundance with an unprecedented accuracy. The proposed observations will therefore bring new measurements of the abundances of neutral and ionized carbon abundances, neutral gas pressure, and ionized gas filling factor in the inner Galaxy that will provide a complete picture of the respective volume and mass filling factor of the ISM phases in the inner Galaxy

Kinematics and Chemistry in Ultracompact HII regions: the case of Mon R2.

Proposal ID: OT1_mgonza01_1

Principal Investigator: Manuel Gonzalez

Time: 3.4 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

Ultracompact HII regions are defined as regions of ionized gas with diameters smaller than 0.1 pc. Mon R2 is the only nearby Ultracompact HII region that can be resolved with Herschel. This source has already been observed and has been proved to host a dense photon-dominated region surrounding the Ultracompact HII region. For the simplicity of its geometry and the absence of shocks, this source is an excellent target to investigate the chemistry of extreme PDRs. Observations done with HIFI during the Prioritary Science Phase combined with previous observations from the IRAM 30m telescope permitted to constrain a simple scenario to describe this region: a dense PDR layer ($n\, =\, 5\times10^6\, cm^{-3}$) surrounded by a lower density ($n\, =\, 10^5\,cm^{-3}$ ) UV protected envelope. We propose to do maps of tracers of the regions of the PDR close to the HII region in order to characterize its movement. At the same time, we propose to observe some hydrides molecules, which chemistry is poorly known in such regions. HIFI is a unique oportunity to study such hybrides with fine/hiperfine structures, due to its high resolution. That way, with only 3.4 hours of observation and some work in modeling and interpreting the results we would be able to characterize the kinematics and chemistry of this region, that can be used as a template of similar objects, like the surface layers of circumstellar disks and/or the nuclei of starburst galaxies.

Deep HIFI searches for cold water vapor in protoplanetary disks

Proposal ID: OT1_mhogerhe_1

Principal Investigator: Michiel Hogerheijde

Time: 46.8 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Water vapor inside planet-forming disks is expected to show large variations. In the warm (~200 K) inner few AU of the disk all oxygen is locked up in water vapor. In the colder outer region water quickly freezes out onto dust grains. However, efficient photodesorption by stellar ultraviolet radiation will return an appreciable fraction back into the gas phase in the upper disk layers. This coupled water ice/vapor system explains the Spitzer observations of warm water in several disks, and predicts the presence of cold water vapor in the outer disk. Through the `Water in Star Forming Regions' (WISH) Key Program, we have recently clearly detected the groundstate line of cold water vapor to TW Hya and very tentatively detected it to DM Tau. Both lines are factors 10-50 weaker than expected. We hypothesize that up to 99% of icy grains have settled to the disk's midplane thus `freeze drying' the upper disk layers. The WISH data do not go deep enough to probe cold water vapor content now that we know that the outer disk is freeze-dried. The only clear detection is TW Hya, which has a distance of only 51 pc. At more typical distances of 100-140 pc, line strengths are lower by factors 5-8, beyond the sensitivity of WISH. We propose much deeper HIFI observations of the H2O 110-101 line at 557 GHz of four targets: DM Tau (to confirm or reject WISH's `very tentative' detection), and HD100546, HD163296, and AA Tau. These disks are, after TW Hya, the closest and largest disks that offer the best chances of detection. Because of the sensitivity of H2O 110-101 to cold water vapor in the outer disk, our observations probe as-of-yet unexplored grain settling in the outer disk and enrichment of the midplane with icy grains. This can boost planet formation, since icy grains coagulate more easily. Our proposal also contains a small request for velocity-resolved CO 10-9 observations with HIFI to study warm (~200 K) gas in these four disks, and investigate if preferential settling of icy grains also affects CO.

A Search for Cold Dust Orbiting GD 362, a Highly Polluted White Dwarf With Detected Warm Dust

Proposal ID: OT1_mjura_1

Principal Investigator: Michael Jura

Time: 1.1 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to observe GD 362 to measure the amount of cold dust orbiting this white dwarf which is already known to possess warm dust. There are two models to account for the large amount of atmospheric hydrogen in this externally-polluted star whose atmosphere is largely helium. (1) The star is accreting from a single Mars-mass parent body. In this case there is no reason to expect cold dust. (2) The star is accreting from an ensemble of 100's of Ceres-mass asteroids; a large amount of cold dust likely is present. If so, the source could be detected with PACS.

Crystal clear: revealing midplane dynamics of protoplanetary disks through the spatial distribution of crystalline dust

Proposal ID: OT1_mmcclure_1

Principal Investigator: Melissa McClure

Time: 28.7 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to obtain PACS range spectroscopy to measure the vertical and radial distribution of crystalline silicates in 22 protoplanetary disks around pre-main sequence stars. Dynamical processes, such as nebular shocks and meridional flows, are predicted to generate crystals within the warm, inner-most parts of these disks and transport them further out into the planet-forming regions. Therefore the spatial distribution of crystals, which have broad, mid-infrared spectral features, can be used to trace such mechanisms. Since these processes influence core-building and migration, determining their scope is paramount to our understanding of planet-formation as a whole. Recent studies using Spitzer Space Telescope IRS spectra suggest crystals are distributed farther out in protoplanetary disks than can be accounted for by current theories. Over the Herschel PACS 51-73 micron range, the continuum is extremely sensitive to changes in crystallinity as a function of radius, while the dust emission features over this range and the continuum from 102-146 micron are sensitive to changes in crystallinity in the vertical direction. By using irradiated accretion disk models to do a self-consistent analysis of the combined PACS and Spitzer IRS spectra of our 22 targets, we will unveil the midplanes of these disks and trace the influence of inner disk dynamics on the planet-forming region.

First steps toward star formation: unveiling the atomic to molecular transition in the diffuse interstellar medium

Proposal ID: OT1_mmiville_2

Principal Investigator: Marc-Antoine Miville-Deschenes

Time: 31.4 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We propose to map molecular material that is forming in the diffuse insterstellar gas, exploiting the unique capabilities of PACS and SPIRE: large area mapping at high angular resolution, sensitivity, and wavelength coverage spanning the peak of the dust spectral energy distribution. The main scientific goal is to discover the physical conditions in cirrus clouds that lead to the formation of the seeds of molecular clouds. Molecular hydrogen formation is fundamental to understanding the structure of molecular clouds and the core mass function (CMF) in the framework of the turbulent, magnetized and thermally bi-stable interstellar medium.

Our strategy is to map two regions at high Galactic latitude with PACS and SPIRE and use the dust opacity deduced from Herschel data to map the total column density of matter. Then using our high resolution 21-cm data for these fields, the atomic-correlated contribution can be removed, leaving a map dominated by dust in the molecular gas. Statistical properties of the molecular structures will be related to the properties of interstellar turbulence, thermal instability, and CMF seen in molecular clouds. The H I data are essential to this project, not only to uncover the molecular gas but also to probe the dynamical conditions in which the molecular gas has formed.

Both fields are part of a large project of H I observations of high Galactic latitude fields. The Spider field, a faint cirrus cloud with highly filamentary structure, is representative of the formation of H2 in dynamical conditions dominated by interstellar turbulence, with an average amount of molecular gas for diffuse clouds (estimated at about 15-20%). The Draco nebula, the archetype of interstellar matter re-entering the local interstellar medium after being expelled into the halo via the Galactic fountain, has a strikingly clumpy structure induced by its bulk motion with respect to the local ISM. There is a wide range of conditions to be modeled, including patchy CO emission.

Probing the mechanical and radiative feedback from young stars in the molecular clump containing HH 1/2 and NGC 1999

Proposal ID: OT1_mpuravan_1

Principal Investigator: Manoj Puravankara

Time: 13 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose PACS spectroscopic observations in the line and range scan mode of the HH 1/2 jet, its driving source, and a nearby cloud cavity irradiated by a B9/A0 star in an intermediate-mass molecular clump in L1641. Our aim is to study the details of the mechanical and radiative feedback from new born stars on their immediate cloud environment and how it affects the structure, stability and star formation potential of the cloud clump from which they have formed. We will map the HH 1/2 outflow, and the newly discovered cavity in NGC 1999, in the far-infrared fine-structure lines of [C II] and [O I], and in several rotational lines of CO and H$_2$O. From these observations we will spatially separate the various sources of energy and momentum, and place strong contraints on the density and temperature of the emitting gas. We will follow the spatial variations in the shock structure along the jet to probe the interaction of the jet with the surrounding molecular gas. By constraining the temperature and density of the surface walls of the cavity in NGC 1999 we will test if the temperature is high enough to represent photoevaporation, and estimate the rate of photoevaporation.

ASCII: All Sky observations of Galactic CII

Proposal ID: OT1_mputman_1

Principal Investigator: Mary Putman

Time: 10 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

The Milky Way and other galaxies require a significant source of ongoing star formation fuel to explain their star formation histories. A new ubiquitous population of discrete, cold clouds have recently been discovered at the disk-halo interface of our Galaxy that could potentially provide this source of fuel. We propose to observe a small sample of these disk-halo clouds with HIFI to determine if the level of [CII] emission detected suggests they represent the cooling of warm clouds at the interface between the star forming disk and halo. These cooling clouds are predicted by simulations of warm clouds moving into the disk-halo interface region. We target 5 clouds in this proposal for which we have high resolution HI maps and can observe the densest core of the cloud. The results of our observations will also be used to interpret the surprisingly high detections of [CII] for low HI column density clouds in the Galactic Plane by the GOT C+ Key Program by extending the clouds probed to high latitude environments.

Hot CO in the Massive Star Forming Region DR21

Proposal ID: OT1_mrllig_1

Principal Investigator: Markus Röllig

Time: 11.6 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

We plan to resolve the detailed physical and dynamical structure of the massive star forming (SF) region DR21~C which has a prominent bipolar outflow visible in 2 micron emission of vibrationally excited H2, tracing hot, shocked gas. While, the shock is hardly affecting most of the molecular line emission of the region (Lane et al. 1990, Ossenkopf et al. 2010), only [CII] is showing an additional broad blue wing indicating that the [CII] emission is not only originating from that warm gas, but also from the ionized wind in the blister outflow. H2 and CO are at least partly co-existent and hence should show similar signs of shocks, but surprisingly 13CO(10-9) doesn't, so many question remains:

- Is there any CO that is directly affected by the shock and if so, at at which AV does the shock excitation stop? - Why does CO up to 10-9 show no direct signature of shock heating or outflowing material? - Does the shock only affect H_2 and ionized material? - Which volume of the source is affected/heated by the shock? - Which volume of the source is heated by the UV radiation from the cluster?

The aim of this proposal is to understand how shock/outflow and UV radiation from the embedded OB cluster contribute to the excitation of the surrounding material and where exactly the transition from shocked to unshocked material occurs.

Confirming a sample of luminous debris disk candidates identified in the Herschel ATLAS

Proposal ID: OT1_mthomp01_1

Principal Investigator: Mark Thompson

Time: 1.4 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Debris disks are the remains of planetary system formation, tracing the existence of planetesimal-sized objects in orbit around main sequence stars. Current and planned surveys of debris disks (including the Herschel Key Projects DEBRIS and DUNES) are deep surveys aimed at characterising the typical population of disks and targeted at samples of a few hundred nearby objects. These deep narrow surveys are relatively insensitive to the rarities in the debris disk population, some of which may be luminous and/or massive disks that have undergone recent disruptive collisional events. We have recently shown that the primarily extragalactic Key Project, the Herschel-ATLAS, can be used as a wide and shallow survey of debris disks by combining its excellent optical coverage and statistical techniques more commonly employed to identify galaxies. The combination of Herschel-ATLAS, DEBRIS and DUNES thus forms a powerful nested tier of surveys that will be sensitive to disks across the spectrum from exosolar analogues to rare disks that cannot be inferred from local populations. In this proposal we seek time to image the three candidate disks that we discovered in the Herschel-ATLAS Science Demonstration Phase with PACS so that we may confirm them as true debris disks and model their SEDs to extract mass, temperature and fractional luminosity. We will confirm whether these disk candidates are in fact the most luminous disks yet detected.

Characterizing the structure of an unusually cold high latitude cloud

Proposal ID: OT1_mvenezia_1

Principal Investigator: Marcella Veneziani

Time: 6.8 hours priority 1

Category: Galactic Other

Summary:

We propose a PACS and SPIRE photometric observation at 100, 160, 250, 350 and 500 micron to study an unusually cold cloud detected by the BOOMERanG experiment at high galactic latitudes (b = -31 deg). This cloud has a temperature of T = 7 +- 3 K and this measurement is confirmed also by Planck-HFI data. Even if the temperature is so low, other properties are not that extreme: it has normal HI column density, gas-to dust ratio and no molecular material. A closer look at 100 micron shows, at 4' resolution, a wealth of brighter clumps embedded in the cloud that could be mostly molecular, hence hidden from the large beam HI and CO surveys. They can be pre-stellar cores and this would explain the low temperature. We propose to map a 30'x30' area centered on the cloud to study the substructure and the composition of that region. The observation with the Herschel angular resolution and band coverage will improve the knowledge of the early stages of star formation and of the structure and composition of the interstellar medium at tens of arcseconds angular scale. This is particularly interesting as the region is located at high latitudes, in an area that is supposed to be poor of star formation activity. With Herschel data we will be able to characterize the properties of the clumps and of the dust around, like temperature, spectral index, mass and density in order to better determine the physical processes occurring in this region and structure and substructures composition.

HYSOVAR: Circumstellar Disks Variability around Young Stellar Objects in the Orion Nebula Cluster with Herschel/PACS

Proposal ID: OT1_nbillot_1

Principal Investigator: Nicolas Billot

Time: 9.9 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

The variability of Young Stellar Objects (YSOs) have been demonstrated over half a century ago from optical observations. More recent time series photometry of YSOs in the thermal infrared have shown their great potential to probe the structure of inner circumstellar disks (r << 1 AU), in particular the presence of warps and `clouds' in the disks which may owe their existence to the gravitational torques from close-in planets. For instance the YSOVAR program used the Spitzer IRAC instrument to monitor over 1400~YSOs and establish that 70% of them show significant variability in the mid-IR. Today the Herschel/PACS spectral coverage, sensitivity and stability offer a unique opportunity to access the wavelength regime sensitive to the dust thermal emission from the terrestrial habitable zone through the ice-line where gas giants are expected to form. We propose the HYSOVAR program, an expansion of YSOVAR with the Herschel/PACS Photometer, to monitor the flux variations of 100+ Class I YSOs in Orion over weeks-to-years time scales. This small (9.9 hours) exploratory program would greatly increase the statistics and sensitivity of previous studies in the far-IR, and it would help us identify the physical processes responsible for the observed infrared variability by placing strong constraints on existing models of star and planet formation.

A Deeper Look at the 3-10 Myr Old Disks in the Orion OB1 Association

Proposal ID: OT1_ncalvet_1

Principal Investigator: Nuria Calvet

Time: 39.6 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to obtain deep 70/160 micron PACS Photometer observations of populations in the Orion OB1 association, spanning the critical 3 to 10 Myr range of ages when disks are supposed to dissipate and planets to form. Our ongoing large-scale survey of the Orion OB1 star-forming regions has allowed us to find the elusive low mass population in the older parts of the association, and secure the photometric and spectroscopic data to fully determine the stellar and accretion properties of these objects. We propose to obtain slow-speed scans of five 30'x30' fields, covering sections of the ~ 3 Myr old cluster sigma Ori, a ~ 5 Myr old group in the Ori OB1b subassociation, and the ~ 9 Myr old 25 Ori group, the most populous stellar group at this age within 500 pc. Our Spitzer IRAC and MIPS data for the proposed fields allow us to estimate that we will detect at least 62 disks in our PACS observations, 48% of which also have Spitzer IRS data. With the Herschel far-infrared fluxes and our mid-infrared and optical fluxes we will construct the most complete spectral energy distributions for a large sample of 3-10 Myr disks. The interpretation of these SEDs with our irradiated accretion disk codes, constrained by the stellar parameters and mass accretion rates determined independently from the UV excess, will allow the best characterization to date of disks in this age range, and provide essential constraints on theoretical models of disk evolution and planet formation.

Pillars of creation: physical origin and connection to star formation

Proposal ID: OT1_nschneid_1

Principal Investigator: Nicola Schneider

Time: 31 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Herschel SPIRE/PACS photometry observations performed within the HOBYS (Herschel imaging survey of OB Young Stellar objects) key program have revealed a wealth of interesting structures in high-mass star forming regions. The most spectacular of those are 'pillars' and 'globules'. These features -- partly known from Hubble Space telescope or Spitzer images -- are formed due to photoevaporation at the interface between a molecular cloud and an HII region, and are thus intimately linked to high-mass star formation. The process of how these pillars are created, and under which conditions low- or high-mass stars form within them, are not yet clear. Classical approaches (e.g. Rayleigh-Taylor) can not explain pillar formation, so we have embarked upon a dedicated project to fully simulate pillars and globules using the (magneto)-hydrodynamic code HERACLES that comprises gravity and ionization. The model is intended to be coupled with a radiative transfer photon dominated region code (KOSMA-tau).

We propose here to make use of the Herschel spectroscopy capacities to map/make single pointings, in a number of atomic and molecular lines, of selected pillars and globules in three different regions (Rosette, Cygnus, M16), spanning a large range in UV intensity and density. We intend to observe the important cooling lines of [CII] at 158 micron and [OI] at 63 and 145 micron with PACS, the [CI] finestructure lines at 370 and 609 micron and the mid-to high-J CO and HCO+ ladder with the SPIRE FTS. Spectrally resolved [CII] mapping with HIFI is also required to derive the velocity information. These observations will be compared to the large existing complementary data set for each source, to study the physics of pillars and will additionally serve as input for the models, to ultimately explain pillar formation and star formation within them.

Herschel spectroscopic study of the extraordinary disk Gomez's Hamburger

Proposal ID: OT1_oberne_3

Principal Investigator: Olivier Berne

Time: 10 hours priority 1

Category: Circumstellar/Debris disks

Summary:

"Gomez's Hamburger" (GoHam) is a gas rich protoplanetary disk around a pre-main-sequence A star. Recent observations at infrared and millimeter wavelengths have reveal the extraordinary nature of this source: it is seen almost perfectly edge-on, it is massive and therefore intense in the infrared and millimeter: offering the possibility to detect key species (e.g. H2O, High J CO lines), it is large enough to be spatially resolved at most wavelengths, and it is likely in the process of forming planets. Overall, it appears that GoHam is a key object to study the mechanisms that lead to planetary formation, and it has been left behind in the guaranteed time. Here, we propose to observe this object with the three instrument onboard Herschel to complete the data set we have already gathered for this source. The team, composed of experts in molecular astrophysics, disks, radiative transfer, chemistry, and dust properties, will then make best use of these observations to probe the gas temperature, density, velocity and the dust size distribution as a function of the radial and vertical dimension of the disk. Such results are needed, in the end, to constrain the hydrodynamical models of planetary formation, and chemical models explaining the formation of complex molecules. The total requested time for this program is 10 hours.

Spatially resolved far-infrared imaging of bright debris disks: studying the disk structure and the stirring mechanism.

Proposal ID: OT1_pabraham_2

Principal Investigator: Peter Abraham

Time: 14.8 hours priority 1

Category: Circumstellar/Debris disks

Summary:

A significant fraction of main-sequence stars are encircled by dusty debris disks. The short lived dust particles of these disks are believed to be replenished through destructive collisions between unseen planetesimals whose orbits are stirred up by some mechanism. In the literature three candidate mechanisms compete: the most commonly invoked self-stirring, the giant planet induced planetary stirring and close stellar flyby. Here we propose to study 10 carefully selected debris disks with Herschel/PACS and Herschel/SPIRE, where young age and a rough estimate of disk size from Spitzer observations hint for stirring mechanisms other than self-stirring. With the new observations we will resolve the debris disks at 70 micron (and in some cases at 100/160 micron as well) and will analyze in detail their structure and to identify stirring mechanism. In our programme we aim to 1) resolve the dust disks and characterize their spectral energy distributions; 2) to study the radial and azimuthal distributions of the cold debris; 3) to identify the stirring mechanism in the disks; 4) to perform a detailed investigation of HR 8799 a star with three large outer planets. The proposed observations will contribute to a deeper understanding of the stirring mechanisms by utilizing the superior spatial resolution of Herschel. The total requested time is 14.8 hours.

A deep 70 micrometer study of cold circumstellar disks in rho Oph: down below the brown dwarf limit

Proposal ID: OT1_pabraham_3

Principal Investigator: Peter Abraham

Time: 12.8 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Most stars form in clusters, and the nearest example of an embedded young cluster is the one in the L1688 cloud of the rho Ophiuchi region. It is one of the best explored star-forming region, an intermediate exemplar between the sparse regions of Taurus and the rich, massive cluster of Orion. With the aim of detecting brown dwarfs (BDs) with masses down to a few Jupiter masses, our group conducted a major preparatory observational project in L1688, where we have spectroscopically confirmed 28 new brown dwarfs. The new discoveries increased the known population of BDs by a factor of 3 and provided the so far most complete census of the (sub)stellar population of the rho Oph cluster. Here we propose a comprehensive study of the cold circumstellar disks of the pre-main sequence population, with particular emphasis on the very low mass objects and BDs. Utilizing the unprecedented far-infrared sensitivity and spatial resolution of Herschel, we will obtain deep 70 and 160 micrometer maps of a 1.6 deg^2 area centred on the L1688 cloud, covering also the location of the 28 new brown dwarfs. We intend to (1) study the most complete population of brown dwarf disks in rho Oph; (2) analyse disk properties and evolution across the stellar mass range; and (3) characterize the protostar population and its luminosity function. Our programme provides the opportunity to characterize the complete, homogeneous population of disks around both young BDs and low-mass stars in "the benchmark protocluster" of rho Oph. The produced deep 70 micrometer map of the region will also have a very high legacy value, since flux densities for sources to be discovered (e.g. new confirmed BDs) can be extracted in the future. The total Herschel observing time for the proposed programme is 12.8 h.

Follow-up spectroscopy of two selected filaments found in the Herschel Gould Belt Survey: A turbulent shock origin ?

Proposal ID: OT1_pandre_4

Principal Investigator: Philippe Andre

Time: 58.3 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

One of the early discoveries made with Herschel during the science demonstration phase is the fascinating omnipresence of filamentary structures in the cold interstellar medium and the apparently intimate relationship between the filaments and the formation process of prestellar cloud cores. Our first results from the Gould Belt survey in the Aquila Rift and Polaris Flare regions suggest a picture of core formation according to which filaments form first in the diffuse ISM, probably as a result of interstellar turbulence, and then prestellar cores arise from gravitational fragmentation of the densest filaments. To get further insight into the formation of prestellar cores, it is crucial to clarify the origin and nature of the filaments seen in the wide-field SPIRE/PACS images. Here, we propose follow-up observations of the central parts of two selected filaments with the SPIRE and PACS spectrometers to characterize the physical conditions of the gas and test the hypothesis that the filaments are formed behind low-velocity interstellar shock waves associated with the dissipation of turbulent energy. If this is indeed the case, we expect to detect a number of emission lines such as [CII] (at 158 microns) and [CI] (at 609 microns), and several high-J CO lines which are primary coolants of the postshock gas.

Galactic Origins of Star Formation in the W43 Complex (GLOW)

Proposal ID: OT1_pcarlhof_1

Principal Investigator: Philipp Carlhoff

Time: 10 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Star formation is one of the most important processes in the universe, strongly influencing the evolution and structure of matter on all scales. Still the early phases are not totally understood. The progression from low density gas and dust to star forming cores still awaits a persistent description.

One model that aspires to explain molecular cloud formation is the "converging flows" model. The term refers to the convergence of HI streams that can naturally be driven by gas motion within Galactic arms. The theory of converging flows is the first one that can explain star formation self-consistently. It sets the stage for rapid dispersal (fragmentation into filamentary structures) of molecular clouds and explains naturally the observed short lifetimes of star forming stages which have, for long, been a problem.

We propose to map three parts of the giant molecular complex W43, that show examples of converging flows and filamentary structure in C+. This line is known to be a good tracer of the transitional phase between atomic and molecular gas, particularly the phase where the gas is already molecular, but CO has not formed yet. We strive to observe the selected targets with Herschels HIFI instrument, to obtain detailed spectral information. With the addition of large scale maps of 13CO, that we have taken with the IRAM 30m and JCMT, this will give us a coherent picture of the region, needed to investigate the fluctuation of the molecular gas and compare these results to the theoretical models of converging flows.

The main scientific questions of this project are: (a) How do colliding flows of molecular gas form and how do they form filamentary structures? (b) How do these flows affect the formation of dense cores and thus accelerate star formation? The results of this proposal, complemented by other projects, will give deep insight into unknown mechanisms of star formation and, beyond that, pave the way to follow-up observations with Herschel and other observatories.

Molecular Oxygen in Orion

Proposal ID: OT1_pgolds01_4

Principal Investigator: Paul Goldsmith

Time: 12.1 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Observations carried out to date for the Herschel Oxygen Project (HOP) indicate that the abundance of a potentially major oxygen-bearing species, O2 (molecular oxygen), predicted to be as high as 1e-4, is less than 1e-7. One extremely interesting exception is Orion. We have 2 hours of integration on the 487 Ghz and 774 GHz O2 transitions, and see statistically significant emission in two velocity features, at ~ 6 km/s and ~ 12 km/s. These data were taken at the Peak 1 position of strong H2 vibrational emission, approximately 40" from the KL/hot core position. Plambeck and Wright (1987) found that the Peak A position near the hot core is a strong source of HDO emission at ~12 km/s. Since HDO is thought to be released from recently warmed grains, this may be intimately connected with the low O2 abundance being a result of atomic oxygen being frozen on cold grains and hydrogenated to water ice. When released after grain heating, it produces a significant gas-phase abundance of water and molecular oxygen. The HOP project did not include the KL/hot core position (Peak A is within 5") due to concerns about line confusion. However, data from the HEXOS survey confirms that the the O2 lines are in relatively windows, and shows O2 emission at the same 6 km/s and 12 km/s velocities. The line intensities are a factor ~ 5 stronger than at the H2 Peak 1 position, although noise is very large due to limited integration time. This suggests that the emission is from the hot core (6 km/s) and Peak A (12 km/s). We thus request 12 hours of time to carry out deep integrations at the frequencies of the 487, 774, and 1121 GHz, O2 lines, pointing at a position that includes the hot core and Peak A. This will confirm the identification as molecular oxygen (with three transitions at matching pair of velocities) and give a good handle on the temperature of the region producing O2 emission and its total column density. The total time requested is 12.1 hours.

The Structure of a Molecular Cloud Boundary

Proposal ID: OT1_pgolds01_5

Principal Investigator: Paul Goldsmith

Time: 17.3 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Molecular clouds do not exist in a vacuum, but are embedded in a warm, diffuse interstellar medium containing hydrogen largely in atomic form, and ionized carbon. Based on theoretical modeling, dense, cold clouds are surrounded by an intermediate temperature envelope in which the hydrogen is molecular (due to efficient self-shielding) and in which carbon changes from ionized to atomic, to molecular (primarily CO) as one moves to regions of greater extinction. This cloud envelope is expected to have a major impact on the structure of dense cloud in which star formationtakes place, as it can add to the pressure support confining them, and can serve as a conduit for energy flowing into the molecular cloud that can be critical for sustaining observed turbulence. This boundary layer is not readily observable in CO since the abundance of this species has dropped dramatically, and it is also difficult to study in molecular hydrogen emission, as the temperature is too low to significantly populate even the lowest excited rotational states. The boundary, sometimes called "dark gas", possibly contains a significant fraction of the total mass of the dense ISM. Based on detection of weak H2 emission from the boundary of the Taurus molecular cloud by Goldsmith et al. (2010), we here propose to use the unique capabilities of Herschel to make a well-calibrated cut through the "linear edge" boundary region in Taurus in the 158 micron fine structure line of CII, and both the 492 GHz and 810 GHz fine structure lines of CI. Accurate calibration is essential and cannot be achieved using ground-based facilities. We propose to use the HIFI instrument to resolve the line widths and probe the kinematics in the boundary layer. The ratio of the CI lines yields the density, and these lines, together with the distribution of intensity of CII and H2 will allow us to develop a well-defined model for the boundary layer. This will address important questions about molecular cloud structure, total mass, and evolution.

The Auriga-California Molecular Cloud: A Massive Nearby Cloud With Powerful Diagnostics For Early Stages of Star Formation

Proposal ID: OT1_pharve01_3

Principal Investigator: Paul Harvey

Time: 19.1 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to map the Auriga-California Molecular Cloud (AMC) with the same observing parameters as being used for the rest of the clouds in the Gould Belt by the Herschel GT team conducting that program. The AMC was not included in that program BUT is extremely important as a counterpoint to the Orion Molecular Cloud (OMC) because it is as large and massive as the OMC but has a factor of 10 lower level of star formation, most of which is concentrated at the southeast end near the LkHalpha 101 cluster. We already have complete Spitzer survey data on this cloud and are in the process of obtaining JCMT line and continuum survey observations. The OMC has informed our understanding of star clusters and massive star formation. It is essential, however, to test that understanding by observing other massive clouds with differing levels of star formation. The combination of Herschel data with our existing Spitzer and molecular line data is vital to understand the physical reasons underlying the large differences in star formation between these two regions. Herschel's combination of angular resolution and 5-band imaging for dust temperature and emissivity measurements permit a uniquely high level of analysis of the far-IR emission from the AMC and comparison with the OMC.

The chemistry of nitrogen in dark clouds

Proposal ID: OT1_philybla_1

Principal Investigator: Pierre Hily-Blant

Time: 29.4 hours priority 1

Category: Galactic Other

Summary:

Nitrogen is the fifth most abundant element in the local Universe. It is essential component of molecules associated to Earth-type life. Yet, the reservoir of nitrogen in the dense ISM, where stars, and ultimately planets, form, is not known. This is for good reasons. The main reservoir of gas-phase nitrogen are expected to be N or N2, and it is likely that most of the nitrogen be indeed frozen-out on dust grains in the form of ammonia ices. However, N and N2 are not observable in the shielded environments characterizing the embryos of star-forming regions. Hence, all what is know about nitrogen must rely on indirect observations of N-bearing molecules, the lightest (and thus among the easiest to form) of which are hardly detectable from the ground. To date, and despite longstanding efforts, our comprehension of the chemistry of nitrogen remains elusive. The HSO/HIFI instrument is opening new avenues in this respect, allowing astronomers to readily detect nitrogen hydrides and several key species of the nitrogen chemistry. This is the aim of this proposal. We propose the observation of key species that are observable only with Herschel. Those include NH, NH2 and NH3 (in their ortho and para forms), as well as their deuterated isotopologues, and other pivotal species like CH and CH2. This corpus of observations in order will allow to assess our understanding of the chemistry of nitrogen in dark cloud conditions, and answer the fundamental and open question, whether dust processes are necessary catalysts in this chemistry.

High-J lines of HCN as tracer of feedback processes in high-mass star formation

Proposal ID: OT1_pschilke_2

Principal Investigator: Peter Schilke

Time: 16 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

The mechanisms involved in the formation of massive stars, and particularly the process of feedback from already-formed stars, are not well understood. Recent models of star formation have started to investigate the role of mechanic (outflows) and radiative feedback, but observational evidence for these processes altering the star formation process has been lacking. In an analysis of the HEXOS data, we have found that high-J HCN lines are perfectly suited to study this phenomenon: in SgrB2(M), they show a reversal of the infall profile at high J, indicating that in the inner regions the onset of feedback is halting the inflow, and the gas is actually expanding again.

In this proposal, we want to apply this powerful technique to a sample of high-mass star-forming cores at similar stages of development as SgrB2(M).

Luminosity and mass loss history of the high-mass protostar IRAS20126+4104

Proposal ID: OT1_rcesaron_1

Principal Investigator: Riccardo Cesaroni

Time: 11.5 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

The main goal of this project is to estimate the luminosity of the high-mass protostar IRAS20126+4104 and obtain a direct measurement of the mass loss rate of the associated bipolar outflow. This is a well studied object, where a 7 Msun protostar is surrounded by a Keplerian disk and powers a bipolar outflow. The relatively small distance (1.64 kpc) and the limited complexity of the surroundings of this object, combined with the unique angular resolution of HERSCHEL in the far-IR, make it possible to reconstruct the spectral energy distribution and thus obtain an accurate estimate of the stellar luminosity. Knowledge of the mass and luminosity will set constraints on the evolutionary stage of the young stellar object. We also want to observe the OI 63 micron line which is strictly related to the mass los rate of the outflow. The latter can thus be obtained independent of the usual drawbacks (uncertain molecular abundance, unknown outflow inclination angle) of the estimates obtained from CO and other typical outflow tracers. Moreover, since the outflow is precessing, one can also relate the position along the outflow with the time of ejection and reconstruct the mass loss rate history of this object. We will also observe the OI 145 micron line to verify possible opacity effects in the 63 micron line, from the ratio between the two lines. These data will be complemented with observations of the CI line to image possible photo dissociation regions, plus a number of CO lines observed with SPIRE, PACS, and HIFI, to reconstruct the excitation structure of the outflow, both in space and velocity.

A Herschel SPIRE/PACS Imaging Survey of the MonR2 and CepOB3 Molecular Clouds

Proposal ID: OT1_rgutermu_1

Principal Investigator: Rob Gutermuth

Time: 41.3 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose complete surveys of the MonR2 (830 pc) and CepOB3 (700 pc) molecular clouds with SPIRE and PACS on Herschel to complement extant surveys with NEWFIRM and Spitzer at near-IR and mid-IR wavelengths, respectively. These two clouds complement cloud surveys of Orion and the Gould Belt clouds, as they are actively forming both low and high mass stars, and they are found at different evolutionary states relative to Orion. They are also closer to the galactic plane than Orion, implying a higher density of background stars and more reliable extinction maps. This study will impact our knowledge of two essential problems in star formation: the physical factors which determine the star formation rate and the initial mass function. We will produce high resolution maps of the large-scale dust column density and temperature from the SPIRE data maps and compare these to the density of protostars to determine the rate of star formation per area relative to the gas column density. We will use this data to reconcile inconsistent star formation rate vs gas column density correlations recently reported in the literature by measuring this relationship by independent means in a single cloud. To study the IMF, and its possible dependence on environment, we will look at factors that may determine the IMF: the mass of the pre-stellar core and the protostellar luminosity (which has a significant contribution from accretion). Pre-stellar cores will be extracted and characterized in terms of structure and mass. By combining the protostellar SEDs from Spitzer with PACS photometry, particularly 70~$\mu$m, better characterization of protostar bolometric luminosity and temperature distributions can be produced and compared among the clouds observed. With this data, we can examine how the core mass function and protostellar luminosity function can vary with density of young stars and cores and with the local conditions of the molecular gas, and how these vary from cloud to cloud.

PACS and SPIRE observations of Galactic anomalous emission sources.

Proposal ID: OT1_rpaladin_1

Principal Investigator: Roberta Paladini

Time: 13 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Despite the increasing evidence that the anomalous emission is a new physical mechanism acting in the diffuse interstellar medium, the nature and distribution of this component remains elusive. The currently most favored models attribute the observed microwave excess to rotating very small dust grains (PAHs and VSGs). Nonetheless, the infrared properties of the sources which, to date, are known to exhibit this type of emission are very poorly known mostly due to the limited angular resolution and frequency coverage of DIRBE and IRAS data.

We propose HERSCHEL PACS and SPIRE mapping of three Galactic anomalous emission sources (LDN 1780, LDN 675 and LDN 1111). This data, when combined with ancillary NIR and mid-IR data of comparable angular resolution (mainly from Spitzer), and coupled with available dust models, will allow to set tight constraints on the radiation field in the emitting sources as well as in their immediate surroundings. Such constraints, in turn, will allow to estimate the abundances of PAHs, VSGs and BGs, hence to shed light on the potential link between these dust populations and the observed microwave excess.

HIFI Observations of the C18O and C17O J = 5-4 to 15-14 Transitions in Hot Cores: A Direct Method to Obtain Total Column Densities

Proposal ID: OT1_rplume_1

Principal Investigator: Rene Plume

Time: 35 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Using CO to trace the total H2 column density in molecular clouds is a common practice. This practice, however, can be fraught with difficulties. First of all, CO is often optically thick, especially towards the highest column density regions in molecular clouds (where stars are born) and so the analysis of CO emission requires complicated radiative transfer modelling. Second, the conversion from CO to H2 relies on an often unknown conversion factor and so a canonical value of 1:10,000 is usually assumed. This is especially problematic in cold (T < 20 K) dense gas, in which CO can be depleted onto dust grains. However, in warm gas surrounding massive or even low mass protostars (so called "hot cores''), depletion can be circumvented and the rarer isotopologues (13CO, C18O and C17O) are optically thin enough that they can be used as column density tracers.

We propose to use Herschel/HIFI to directly derive total C18O and C17O column densities in a number of high mass protostars. The method we will use offers an unprecedented opportunity to derive this fundamental quantity in a model independent fashion. The basic idea is simple. For an optically thin line the observed integrated emission is proportional to the column density in the upper state. This quantity can be derived without any assumptions regarding density or temperature. If you observe enough transitions of C18O one can simply estimate the total column from summing all the observed states and correcting for the missing population. In high mass star forming regions, the high densities and temperatures mean that the higher-J states can be significantly populated and an estimate of the total column density based on only a few low energy transitions can be seriously in error. With HIFI, we have access to > 7 high-J C18O transitions, and therefore we can calculate the total C18O column densities with great accuracy.

Water emission from outflows and hot cores in the Cygnus X proto-stars

Proposal ID: OT1_sbontemp_1

Principal Investigator: Sylvain Bontemps

Time: 36.2 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

The impressive first results from the WISH GT key program by van Dishoeck et al. indicate that water emission is bright towards the embedded proto-stars of all masses. These emissions are tracing outflows and warm inner regions of the collapsing envelopes (radiatively heated hot cores) which are unique probes of the cooling of these regions and of the kinematics of the dense warm gas. But WISH is limited by the reduced number of targets, and by the unavoidable biases introduced by the stringent selection of sources. The intermediate to high mass range is critical to challenge protostellar evolution models, and we argue that water emission from a complete sample of proto-stars in this mass range will be an important piece of knowledge for outflows to trace indirectly accretion and for hot cores to follow their time of appearance. Only Cygnus X is nearby and rich enough to provide a large sample of such proto-stars. We propose here to dramatically change the level of significance of WISH results by observing as many as 92 proto-stars covering the (final stellar) mass range of 3 to 20 Msun in the single complex of Cygnus X.

Conditions for Giant Planet Formation: a Herschel Study of Raw Materials in Selected Debris Disks

Proposal ID: OT1_sdodsonr_1

Principal Investigator: Sarah Dodson-Robinson

Time: 26.5 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Due to the observational difficulties of spatially resolving protostellar disk midplanes near the ice line, where most giant planet formation is thought to take place, most constraints on the possible locations and methods of giant planet formation have come from theory. We propose to use Herschel PACS and SPIRE photometry, and PACS spectroscopy, to observe five debris disks around Solar-type stars, in order to (1) observe young systems where giant planets cannot form, and (2) identify the available raw materials for typical planet formation. We will constrain the range of dust temperatures, and search for crystalline forsterite grains, as well as indirect diagnostics of ice and refractory carbon through deep line scans for [C II] (158 microns) and [O I] 63.2 microns.

Synchrotron Radiation in Stellar Flares

Proposal ID: OT1_shawley_2

Principal Investigator: Suzanne Hawley

Time: 30 hours priority 2

Category: Galactic Other

Summary:

Stellar flares emit copious radiation at X-ray, optical and radio wavelengths but have not yet been investigated in the far-infrared. Recent observations at millimeter wavelengths provide tantalizing evidence that a population of ultrarelativistic electrons may be accelerated during flares and may provide significant synchrotron radiation in the far-infrared and sub-millimeter wavelength regimes. Herschel observations of two very active stars with a history of strong, frequent and energetic flares will probe this wavelength regime for the first time. Ultrarelativistic electrons may hold the key to explaining the photospheric flare heating that is necessary to produce the observed white light flare emission which carries more than half of the total flare energy. Our team brings together experts in stellar flare optical and radio observations, particle acceleration and plasma physics, and radiative hydrodynamical atmosphere modeling. We propose to carry out a Herschel flare observing campaign together with several ground-based optical and radio observatories and to produce a new generation of flare models that include the ultrarelativistic electron population.

Hi-GAL360: the crucial step toward a global understanding of star formation in the Milky Way

Proposal ID: OT1_smolinar_5

Principal Investigator: Sergio Molinari

Time: 276.8 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Hi-GAL360 will use PACS and SPIRE in parallel mode to obtain a 5-band photometric survey of the Outer Galactic Plane (OGP, beyond the solar circle) in the longitude range complementary to the Hi-GAL Open Time KP, i.e., 68° < l < 288° in a 2°-wide strip in latitude following the mid-plane of emission.

Hi-GAL360 data will enable a complete census of temperature, mass, density, column density and luminosity of filaments, clumps, and cores in the less confused outer Galaxy, where the assembly of filamentary structures and clouds and their fragmentation into clumps and cores can be uniquely characterised in low-metallicity and HI-dominated environments that are so different with respect to the inner Galaxy.

A complete OGP survey is required to obtain a statistically significant sampling of Galactic diversity - the full range of spiral arm, inter-arm, dust cloud, and star formation region properties - avoiding biases introduced by the study of specific or limited regions.

Hi-GAL360, together with Hi-GAL, will chart the Star Formation Rate and Efficiency from the Galactic Center to the far outer Galaxy, mapping the location and properties of star formation thresholds, thus providing the much needed connection between global scaling laws and the diversity of physical processes at work in the Galaxy. It will lay the foundations for a predictive, quantitative model of how star formation is triggered and regulated on all scales in the Milky Way. Such a model is vital to a full understanding of galaxy formation and evolution.

The merged Hi-GAL360/Hi-GAL `Atlas of the Galaxy' will provide essential `ground truth' for the interpretation of Herschel data on other galaxies from the Local Group to the high-redshift Universe where these objects are blended, and it will be the Herschel legacy that will remain unsurpassed for decades as the definitive survey of far-IR emission from the Galaxy.

Given our demonstrated community-oriented approach, we again waive our proprietary period.

Measuring Emissivity Indices of Dust in Dense Cores with the SPIRE/FTS

Proposal ID: OT1_sschnee_1

Principal Investigator: Scott Schnee

Time: 6.2 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Maps of the thermal emission from dust in nearby star-forming regions have revealed an apparent similarity between the mass distributions of dense cores (CMF) and the stellar initial mass function (IMF). However, deriving the mass of a core from measurements of dust emission is not straightforward. The primary difficulty comes from uncertainty in the dust emissivity, and in particular the slope of the dust emissivity at long wavelengths (the emissivity spectral index). Ground-based observations of the continuum emission from cores suffer from atmospheric contamination, so the best way to derive the emissivity spectral index is from space-based observations. Here we propose to use SPIRE/FTS to map the spectral energy distribution (SED) in a sample of dense cores and constrain the emissivity spectral index of the dust emission. These observations will be supplemented with GBT ammonia observations to break the degeneracy between temperature and the emissivity spectral index inherent in SED fits. We will then be able to derive much more accurate core masses, test the similarity between the CMF and the IMF, and search for variations of the dust properties with environmental factors such as temperature and density.

WATCH - WATer Chemistry with Herschel

Proposal ID: OT1_swampfle_1

Principal Investigator: Susanne Wampfler

Time: 19.4 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Water is one of the most abundant species in star-forming regions and plays important roles in both the energy balance, acting as a coolant, and the chemistry of star formation. Many of the species involved in the water chemistry emit in the far-infrared and are thus not observable from ground based facilities because of atmospheric absorption. Therefore, the Herschel Space Observatory provides a unique opportunity to study the chemical reactions involved in the formation and destruction of water and to probe the energetic processes in star-forming regions. Previous results from Herschel have shown that two species, OH+ and H2O+, that were thought to be important in the water chemistry of young stellar objects, are now mainly attributed to foreground clouds. These results raised the question on which chemical paths the formation and destruction of water takes place in the interior of protostellar envelopes. In this proposal, we plan to observe the different formation and destruction routes of water in a sample of eight nearby young stellar objects, which were chosen to cover a broad range of masses, luminosities and evolutionary stages. We propose to observe H3O+ and HCO+, two species that are closely linked to the formation and destruction of H2O and require high temperatures for excitation, in serveral high-J lines. This effort is complementary to the observations of H2O and OH done in the 'Water in star-forming regions with Herschel (WISH)' key project. The combination of the information from the H2O, OH, H3O+ and HCO+ emission will tell us on which routes the formation and destruction of H2O in protostellar envelopes proceeds.

Unraveling the Mysteries of Complex Interstellar Organic Chemistry using HIFI Line Surveys

Proposal ID: OT1_swidicus_1

Principal Investigator: Susanna Widicus Weaver

Time: 42 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We propose HIFI spectral line surveys of interstellar clouds to probe the influence of physical environment on molecular complexity. We will observe a statistically-significant sample of sources, cover a range of physical environments, and target selected frequency windows containing transitions from several known complex organic molecules. The goal of these observations is to correlate the relative abundances of organic molecules with the physical properties of the source (i.e. temperature, density, age, dynamics, etc.). Our broader research goal is to improve astrochemical models to the point where accurate predictions of complex molecular inventory can be made based on a given source's physical and chemical environment. The information gained from our proposed Herschel observations will serve as a benchmark for these astrochemical models and holds the promise of significantly advancing our understanding of interstellar chemical processes.

Probing the HH111 Molecular Outflow with Herschel

Proposal ID: OT1_tbell_1

Principal Investigator: Tom Bell

Time: 17.4 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Outflows play a crucial role in star formation, since they carry away angular momentum from the protostars that drive them, allowing accretion to continue and the protostars to grow. They also represent a fossil record of the mass loss from their young hosts, providing valuable insights to the processes that govern accretion and outflow. Though jets and molecular outflows have been the subject of much scrutiny, the mechanisms responsible for launching and collimating the gas are still unclear and the relationship between the narrow optical jets and larger molecular outflows they accompany has still to be determined.

In order to understand the vital role of outflows in star formation, a detailed characterization of their physical, chemical and kinematical properties is essential. Accurate values for the mass, mass transport rate and momentum in outflows can then be derived to test competing formation scenarios, and the shock conditions can be determined. The HH111 jet and associated molecular outflow and CO bullets represent an excellent prototype of these outflow phenomena in which to accomplish this. We therefore propose to obtain a complete physical, chemical and kinematical picture of the hot molecular gas in the HH111 jet with Herschel by performing HIFI observations of selected CO rotational lines, SPIRE FTS mapping spectroscopy of the outflow region and SPIRE and PACS photometric maps of the same region. Together, these observations will enable a comprehensive study of the molecular gas and dust contained in the HH111 outflow, allowing an unparalleled determination of its physical properties and the role it plays in the mass loss from the central protostar. This, in turn, will give key insights into the mechanisms that power outflow phenomena in general.

Probing The Unique Environment Around Sgr A*

Proposal ID: OT1_tbell_2

Principal Investigator: Tom Bell

Time: 40 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We propose to study the extreme conditions in the molecular gas surrounding Sgr A* by obtaining a full spectral survey of this source with Herschel/HIFI. This will provide a complete chemical inventory, containing multiple transitions spanning a broad range of excitation conditions, and will constitute a unique resource with which to explore the diverse physical processes at work and confront current models with important new constraints. The molecular gas in this circumnuclear disk also serves as a template for the study of central regions of other galaxies, helping to elucidate the properties in those distant sources. These data will also include absorption lines from many important hydrides in diffuse clouds along the line of sight, and we will also perform deep integrations at specific frequencies to target key metal hydrides, which will allow depletion, diffuse cloud chemistry and key chemical reactions to be probed. The plethora of emission and absorption lines that these observations will provide, across a frequency range that is largely inaccessible from the ground, will constitute a detailed chemical and physical portrait of the interstellar medium under a diverse and extreme range of conditions. As such, the proposed spectral survey and deep integrations represent a valuable legacy dataset for the future.

Extinction towards the Galactic Center

Proposal ID: OT1_tfritz_1

Principal Investigator: Tobias Fritz

Time: 6.7 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We want to use far infrared hydrogen recombination lines for 6.7 hours from the Galactic Center with Herschel/PACS. We then combine the far infrared measurements with existing near and mid infrared measurements of hydrogen lines for obtaining the differential extinctions between the lines. Above 100 microns the extinction is below 0.05 mag such that be obtain the absolute extinction over the full infrared.

Firstly the absolute extinction can be used for following goals:

Many of the bright stars in the Galactic Center are massive, young O- or WR-stars. Their stellar types and ages have been derived individually by means of atmosphere modeling.

Putting a reliable, absolute magnitude scale to the near infrared emission from Sgr~A* allows one to relate properly radio, submm, near infrared and X-ray data with each other.

The 'red-clump' feature in the HR-diagram is well visible for the Galactic Center stars. Its apparent magnitude combined with the extinction measures the distance to the Galactic Center, R_0, independent from other methods.

Secondly the extinction law in the whole infrared regime can be used for testing the surprisingly flat extinction law in the mid infrared found by previous work constraining. This extinction law can then constrain dust grain modells.

PACS Imaging of the CepOB3b Cluster: Observing the Truncation of Disks in a Rich Young Cluster

Proposal ID: OT1_tmegeath_5

Principal Investigator: Tom Megeath

Time: 8.3 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose deep PACS 70 and 160 micron imaging of the Cep OB3b cluster. After the Orion Nebula Cluster (ONC), Cep OB3b cluster is the 2nd nearest, large (2000 member), young (3-5 Myr) cluster to the Sun. It is older and more evolved than the ONC, making it a superb laboratory for studying the evolution of disks in the cluster environment. The cluster contains two distinct, coeval sub-clusters. Spitzer observations show a lower disk fraction in the sub-cluster containing an O7 star, suggesting that disks are being photoevaporated and destroyed by the UV radiation from the O star. The proposed PACS observations, coupled with near-IR and mid-IR photometry, will measure the truncation of the remaining disks by UV radiation. With these data, we will probe the truncation and alteration of disks in an environment which is likely to be similar to that experienced by the young Solar Sytem.

FIR study of dust processing in the Carina region

Proposal ID: OT1_tonaka_2

Principal Investigator: Takashi Onaka

Time: 13.1 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

We propose to study dust processing and search for a signature of dust properties associated with massive star formation in a region of the Carina nebula, where a clear variation has been found by mid-infrared spectroscopy. ISO/SWS and Spitzer/IRS observations indicate the presence and variation of the feature around 22 micron in an interface region between the ionized gas and molecular cloud in the Carina nebula. The feature appears to be strongest around the ionization front and significant dust processing is indicated to take place. We propose to study this highly interesting region by PACS SED and line spectroscopy modes and SPIRE spectroscopy. We investigate the variation in the dust size distribution and degree of coagulation and search for possible features associated with the massive star-forming region. The present observation will provide the systematic far-infrared data of the region where clear evidence of dust processing is indicated for the first time and give crucial information on the study of material evolution in the interstellar medium.

Depletion and Deuteration of Ammonia in Pre-stellar Cores

Proposal ID: OT1_tpillai_1

Principal Investigator: Thushara Pillai

Time: 2.6 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Molecular line studies of dense cores have shown that NH3 is an excellent tracer of pre-stellar gas, which is the earliest phase in the formation of stars. Unlike most other molecules (mainly CO), ammonia does not deplete out in dense cores. This apparent non-depletion is still a mystery. To make matters worse, ammonia abundance has been shown to increase at the highest densities. The answer might lie in the choice of ammonia transitions that have been observed to propose non-depletion. These are the para-NH3 23 GHz rotational transitions that have critical densities of ~ 10^4 cm^-3 while NH_3 depletion is expected to occur at densities two orders of magnitude higher! However, the NH3 ground state transition at 572.5 GHz observable with Herschel has a critical density few orders of magnitude higher, close to where we expect to see depletion. We propose to unravel the ``seeming'' ammonia non-depletion in dense cores by mapping the densest region of a pre-stellar core (with heavy CO depletion) in ammonia. The molecular depletion is closely linked to molecular deuteration. NH2D is expected to be abundant in cold regions with significant CO depletion. The D/H ratio derived from the ratio of NH3 and NH2D column densities is consistently higher than that derived from other molecules, most importantly N2H+. The discrepancy is worse for higher mass cores where NH2D/NH3 ratios of up to 0.8 have been found! While other astrochemical processes may be at play, one of the prime suspects is again the poor choice of para-NH3 (1,1) transitions as dense gas tracer. We believe that this leads to ammonia column densities being underestimate. Here, we propose to observe NH3 J_K= 1_0-0_0 toward a high mass core where very high deuteration ratio has been found and derive the "true" NH3 column density. This proposal will address two fundamental issues with our understanding of ammonia chemistry in dense cores, (i) the seeming ammonia non-depletion and (ii) very high ammonia deuteration.

Under pressure: Revealing the thermal and spatial structure of strongly irradiated clouds in the Carina Nebula, the nearest laboratory of massive star feedback

Proposal ID: OT1_tpreibis_1

Principal Investigator: Thomas Preibisch

Time: 6.9 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

The Carina Nebula contains some of the most massive and luminous stars in our Galaxy and is the best site to study in detail the physics of violent massive star formation and the resulting feedback effects, i.e.~cloud dispersal and triggering of star formation. We are engaged in a comprehensive multi-wavelength study of the Carina Nebula. Our new X-ray and near-infrared data, and mid-infrared data reveal and characterize the full stellar population. We also have used LABOCA at the APEX telescope to obtain a wide-field sub-mm map of the Carina Nebula; while it shows the morphology of the cold clouds in unprecedented detail, these single wavelength data do not permit to determine cloud temperatures, and thus cloud column densities and masses. Here we ask for 7.2 hours SPIRE/PACS time to map the full spatial extent of the clouds (5.4 square-deg.) simultaneously at 5 wavelengths. The HERSCHEL maps will yield fluxes at the critical far-IR wavelengths and allow us to reliably determine cloud temperatures, column densities, and thus cloud masses. This will yield a complete inventory of all individual clouds in the complex, down to cloud masses of 1 Msun, and allow us to detect the youngest and most deeply embedded protostars (down to 0.1 Msun). We will map large-scale temperature gradients and changes in the dust properties that are expected as a consequence of the strong feedback by the massive stars, and establish and compare the clump mass functions in different parts of the complex. By comparison with similar HERSCHEL data for other star forming regions, we can address the question of how the particularly high levels of massive star feedback influence the evolution of the clouds and the star formation process. These HERSCHEL data will also reveal the small-scale structure of the irradiated clouds and allow a meaningful comparison to our dedicated numerical simulations of the disruption of molecular clouds, the origin of the observed pillar-like structures, and the triggering of new stellar generations.

Structure of translucent clouds observed with HIFI [CII] 1.9THz and in H2 in absorption by FUSE

Proposal ID: OT1_tvelusam_1

Principal Investigator: Thangasamy Velusamy

Time: 22.7 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We propose HIFI observations of 1.9 THz (158 micron) [CII] line emission in selected 27 lines of sight (LOSs) which have been observed in H2 absorption in UV by FUSE, and three observed in [CII ]2325A absorption by STIS. [CII] observations provide a powerful probe of warm diffuse clouds, and [CII] is a useful as a tracer of their warm H2 content. By combining FUSE and STIS which directly detects H2 and C+ in absorption and the HIFI [CII] data we can better constrain many of the physical conditions in the cloud including the density and pressure of the C+ gas. The [CII] line emission spectra will be complimentary to those observed in absorption in UV and, in addition to its extremely high velocity resolution, help us resolve the narrow absorption features in the H2 and HI gas. A comparison of the molecular H2 column densities inferred from the 1.9THz [CII] line in the clouds along the FUSE/STIS LOS with those directly measured by them will validate the interpretation of the HIFI [CII] emission observed by larger scale Galactic surveys. We request 22.7 hrs of observing time on HIFI in band 7b.

HIFI studies of the small-scale structures in the Galactic diffuse clouds with [CII] and [CI]

Proposal ID: OT1_tvelusam_2

Principal Investigator: Thangasamy Velusamy

Time: 33.2 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

The 1.9 THz [CII] observations provide a powerful probe of warm diffuse clouds, because they can observe them in emission and are useful as a tracer of their molecular H2 not directly traced by CO or other means. HIFI observations of [CII] provide a high resolution of 12 arcsec, better than that for single dish CO (> 30 arcsec) maps, and much better than HI (>30 arcsec). Thus with HIFI we have an opportunity probe the small scale structures in diffuse clouds in the inner Galaxy at distances > 3 kpc. To study the structure of diffuse ISM gas at small scales we propose HIFI maps of 1.9 THz (158 micron) [CII] line emission in a selection of 16 lines of sight (LOSs) towards the inner Galaxy, which are also being observed as part of the GOT C+ survey of [CII] in the Galactic plane. GOT C+ provides mainly single point spectra without any spatial data. Maps of [CII] will constrain better the cloud properties and models when combining [CII] and HI data. The proposed OTF X map will be along the longitude and latitude centered on 18 selected GOT C+ LOS over a length of 3 arcmin in each direction, which is adequate enough to provide sufficient spatial information on the small scale structures at larger distances (>3 kpc) and to characterize the CII filling factor in the larger beams of the ancillary (HI, CO, and CI data). The [CI] 609 & 370micron and the 12CO(7-6) (which lies within the CI band) are excellent diagnostics of the physical conditions of transition clouds and PDRs. We will use the ratio of the [CI] lines to constrain the kinetic temperature and volume density of the CII/CI/CO transition zones in molecular clouds using radiative transfer codes. We also propose OTF X maps in both the [CI] lines for all CII target LOSs. We anticipate fully resolved structural data in [CII] on at least 300 velocity resolved clouds along with their [CI] emissions. We request a total of 33.2 hrs of HIFI observing time.

Tracing Remnant Gas in Planet Forming Debris Disks : Confronting Theories of Ice-Giant Planet Formation

Proposal ID: OT1_vgeers_2

Principal Investigator: Vincent Geers

Time: 4.9 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Recent studies of gas emission lines with Spitzer and sub-millimeter telescopes have shown that 10-100 Myr old stars with debris disks have too little gas left to form Jupiter like gas giant planets. Whether enough gas remains in these systems to form ice giant planets is still unanswered. The [OI] emission line at 63 micron is the most sensitive tracer of gas in the ice-giant region of 10-50 AU in disks, and Herschel PACS is therefore uniquely suited to test theories of ice-giant planet formation. We propose to obtain PACS line spectroscopy of [OI] (63 micron) for a carefully selected sample of four young stars from the FEPS Spitzer Legacy Science Program with ages from 10 to 100 Myr. These extremely well systems harbour prominent debris disks that could be in the process of forming ice giants such as Neptune and Uranus. The proposed observations will probe down to gas masses of 0.3-4 Earth masses, and allow us to constrain prospects for ice giant formation, measure gas-to-dust ratios of 1-10 in evolved disks to compare with planet formation / disk evolution models, and put constraints on whether the dust dynamics in these systems is driven by the remnant gas or by the radiation.

The origin of H2O+ in dense clouds

Proposal ID: OT1_vossenko_4

Principal Investigator: Volker Ossenkopf

Time: 18.1 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We try to resolve the chemical evolution of oxygen hydrides in radiatively heated dense clouds. This involves in particular H2O+ and chemically related species, which are formed by gas-phase reactions initiated by cosmic ray ionization in diffuse clouds, but may be predominantly produced by the evaporation of icy grain mantles and the subsequent ionization of water by UV radiation in heated dense clouds. We will investigate the full chain of species OH+, H2O+, H3O+, OH, and H2O, connected by gas phase reactions, to quantify the contribution of ice evaporation in dense clouds.

We propose to observe these species in the dense layers known to exist in two massive star-forming regions, DR21(C), where indications of H2O+ from hot gas were already found and where the hot layer is affected both by UV radiation and a strong shock from a bipolar outflow, and Mon R2, a PDR with similar parameters but no indications of shock processing of the hot layer.

Differences between the results from the two sources will provide an estimate for the impact of shocks on the H2O+ production. By comparing the observed abundances of OH+, H2O+, H3O+, OH, and H2O with steady-state PDR models, we will be able to quantify the amount of water that is fed into the gas phase by the evaporation or photodesorption of ice mantles from dust grains.

The chemistry of CH+ in disks around HerbigAe stars

Proposal ID: OT1_wthi01_1

Principal Investigator: Wing-Fai Thi

Time: 1.5 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Chemistry of protoplanetary disks have focused on the inner (R<5AU) or outer disk (R>100 AU) but not in the 5-30 AU region where giant planets are formed. The hot organic chemistry of 5-30 AU region can be explored with Herschel. We tentatively detected CH+ emission in four disks at 72.14 micron. CH+ is a starting ion in the reaction network leading to methane, HCN, of C2H2. Two of the disks are known to have an inner gap up to ~10AU. We propose to obtain deep observations of three rotational transitions of CH+ with Herschel-PACS. The aims of the proposals are: 1) confirm the detections, 2) study the excitation condistions of CH+ in disks, 3) explore the hot carbon chemistry in disks with our chemical code, 4) understand the role of inner gap in the disk chemistry.

Herschel Imaging of the remnant of a hot disk that is gone.

Proposal ID: OT1_zwang01_1

Principal Investigator: Zhongxiang Wang

Time: 1 hours priority 1

Category: Circumstellar/Debris disks

Summary:

The millisecond pulsar (MSP) binary J102347.67+003841.2 is unique since it once contained an accretion disk around 2001, indicating that it is the first such binary found at the end of its transition from a low-mass X-ray binary to a radio MSP. The accretion disk was likely disrupted by the pulsar wind from the MSP. Using Spitzer, we have found mid-infrared excess emission in the source, probably arising from the remnant of the previous accretion disk. Here we request Herschel/PACS imaging of the binary, seeking to detect the source at 70 and 160 microns. The detection will help establish the general properties of the putative remnant, which is part of our effort to fully study this rare MSP binary system.

Search for fallback disks around nearby, slowly rotating neutron stars

Proposal ID: OT1_bposselt_1

Principal Investigator: Bettina Posselt

Time: 15.5 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We propose to observe eight nearby, slowly rotating, strongly magnetized neutron stars with the Herschel PACS detector to search for dusty fallback disks and infer their properties. Such disks are generally predicted to be created after the supernova explosion by ejecta that fail to escape and remain bound. However, despite several searches, neutron star fallback disks remain elusive. Only one possible fallback disk has been detected so far -- around the slowly rotating (P = 8.7 s) magnetar 4U 0142+61 at a distance of around 4 kpc. Our proposed target sample includes seven radio-quiet, middle-aged neutron stars with similar periods, P = 3 - 12 s, and strong magnetic fields, B = (1 - 3) x 10^(13) G (the so-called Magnificent Seven), and one radio pulsar with similar P and B. All targets are much closer than 4U 0142+61 (d < 1 kpc). Their slow rotations allow the fallback disks to survive and increase the chance for disk detections. Our targets belong to the class of neutron stars that is discussed as a link between the ordinary rotation-powered pulsars and the magnetars. The possession of a fallback disk is one of the key parameters for understanding these different populations.

Dust processing and grain growht in Keplerian discs around binary post-AGB stars.

Proposal ID: OT1_cgielen_2

Principal Investigator: Clio Gielen

Time: 15 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We propose to use the Herschel-PACS/SPIRE instruments to study the far-infrared continuum emission of a sample of evolved stars, both in the Galaxy and the Large Magellanic Cloud (LMC). All these stars are proven or suspected binaries surrounded by a long-lived circumbinary disc. Our analysis of the SPITZER mid-infrared spectra of these stars showed that grain processing is very effcient in these discs, despite the very short evolutionary timescale of the post-AGB central star. Extending the spectral energy distribution (SED) to far-infrared wavelengths is an essential complement in constraining the disc characteristics. The long-wavelength flux is very sensitive to the amount of large grains, and thus the total dust mass, and grain-size distribution within the disc. The ultimate goal of our research is to study the structure, formation and evolution of the very common discs around evolved binary stars, and constrain their impact on the evolution of the binary systems.

Far-IR bands of PAHs in the Red Rectangle

Proposal ID: OT1_cjoblin_2

Principal Investigator: Christine Joblin

Time: 24.8 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Observations in the far-IR window should make a major contribution to solving two major problems in molecular astrophysics - the identity of the carriers of the Aromatic Infrared emission Bands (AIBs) and the Diffuse Interstellar absorption Bands (DIBs). The DIBs are generally attributed to carbon-based molecules but none has been assigned. Polycyclic aromatic hydrocarbons (PAHs) are commonly accepted to be the carriers of the AIBs but the hypothesis suffers from the lack of identification of individual species. This seriously limits the potential of these spectral signatures as probes of astrophysical conditions and processes.

We propose to exploit the unique capabilities of Herschel to record the far-IR emission features of PAHs in the Red Rectangle. These features are very specific to the exact molecular identity and are a very attractive route for the spectroscopic identification of PAHs. Most of them carry a sharp Q branch increasing the contrast for their detection. We ask for 24.8 hours to perform deep PACS and SPIRE FTS spectroscopy to search for these Q branches.

The unique carbon-rich Red Rectangle nebula is in an active stage of dust condensation and displays the strongest AIBs known as well as emission bands connected to the DIBs. Small molecules are underabundant and the Red Rectangle is clearly the place where the formation of large molecules can be tracked and the link between the AIB and DIB carriers should be explored.

The analysis of the bands will be performed using spectroscopic data, both theoretical and experimental, as well as Monte Carlo modelling to simulate the emission process. Even in the worst case of no band identification, comparison of model predictions with the Herschel spectra will strongly constrain the PAH model. If some lines are identified, we will apply for follow-up observations with HIFI to resolve the hot band structure of the Q branches and structure in the P and R branches.

Considering the short life of Herschel, this proposal is therefore very timely.

Molecular complexity of the O-rich pre-Planetary Nebula OH231.8

Proposal ID: OT1_csanch01_1

Principal Investigator: Carmen Sanchez Contreras

Time: 32.4 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Envelopes around evolved stars are extraordinarily efficient factories of complex molecules and dust particles that will eventually enrich the ISM. To date, most chemistry studies have focused on C-rich envelopes, expected to show the largest molecular variety and abundances. Recent observations suggest that O-rich shells may be as chemically diverse as their Carbon counterparts, however, no serious attempt has been made yet to perform a full frequency scan of such objects. We propose to carry out a line survey with HIFI of the well known, O-rich pre-PN OH 231.8, which displays fast (>400 km/s), bipolar outflows and a molecular richness unparalleled amongst O-rich AGB and post-AGB stars. Results from our exploratory mm line survey with the IRAM 30 m antenna of this object has led to the detection of hundreds of lines from different species that clearly point to non-equilibrium/shock-induced molecule formation processes in the fast flow. The HIFI could be potentially effective to reveal the dense and warm regions near the centre, which is strongly affected by shocks.

At its completion, this project will provide the sorely needed molecular inventory and abundance measurements in O-rich CSEs, which are required to obtain a better understanding of the intricate, non-equilibrium molecule formation processes in O-rich environments. We will use our radiative transfer and chemistry models to reproduce the observed spectra and empirically derived abundances, respectively, and constrain the nebular physical and chemical conditions in the envelope of OH231.

The puzzle of water vapour in carbon-rich stars

Proposal ID: OT1_dneufeld_2

Principal Investigator: David Neufeld

Time: 28 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Using the HIFI instrument, we will address the puzzling - but widespread - appearance of water vapour in carbon-rich stars. Following up on detections of water in ALL SIX carbon-rich AGB stars observed to date in a pilot study performed in the HIFISTARS Key Program, we will target additional water transitions in four stars already observed or expected to show the most luminous water emissions. The target stars are CIT6, IRAC 15194-5155, V Cygni, and S Cep, and the additional transitions are the 4(22)-3(31) and 3(12) - 2(21) transitions at 916 GHz and 1153 GHz. Combined with spectra already obtained for the low-lying water transitions, and interpreted in the context of water excitation models, the proposed observations will place strong constraints upon the location of the emitting water. We will therefore be able to distinguish between various hypotheses that have been proposed for the origin of the observed water: the vaporization of orbiting comets or dwarf planets; catalytic formation on dust grains; or chemical processes initiated by the photodissociation of CO. In addition, we will carry out deep integrations to observe the lowest 1(11) - 0(00) transition of para-water at 1113 GHz in two carbon-rich AGB stars: IRAS+40540 and V Hya; here, ortho-water has been securely detected but existing observations of the 1113 GHz para-water line yield weak detections that lack the signal-to-noise ratio needed to constrain the ortho-to-para ratio.

A detailed study of the physics and chemistry in the Planetary Nebula NGC7027

Proposal ID: OT1_Fherpin_1

Principal Investigator: Fabrice Herpin

Time: 19.4 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Molecular spectroscopy at sub-mm and FIR wavelengths is an extremely powerful tool to investigate the latest stages of stellar evolution. The process of mass loss from evolved stars is not well understood, and molecular emission offers a unique avenue to trace the kinematics and structures of such objects, from AGB stars and their successors, Planetary Nebulae (PN), to massive supergiants. In addition, circumstellar shells of evolved stars foster a remarkable chemistry, producing unusual molecular species not easily observed in other environments, including long carbon chains, anions, metal-bearing molecules, and phosphorus compounds. The mechanisms by which this chemical synthesis takes place, its relationship to dust formation, and its evolution during the AGB and post AGB-phases, are all important questions that have yet to be understood. This proposal and the related other proposals submitted by our collaborators seek to answer these questions. Through the study of the emission from specific species combined with selected spectral surveys towards the PN NGC7027, we aim at understanding more specifically the physics taking place in the beginning of the PN stage, more exactly to precise the physical conditions ruling the molecular envelope, the ionized region and the thin interface between both, i.e. the PDR, through the quantification of the UV and shocks influence.

Clues to the Evolutionary History of the R Coronae Borealis Stars

Proposal ID: OT1_gclayton_1

Principal Investigator: Geoffrey Clayton

Time: 25.6 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

The unexpected discovery that the R Coronae Borealis (RCB) stars have isotopic abundances of 18O which are up to 500 times greater than those seen in other stars has increased the likelihood that these rare hydrogen-deficient carbon stars are the result of a double degenerate white dwarf (WD) merger (DD) rather than a final helium shell flash (FF). But other pieces of the puzzle have yet to be explained. For instance, a few RCB stars, including R CrB itself, show enhanced Li abundances, which favors the FF scenario. Also, IRAS images show that several RCB stars possess large dust shells which are consistent with fossil Planetary Nebula (PN) shells where the gas is no longer ionized. If these are PN shells, then that would point strongly toward the FF scenario. But other explanations for the dust shells include the FF outburst itself and new dust from the recent RCB phase. In addition, newly acquired Herschel/Spire images have called into question the reality of the shells themselves. The much improved spatial resolution over previous IRAS and MIPS images shows that some or all of the R CrB 100-micron shell is due to a cluster of galaxies lying directly behind the star. It is imperative that new high spatial resolution PACS and Spire images be obtained to verify the existence of these RCB star dust shells, as well as to analyze the morphology of the shells to deduce their nature and help decide between the DD and the FF scenarios. Furthermore, the new Herschel images, covering the wavelength range 70-500 microns, will be used together with archival IRAS, Spitzer and other datasets to produce SEDs for each star which will be modeled using Monte Carlo radiative transfer codes to determine the total dust mass, and total mass loss over the lifetime of the stars. It is a very exciting prospect that the RCB stars could be shown to be the product of a WD merger. This small group of stars would become even more interesting as they would be low-mass analogies to Type Ia supernovae.

How Cool Are Planetary Nebulae?

Proposal ID: OT1_hdinerst_1

Principal Investigator: Harriet Dinerstein

Time: 6.1 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We propose to observe the [O III] 52 and 88 micron fine-structure lines with PACS in planetary nebulae, in order to investigate whether they contain a cold and possibly metal-rich component in addition to the ordinary hot (10,000 K) material. The presence of cold gas has been proposed in order to account for the excessive strengths of optical emission lines from recombining O++ ions, and low temperatures (500 - 5000 K) indicated by some diagnostics. If planetary nebulae truly have such inhomogeneous physical conditions and abundances, this calls into question our fundamental understanding of the composition of the nebular gas, a major source of recycled material to the ISM. The FIR [O III] lines offer a unique opportunity to address this issue because, due to their low excitation energies, they are emitted from both cold and hot gas, while the optical [O III] lines arise only from hot gas. The bright 52 and 88 micron lines were easily observed in some of our sample using less sensitive, large-beam instruments such as the Kuiper Airborne Observatory (by this P.I.) and ISO-LWS. For several targets the previous observations indicate O/H values greater than solar, supporting the idea that metal-rich gas is present, but the higher angular resolution of PACS is needed in order to discern whether the metal-rich material is concentrated towards the central regions, as claimed by optical studies. For several objects we propose to also measure the 88.8 micron 13–12 H I line, which will not only provide a measurement of H+, but also a probe of temperature by comparing its strength to that of shorter-wavelength H I lines. The latter will be taken from Spitzer-IRS maps (for a few targets), and optical integrated-field unit spectral maps either already obtained, or to be obtained, at McDonald Observatory. These observations may enable us to prove or disprove the presence of cold O-rich material in planetary nebulae.

Additional Hpoint observations of large post-AGB sources from HIFIStars

Proposal ID: OT1_jalcolea_1

Principal Investigator: Javier Alcolea

Time: 13 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

One of the most spectacular phases in the evolution of intermediate mass stars takes place at the end of their lives. At the end of the AGB, the central star dashes across the HR diagram from the red giant to the blue dwarf region. At the same time, the spherically symmetric and slowly expanding circumstellar envelopes around AGB stars become planetary nebulae (PNe), displaying a large variety of shapes and structures far more complex. This transformation takes place at the very end of the AGB, and it is due to the interaction of fast and bipolar molecular winds with the fossil AGB circumstellar envelope.

The origin of these post-AGB winds is still unclear, but we know that the resulting two-wind interactions are only active during a very short period of time, ~ 100 yr, but still they are able to strongly modify the kinematics of the nebulae and re-shape them. To better understand these processes we must study the warm molecular gas component of early post-AGB sources, both pre-planetary nebulae (pPNe) and young PNe. Herschel/HIFI is very well suited at this, because its spectral coverage, high velocity resolution, and superb sensitivity.

For these reasons, 10 pPNe and young PNe were included in the KPGT HIFIStars, were a large number of spectral lines are observed in a moderate number of frequency setups, but just at the central point. In many cases this is simply enough, since most of post-AGB sources in HIFIStars are compact. However there are three cases in which the non spherically symmetric structures seen in the warm gas are larger than the beam of the telescope: OH 231.8+4.2, NGC 7027 and NGC 6302. Therefore we propose to perform some additional pointing in these three sources in a selected sample of HIFIStars frequency setups, were we have detected strong lines of CO, H2O, NH3 and OH. These observations are crucial to understand the kinematics and interactions traced by these warm gas probes, and so gain insight in the intricate problem of the post-AGB dynamics.

Characterising the Environment of Fullerene Formation

Proposal ID: OT1_jberna01_1

Principal Investigator: Jeronimo Bernard-Salas

Time: 6 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

The bulk of the dust that is injected into the interstellar medium is formed via a complex chemistry in AGB circumstellar environments, which transforms the atomic gas into molecules and dust. To date, more than 60 individual molecular species of both inorganic and organic nature and a handful of dust minerals have been identified in these outflows. These environments are also thought to be the birthplace for large aromatic species such as polycyclic aromatic hydrocarbons and fullerenes. Because of their remarkable stability, fullerenes have been predicted to survive the harsh conditions of the insterstellar medium. However, targeted searches for the presence of fullerenes in various astrophysical environments were unsuccessful or not conclusive, until now. The Spitzer mid-IR spectrum of Tc1, a young planetary nebula with a low excitation central star and a high C/O abundance ratio, shows clear traces of C60 and C70. This indicates that when conditions are favorable, fullerenes are formed in large quantities. The mid-IR spectra allow us to quantify the abundance of carbon in the fullerenes, estimate their temperature, and detect them in the solid state in circumstellar environments, but to date we have little information on the circumstellar dust or the composition of the gas. We propose to use the far-IR spectrum of Tc1 using the Herschel PACS spectrometer to study the energy balance and characterize the conditions in the circumstellar regions where fullerenes are formed.

Molecular complexity in the circumstellar envelope of the O-rich evolved star VY CMa

Proposal ID: OT1_jcernich_5

Principal Investigator: Jose Cernicharo

Time: 54 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Envelopes around evolved stars are factories of complex molecules (neutrals, anions and cations) and one of the main sites for dust formation. Most chemical studies have focused on C-rich envelopes, in particular on IRC+10216. Recent observations of metal bearing species and hydroxides in O-rich shells suggest that the chemistry in these objects can be as richer as in C-rich circumstellar envelopes. We propose to perform a complete line survey of the prominent O-rich star VY CMa with HIFI.

This study will provide, in addition to all lines of CO, H2O, HCN, SiO, SO2, a complete inventory of the molecular gas in O-rich evolved stars. The comparison with the line survey of IRC+10216 (already carried out with HIFI/Herschel) will permit to distingush the different chemical processes in these objects and the subtle role of the C/O abundance ratio in the molecular composition of the gas at different distances from the central star.

We will use our radiative transfer and chemistry models to reproduce the observed spectra and to derive molecular abundances. The data will also allow a better understanding of the physical structure of the envelope.

Shock Chemistry and Dust Processing in Interacting Supernova Remnants

Proposal ID: OT1_jhewitt_1

Principal Investigator: John Hewitt

Time: 18 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Supernova remnants interacting with dense moelcular clouds provide astroc-hemical laboratories to study heating and cooling of the dense ISM, shock chemistry, destruction and sputtering of dust, and the reformation of molecules. Water is expected to be a major coolant for shocks into dense gas, yet the number of remnants in which IR lines of hydroxyl and water are detected is very limited. We propose Herschel PACS, SPIRE and HIFI observations of three remnants with particularly high shocked gas densities, high dust and IR line luinosities, and extreme ionization environments. The scientific objectives of this proposal are: (1) to determine the abundance and excitation of oxygen-bearing molecules, (2) to study the oxygen chemistry in dense molecular gas shocked by powerful supernova remnant blast waves, and (3) to directly measure dust processing and constrain the effects of dust on shocks and oxygen chemistry.

A HIFI survery of Water Fountain stars: unveiling the inner structure of hit star envelopes.

Proposal ID: OT1_jrizzo_1

Principal Investigator: Jose Ricardo Rizzo

Time: 3 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

``Water fountain'' stars (WF) are considered key objects to our knowledge of the sun-like star evolution processed. At some point soon after AGBs, WFs would develop very fast and highly-collimated outflows, which produces H$_2$O maser emission, spread over more than 100\,\kms, when hitting the AGB previous envelope. Very recently, our group has detected low-$J$ CO and $^{13}$CO line emission arising in the cold, outer parts of the envelope. Based on these results, we ask for HIFI observations of mid- and high-$J$ lines of CO, together with a set of thermal H$_2$O lines, and CI. With these data, we plan to probe the inner, hotter, and denser parts of the envelopes, and to give some insights about the mass-loss history and chemistry; possibles PDRs will also be tested. This information will provide valuable inputs to our models, such as the total mass, and temperature profile. Some physical parameters will be also constrained. We have selected the whole sample of known WFs, a total of 14 sources (two of them still unpublished), for this project.

Measuring the electron spectrum generated by diffuse shock acceleration in the Pulsar Wind Nebula HESS J1632-478.

Proposal ID: OT1_mbalbo_1

Principal Investigator: Matteo Balbo

Time: 0.5 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Relativistic collisonless shocks propagating in plasmas are an essential ingredient to explain particle accelerators such as gamma-ray bursts, supernovae remnants, pulsar and stellar winds. Numerical simulations predict particle energy distributions but these are very difficult to test because of the lack of simultaneous observation over 20 decades of frequency, complex geometries or variability.

We propose to use SPIRE in the Small Map configuration to map the infrared emission of a very energetic and old pulsar wind nebula recently detected by HESS. Exploiting the unique resolution and sensitivity of SPIRE at 250, 350 and 500 $\mu$m, we aim at detecting the faint synchrotron emission that will be compared to existing measurements in the radio, X-rays and gamma-rays. These wavebands, located between the CMB and dust emission, are centered where the synchrotron emission from the predicted relativistic Maxwellian distribution peaks, providing a constraining flux measurement.

Herschel PACS and SPIRE investigation of water fountains

Proposal ID: OT1_mguerrer_1

Principal Investigator: Martin A. Guerrero

Time: 17 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Water fountains (WFs) are late AGB and post-AGB objects that show the earliest known manifestation of collimated mass-loss in evolved stars, with jets that have dynamical ages of only 5-100 yr and sizes as small as 100-500 AU. These fast collimated outflows, impinging onto the circumstellar material at the end of the AGB phase, are presumably responsible for the shaping of asymmetric planetary nebulae (PN), with the highly asymmetric H2O-maser-emitting PNe being presumably the immediate descendants of WFs. Therefore, WFs and H2O-PNe are key objects to study the shaping of PNe. Since their thick envelopes make them strongly obscured in the optical and near-IR, their inner circumstellar structure would be best traced at longer wavelengths.

Here we propose the acquisition of Herschel PACS and SPIRE deep imaging photometric observations of all known WFs and H2O-PNe to be added to near-IR, mid-IR, submm, and mm data to continue building the spectral energy distribution (SED) of these sources, and to check for the presence of extended material. The characterization and theoretical modeling of their SEDs will be used to infer the presence of disks and to estimate the physical parameters of circumstellar disks and envelopes, which in their turn will impose constraints on the models for the generation of jets in evolved objects.

Herschel SPIRE FTS observations of mass loss from a red supergiant in the Large Magellanic Cloud

Proposal ID: OT1_mmatsuur_1

Principal Investigator: Mikako Matsuura

Time: 7.7 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We propose to observe submillimeter CO thermal lines in the brightest red supergiant (RSG) in the Large Magellanic Cloud (LMC). We will use Herschel/SPIRE in the FTS mode. The high sensitivity of this instrument enables us to detect CO thermal lines in a RSG beyond the Milky Way for the first time. The objectives of this programme are (1) to obtain the gas mass-loss rate from the RSG, (2) to evaluate the gas-to-dust mass ratio of the RSG, and (3) compare the gas-to-dust mass ratio of the RSG with that of the LMC interstellar medium (ISM). Those will place important constraints on whether RSGs are important contributors to the chemical enrichment of the ISM.

RSGs lose a large quantity of mass through stellar winds, and these winds consist mainly of molecules whose mass can be measured by the CO thermal lines. Using the newly obtained gas mass-loss rate, and the previously obtained dust mass-loss rate, we will estimate the gas-to-dust mass ratio of the circumstellar envelope (CSE) of the RSG. Of particular interest is whether the gas-to-dust mass ratio is affected by the metallicity of galaxies. The metallicity of the LMC is about half of the solar metallicity, and we will compare our measurements with those of Galactic RSGs. Dust grains are composed of metals, and we expect a higher gas-to-dust mass ratio in the LMC. Further, we will compare our measured CSE gas-to-dust mass ratio to the LMC ISM value. That would aid determining whether these dying stars are important sources of gas and dust in the ISM, or if dust grains gain mass from the gas phase in the ISM, using the dust injected by dying stars as seeds. If the dust mass increases in the ISM, the gas-to-dust ratios should differ between the CSE and the ISM. This will provide the first direct observational evidence of whether additional dust depletion is important in the ISM.

This small (7.7 hour) project will have a great impact on our understanding of both stellar physics and ISM evolution.

Clumping in OB-star winds

Proposal ID: OT1_mrubio_1

Principal Investigator: Maria del Mar Rubio

Time: 9.4 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Massive stars, their nature and evolution, play a important role at all stages of the Universe. Through their radiatively driven winds they influence on the dynamics and energetics of the interstellar medium. The winds of OB stars are the most studied case. Commonly, the mass-loss rates of luminous OB stars are inferred from several types of measurements, the strengths of UV P Cygni lines, H-alpha emission and radio and FIR continuum emission. Recent evidence indicates that currently accepted mass-loss rates may need to be revised downwards when small-scale density inhomogeneities (clumping) are taken into account. We argue that only a consistent treatment of ALL possible diagnostics, scanning different parts of the winds, and analyzed by means of ‘state of the art’ model atmospheres, will permit the determination of true mass-loss rates. To this end we have assembled a variety of multi-wavelength data, but one crucial observational set is missing: far-IR diagnostics of free-free emission, which uniquely constrain the clumping properties of the wind at intermediate heights. We propose, therefore, to use PACS photometric mode to fill this crucial gap, studying the 70 and 110 micron fluxes of a carefully selected sample of 29 O4-B8 stars. These observations will provide the missing information to derive the clumping properties of the entire outflow, to understand the wind physics, and to obtain reliable mass−loss rates.

Hunting for missing evolved stars in the Galactic plane

Proposal ID: OT1_nflagey_1

Principal Investigator: Nicolas Flagey

Time: 39.6 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We discovered more than 400 compact shells in the MIPSGAL 24 microns survey of the Galactic plane. While only 10% of them are detected at shorter wavelengths, about a third are visible in the MIPSGAL 70 microns survey. About 15% of all the objects have been identified previously as planetary nebulae, supernova remnants, Wolf-Rayet stars, luminous blue variables. Spectroscopic follow-ups on a limited sample in the near-IR and mid-IR have revealed several dust-free planetary nebulae with very hot central white dwarf as well as a significant increase in the number of WR/LBV candidates. The remaining 350 or so unknown bubbles are also expected to be evolved stages of low- to high-mass stars that could account for the "missing" evolved stars in the Galaxy. To determine the true nature of a significant fraction of the unidentified bubbles, we propose to observe 35 of the brightest objects in the MIPSGAL 70 microns images with PACS Range Spectroscopy. With these data we will constrain the origin of their far-IR emission. Comparing the proposed spectroscopic to those of known evolved stars from the MESS Guaranteed Time Key Program will allow us to unequivocally identify the MIPSGAL bubbles. The richness of the far-IR emission spectrum of these evolved stellar objects will also provide us with dust and gas (atomic and molecular) features, with which we will characterize in details the physical conditions within each bubble thanks to modeling of these features. "Unveiling hidden details of star and galaxy formation and evolution" is the Herschel observatory's statement, as the mission brochure's cover shows. The observations that we propose here are in perfect resonance with that statement as we aim at lifting the veil on evolved stars hidden in the Galaxy. Furthermore, we propose observations that will build a synergy between two Key Programs (HiGAL and MESS).

Oxygen abundances in carbon-type Wolf-Rayet stars from PACS scan spectroscopy

Proposal ID: OT1_pcrowthe_1

Principal Investigator: Paul Crowther

Time: 8 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We seek 13.6 hours of spectral scans of the [OIII] 88 micron fine-structure line with PACS for a sample of Milky Way carbon and oxygen sequence Wolf-Rayet stars. The proposed observations will: (i) enable reliable oxygen abundances to be determined for WC stars for the first time, to test evolutionary predictions; (ii) refine the degre of clumpig in the outer stellar winds of these stars derived from existing ISO/SWS or Spitzer/IRS datasets.

Physical properties of the dusty circumstellar envelopes of two bright classical Cepheids

Proposal ID: OT1_pkervell_1

Principal Investigator: Pierre Kervella

Time: 2.8 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

The recent discovery of circumstellar envelopes (CSEs) around Cepheids is an indication that many Cepheids, if not all, are surrounded by CSEs. The bright classical Cepheids RS Pup and delta Cephei are particularly interesting members of their famous class of variable stars, as they are known to be surrounded by large CSEs that can be resolved angularly by Herschel. The requested observations will probe the cold extensions of these nebulae, and will be the first observations of any Cepheid in this wavelength domain. The present proposal aims at characterizing the dust in the CSEs using Herschel/PACS and SPIRE imaging photometry. Our scientific goal is to understand the origin of the envelopes: were they formed through evolutionary mass-loss from the Cepheids or are they made of residual interstellar material pre-existing the formation of the Cepheid progenitor? This question is of critical importance both to understand the evolution of the Cepheids themselves (stellar physics) and for the future application of the period-luminosity relation in the thermal-IR domain with the James Webb Space Telescope (extragalactic distance scale). The formation mechanism of the large dusty nebula surrounding these Cepheids is currently unknown, but two hypotheses appear plausible: (A} - it is a result of evolutionary mass-loss from the star through stellar wind, possibly linked to pulsation, that condensed into dust at large distances from the star. (B) - it is a remnant of the interstellar medium from which RS\,Pup formed, blown away by the stellar wind from the Cepheid. Our goal is to test these two hypotheses and characterize physically the cold dust in the envelopes (mass, temperature, distribution, composition).

Herschel's Opportunity to Solve the Nebular Abundance Problem While Creating a Legacy Planetary Nebulae Dataset

Proposal ID: OT1_rrubin_1

Principal Investigator: Robert Rubin

Time: 33.3 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Abundance surveys of a large sample of Galactic planetary nebulae (PNe) have led to the discovery of a group of super-metal-rich nebulae whose spectra show prominent optical recombination lines (ORLs) from C, N, O, and Ne ions. The heavy element abundances derived from ORLs for several PNe are a factor >10 higher than those derived from the traditional method based on collisionally excited lines (CELs). This ratio is called the abundance discrepancy factor (adf). A promising proposition to explain the nebular abundance problem posits that these nebulae contain (at least) two distinct regions - one of "normal" electron temperature, Te (~10000 K) and chemical composition (~solar) and another of very low Te (< 1000) that is H-deficient, thus having high metal abundances relative to H. The latter component emits strong heavy element ORLs and IR fine-structure (FS) CELs but essentially no optical/UV CELs. Efforts to directly detect these inclusions in PNe have been unsuccessful to date. However, there is mounting circumstantial evidence for their existence, such as presented in our recent paper that modeled the high-adf PN NGC 6153 using a 3-D photoionization code. The models that included the low Te, H-deficient knots fit most observations far better than did those models without the clumps. With the launch of Herschel, there is finally the capability to perform a test we've been dreaming of. Measurements have shown that the adf varies with position in a PN and is highest close to the central star. The very low Te inclusions must be cooled via FS IR lines. We propose to use Herschel to map the FS IR lines in 5 bright PNe on the largest adf list, to find if these lines peak where the adf peaks. These spectra will also provide a feast for our other team expertise/interests: a legacy dataset of molecular lines to explore PDRs, how the central star interacts with the AGB ejecta and shapes the PN, how the shocks are produced, what comprises the chemistry of the molecular ejecta, and how do PNe evolve.

A Statistical Sample of Planetary Nebulae in the Galactic Bulge: Measuring Masses and Mass-Loss Rates

Proposal ID: OT1_rsahai_2

Principal Investigator: Raghvendra Sahai

Time: 25 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We propose to exploit Herschel's unprecedented sensitivity to obtain 100-500 micron photometry for a statistical, flux-limited (in the IRAS 60 micron band) sample of Galactic bulge planetary nebulae (GBPNe), using PACS and SPIRE. The Galactic Bulge volume, offers a unique, nearby environment where a statistical population of PNe, all at roughly the same well-established distance, can be studied in order to understand these objects, test theoretical models for their formation and evolution, and address the mystery of the constancy of the PN luminosity function (an important cosmological distance indicator). Much of the mass ejected during the preceding AGB phase is expected to lie outside the ionised shells in these objects, and can only be detected via the thermal emission from cold dust.

Herschel provides us the only platform to measure the mass budgets of a statistical sample of GBPNe, and thus help us address one of the longest standing astrophysical problem: the relationship between the birth mass of solar mass stars and the mass left at the end when they die. PNe are an important contributor to the total mass return to the ISM for the old Bulge population, and the proposed observations will allow us to infer the PN contribution to the total rate of mass loss in the Bulge, a crucial input to evolutionary models. The robust constraints to the progenitor masses of PNe from our study will allow elemental enrichments to be determined as a function of initial stellar mass, providing key information for models of AGB nucleosynthesis.

The proposed observations are a critical component of a broader study comprising existing and future ground- and space-based observations that will produce a combination of nebular masses, mass-loss rates, luminosities, physical sizes, morphologies, radial velocities, ages, and chemical abundances for a statistical sample of planetary nebulae, resulting in a unique dataset describing the final stages of stellar evolution in unprecedented detail.

Searching for Interrupted Mass-Loss in AGB stars: A Herschel Survey

Proposal ID: OT1_rsahai_4

Principal Investigator: Raghvendra Sahai

Time: 13.5 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Although the massive winds of AGB stars are reasonably well understood as resulting from radiation pressure on dust grains, our knowledge of how the mass-loss rates change as stars ascend the AGB is very poor. A small number of carbon-rich AGB stars have been found with detached circumstellar shells that imply that their mass-loss rates dropped dramatically a few thousand years ago. This decrease has been hypothesised to result from a He-shell flash which is believed to occur periodically in these stars; the nucleosynthesis of carbon in this flash, and its subsequent dredge-up to the stellar surface, converts oxygen-rich stars to carbon-rich ones.

We propose to use Herschel's unprecedented far-IR sensitivity and angular resolution to make a systematic search for signatures of interrupted mass-loss such as detached shells in a list of 21 targets which includes C-rich, O-rich and S-type stars (C/O~1) to test this hypothesis. Our list has been constructed using the IRAS point-source catalog to identify objects which have "60-micron excesses": their 60 to 25 micron flux ratio is > 0.4 and thus significantly larger than the average ratio for AGB stars. This excess implies the presence of a cold, extended dust shell, and relatively little hot dust close to the star, as compared to the average mass-losing AGB star. The morphology of detached shells provides a clear indication as to its origin (circular rings due to interrupted mass-loss, paraboloidal bow-shock shaoes due to interaction of the AGB wind with the ISM): hence our proposed PACS observations will thus be able to distinguish between detached shells due to interrupted mass-loss and ISM interactions.

Herschel/HIFI observations of water fountain sources

Proposal ID: OT1_rsoria01_1

Principal Investigator: Rebeca Soria Ruiz

Time: 17 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

One of the most intriguing aspects of the evolution of intermediate mass stars is how these simply spherical balls of gas can evolve resulting in the formation of PNe, which display a variety of shapes far from being isotropic. This transformation takes place after the end of the AGB, when some post-AGB flows collide with the CSEs of the former AGB star. These envelopes, which are spherical and expanding at a low velocity, are accelerated and re-shaped due to the interaction of the post-AGB flows, which are much faster and highly bipolar. Later, the star becomes much hotter, ionizing the surrounding material and forming the PN.

This wind interaction is active only during a very short times, ~ 100 yr, and to gain insight into the subject we need to study objects in which this transformation is taking place, or it has happened very recently. So far, the earliest post-AGB sources we know about are the "water fountains". These are OH/IR sources in which, contrarily to what happens in AGB stars, the H2O masers show very wide velocity ranges, wider than OH masers. VLBI observations tell us that in "water fountains" H2O masers trace very fast bipolar outflows, with kinematic ages as short as 40-100 yr, comparable to the expected duration of the post-AGB acceleration of the envelope.

Unfortunately, the main properties of water fountain nebulae are now well known, as the masers do not provide information on the density and temperature of the gas. The usual probe, low-J transitions of CO, becomes unusable in most cases, as these sources suffer from strong interstellar contamination. We can overcome these problems with Herschel/HIFI, by observing higher J-transitions of CO, where contamination is negligible, and the strong lines of H2O and OH available within the band. Here we propose to observe six water fountains in five frequency setups, to study the molecular envelope of these sources by means of the observation of several lines of these very abundant molecules in their envelopes.

The Herschel view on supergiant High Mass X-ray Binaries: revealing the most obscured high-energy source of our Galaxy

Proposal ID: OT1_schaty_1

Principal Investigator: Sylvain Chaty

Time: 16 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Among the high-energy binary sources, a new type of sources has been recently discovered by the high-energy observatory INTEGRAL. They are constituted of intrinsically highly obscured supergiant High Mass X-ray Binaries, of which IGR J16318-4848, a compact object orbiting around a supergiant B[e] star, seems to be the archetype. These sources have been partly unveiled by means of multi-wavelength X-ray, optical, near- and mid-infrared observations. However the fundamental questions about these sources, namely their formation, their evolution, and the nature of their environment, are still unsolved. After the successful multi-wavelength observations that we have performed on these intriguing sources, we propose here to get Herschel/PACS photometric observations, in order to detect the presence and characterize the nature of absorbing material (dust and/or cold gas) enshrouding the whole binary systems. This study will allow us to get a better understanding of the formation and evolution of such rare and short-living high mass binary systems in our Galaxy.

Measurements of the Atomic Carbon Isotope Ratio in Evolved Stars

Proposal ID: OT1_smilam_1

Principal Investigator: Stefanie Milam

Time: 16 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We propose to use Herschel-HIFI to observe the atomic carbon isotope ratios of evolved stars. The sample of circumstellar envelopes to be studied are being observed by the HIFISTARS program, where the oxygen isotope ratios will be measured via H2O. The proposed observations will allow us to determine the carbon isotope ratio in various types of stars (C-rich, O-rich, and S-type) as well as constrain chemical fractionation that may occur in the outer envelopes of these objects and/or provide insight into other nucleosythetic processes that may alter the CNO-isotopic abundances. The data in this program are complimentary and will employ the results obtained from the HIFISTARS program.

The Homunculus: Clues to Massive Ejection from the Most Massive Stars

Proposal ID: OT1_tgull_3

Principal Investigator: Theodore Gull

Time: 24.3 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

Eta Carinae is a lynchpin between mass ejection by highly evolved massive stars and the enriched ISM. The Homunculus, a very dusty, neutral bipolar shell ejected in the 1840s, is known to contain at least 12 solar masses, based upon gas/dust=100. But this ejecta is very N-rich with C and O being 0.02 that of solar abundance. What dust formed and how much total mass was ejected? Our ultimate goal is to obtain the total ejected mass. We propose to obtain full spectral scans of the Homunculus with PACS and SPIRES and selected scans with HIFI. We will use these spectra to identify molecules and atomic species associated with this C- and O-depleted gas. While most of this depletion is due to CNO processing and conduction in stars > 60 solar masses, additional depletion is likely due to the first molecules and dust formed at high temperatures during the 1840s eruption. In line of sight we see overabundances of metals not ordinarily seen in the ISM: Sr, Sc, V. These metals have been trapped in atomic state due to limited O and C being available to form molecules. Yet dust has still formed. But what kind of dust? Through existing HST/STIS and VLT/UVES spectra combined with the proposed Herschel spectra and detailed modeling, we will gain much better insight on how molecules and dust can formed in depleted C,O conditions, and in turn provide an improved estimate of the total mass loss. Implications from this study apply to the first massive stars and the earliest dust in the Universe.

Characterizing the Mid/Far-Infrared Excesses of Cataclysmic Variables

Proposal ID: OT1_tharriso_1

Principal Investigator: Thomas Harrison

Time: 7 hours priority 1

Category: Galactic Other

Summary:

Spitzer and IRAS observations have shown that cataclysmic variables (CVs) are sources of mid/far-infrared emission. While the excesses detected by Spitzer have been attributed to circumbinary disks (CB), as currently envisioned, such disks could not be reponsible for the IRAS detections. If due to dust, the IRAS detections imply much more extended CB disks then previously proposed, or perhaps, dust shells ejected by ancient classical novae eruptions. Alternatively, the Spitzer and IRAS detections may be due to synchrotron emission from these objects. Recent Spitzer and radio observations have now confirmed that CVs are synchrotron sources. If most CVs are synchrotron sources, this would solve the mystery of the unexpectedly large IRAS detection rate for CVs. Both CB disks and synchrotron emission can provide additional sources of angular momentum loss. Currently, there is considerable debate in the CV community over whether the commonly invoked mechanisms for momentum loss are sufficient to explain CV evolution. If most CVs have CB disks or synchrotron jets, they could provide the additional angular momentum loss required to keep CVs contact binaries. We propose to conduct a small survey spanning the major subclasses of CVs. All eight targets have mid/far-infrared excesses. Our program requires 7.0 hr of Herschel time.

Imaging and Spectroscopy of the Infrared Shell Surrounding the Pulsar Wind Nebula G54.1+0.3

Proposal ID: OT1_ttemim_1

Principal Investigator: Tea Temim

Time: 8.9 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We propose to obtain Herchel PACS imaging and spectroscopy of G54.1+0.3, a young pulsar wind nebula (PWN) surrounded by a shell of supernova (SN) ejecta and freshly-formed dust. The dust and gas seem to be illuminated by the expanding PWN and the members of a stellar cluster in which the SN exploded, making them observable at infrared wavelengths. Our recent Spitzer study suggests that the shell contains 0.1 solar masses of dust, possibly the largest amount observed to date, and that this dust has not yet been processed by supernova remnant (SNR) shocks. The proposed observations will allow us to 1) determine the composition, temperature, mass, and spatial distribution of pristine SN dust that has not been altered by shocks, 2) search for a colder dust component to constrain the total amount of dust in the system, and 3) measure composition and velocity of the surrounding SN ejecta that will provide information on the SN progenitor and the evolution of the PWN. A Hersche study of this unique system promises to shed light on the outstanding questions regarding the nature and quantity of dust produced in SNe.

Far-IR Emission from Planetary Nebulae: Simultaneous Mapping and Spectral Probing of the Multi-Phased Dusty Gaseous System

Proposal ID: OT1_tueta_2

Principal Investigator: Toshiya Ueta

Time: 197.5 hours priority 1

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

We propose to undertake an ambitious Herschel large survey of planetary nebulae (PNs), mustering the full strengths of Herschel's broadband mapping, spectral mapping, and spatio-spectroscopic capabilities. Our proposed PN survey will exploit Herschel's unprecedented spatial-resolving power in the far-IR wavelengths to its fullest potential. We will perform (1) deep PACS/SPIRE broadband mapping to account for the coldest dust component of the nebulae in the target PNs and determine the spatial distribution of the dusty PN haloes, (2) exhaustive PACS/SPIRE line mapping in far-IR fine-structure and CO transition lines in two representative PNs to diagnose the energetics of the nebulae as a function of location in the nebulae, and (3) PACS/SPIRE spectral-energy-distribution spectroscopy at several positions in the target PNs to understand variations in the physical conditions as a function of location in the nebulae. This PN survey is distinguished from the existing MESS KPGT program by the extra dimension added by spectral mapping and spatio-spectroscopy that permit simultaneous probing of the gas and dust component in the target PNs. Through these investigations, we will consider the energetics of the entire gas-dust system as a function of location in the nebulae. Herschel will allow us to take this novel approach which has rarely been taken previously. The proposed Herschel survey will be conducted in collaboration with the recently-approved Chandra X-ray Observatory Large Project to furnish substantial PN data resources that would allow us - a community of PN astronomers - to tackle a multitude of unanswered issues in PN physics, from the shaping mechanisms of the nebulae to the energetics of the multi-phased gas-dust system surrounding the central white dwarf. The proposed Herschel survey and the approved Chandra survey, combined with the community assets from optical to mid-IR, will provide an extremely valuable and comprehensive compilation of PN resource that carries a significant Legacy value.

Low-excitation atomic emission from young planetary nebulae

Proposal ID: OT1_vbujarra_4

Principal Investigator: Valentin Bujarrabal

Time: 24 hours priority 2

Category: Evolved Stars/Planetary Nebulae/Supernovae

Summary:

AGB stars evolve to form blue dwarfs in a very short time, about 1000 yr. Simultaneously, the circumstellar envelope around the AGB star, which is spherical and expands at moderate velocity, also evolves to form a planetary nebula (PN) around the dwarf, which usually shows axial symmetry and fast bipolar flows. This change is due to very strong shock interaction between the fossil AGB envelope and fast and collimated post-AGB jets.

The nature of the gas also changes: the AGB shells are molecular and cool, 50 - 500 K, while gas in evolved PNe is fully ionized and hot, about 10000 K. This change is thought to proceed progressively during the intermediate phase of protoplanetary nebula (PPN), in which an intermediate phase of low- or intermediate-excitation atomic gas is expected to develop, due to photodissociation (in a PDR) or to gas heating in the shocks. This neutral or slightly ionized atomic gas can only be observed by means of fine-structure lines of abundant atoms. ISO detected a few nebulae in such lines, but the relatively poor sensitivity of that instrument and the lack of spectral resolution prevented any deep study of this component. Herschel/HIFI can significantly improve those data, in particular yielding accurate line profiles, from which we will be able to identify the emission from the different nebular components. New observations will allow us to study the properties of low-excitation atomic gas in PPNe and, in particular, to discern the origin the molecular dissociation, in a PDR or in shocks, from analysis of the fine-structure line profiles.

We accordingly propose observations of the CII (158 microns), CI (609, 370 mic), and OI (63 mic, using PACS) lines in a sample 13 objects, mostly PPNe and young PNe, but also including a few red (super)giants and more evolved PNe for comparison.

SPIRE Photometry on Lensed Quasars

Proposal ID: OT1_abercian_1

Principal Investigator: Alicia Berciano Alba

Time: 10 hours priority 2

Category: Active galaxies/ULGs/QSOs

Summary:

Observations of different CO transitions in high-z quasars can help us to characterise the physical conditions of the star-forming gas, and improve current models of the co-evolution of star formation and SMBH growth. However, emission of the mm/submm continuum and/or CO lines with ground-based facilities has been observed only in a relatively

small number of QSOs, limiting our current knowledge of the dust and molecular gas properties of this important objects. We propose a low cost, high-return 10 hour detection experiment that will deliver SPIRE photometry in 3 bands for 103 targets with 0.45 < z < 4.8 (all currently known optical/radio selected QSOs lensed by foreground galaxies) as first step towards building candidate list for follow up studies.

Origin of massive outer gas reservoirs in early-type galaxies

Proposal ID: OT1_acrocker_1

Principal Investigator: Alison Crocker

Time: 24 hours priority 2

Category: Nearby galaxies

Summary:

A surprising number (~50%) of field early-type galaxies (E and S0s) contain a cool interstellar medium phase detected through the 21cm hyperfine transition of neutral hydrogen. In some cases, this gas is distributed in extremely extensive outer distributions of up to a few 10^9 solar masses of HI. The origin and relation of such outer gas reservoirs to their host early-type galaxies is currently unknown. The gas may be directly accreted from the IGM, stripped during a tidal interaction, or acquired during a gas-rich merger. Alternatively, such gas may have been long associated with the early-type galaxy, not being exhausted due to a low star formation efficiency. In each of these cases the gas is expected to have a different enrichment history and thus a different present-day metallicity and dust-to-gas ratio. With Herschel PACS and SPIRE photometry, we propose to measure dust masses in the outer HI distributions of 15 nearby early-type galaxies. With interferometric HI data already in hand, we can then calculate dust-to-gas ratios and constrain the origin of such gas. The sample size and variety of HI masses, radial extents and morphologies will let us test if the dust-to-gas ratios vary among the sample in a way described best by a single accretion scenario. Additionally, the temperature derived for the dust in the outer gas will let us constrain the possible heating sources for the dust. In some sample galaxies, coincident UV emission suggests young stars are present. If heating from these young stars is important, we expect a variation of dust temperature in systems with and without UV emission.

A definitive Herschel study of the most powerful local radio galaxy - Cygnus A

Proposal ID: OT1_aedge_4

Principal Investigator: Alastair Edge

Time: 5.9 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

Powerful radio galaxies have played a central role in our understanding of active galaxies over the past five decades. Cygnus-A, the brightest and most nearby FR-II source, has been a "Rosetta Stone" in this study. It appears to have the outward characteristics of a normal radio galaxy but it's proximity allows us to identify the more subtle properties of an obscured quasar. The energy provided by this very active galaxy is sufficient to launch the energetic jets we observe but the transport of the energy to the hotspots is poorly constrained and understood. The growing realisation that AGN directly affect their host galaxy through a direct feedback mechanism throughout the lifetime of the galaxy makes it especially important for the most nearby obscured quasar to be observed with the widest possible spectral coverage. We propose to use Herschel to reveal the heating of the central region and the energetics of the hotspots. We request observations of the atomic cooling lines [OI], [OIII] and [CII] that will allow us to compare the energetics of the ISM in Cygnus A with other local and more distant galaxies.

Search for dust emission from circumstellar dust in Type Ia supernovae

Proposal ID: OT1_agoobar_1

Principal Investigator: Ariel Goobar

Time: 12 hours priority 1

Category: Extra-Galactic Other

Summary:

We propose a pilot program to investigate the nature of the non-standard extinction law of Type Ia supernovae through sub-mm observations near the supernova lightcurve maximum. If scattering and absorption by circumstellar dust contributes to the observed extinction, dust emission at sub-mm wavelengths is expected. Thus, we plan to target nearby reddened Type Ia supernovae around peak luminosity. A detection of sub-mm emission from the supernova location would dramatically improve our understanding of the processes behind the dimming of supernovae, with far reaching implications for their use as distance indicators in cosmology.

Dust-Based Molecular Gas Maps of Nearby Low-Metallicity Galaxies

Proposal ID: OT1_aleroy_1

Principal Investigator: Adam Leroy

Time: 20.1 hours priority 1

Category: Nearby galaxies

Summary:

We propose deep PACS 100 and 160 micron imaging of three nearby, star-forming, low metallicity galaxies. These data will allow us to make sensitive, high-resolution estimates of dust mass. We will combine these measurements with our in-hand HI maps to measure the dust-to-gas ratio and estimate the molecular gas (H2) content in each galaxy. This is a challenging measurement that requires requires the resolution of PACS and good sensitivity, but H2 masses at low metallicity are very difficult to estimate by any other means. We will use these H2 measurements to test recent models of H2 formation in galaxies, improve the calibration of the CO-to-H2 conversion factor, and assess the efficiency of star formation from H2 at low metallicity. We will also be able to put constraints on the life cycle of dust at low metallicity from gradients in the dust-to-gas ratio. These are all open questions that can best be addressed by observing the molecular gas in low metallicity galaxies. Carrying out such an experiment outside the Local Group is necessary something that only Herschel can do.

Probing the Interstellar Medium Conditions in High Redshift Starburst Galaxies

Proposal ID: OT1_apope_2

Principal Investigator: Alexandra Pope

Time: 21.9 hours priority 2

Category: Extra-galactic ISM

Summary:

Far-infrared and submillimeter emission lines trace the massive gas reservoirs which fuel the increased star formation seen at high redshift. While [CII] emission at 158 microns is the dominant cooling line in galaxies and directly traces the conditions in the interstellar medium, only a handful of studies have managed to detect CII at high redshift. We propose to double the number of published high redshift [CII] detections by observing 4 ultra-luminous infrared galaxies at z=1.2-2.5 with the SPIRE FTS. Our sample is unique in that it already has exquisite measurements of mid-IR spectral features and CO emission ensuring that we are observing gas-rich, starburst-dominated systems. Combining the [CII] measurements with line luminosities from CO and mid-IR spectroscopy we will complete a full diagnosis of the interstellar medium in these intensely star forming systems constraining the gas density, and the strength and source of the UV radiation field. This program is an excellent way to push the limits and showcase the capabilities of the SPIRE/FTS. We request a modest allocation of 21.7 hours (5.5 hours per source) to complete this detailed study of the astrophysical conditions in high redshift ultra-luminous infrared galaxies.

Velocity resolved HIFI spectroscopy of water lines in actively starforming galaxies

Proposal ID: OT1_aweiss01_1

Principal Investigator: Axel Weiss

Time: 63.6 hours priority 1

Category: Nearby galaxies

Summary:

Recent Herschel spectroscopy has shown that water lines can be very prominent in the submm spectra of infra-red (IR) bright galactic nuclei. Water can efficiently be excited by the IR photons of the dust continuum and via collisions of shock-heated gas in starforming regions. In the later case H$_2$O contributes significantly to the gas cooling. So far, the relative importance of the processes driving the water excitation are largely unknown. This is mainly because the submm lines of water in extragalactic systems have only become accessible with the launch of Herschel.

Our first velocity-resolved HIFI spectroscopy of low-level water transitions in actively starforming galaxies shows that water line profiles are formed by a mix of emission and absorption features and that the line profiles strongly vary between different water transitions. This shows that a lot of information on the underlying ISM structure is imprinted on the line profiles. On the other hand this implies, that velocity resolved spectroscopy is required in order to investigate the water excitation and the underlying physical conditions of the ISM.

We here propose to observe a set of five medium and high energy water lines using HIFI in a sample of active galaxies which are representative for a wide range of nuclear environments. In conjunction with the low-level water lines form the HEXGAL GT-KP this line selection will allow us to model the water excitation in outstanding detail and to investigate the relative contribution of the water excitation channels as a function of environment, derive chemical abundances and to investigate the underlying physical parameters of the gas.

New HErschel Multi-wavelength Extragalactic Survey of Edge-on Spirals (NHEMESES)

Proposal ID: OT1_bholwerd_1

Principal Investigator: Benne Holwerda

Time: 10.3 hours priority 2

Category: Nearby galaxies

Summary:

Edge-on spiral galaxies are a unique perspective on the vertical structure of spiral disks, both stars and the iconic dark dustlanes. The thickness of these dustlanes can now be resolved for the first time with Herschel in far-infrared and sub-mm emission.

Resolved far-infrared and sub-mm observations of edge-on spirals will impact on several current topics. First and foremost, these Herschel observations will settle whether or not there is a phase change in the vertical structure of the ISM with disk mass. Previously, a dramatic change in dustlane morphology was observed as in massive disks the dust collapses into a thin lane. If this is the case, the vertical balance between turbulence and gravity dictates the ISM structure and consequently star-formation and related phenomena (spiral arms, bars etc.). We specificaly target lower mass nearby edge-ons to complement existing Herschel observations of high-mass edge-on spirals. Secondly, the combined data-set, together with existing Spitzer observations, will drive the generation of spiral disk Spectral Energy Distribution models. These model how dust reprocesses starlight to thermal emission but the dust geometry remains the critical unknown. And thirdly, the observations will provide an accurate and unbiased census of the cold dusty structures occasionally seen extending out of the plane of the disk, when backlit by the stellar disk.

The proposed 10.4 hours of PACS and SPIRE observations of low- and intermediate-mass disks complement slated Herschel observations of massive edge-on spirals and existing Spitzer observations in the near- infrared.

Physical conditions in disky U/LIRGs from [C II] and [O I] spectra - low-z analogs for high-z starforming galaxies

Proposal ID: OT1_bweiner_1

Principal Investigator: Benjamin Weiner

Time: 9.1 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We propose to use Herschel/PACS spectroscopy of the [C II] 158 micron and [O I] 63 micron lines to observe a sample of 16 low-redshift infrared-luminous galaxies, at log L_IR = 11.8 to 12.3 Lsolar, that are distinguished by large size and non-merger structure. These galaxies are interesting because they have high star formation rate activity spread over a large physical area, rather than concentrated into extremely dense regions as in the nucleus of a major merger, as in most local ULIRGs. They are potentially good analogs for high-redshift IR-luminous galaxies, which appear to have far-IR spectral shapes different from local ULIRGs. [C II] is a major cooling line in photo-dissociation regions and [O I] and [C II] probe the physical conditions and UV intensity in IR-emitting regions. In a few extreme lensed high-z ULIRGs where [C II] can be measured, the high-z objects have L([C II])/L(FIR) ratios that are high, more like those of local starbursts than local ULIRGs. At z>1, much of the star formation in massive galaxies is occurring at LIRG and ULIRG levels, and U/LIRGs dominate the IR luminosity density. Understanding star forming regions in high-z IR-luminous galaxies is necessary to understand the conditions in which most of the stars in massive galaxies formed. The proposed measurements of [C II] and [O I] in this local sample of high-z analogs will test the hypothesis that redshift evolution in the IR SED shape and the [C II]/FIR ratio are due to different physical conditions in high-z IR-luminous galaxies, because of the larger physical extent of the star forming area.

Coordinated Study of Flare Emission from Sgr A*, the Closest Supermassive Black Hole

Proposal ID: OT1_cdowell_2

Principal Investigator: C. Darren Dowell

Time: 27.5 hours priority 1

Category: Galactic Other

Summary:

Coordinated study of flare emission from Sgr A*, the closest supermassive black hole, reveals information about the hydrodynamics, energetics, and accretion behavior of matter within the innermost ten Schwarzschild radii. We propose to use the unique capability of Herschel/SPIRE and XMM in order to characterize flare emission simultaneously at many different wavelengths, the most important of which are completely unavailable from the ground. These measurements will explore the nature of emission at the peak of the spectrum of Sgr A* and will determine the transition wavelength at which the variable emission becomes optically thin. In particular, we will test the prediction that there will be time delay between X-ray flares and the peak emission at 250, 350, and 500 microns. We will take advantage of the calibration stability of Herschel resulting from the L2 placement to detect Sgr A* in SPIRE difference images. The proposed Herschel and XMM observations form the cornerstone of a multi-wavelength campaign that includes observations in near-IR and radio wavelengths. The cross correlation of flare emission at multiple wavelengths will have far-reaching implications for testing the emission mechanism of Sgr A* and for understanding the processes of accretion onto and outflow from the closest supermassive black hole. Lastly, a long flux monitoring of Sgr A* with Herschel over long and nearly continuous baselines will characterize the fraction of time that Sgr A* is active in submm wavelengths and will provide a legacy to unravel the key properties of the best example of a low-luminosity massive black hole.

A Complete Herschel-Spitzer Legacy Survey of the low-redshift ULIRG Population

Proposal ID: OT1_dfarrah_1

Principal Investigator: Duncan Farrah

Time: 250 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We propose to establish a large, complete Herschel spectroscopic atlas of the low-redshift ULIRG population, via PACS/SPIRE spectroscopy of 45 local ULIRGs. Our observations will combine with existing Herschel data to complete a purely flux limited sample of 52 ULIRGs at z<0.2. This sample comprises the most well-studied low-redshift ULIRGs in existence; they all have mid-IR spectra from Spitzer in both low and high resolution mode, many have HST imaging, and about half have X-ray observations. We will measure the physical & chemical properties of the starbursts and AGN in unprecedented detail, construct new mid/far-IR diagnostic diagrams, and determine robust calibrations for key observables of ULIRGs in the distant Universe. Our program will form a cornerstone of the Herschel spectroscopic legacy, providing (1) a comprehensive database for community exploitation, (2) a firm anchor for studies of ULIRGs in the high redshift Universe, and (3) one of the most important input catalogues for ALMA. As our intention is to create an atlas for the community, we waive all proprietary rights.

Characterizing Molecular Clouds at Low Metallicity

Proposal ID: OT1_dhunter_3

Principal Investigator: Deidre Hunter

Time: 53.7 hours priority 1

Category: Nearby galaxies

Summary:

Molecular gas is difficult to detect from traditional millimeter CO transitions in dwarf galaxies below a certain metallicity. Yet, there is evidence for lots of molecular H_2 in these galaxies. Fortunately, Photo-dissociation Regions are a better tracer of the molecular material in low metallicity systems. In metal-poor galaxies, PDRs dominate the molecular core where CO is found, and in the current paradigm the PDR grows and the core shrinks as metallicity decreases. Thus, we expect critical differences in the molecular clouds of dwarfs compared to spirals, with the differences becoming more extreme with lower metallicity. Yet, understanding these differences and their consequences to star formation is essential to understanding the processes that drive star formation at low metallicities. Therefore, we propose to observe the PDRs in 5 regions in 5 typical metal-poor dwarf galaxies spanning a range in oxygen abundance. We will use these observations to characterize the molecular gas, examine the correspondence between the molecular clouds and the atomic gas and star formation characteristics, and determine the characteristics of the atomic ISM that are necessary for the formation of these dense molecular clouds. We will also test the molecular cloud structure paradigm as a function of metallicity.

Herschel-GOALS: PACS and SPIRE Imaging of a Complete Sample of Local LIRGs

Proposal ID: OT1_dsanders_1

Principal Investigator: David Sanders

Time: 84.9 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We propose to obtain high-quality, PACS (70, 100, 160 micron) and SPIRE (250, 360, 520 micron) images of a complete sample of 201 local (z<0.08) luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS). These systems are primarily interacting or merging disk galaxies undergoing enhanced star formation and AGN activity, and represent an important evolutionary phase in the lives of massive galaxies. Herschel will measure a critical wavelength range of the FIR/submm spectral energy distribution (SED), which will enable accurate determinations of bolometric luminosities, dust temperatures, IR surface brightness and star-formation rates within the GOALS targets on spatial scales of 2-5kpc. The high-resolution PACS data will better resolve binary nuclear regions, disks, and tidal bridges and tails of colliding galaxies at different interaction stages. SPIRE will probe the hidden cold component of the ISM and will constrain the total amount of gas and dust available to fuel the starburst and AGN activity. Studies of the FIR-submm SEDs will allow us to derive the relative amounts of warm and cold dust along the merger sequence. The proximity, size, and completeness of the GOALS sample makes it well suited for studying the full range of infrared properties for LIRGs as a function of dynamical age, infrared luminosity, spectral type and merger phase. Finally, this Herschel program will provide crucial statistical results for LIRGs and ULIRGs that will enable researchers to understand high- redshift infrared galaxies in the context of local, well-resolved objects.

Comparing [CII] 158 micron Luminosities to Spectral Properties of Luminous Starburst Galaxies and AGN

Proposal ID: OT1_dweedman_1

Principal Investigator: Daniel Weedman

Time: 20.2 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

Herschel PACS spectroscopy of the [CII] emission line at 158 microns is proposed for a carefully selected sample of 123 sources that already have complete low and high resolution mid-infrared spectra between 5 microns and 35 microns from the Spitzer Infrared Spectrograph, and which also have spectral energy distributions (SEDs) from IRAS and Akari photometry. [CII] 158 um is the strongest far-infrared emission line and therefore crucial to compare with other features in luminous, dusty galaxies. Sources have 0.004 < z < 0.34 and 43.0 < log L(IR) < 46.8 (erg per sec) and cover the full range of starburst galaxy and AGN classifications. Obtaining these [CII] line fluxes with PACS will allow: 1. determining how precisely [CII] luminosity measures star formation rate by comparing to PAH features and emission lines that arise in starburst galaxies; 2. determining how [CII] luminosity and equivalent width changes with starburst/AGN fraction, by comparing with strength and equivalent width of PAH and [NeII] emission arising from starbursts, and with strength of high ionization lines [NeV] and [OIV] and silicate absorption or emission arising from AGN; 3. determining how [CII] luminosity and equivalent width changes with dust temperature and bolometric luminosity, as derived from spectral energy distributions, and whether this depends on the starburst/AGN fraction. These determinations will allow interpretation of high redshift sources for which the only available diagnostics are the luminosity and equivalent width of the [CII] line and the far-infrared rest-frame SED. The total observing program requires 20.2 hours of Herschel observing time.

Constraining the nature of high redshift infrared-faint radio sources

Proposal ID: OT1_emiddelb_1

Principal Investigator: Enno Middelberg

Time: 6.4 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

One of the most puzzling discoveries of the Australia Telescope Large Area Survey (ATLAS) is the population of infrared-faint radio sources. While relatively bright at 1.4 and 2.3 GHz (10-20 mJy) these sources are neither seen on optical (r=25mag) nor on near- and mid-infrared (3.6-70 micron) Spitzer maps. Existing multiwavelength data, e.g. from SWIRE, suggests that these sources are high-redshift (2<z<5) radio-loud AGN, suffering from heavy obscuration of their optical/NIR emission. Therefore, powerful FIR re-emission is expected, but the FIR-submm maps obtained with Herschel (in the HERMES key project) are too shallow (50 mJy at 160 micron, 30 mJy at 250 micron) to detect these sources. If they are obscured high-z analogues of local templates like 3C48 the predicted 100-500 micron flux density is about 20 mJy, well detectable with Herschel. Therefore, we propose deep PACS 100+160 micron and SPIRE 250+350+500 micron maps of six representative sources, in order to determine the nature of these infrared-faint radio sources. This will provide crucial new insights on those radio-loud high redshift AGN, which cover a lower flux/luminosity range and are therefore more characteristic than the few extremely luminous high-z radio galaxies studied so far.

Measuring the physical properties of submillimeter galaxies around high redshift QSOs

Proposal ID: OT1_fcarrera_1

Principal Investigator: F.J. Carrera

Time: 2.9 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We have detected strong overdensities of submillimeter galaxies (SMGs) around a sample of z~2 QSOs using SCUBA 450 and 850 micron maps. In at least one case we have proved that most of those objects are indeed at the same redshift as the QSO, and hence related to it. If the other SMGs are also related to their entral QSOs they would represent high density peaks in the density of the early Universe, where present-day massive galaxies are thought to form. However, our understanding of the origin of such emission (expected to be due to thermal emission by dust heated by star formation) is very sketchy, since we only have one or, at best, two measurements of their far infra-red/submm Spectral Energy Distribution.

Small scan maps with PACS and SPIRE on-board Herschel would provide crucial data around the expected peak of the emission for those SMGs, allowing an unambiguous determination of its spectral shape and strength, and hence proving its origin and providing accurate estimates of the physical properties of the emitting dust. This in turn can be used to quantify the star formation rates and dust masses, to understand the evolutionary status of these objects.

Additionally, the high-sensitivity Herschel maps would probe the source counts around the QSOs in hitherto unexplored bands to unprecedented depth, providing vital clues to really understand the role of these objects in the formation of galaxies in these early peaks in the density of the Universe.

Water and CO: Signatures of Microturbulent Shocks in NGC 891

Proposal ID: OT1_gstacey_4

Principal Investigator: Gordon Stacey

Time: 22.1 hours priority 1

Category: Nearby galaxies

Summary:

We propose to detect and map rotational line emission from water and CO in the edge-on spiral galaxy, NGC 891. Both water and CO rotational lines are important coolants for low velocity C-shocks resulting from micro-turbulence in molecular clouds. The water lines are of particular interest, as they are definitive shock tracers on galactic scales. Micro-turbulent shocks are an important process through which molecular clouds dispel their turbulent kinetic energy enabling them to collapse and to form stars. NGC 891 is the ideal source for detecting shock tracers from the more quiescent ISM within a normal spiral galaxy: it is presented to us edge-on so that column densities along the line of sight are quite large, and it is nearby so that the edge-on geometry still nearly fills the Herschel spectrometer beams. The combination of high columns, and good beam match enables the detection of particularly weak lines. Our search is motivated by our recent study of NGC 891 in its H2 rotational line and [OI], [CII], and [NII] fine-structure line emission that provides strong evidence for micro-turbulent shock excitation of the S(2) and S(1) rotational lines. These lines are bright, and within C-shock models, several water lines are predicted to be nearly equally bright, and readily detectable with Herschel/PACS and HIFI, and the rotational ladder of CO is detectable with SPIRE. The proposed Herschel observations of water CO will provide the first definitive indicators of the micro-turbulent shocks that along with H2 line emission are the dominant coolants for molecular cloud interiors. Herschel is the only facility that can observe these water lines that are totally obscurred by the Earth's atmosphere even at aircraft altitudes.

Herschel study of black hole and galaxy evolution: The z<0.3 QUEST AGN sample.

Proposal ID: OT1_hnetzer_1

Principal Investigator: Hagai Netzer

Time: 15.6 hours priority 2

Category: Active galaxies/ULGs/QSOs

Summary:

We propose 15.6 hours of Herschel time to secure high quality data,over the entire 70-500 micron range, for a group of 27 local, luminous active galactic nuclei (the QUEST AGN sample). The sources represent well the optically selected PG-QSO sample with redshifts up to z=0.3, and have been investigated, in great detail, in almost all other wavelength bands. The new far infrared (FIR) data set will be ideal to study various fundamental questions related to the connection and co-evolution of AGN and their host galaxies. Our previous Spitzer/IRS work on the sample has already revealed a clear relationship between the total AGN luminosity and the star formation rate (SFR) in their hosts. However, the previously undetected FIR sources may be situated in red-and-dead hosts and the Herschel observations can find these objects and allow a direct comparison of their AGN properties, like black hole (BH) mass and accretion rate, with those of the sources with high SFR. The observations will also provide unique information about the "intrinsic infrared AGN spectrum" with consequences to dust properties and distribution in such objects. Our sample is a needed ingredient in any Herschel-based studies that combine FIR-selected (IRAS, Spitzer, Herschel) and optically selected samples with their different biases. Its later comparison with similar high redshift observations will provide invaluable information about the cosmological evolution of AGN and star forming galaxies.

Black hole growth and star formation in the early universe: the z=4.8 sample

Proposal ID: OT1_hnetzer_2

Principal Investigator: Hagai Netzer

Time: 13 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We propose to secure Herschel PACS and SPIRE observations for a unique sample of 44 z=4.8 active galactic nuclei (AGNs). This is a genuine optically-selected flux limited sample that was observed by us from the ground thus providing reliable black hole (BH) and accretion rate estimates based on the properties of the strong MgII 2800A line. Reliable BH mass estimates at z>2 can only be obtained in narrow redshift bands at around z=2.3, z=3.3, z=4.8 and z=6.5. Our z=4.8 sample is thus a corner stone for answering any question related to galaxy and BH evolution, in particular the co-evolution (if any) of BHs and star formation (SF) in the early universe. The Herschel observations will provide invaluable information about the SF rate (SFR) in the host galaxies of the z=4.8 AGNs which, when combined with observations in the other redshift bands will trace the growth of the most massive BHs and the stellar mass in their hosts. SPIRE observations will provide SFRs (or upper limits on the SFR) in all sources. PACS observations of the more luminous sources in the sample will provide a. priors for the SPIRE observations that will allow us to go below the confusion limits and b. unique information about the 17-40 micron (rest) emission by warm (200K) dust close to the centers of these sources.

Ram pressure-induced shocks in stripped Virgo spirals

Proposal ID: OT1_iwong_2

Principal Investigator: Ivy Wong

Time: 22 hours priority 2

Category: Nearby galaxies

Summary:

We propose to investigate the presence of ram pressure-induced shocks in three Virgo cluster galaxies with clear evidence for on-going ram pressure stripping, from a wealth of radio continuum, optical, infrared, and HI data. To achieve our aims, we will perform PACS spectroscopy to measure the [OI] and [CII] emission line strengths of three outer-disk regions located along the leading edge of interaction between the hot intracluster medium (ICM) and the cooler galaxy interstellar medium (ISM). The ionization state of the ISM gas within the leading edges will be revealed by the ratios of these two emission lines since they are the dominant coolants in the neutral and ionised ISM at low temperatures. Previous Spitzer IRS observations hinted at the presence of shock-excited molecular Hydrogen. Hence, these proposed PACS spectroscopy observations will provide independent confirmation of ram pressure-induced shocks in the cold ISM along the leading edges of these ram pressure-stripped galaxies. Evidence for shock excitation throughout the ISM may also explain the enhanced global radio-toratios observed in galaxies which are experiencing strong ram pressure.

Do Ultraluminous X-Ray Sources Really Require Intermediate Mass Black Holes?

Proposal ID: OT1_jbregman_1

Principal Investigator: Joel Bregman

Time: 11.4 hours priority 1

Category: Extra-Galactic Other

Summary:

Ultraluminous X-ray sources are non-nuclear sources in normal disk galaxies that are second only to AGNs in point-source luminosity. Their X-ray luminosities exceed the Eddington limit for stellar mass black holes (15 Msun), suggesting the need for intermediate mass black holes. This inference depends on the X-ray emission being isotropic, an assumption that we test here. X-ray spectral studies show that much of the soft X-ray emission is absorbed by gas and dust, which will be reemitted isotropically in the far-infrared. The ratio of the absorbed X-ray luminosity to the FIR luminosity is a direct measure of the anisotropy of the X-ray emission. Our previous study with Spitzer, which focused on PAH emission, suggests that the X-ray emission is highly anisotropic. However, if the X-rays destroyed the PAHs, we should focus on the longer wavelength emission, where MIPS observations indicate weak detections. The limitations of the MIPS observations were the poor point spread function and short exposure time, which will be improved upon by the proposed PACS 70 um observations of three highly luminous and nearby ULXs. These data will determine whether ULXs are sub-Eddington or super-Eddington emitters.

NGC 1266: Probing an extraordinary phase of galaxy evolution with Herschel

Proposal ID: OT1_jglenn_1

Principal Investigator: Jason Glenn

Time: 6.3 hours priority 1

Category: Nearby galaxies

Summary:

Two important, coupled questions in galaxy evolution are: how did gas-rich galaxies deplete their interstellar media to become gas poor and how do feedback mechanisms from star formation and active galactic nuclei (AGN) regulate star formation and supermassive black hole growth? Thus, observing galaxies with substantial gas content, nuclear activity, and outflows can make a significant impact on our understanding of galaxy evolution. Recently, observations of an early-type galaxy, NGC 1266, an S0 LINER, revealed a powerful molecular outflow associated with a compact (300-pc radius) and massive reservoir (of order 10^9 solar masses) of molecular gas. The outflow velocity exceeds the galaxy escape velocity, with an estimated flow of 40 solar masses per year. At this rate, the galaxy will deplete its molecular gas within 30 Myrs. There is evidence for an AGN, but the star-formation activity is weak given the gas surface density and no companion galaxy is visible. These unusual characteristics make NGC 1266 an excellent candidate for detailed study of the molecular gas with Herschel to help characterize gas depletion and feedback mechanisms in galaxies. With HIFI and the SPIRE FTS, the CO spectral lines will be measured, from J = 5 – 4 to J = 13 - 12, which, combined with detailed models of the line emission, will yield precisely the temperature, density, optical depth, and mass of the molecular gas in the core and outflow. High signal-to-noise line detections and good velocity resolution, provided by HIFI, will enable the core line emission to be robustly separated from the outflow line emission, and to study the dynamics of the outflow. With the SPIRE-FTS, a full low resolution spectral view from 450–1500 GHz will be obtained to detect tracers of dense gas, such as HCN, HCO+, and HNC. The dense fraction of the gas can be assessed and the dust continuum emission can be used to infer an independent measure of molecular gas mass. Herschel is the only facility capable of making these observations.

A Population of Dusty B Stars in the SMC: The First Extragalactic Debris Disks?

Proposal ID: OT1_jsimon01_1

Principal Investigator: Joshua Simon

Time: 9 hours priority 1

Category: Local Group galaxies

Summary:

Using data from the Spitzer Survey of the SMC, we have discovered a population of 120 main sequence B stars with large 24 micron excesses. Optical spectroscopy and the IRAC SEDs demonstrate that they are not ordinary YSOs or Be stars. We suggest instead that these objects may be debris disks around massive main sequence stars. Confirmation of this hypothesis would provide one of the only ways to study the process of planet formation in a low-metallicity external galaxy. We have measured the mid-IR SED of the dust emission with IRS spectroscopy and determined that both cold and warm dust is present. We now propose PACS photometry at 70 microns to unambiguously separate the dust into its warm (and therefore circumstellar) and cold (possibly interstellar) components. These data will enable us to determine how much of the dust is warm and better constrain the temperature distribution; any targets with substantial amounts of warm dust are almost certainly debris disks. If the B stars do indeed host debris disks, they provide perhaps the only plausible method for constraining planet formation in an external galaxy for the foreseeable future.

Beyond the Peak: Resolved Far-Infrared Spectral Mapping of Nearby Galaxies with SPIRE/FTS

Proposal ID: OT1_jsmith01_1

Principal Investigator: J.D. Smith

Time: 149.4 hours priority 1

Category: Nearby galaxies

Summary:

We propose a spatially-resolved far-infrared spectroscopic survey of a sample of 23 nuclear and extranuclear regions within 22 nearby galaxies, selected to represent the broadest range of key physical properties, including luminosity, gas and stellar mass, star-formation density, and infrared activity. Combined with our wealth of ancillary imaging and spatially resolved spectroscopy from the heritage of SINGS/KINGFISH and related surveys (ultraviolet, optical, infrared, low-J CO, and radio), the proposed SPIRE/FTS dataset will provide key insights into the processes that shape the interstellar medium and govern star formation. Detection of the continuum emission from large grains over 200-650 microns will place new constraints on the long-wavelength behavior of dust emissivity. The richness of the emission line spectrum in this wavelength regime will allow us to quantify the excitation conditions of CO over a wide range of environments, and to characterize the physical properties of warm and dense gas within galaxies on kiloparsec scales, interpreting these properties using models of photo- and X-ray-dissociated gas, and comparing directly with resolved tracers of star formation, heating, and AGN activity. With capabilities unmatched by existing or planned ground- or space-based facilities, SPIRE/FTS mapping of a well-studied sample of nearby galaxies will serve as a crucial, unique, and lasting foundation for interpreting ALMA observations of galaxies at high redshift.

A benchmark study of Active Galactic Nuclei

Proposal ID: OT1_jstevens_1

Principal Investigator: Jason Stevens

Time: 55.1 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We propose Herschel observations of a sample of 176 AGN selected over a narrow redshift range (0.9<z<1.1) but spanning 5 magnitudes in optical luminosity. This selection allows us to decouple luminosity dependent effects from evolutionary effects in a sample selected close to the peak of AGN activity. Combined with our existing multiwavelength dataset (Spitzer, XMM-Newton, SWIFT, UKIRT...) the Herschel observations will provide a benchmark for all future high-redshift AGN studies. We have three primary science goals: (1) to determine the evolutionary status of the AGN by measuring their stellar masses, black-hole masses and star-formation rates, (2) to determine how the spectral energy distributions of the AGN vary as a function of luminosity, and (3) to determine the evolutionary status of the `galaxy clusters' known to be forming around the AGN. The aims of this proposal can only be achieved with pointed observations made with the Herschel Space Observatory.

A Herschel Survey of [OI]63um in 1<z<2 Submillimetre Galaxies in the ECDFS: A Bridge to ALMA

Proposal ID: OT1_kcoppin_1

Principal Investigator: Kristen Coppin

Time: 26.3 hours priority 1

Category: Extra-galactic ISM

Summary:

Luminous obscured galaxies likely dominate the total bolometric emission from star-formation at the early epochs of z~2-3, and are most efficiently identified through their (sub)millimetre emission and are so-called submillimetre galaxies (SMGs). The intense starbursts in SMGs are fuelled by their large observed H2 gas reservoirs, as traced by CO interferometric surveys, although the details of how their immense luminosities (L_fir>5x10^12 Lsun) and star-formation rates (~100-1000 Msun/yr) are powered are not well understood: Are SMGs just scaled up ULIRGs with star-formation occurring in a highly-obscured nuclear region (with perhaps some contribution from an AGN)? Or does the star-formation occur in a more extended, cooler component, such as in "normal" star-forming galaxies. One route to tackling this question is to construct a data set of the brightest fine-structure ISM emission lines ([CII] and [OI]) in a well-defined sample of SMGs, which with ancillary CO data, will allow us to study the physics of the ISM and its interplay with the heating source. Similar benchmark data sets are being compiled by several Herschel programs for local LIRGs and ULIRGs, which will act as a link to help interpret the high-redshift SMG observations. Here we propose a timely and systematic study with the PACS spectrometer of [OI]63um in a flux-limited sample of SMGs with secure spectroscopic redshifts between 0.7<z<2 in the ECDFS - the premier cosmological survey field for ALMA due to its southern declination and wealth of existing ancillary datasets. The combination of these Herschel data ([OI]) and future ALMA data ([CII] and CO) with state-of-the art PDR modelling will reveal new insights into the typical physical conditions of the ISM in the most active high-z star-forming population of galaxies, including the average gas temperature, density, abundance, and radiation field strength integrated over the galaxy.

Tidal Tales of Dark Gas: Searching for [CII] in CO-Deficient Star Forming Tidal Tails

Proposal ID: OT1_kknierma_1

Principal Investigator: Karen Knierman

Time: 9.4 hours priority 1

Category: Nearby galaxies

Summary:

How is star formation in tidal debris affected by gas properties? To probe the molecular gas properties of 3 tidal tail regions, we propose to use the PACS spectrometer on Herschel to observe the [CII] 158 micron line. Two particular tidal tail regions of interest are Clump II in the M81 group and the western tail of NGC 2782. These two regions are HI-rich and have young blue stars or star clusters detected in optical broadband and narrowband H-alpha imaging; however, observations of CO 1-0 show non-detections down to low limits. In contrast to these two regions, the base of the eastern tail of NGC 2782 is rich in HI and CO and has young star clusters. Although the non-detection of CO suggests that there is no molecular gas in Clump II and NGC 2782W, we expect the molecular gas to have a higher fraction of "dark gas" or mostly unobservable molecular hydrogen and C+. One way to observe this "dark gas" is to use the far infrared fine structure line of [CII] at 158 microns. Using these [CII] observations and previous data in optical, near-infrared, submillimeter, and radio, we will compare the measurements of gas and young stars in Clump II and NGC 2782W to those in NGC 2782E to examine the dependence of star formation in tidal tail regions on gas properties.

ISM Heating and Cooling in Massive Galaxies: The Andromeda Galaxy as Fundamental Calibrator

Proposal ID: OT1_ksandstr_1

Principal Investigator: Karin Sandstrom

Time: 47.1 hours priority 1

Category: Local Group galaxies

Summary:

M31, the nearest massive galaxy, affords a unique opportunity to draw up the energy balance of the star-formation (SF) process on the spatial scales (<50 pc) of individual SF regions and of the presumed SF energy deposition. For the `heating terms', UV to near-IR data from the Pan-chromatic Hubble Andromeda Treasury (PHAT) provide a direct census of all young stars in M31; for the `cooling terms', a rich set of existing multi-wavelength data (far-UV to HI) provide many of the cooling diagnostics for the gas and dust. Here we propose to obtain the crucial missing link in the overall ISM energy budget by mapping the dominant, and hence indispensable, cooling lines of the neutral medium, [CII] and [OI].n Specifically, we propose PACS [CII] and [OI] line mapping of several selected (700pc x 700pc) regions in M 31 with ongoing SF, complemented by [N II] observations. These data will enable a foundational study of the energy budget and feed-back of star formation. The data will also provide a stringent calibration of the [CII] line as a local star-formation indicator. Finally, the data set provides the opportunity to understand the sub-grid physics that is needed both for galaxy formation simulations and for interpreting the enormous wealth of gas and dust diagnostic data in more distant galaxies.

Balancing the Energy Budget in LIRGs: A PACS Spectroscopic Survey of Luminous Infrared Galaxies in GOALS

Proposal ID: OT1_larmus_1

Principal Investigator: Lee Armus

Time: 154 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

Luminous Infrared Galaxies (LIRGs; having LIR > 10^11 Lsun), emit a significant fraction of their bolometric luminosity in the far-infrared and are a mixture of single galaxies, interacting systems and advanced mergers, exhibiting enhanced star formation rates and a higher fraction of Active Galactic Nuclei (AGN) compared to less luminous galaxies. With the Great Observatories All-sky LIRG Survey (GOALS), we are measuring the properties of a large, complete sample of 202 low-redshift LIRGs across the electromagnetic spectrum using Spitzer, HST, Chandra, GALEX and a number of ground-based observatories. Here, we propose to measure the [CII] 157.7, [OI] 63.2 and [OIII] 88 micron far-infrared emission lines and the OH 79 micron absorption feature in the GOALS sample with the PACS on the Herschel Space Observatory. We will target 154 LIRGs in [CII], [OI], and OH and 66 LIRGs in [OIII] for a total requested time of 166.9 hrs. The PACS data will allow us to penetrate the dust and measure the spatial distribution, dynamics and overall energy budgets in a large sample of LIRGs at low redshift for the first time. In addition to providing a measure of the physical conditions in the warm, neutral and ionized interstellar medium (ISM) in LIRGs, these data will allow us to establish a precise, quantitative FIR-based measure of the star formation rate that can be used across a wide range of galactic luminosities, even in the presence of powerful AGN. GOALS, with its rich ancillary dataset that covers X-ray through millimeter wavelengths, provides the perfect sample for this study. Our proposed observations will greatly extend the work started with ISO, and lay the foundation for high-redshift galactic studies with future facilities (e.g., ALMA) that will target the FIR and sub-mm spectral regions over the next decade.

Completing the PACS coverage of the Herschel Reference Survey

Proposal ID: OT1_lcortese_1

Principal Investigator: Luca Cortese

Time: 50.8 hours priority 2

Category: Nearby galaxies

Summary:

The Herschel Reference Survey (HRS) is a Herschel Key Program focused on the study of the interplay between dust and star formation in the local universe. The HRS represents the only volume- and magnitude-limited Herschel survey of resolved nearby galaxies, spanning the whole range of morphological types (ellipticals to late-type spirals) and environments (from the field to the center of the Virgo Cluster).

Here we propose to use Herschel to acquire PACS 100 and 160 micron maps for 235 HRS galaxies. This will complete the coverage of the HRS in the spectral range 100-500 microns, currently biased towards early-type, cluster galaxies. These data are essential to characterize the far-infrared and sub-millimetre dust spectral energy distribution (SED) and to investigate how it varies with internal properties and environment. With complete PACS coverage, the HRS will be the ideal sample for statistical studies in the FIR/submm regime at z~0 and the reference for investigations at cosmological distances. In particular, we plan to combine the Herschel observations with UV, HI, CO, optical and near-infrared data already available to investigate the interplay between the interstellar radiation field and dust, to study the effects of the environment on dust content and star formation activity, to carry out the first complete morphological study of local galaxies in the far-infrared and to provide the community with the largest catalogue of UV-to-radio continuum integrated and resolved (at a kpc scale) SED. Thanks to its selection and multi-wavelength coverage, the HRS will thus represent a legacy for galaxy studies for many decades to come.

Measuring the ISM Content of a Large Volume Limited Sample of Nearby Quasars

Proposal ID: OT1_lho_1

Principal Investigator: Luis Ho

Time: 43.2 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

The coevolution of central black holes (BH) and their host galaxies driven by starbursts and the feedback of AGN are major elements of recent galaxy evolution models. Here we propose to investigate these processes in a volume limited sample of PG QSOs, by examining if and how their ISM properties reflect the evolutionary stages of the host galaxy, and the mass of the central black holes. PG QSOs are ideal for such a study because there are complete and uniform data on their BH masses, X-ray to MIR SEDs, NIR and MIR spectral characteristics as well as HST imaging. As such their accretion rates are well known. Here, we request 43.2 hours of PACS and SPIRE observations to measure the full FIR SEDs for a complete sample of 87 PG-QSOs. These data will provide unique sampling of the ISM content of the hosts with measurements of the dust masses, luminosities and temperatures. For objects at the mean redshift of z = 0.2, the proposed PACS photometry will be used to constrain the mass of hot (~60 K) and cold (~25K) dust down to 3e5 and 3e7 Solar Masses respectively, that is total ISM masses similar or less than the Milky Way. As such the proposed data will provide extremely impressive measurements of (1) the ISM masses and luminosities present in the PG-QSO hosts and (2) the relative amounts of gas in high activity (hot dust -- star-formation or AGN) versus low radiation field environments. These data will provide the fundamental dataset for studies of the IR radiation from optical QSOs and understanding the host galaxy properties. The goals of this proposal mesh well with one of Herschel's main mission statements: "Unveiling hidden details of star and galaxy formation and evolution".

The Interstellar Medium, Star Formation and Galaxy Evolution in Early-Type Galaxies

Proposal ID: OT1_lyoung_1

Principal Investigator: Lisa Young

Time: 60.7 hours priority 1

Category: Low-z galaxies

Summary:

We propose spectroscopic observations of the primary ISM cooling lines and the high-J CO ladder in a well-defined sample of nearby elliptical and lenticular galaxies. FIR line and line/continuum ratios will be used in conjunction with PDR models to constrain the physical conditions (gas density and strength of UV radiation field) in the ISM of these early-type galaxies. Similar work has been done extensively for spiral galaxies and (U)LIRGS but has only sporadically been done for quiescent ellipticals and lenticulars. We already have a broad suite of ancillary data for our targets, including HI and CO maps, high density molecular tracers, maps of the stellar populations (ages and metallicities) and optical emission lines. Our targets make an important bridge between normal star-forming spirals and cooling flow cluster galaxies, as they have some properties in common with both other types. Thus, this project is essential for placing other Herschel approved projects into the broader context of the interactions between gas and stars across the entire Hubble sequence.

The Impact of Quasars on their Host Galaxies: Gas Conditions and Star Formation in the Central Kiloparsec

Proposal ID: OT1_mbradfor_1

Principal Investigator: Matt Bradford

Time: 43.7 hours priority 2

Category: Active galaxies/ULGs/QSOs

Summary:

We propose to study the impact of powerful quasars on the star-forming gas in their host galaxies' central kiloparsec with a 44-hour program using the PACS and SPIRE spectrometers. We are targeting four intrinsically luminous and gravitationally-lensed AGN systems in the z~2-4 era which show evidence of obscured star formation in their hosts. We will measure the five bright far-IR fine-structure transitions: [SiII] 35, [OI] 63, [OIII] 52 & 88, and [CII] 158 which are the dominant interstellar gas coolants in galaxies. We will combine the Herschel line fluxes with Z-Spec measurements of the peak of the CO spectrum to provide a complete census of the atomic and molecular gas mass and cooling in the central kpc of these systems.

Our datasets will allow us to perform two key experiments: 1) What heats the gas in the central kpc? When compared with one another and the dust continuum, the line measurements distinguish between UV-photon heating in photo-dissociation regions (PDRs) and bulk heating due to X-rays and/or cosmic rays. Relative to the PDRs, the bulk heating sources are very efficient at heating the gas and produce strong line-to-continuum ratios as well as an enhanced [SiII] / [CII] ratio. If X-rays or cosmic rays are really an important heating source, we will see unusually strong [SiII] and [OI] in these systems.

2) Is the stellar mass function biased toward high masses in these systems? It has been proposed that bulk heating mechanisms are likely to impact the stellar IMF, boosting the characteristic mass by as much as an order of magnitude relative to the Galaxy. Our measurements of the [OIII] transitions, when compared with the far-IR continuum or [CII] which trace total star formation provide a measure of the fraction of very massive stars in the stellar IMF. Similarly, comparison of the [OIII intensities and lower-ionization species (including upper limits) probe the stellar effective temperature through comparison with nebular models.

Death by Debris: Testing a new picture of Star Formation Quenching in Compact Groups

Proposal ID: OT1_mcluver_2

Principal Investigator: Michelle Cluver

Time: 80.6 hours priority 2

Category: Nearby galaxies

Summary:

Recent studies show that compact groups appear to follow an evolutionary sequence, linked to gas depletion, caused by interactions in the dense environment. Spitzer photometry of Hickson Compact Groups show a distinctive gap in IRAC colour-colour space, suggesting rapid evolution from dusty to dust-free systems which seems to correlate with HI-depletion in the galaxies, but the mechanism responsible is poorly understood.

Originally ram-pressure stripping, by analogy with clusters, was thought to be responsible, but the HI depletion is uncorrelated with the presence of hot X-ray gas. Based on our recent Spitzer spectroscopy of a sample of HCGs, we propose a new hypothesis that connects the colour evolution to the HI-depletion seen in the group galaxies. In this scenario, galaxies collide with previously stripped tidal debris, that either heats the disk ISM or strips it, thus shutting off star formation and accelerating the transition from dusty, gas-rich disks to gas-poor, dust-free systems. PACS deep [OI]63 and CII[158] maps allow us to look for smooth bow shock or clumpy shock signatures to discern between heating and stripping of the disk gas. SPIRE cold dust imaging will allow us to search for additional evidence of disk disruption and truncation. This project requires 80.6 hours of observing time.

The Herschel Legacy of powerful 3C radio galaxies and quasars at z<1

Proposal ID: OT1_mhaas_2

Principal Investigator: Martin Haas

Time: 20.5 hours priority 2

Category: Active galaxies/ULGs/QSOs

Summary:

We propose Herschel observations of a complete sample of 3C radio-galaxies and quasars at redshift z<1. For all sources Spitzer mid-IR spectra are available. The aim is to quantify the orientation-dependence of AGN radiation (AGN unification), to investigate the interplay between accretion onto the central black-hole and star-formation in the hosts, and to understand the evolution of the black-hole/stellar-bulge relation. The low-frequency radio-selection provides us with powerful and massive active galaxies free from any orientation/obscuration bias, a requirement for testing AGN unification. The properties of the 3C sources are well known throughout the electromagnetic spectrum, except in the far-IR/sub-mm, where most of them were hitherto outside the capability of space missions to reach reliable measurements. We propose PACS 70-160 micron photometry of 72 sources supplemented by SPIRE 250-500 micron photometry of 11 sufficiently bright sources, in order to measure their detailed spectral energy distributions between available Spitzer and SCUBA/MAMBO data. Depending on redshift of the sources and predicted flux, the filter choice is optimised to provide best rest-frame FIR coverage. The rest-frame FIR emission serves as an isotropic calorimeter and the MIR/FIR luminosity ratio is determined by the relative strength of the AGN and star-forming contributions combined with dust obscuration. These observations will return crucial new information on the energy processes in powerful AGN and their hosts at z<1, providing an essential anchor for studies of galaxy and AGN evolution, in particular for a consistent comparison with Herschel observations of several (radio-loud) AGN samples at cosmic epochs z>1.

GRB Afterglow Photometry with Herschel Infrared Cameras

Proposal ID: OT1_mhuang01_1

Principal Investigator: Maohai Huang

Time: 23.6 hours priority 2

Category: Extra-Galactic Other

Summary:

GRB Afterglow Photometry with Herschel Infrared Cameras (GRAPHICS)

Gamma-ray bursts (GRBs) are the most luminous explosions in the universe. It has been difficult to obtain a full spectral picture of the phenomena in the short period when GRBs become ``alive'', i.e. when they generate bursts in Gamma-ray and produce afterglows in other wavelengths. Between NIR (12micron) and submillimeter (850micron) there lies nearly two orders of magnitude of spectral range where GRB afterglows have never been detected. Herschel is unique in its cutting edge sensitivity, efficiency, and readiness in FIR observations, and is capable of detecting GRB afterglows. Observing GRB afterglows with Herschel would greatly enrich our understanding of GRB physics and conditions of the Universe in early epochs.

We propose Target of Opportunity studies using the SPIRE and PACS instruments of Herschel to observe 3 bright GRB afterglows, each within a few hours to a few tens of days after burst. We will make follow-up observations after the initial one to photometrically measure GRB light curves and IR SEDs. We will make ground optical observations to compliment Herschel data, and have the the GRB community informed. Observing the forward shock peak in the FIR light curve and compare it (both the flux and time) with those in the optical and radio bands would give a unambiguous test to the fireball model, and offer a direct measurement of the density profile of the circumburst material. Catching the short-lived reverse shock emission and measure its magnitude would lead to constraints on some important parameters of the GRB ejecta and address the unknown composition of GRBs, baryonic vs. magnetic.

The Nature of Star-formation in Halos: The HI bridges in the M81/M82 group

Proposal ID: OT1_mlehnert_1

Principal Investigator: Matthew Lehnert

Time: 21.6 hours priority 2

Category: Extra-galactic ISM

Summary:

We have now reached a relatively mature understanding of the physical processes that regulate the interstellar medium in galaxies, but we are woefully ignorant of the details of the cycles between gas in and outside of galaxies. This is unfortunate because understanding the gas physics in a wide variety of environments is the key to determining the relevance of the physical mechanisms that have been invoked for driving galaxy evolution -- from the feeding of star formation through accretion of cold gas to the regulation of star formation through the mechanical energy ejected by massive stars and AGN.

To help to overcome our ignorance about the nature of star-formation in different environments, in this case in a galaxy halo, we propose to use PACS to observe [CII] in many selected regions of the "bridges" of HI in the nearby group of M81, one of the nearest intergalactic gas flows. The M81 group is an excellent target for this type of study because it has a wide range of HI column densities and stars have recently formed in the gas flow between its galaxies. [CII] is the main coolant and an excellent tracer of the cold neutral medium in galaxies. By combining these data with dust maps from Spitzer and Herschel and HI observations, we will investigate the mass balance between the warm and cold neutral medium to constrain the role of turbulence in regulating this balance, which is key to the cooling and fragmentation of gas and to regulating star formation. N-body/SPH simaulations of the interaction will be used to constrain the overall injection of energy in the tidal streams which powers this turbulence and hence the overall phase balance in the gas. Investigating the nature of star-formation in a halo of a galaxy or group is one of the critical first steps in understanding what occurs during the cosmological accretion of gas and thus help determine what processes drive the evolution of the ensemble of galaxies.

Star Formation in X-ray Absorbed QSOs through cosmic time

Proposal ID: OT1_mpage_1

Principal Investigator: Mat Page

Time: 3.1 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

The nature of the connection between the growth of a black hole via accretion and that of its host galaxy bulge via star formation remains a fundamental question in galaxy evolution. SCUBA/850micron observations of matched samples of high redshift X-ray absorbed and unabsorbed QSOs demonstrated that the X-ray absorbed QSO were far more likely to be detected suggesting that their host galaxies had very high star formation rates. This result implies that the z~2 X-ray absorbed QSO population are undergoing the transition from the main star forming phase and the QSO phase of a massive galaxy. Follow-up X-ray observations of the absorbed X-ray QSOs found that the X-ray absorption is due to an outflowing, ionized wind which is potentially the feedback invoked by theorists to terminate star formation in the host galaxy. However, no QSOs from the samples, X-ray absorbed or unabsorbed, were detected with SCUBA below z=1.5. We propose SPIRE and PACS observations of a sample of 10 X-ray absorbed QSOs in the 1<z<1.5 redshift range, with the aim of identifying the star-formation properties of their host galaxies as well as their locus within the luminous infrared galaxy population at these redshifts. Our sample is selected such that it will enable us to probe the transition between the star-formation and QSO phases of massive galaxies to lower redshifts than previously and hence allow us to assess the differences (if any) in the relationship between accretion and star formation in massive galaxies as a function of cosmic epoch.

Determining the structure of blazar jets with joint SPIRE and PACS observations

Proposal ID: OT1_msikora_1

Principal Investigator: Marek Sikora

Time: 21 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

The current time-resolved broad-band spectral data for jet-dominated active galaxies cover spectral ranges from radio to gamma-ray bands, with the notable absence of far infrared to sub-millimeter observations. Those observations are absolutely essential in studies of physics and structure of relativistic AGN jets. They will allow to determine the characteristic frequency of synchrotron self-absorption of the radiating material and probe the electron energy distribution in the critical region below the break associated with the synchrotron luminosity peak. Such measurements are required to determine the location and the spatial structure of the dissipation region of the jet. Here, we propose a series of short observations by both SPIRE and PACS of two blazars, PKS 1510-089 and AO 0235+164, repeated every 2 weeks during a 6-week visibility period over two consecutive visibility windows to provide time-resolved history of broad-band spectra in the IR/sub-mm bands. Those observations, together with data in other bands - which will be available via our on-going monitoring programs covering radio, optical, X-ray, and gamma-ray ranges - will provide a unique data set that will greatly advance our understanding of the blazar jets.

Herschel Spectroscopic Survey of Warm Molecular Gas in Local Luminous Infrared Galaxies

Proposal ID: OT1_nlu_1

Principal Investigator: Nanyao Lu

Time: 83.5 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We propose to survey CO spectral line energy distribution (SLED), from J=4-3 up to J=13-12, on 93 local luminous infrared galaxies (LIRGs; L_{IR} > 1.0E11 L_{sun}) with Herschel SPIRE FTS spectrometer. These galaxies, plus 32 additional LIRGs that will have similar data from existing Herschel programs (mainly the HerCULES project), form a flux-limited subset of the Great Observatories All-Sky LIRGs Survey (GOALS) sample. Our proposal is built on the legacy of GOALS and extends beyond the existing Herschel HerCULES program, which emphasizes more on ULIRGs, to a much needed sample coverage of the more numerous and diverse population of less luminous LIRGs. The data from the proposed observations will not only provide much needed local LIRG templates for future ALMA studies of high-redshift counterparts, but also lend us a powerful diagnostic tool to probe the warm and dense molecular gas that are more closely related to the starburst or AGN activity in the nuclei of LIRGs. The data from this proposal will provide important statistical clues to the interplay between the cold and warm molecular gas, IR luminosity, star formation rate and efficiency, and the diverse properties of LIRGs. Specifically, using the homogeneous CO SLED data from this proposal, together with ground-base, low-order CO line data (mainly J=1-0) and other data that have been compiled for the GOALS sample, we will address the following questions: (1) What is the dominant nuclear power source in individual sample galaxy: starburst or AGN? (2) What are the typical physical properties of warm molecular gas in the nuclei of LIRGs? (3) How do the nuclear warm gas components correlate to the cold gas component, star formation rate and efficiency, dust temperature, etc? and (4) How does molecular gas excitation change along a merger sequence?

Characterizing the Dense Molecular Gas in M82 and NGC 1068: Star Formation versus AGN

Proposal ID: OT1_nrangwal_1

Principal Investigator: Naseem Rangwala

Time: 4.4 hours priority 1

Category: Nearby galaxies

Summary:

We propose to use HIFI to observe high-J rotational transitions of HCN, HNC and HCO+ in M82 and NGC 1068. These molecules are excellent tracers of dense molecular star-forming gas. Their high-J transitions (> J = 4-3), which have never been observed before, trace the densest and warmest regions of the molecular clouds, and their detection is only possible with Herschel. M82, a starburst galaxy with no detectable AGN, and NGC 1068, which harbors a luminous AGN, are ideally suited to test models that discriminate between the energy inputs from star-formation versus X-ray radiation from an AGN. The two sources produce significant differences in the gas physics and chemistry in the interstellar medium, and hence can be distinguished by deriving the physical properties of the molecular gas, and looking at diagnostic line ratios. These two galaxies are also important templates for understanding the physical processes in luminous star-forming and supermassive black hole-forming galaxies at high redshifts, which are too faint and highly obscured by dust. In 4.4 hours, we can obtain a total of 22 spectral lines for these molecules for the two galaxies. Combining these high-J observations with low-J measurements from the ground will provide at least 16 lines per galaxy for non-LTE modeling -- an unprecedented number that will put tight constraints on the physical parameters such as gas kinetic temperature, density, column density and mass. The models will also produce line optical depths, excitation temperature, and level populations providing insight into the excitation mechanism. We will use the line ratios of these molecules in the two galaxies to distinguish between excitation from a starburst and AGN by comparing them to the predictions from models in the literature. These two galaxies are also being observed as a part of the VNGS guaranteed time key project with SPIRE-FTS. The CO lines from FTS will probe and characterize the diffuse molecular gas, and will powerfully complement the results of this proposal.

Coeval Black Hole and Host Galaxy Growth in High Redshift Radio Galaxies

Proposal ID: OT1_nseymour_1

Principal Investigator: Nicholas Seymour

Time: 26.8 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

High-redshift radio galaxies (HzRGs) are unique markers of the most massive and powerful galaxies in the early Universe, showing signatures of both active galactic nuclei (AGNs) and extreme starbursts. Hence, if the radio-loud AGN phase has a strong effect on the evolution of the host galaxy, it will be most evident in HzRGs. We used Spitzer to carry out a comprehensive survey of 71 HzRGs uniformly covering the redshift range 11e11Msun) out to the earliest epochs probed, and mid-infrared AGN luminosities consistent with the most powerful QSOs. To fully understand the evolutionary state of these HzRGs, we now require accurate star formation rates (SFRs), a measurement which is only possible with Herschel. By combining our Spitzer and ground-based sub-millimeter data with five photometric data bands from PACS and SPIRE, we will separate the AGN and star-forming contributions to the total infrared luminosities. Comparing parameters such as specific SFR against AGN power and radio power, and SFR normalised by accretion rate (from the AGN IR luminosity) against radio jet size, we will test theories of how the radio-loud phase stimulates or suppresses star formation (e.g., 'feedback'). HzRGs also reside in large dark matter over-densities, and are often found in rich (proto-)clusters. The most efficient SPIRE observing mode provides a five arcminute diameter map, which is well matched to our Spitzer data, thereby allowing environmental studies of the HzRGs. Above z=2, Spitzer and SPIRE colours will allow us to select candidate cluster members with redshifts similar to the HzRG. In total, we request 26.8 hours of PACS and SPIRE imaging of the 62 (out of 71) HzRGs which are not in the ROL. These data will enable us to investigate the interplay between AGN and star-formation activity in the early Universe, which in turn will allow us to test predictions of AGN-driven feedback at this crucial epoch. We will also study the HzRG environments.

Understanding the physics of cold gas in the nearby proxies of distant cooling cores

Proposal ID: OT1_nwerner_1

Principal Investigator: Norbert Werner

Time: 23.9 hours priority 1

Category: Low-z galaxies

Summary:

We propose to observe nine nearby Halpha and X-ray bright giant elliptical galaxies to study the physical properties of their coldest gas phases. Recent CO and IR observations reveal that giant elliptical galaxies contain large amounts of cold dust and gas. These systems also often exhibit powerful Halpha emission, but relatively little star formation. These nearby massive galaxies are the lowest redshift proxies of the more distant cluster cooling cores. The first goal of the proposed observations is to understand the physical properties of the coldest gas phases in the nearest, most massive giant elliptical galaxies and to correlate them with the X-ray properties of these systems to understand why this cold gas does not proceed to star-formation. Furthermore, in these galaxies a tight correlation has been found between the their Bondi accretion rate of hot gas and the jet power. An important question, that we seek to answer is: is this correlation so tight because of a steady accretion of hot gas only, or is there another tight correlation between the hot and cold gas phases, leading to an apparent correlation between the Bondi accretion and the jet power? In order to address these question, we will use Herschel to target the atomic cooling lines of [CII] and [OI]. The proposed Herschel PACS observation in combination with existing and upcoming CO, NIR, optical, UV, X-ray, and radio data, will allow us to test our ideas about the mixing of the cold and hot gas phases in the nearest, brightest giant elliptical galaxies and to discriminate between models of heat input into the cold gas by mixing layers and alternative models, such as heating by conduction or shock heating from colliding clouds. In combination with existing and upcoming CO observations, we will be able to determine the mass of the cold gas in the cores of these giant elliptical galaxies. This will enable us to look for a possible relation between the hot and cold gas phases.

Charting the Cooling Pathways in High-Speed Extragalactic Shocks

Proposal ID: OT1_pappleto_1

Principal Investigator: Philip Appleton

Time: 37.2 hours priority 1

Category: Nearby galaxies

Summary:

Following in the footsteps of ISO, recent observations with Spitzer have revealed a population of galaxy systems which emit a huge amount of luminosity in their pure rotational mid-IR molecular hydrogen lines, in some cases reaching 10-30 percent of the bolometric luminosity. These large line-luminosities are believed to be powered by galactic-scale shocks, which efficiently transfer kinetic energy to smaller dense clouds in the turbulent post-shock medium. However, nothing at all is known about the other important cooling channels for the shocked gas, such as [OI], H2O, OH, and CO, some of which can rival H2 as a coolant. We propose deep PACS and SPIRE spectroscopy of the Giant Shock in Stephan's Quintet and the Taffy Galaxy bridge to quantify the most important cooling channels and determine the physical state of the gas being shocked. The results have implications for understanding the importance of molecular cooling at higher redshift where turbulence and shock-heating may play a role in galaxy formation.

What inflates the torus? Probing the physical properties of geometrically-thick buried AGN with high J CO lines

Proposal ID: OT1_pgandhi_1

Principal Investigator: Poshak Gandhi

Time: 20.6 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

The most significant new population of active galactic nuclei (AGN) discovered in recent years is the 'buried AGN' population, uncovered by the Swift satellite. Sensitive X-ray spectroscopy shows characteristics of heavily obscured AGN in these sources, in addition to a very low scattering fraction of low energy photons, which is interpreted as a result of the AGN being buried in dust and gas tori which have an atypically high geometrical thickness. Comprising up to 20 per cent of the entire AGN population, this class constitutes a very important new family of sources, which may be at an interesting evolutionary phase in the AGN life cycle. Yet, very little is known about them, and usual isotropic indicators such as the optical [OIII] forbidden emission line fail to probe their intrinsic powers. The geometrically thick torus picture can result in 1) high gas and dust masses in the tori; 2) increased velocity dispersions and elevated temperatures and pressures; 3) a broad-band spectral energy distribution dominated by cool optically-thick clouds. Far infrared lines provide excellent probes of the physical conditions in the torus, and we intend to use several high J rotational CO lines to test the above picture with Herschel for the first time on several buried AGN for which detailed X-ray spectroscopy exists. These observations will also enable us to search for dynamical signatures of motion in the torus.

Dust in shocks and star-forming regions outside galaxies: PACS and SPIRE photometry of Stephan's Quintet

Proposal ID: OT1_pguillar_1

Principal Investigator: Pierre Guillard

Time: 13.3 hours priority 2

Category: Extra-galactic ISM

Summary:

Stephan's Quintet (SQ) is an extensively studied compact group of galaxies, where tidal interactions have displaced large amounts of gas into the inter-galactic medium (IGM). Spitzer IRS observations revealed an extremely bright H2 line emission from warm molecular gas, coexisting with a giant (40 kpc), X-ray bright shock, attributed to a high-speed (1000 km/s) galaxy collision. The weakness of PAH and mid-IR dust continuum shows that the H2 gas is not associated with star formation (SF) in the shock, in sharp contrast with standard galaxies. Spitzer photometry suggests that most of the SF rather happens outside the center of the shock and galatic disks. Moreover, an extended FIR component, not connected with the galaxies, but coincident with the X-ray halo of the group, may have been revealed by MIPS, but its poor resolution make this identification difficult. This dust may contribute to cool the hot gas, and thus to fuel SF in the halo. In this context of understanding the processes that control SF in the group, we propose to map the thermal dust emission in all the PACS and SPIRE bands. This will allows for the first time to (1) estimate the total cold gas content in the IGM independently from our CO measurements, (2) make use of the Herschel high spatial resolution to separate the dust emission coming from SF regions, the shock, and the X-ray halo, in order to elucidate the origin of the dust emission in the group and its potential role in cooling the intra-cluster gas, and (3) compare the FIR SED in the different regions of the group to dust models in order to constrain the dust size distribution and the structure of the molecular gas. These observations, together with a companion spectroscopy proposal, will provide the missing pieces of the overall energetic bugdet of the main coolants of the galaxy collision. The results will have important consequences on our understanding of the energetics and the role of dust in high-redshift mergers, and in the formation of the first stars and galaxies.

Radio Jet Feedback on Molecular and Atomic Gas in Radio Galaxies

Proposal ID: OT1_pogle01_1

Principal Investigator: Patrick Ogle

Time: 68.2 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We propose Herschel SPIRE and PACS atomic and molecular line spectroscopy and photometry of 23 H2-luminous radio galaxies. Most of these galaxies are IR-weak, such that the kinetic energy output of the radio jet dominates over the radiative output from the AGN accretion disk and star formation in the host galaxy. This new class of galaxies, discovered by Spitzer, has unique MIR spectra with very strong H2 rotational emission lines but weak PAH features compared to normal star-forming galaxies. We may be seeing the direct effects of AGN radio jet feedback, dramatically and fundamentally disturbing the host galaxy interstellar medium in a way that suppresses star formation. Herschel spectroscopy and photometry are essential to inventory the mass and energetics of the atomic and molecular ISM over a wide range of densities and temperatures, and thereby obtain a better understanding of the radio jet feedback mechanism that regulates massive galaxy evolution. We will use shock models to interpret the [O I] and CO emission line spectra and determine the density, temperature, and energetics of shocked molecular gas. Herschel photometry will probe the peak of the IR SED and yield estimates of the total mass of cold dust and cold molecular gas. This will allow us to assess what fraction of the molecular ISM is disturbed by shocks, and understand why and to what extent star formation is suppressed by radio jet feedback.

Strong AGN feedback onto the ISM and its effects: A SPIRE FTS view of the molecular gas in 3C293

Proposal ID: OT1_ppapadop_1

Principal Investigator: Panteli Papadopoulos

Time: 6.1 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

We propose to use the SPIRE FTS to study the large molecular gas reservoir of the powerful radio galaxy 3C293, the scene of a very strong AGN jet-gas interaction, and the first known case of shock-powered luminous mid-J/high-J CO lines. These were discovered during our large ground-based CO line survey of Luminous Infrared Galaxies (LIRGs) and AGN hosts, and set this object apart as that with the most excited molecular gas of the entire survey, yet with its large gas reservoir (~2x10^9Msol) surprisingly idle in terms of star formation rate (SFR~4Msol/yr). A deep SPIRE FTS spectrum will complete our ground-based CO Spectral Line Energy Distribution (SLED) of this remarkable system and allow excellent constraints to be placed on the thermal state of its molecular gas reservoir and possible suppressing effects of the AGN on star formation in the host galaxy. It will also be the first opportunity to study, locally, powerful AGN mechanical feedback onto the interstellar medium of host galaxies, which will occur frequently in the Early Universe during galaxy formation in the deep gravitational wells of proto-clusters marked by such powerful radio galaxies.

Herschel spectra of low-z QSOs: measuring radiative feedback, radiation pressure and star formation

Proposal ID: OT1_pvanderw_4

Principal Investigator: Paul van der Werf

Time: 28.1 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

Observations with the SPIRE FTS of the ULIRG-QSO Mrk231 have shown that the CO rotational ladder can be used to separate the contribution of Photon-Dominated Regions (PDRs), powered by star formation, from that of X-ray-Dominated Regions (XDRs), powered by the AGN.

We propose to apply this diagnostic to a sample of 5 low-z QSOs with detections in CO, in order to:

(1) derive size, density, column density and X-ray illumination of the circumnuclear medium;

(2) measure radiative feedback and derive radiation pressure by the AGN on the surrounding medium, in order to probe its ability to drive the recently discovered molecular outflows and disperse the nuclear gas, and to assess its importance for the dynamical support of the circumnuclear medium, which will affect dynamical black hole mass measurements;

(3) determine the importance of star formation in the host galaxy for the observed infrared luminosity.

Our observations consist of SPIRE-FTS spectra of 5 QSOs, and PACS spectra to measure the higher CO lines in the brightest object only. These observations will address the evolutionary relation between QSOs and ULIRGs and the role of QSOs as drivers for the transition between actively star forming and passive galaxies. They will also constitute a low-z benchmark for future CO observations of high-z QSOs with ALMA, which can only be provided by Herschel, and which is not covered in the current Herschel programme.

Gas excitation through black hole accretion and star formation in the centers of active galaxies.

Proposal ID: OT1_rmeijeri_1

Principal Investigator: Rowin Meijerink

Time: 22.4 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

Stunning observations with SPIRE FTS of Mrk 231 have shown that CO lines are very bright up to J=13-12, and there is no sign of a decline in the CO Spectral Line Energy Distribution (SLED). Our SPIRE FTS spectra show that this is a common feature of AGN type galaxies. Therefore, we propose to observe a set of 4 very high-J CO line transitions using the PACS spectrometer, for 5 of these well studied proto-typical (Ultra-)Luminous Infrared Galaxies ((U)LIRGs) and one starburst galaxy. The question of the relative role and contribution of AGN to the far-infrared luminosities of local (U)LIRG systems has long been a problem in our understanding of the evolutionary path of these objects, and as well for the interpretation of deep far-infrared surveys.

Our SPIRE FTS and our ground-based CO line observations together with the PACS observations in this program will allow us, for the first time, to complete a full CO SLED for a set of (U)LIRGs. Combining this with our models of Photon Dominated Regions (PDRs) and X-ray Dominated Regions (XDRs), we will then be able to determine the physical state of the interstellar medium and estimate the starburst/AGN contribution to the total energetics of these systems.

Determining the Bolometric Luminosity of AGN

Proposal ID: OT1_rmushotz_1

Principal Investigator: Richard Mushotzky

Time: 59 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

Determining the bolometric luminosities of AGN is key to understanding their evolution. Uncertainties in the total radiation from AGN translate into uncertainties in their lifetimes, Eddington ratios, mass accretion rates, the form of their radiation, and the predicted black hole spin. However, we still have major problems in measuring this critical quantity. AGN and their host galaxies emit a large fraction of their light in the MIR to FIR, but the origin of this radiation and the connection to the AGN are not well understood. It is not clear whether this radiation is associated with the AGN or with star formation in the galaxy.

We propose to use Herschel's unique capabilities to establish the properties of the Swift-BAT all sky sample of local AGN selected at 15-195 keV. We will measure the MIR to FIR (65-500 microns) properties of a complete low-redshift sample (309 objects at z<0.05). The Swift-BAT survey is the least biased all sky survey for AGN with respect to host galaxy properties and obscuration in the line-of-sight, and thus it is superior to optical, IR, or radio surveys for understanding the the nuclear component of the MIR to FIR radiation from active galaxies. The low redshift of our sample, the uniformity of selection, and the large amount of parallel data which have already been obtained (Spitzer, optical, and X-ray spectra, and optical and UV imaging) will allow the most precise determination of the physical origin (AGN versus star formation) of the light. The low redshifts allow the best possible angular resolution for spatially separating star-formation and nuclear components, while only requiring short Herschel exposures.

The Herschel BAT survey will provide a comprehensive database for determining the bolometric light of AGN and will be an invaluable reference sample for analyzing higher redshift AGN. It will be a powerful resource for many years to come. We will make it available in a comprehensive and accessible form as rapidly as possible.

Comparing the Dust Emission from High Redshift Lyman Break Galaxies with their Best Low Redshift Analogs discovered by GALEX

Proposal ID: OT1_roverzie_1

Principal Investigator: Roderik Overzier

Time: 28.6 hours priority 1

Category: Low-z galaxies

Summary:

We propose to use PACS to characterize the dust emission in UV-selected starburst galaxies at z<0.3 from our on-going survey of "Local Lyman Break Analogs" (LBAs). This survey was specifically designed to find and study rare, nearby galaxies from the GALEX all-sky survey that are most similar to the population of Lyman Break Galaxies (LBGs) at z>2-3. The LBAs are similar to LBGs in terms of mass, SFR, age, metallicity, attenuation, size, morphology, kinematics, and ISM. Because of these remarkable similarities, we can perform a much more straightforward comparison of their properties.

Specifically, we will use PACS to sample the far-IR dust emission from 28 LBAs, and study its relation to other physical properties of these starbursts to a level of accuracy that can not be achieved for similar UV-selected starbursts at high redshift. We will address the following questions:

(1) What are the contributions from hot/cold dust emission to the total (UV+IR) energy budget, and how do these compare with LBGs? (2) How do LBAs relate to their IR-luminous counterparts in the local Universe? (3) Do LBAs follow the locally calibrated "beta-IRX relation" that is commonly used to calculate dust-corrected SFRs at high redshift? (4) Can we understand offsets from the beta-IRX relation in terms of other properties (e.g., complex star formation histories or modified extinction laws)? (5) What are the star formation efficiencies in LBAs as a function of their triggering mechanism, and are these similar to those inferred for LBGs?

Combined with our existing broad based, multi-wavelength observations from GALEX, SDSS, HST, Spitzer, VLT, Keck, XMM, and the VLA these data will provide crucial information on the interplay of stars, gas and dust in the LBG analogs. This will aid us in our understanding of their UV-luminous counterparts at high redshift, just as our understanding of local ULIRGs has been fundamental for the study of the most IR-luminous sources at high redshift.

Testing the XDR/High-J CO Paradigm in Nearby Galaxies

Proposal ID: OT1_shaileyd_1

Principal Investigator: Steven Hailey-Dunsheath

Time: 32.2 hours priority 1

Category: Nearby galaxies

Summary:

One of the most exciting first results from SPIRE and PACS spectroscopy is the detection of high-J CO emission in galaxies. Such emission has long been proposed as a tracer of X-ray dominated regions (XDRs) produced by AGN, and as a powerful diagnostic tool for future millimeter-wave study of AGN at high redshift. The shortest wavelength submillimeter CO lines detected by SPIRE-FTS in the X-ray luminous ULIRG Mrk 231 are interpreted as arising from an extended XDR, providing strong observational support for the XDR/high-J CO connection. However, our group (SHINING; PI E. Sturm) has used PACS to detect even higher-J far-IR CO emission in a few nearby galaxies, including 2 starburst galaxies with little evidence of a luminous AGN. Can high-J CO emission also be produced in gas heated by the UV radiation or mechanical output of a starburst? To address this question we propose to measure a set of far-IR CO lines in 4 nearby AGN and 4 starburst galaxies, as well as in 2 merging systems with large masses of shock-heated molecular gas. Does the high-J CO line SED reflect the different excitation mechanisms in these template objects? We additionally propose to use OH line observations to estimate the abundance of this molecule, which is a sensitive tracer of X-ray-driven chemistry. The OH line profiles will also be used to search for evidence of molecular outflows, which may drive shock heating. Each of these galaxies will have SHINING GT observations of the set of far-IR fine-structure lines, which includes important tracers of UV-, X-ray-, and shock-heated gas. The AGN subsample is restricted to the most nearby systems, where the high spatial resolution of PACS is sufficient to separate the nuclear AGN-heated gas from the circumnuclear star-forming regions. The PACS CO data obtained here will provide the first well-sampled far-IR extragalactic CO line SEDs, and will be an essential reference for future high redshift studies.

The physical conditions of star formation at low metallicity: the Magellanic clouds as corner stones

Proposal ID: OT1_shony_1

Principal Investigator: Sacha Hony

Time: 79 hours priority 2

Category: Extra-galactic ISM

Summary:

How galaxies convert their gas reservoirs into stars is a stumbling block in understanding galaxy evolution. The far IR and submm cooling lines arising from photodissociation regions (PDRs) are the key diagnostics of the interplay between star formation and the evolving ISM throughout the course of the history of the universe. While effort has been put into physics of PDRs and star formation in the Galaxy and other metal-rich galaxies, little attention has been put into understanding the effects of the lower metal abundance on the these processes. Here we propose PACS ([CII] 158 um, [OI] 63 um, [OI] 145 um, [OIII] 88 um, [NII] 122 um) and SPIRE FTS spectroscopy towards carefully selected star forming sites in the nearest low metallicity galaxies, the Magellanic Clouds (MCs) as a benchmark study to calibrate the primary diagnostics of low metallicity environments which are crucial for ALMA high redshift science. The proximity of the MCs allows Herschel to resolve molecular clouds at 3 pc scale. Our targeted regions span a wide diversity of environments, including dense molecular gas and ionised regions. These new data, together with existing IRS spectra, Herschel and Spitzer photometry, and a wealth of ground−based data including the MAGMA CO data, will allow us to address important unresolved issues: 1) the amount of molecular gas hidden in a low extinction phase where CO is photodissociated and thus not detected; 2) the dependence of the FIR fine structure lines, CO excitation and gas thermodynamics on environment; and 3) the structure of PDRs at low metallicity. Our results will be key to interpreting FIR fine structure lines and CO observations of more distant systems. We will produce PDR models tested at low metallicity, a library of CO excitation at low metallicity, and a calibration of the amount of "CO−free" molecular gas as a function of environment. In addition, multi−line maps covering the main coolants of the atomic and molecular gas, represent a data product with lasting legacy value.

Exploring the Dust Content of Galactic Winds with Herschel

Proposal ID: OT1_sveilleu_2

Principal Investigator: Sylvain Veilleux

Time: 48.7 hours priority 1

Category: Nearby galaxies

Summary:

We propose a PACS imaging survey to study galactic winds from nearby starburst galaxies. We will obtain very deep PACS 70/160 micron data to map the detailed distribution of cold (T<100 K) dust in a small but representative sample of galaxies that are known to host outflows. These data will be compared to state-of-the-art, 3D numerical simulations of superwinds and predicted PACS fluxes. Direct and indirect evidence shows that dust is present on large (kiloparsec) scales in outflows in some starburst galaxies. However, this dust has never been mapped at wavelengths of 70-160 microns, and its geometry, mass, and energy are almost completely unknown. Recent spectacular SPIRE results on M82, as well as our own Spitzer IRAC 8-micron and MIPS 24-micron maps of the targeted wind galaxies, suggest that this survey will yield exciting new insights on the cold dust in these outflows. We will ascertain the significance of dusty superwinds in the context of outflow physics and the impact of the outflows on the host galaxies and the intergalactic medium. We will compare the distribution, mass, and energy of the cold dust to optical emission-line and absorption-line, mid-infrared, X-ray, and radio data compiled by us and other groups. We note that several of our targets are being mapped with PACS and SPIRE as part of key programs (KPs). However, the objectives of these programs are heterogeneous and often neglect the importance of outflow science. This is reflected in the depth of the observations at the critical shorter wavelengths, near the peak of the IR SED: the PACS KP data will not be able to detect the FIR emission expected from a M82-like wind in our galaxies. There is currently no plan to address this problem but one is necessary to take full advantage of Herschel in this field. The proposed PACS survey will go nearly an order of magnitude deeper than the KP data and will complement the SPIRE portion of the KPs, while providing many advantages over the SPIRE data.

Molecular Outflows in Gas-Rich Mergers

Proposal ID: OT1_sveilleu_3

Principal Investigator: Sylvain Veilleux

Time: 32.5 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

The role of galactic winds in gas-rich mergers is of crucial importance to understand galaxy and supermassive black hole evolution. In recent months, our group has had two major scientific breakthroughs in this area: (1) the discovery from our SHINING guaranteed-time PACS survey of ultraluminous infrared galaxies (ULIRGs) of a 1400-km/s molecular OH wind in the nearest quasar, Mrk 231. (2) The independent discovery from mm-wave CO interferometric observations in the same object of a spatially resolved molecular wind with estimated mass outflow rate 4-10x larger than the star formation rate. Remarkably this CO outflow coincides spatially with blueshifted neutral gas in our optical spectra. This powerful outflow may be the long-sought "smoking gun" of quasar mechanical feedback purported to transform gas-rich mergers. However, our SHINING survey contains only 2 other warm quasar-dominated late stage mergers like Mrk 231 (one of them also shows a high-velocity OH outflow, while the other has not yet been observed). So here we request 32.5h to obtain high-S/N OH 119 um spectra of 15 additional quasar-dominated late stage mergers. We have a comprehensive set of multiwavelength data on all of these objects, including crucial spatially resolved optical Na ID absorption spectroscopy. The combined sample of 20 cold ULIRGs and 18 warm ULIRGs/QSOs will allow us to address the role of mechanical feedback in mergers after the first peri-passage, i.e. when mechanical feedback from the starburst/QSO is predicted to be at its maximum. We will look for trends between the basic measured properties of OH (incidence of absorption, kinematics, column densities) and host/evolutionary indicators. In cases of kinematic match between OH features and spatially resolved neutral-gas clouds, we will be able to infer the masses and kinetic energies of these outflows. Measured velocities in excess of ~1000 km/s or inferred mass outflow rates much larger than the star formation rates would be telltale signs of AGN-driven winds.

Hydrogen Fluoride Absorption Toward Luminous Infrared Galaxies

Proposal ID: OT1_tphill01_1

Principal Investigator: Thomas Phillips

Time: 40.5 hours priority 2

Category: Nearby galaxies

Summary:

We propose to carry out a HIFI survey of the fundamental transition of HF at 1.232 THz toward 24 relatively nearby IR-bright galaxies to probe their ISM physical conditions. HF is a very new tracer of the diffuse and dense ISM, with its use originating with the ISO detection of the J=2-1 transition in absorption toward Sgr B2. Widespread HF J=1-0 absorption toward galactic starforming regions has been recently detected by HIFI and HF emission in an extragalactic nucleus has been detected at low spectral resolution by SPIRE. We intend to make use of this unique probe by conducting a high spectral resolution (10-20 km/s) HIFI absorption survey toward continuum-bright external galactic nuclei exhibiting a wide range of physical properties (AGN, starbursts, mergers). HF is chemically very strongly bound and therefore resistant to photodissociation. Our study is facilitated by this resistance of HF molecules to destruction, which will occur in the extreme environments in the galactic nuclei. HF will thus be a very useful probe in regions of the ISM where more traditional gas probes, such as CO, are more prone to error (e.g., the use of the X-factor). With the simplifying assumption that all fluorine is likely to be locked up in HF, and that the HF molecules will reside in the ground rotational state, we can measure the hydrogen column density and mass of the nearby IR-bright galaxies. Observations of the local galaxies proposed here are the first step toward using HF as a tracer of the gas in high-redshift galaxies. By looking at extragalactic continuum-bright nuclei, we will also be able, through the use of the HIFI Wide Band Spectrometer, to simultaneously search for absorption through the Milky Way halo cloud population. Here, the rapid formation rate of HF and its strong molecular bond will allow us to detect HF absorption toward the tenuous and quiescent mostly HI clouds making up the galactic halo. These diffuse, cold regions may not otherwise be detectable in CO emission or other commonly uses tracers.

Monitoring of the far-IR SED of two archetypical quasars

Proposal ID: OT1_tsavolai_1

Principal Investigator: Tuomas Savolainen

Time: 6.8 hours priority 2

Category: Active galaxies/ULGs/QSOs

Summary:

We propose quasi-simultaneous multiband photometry with Herschel and other ground- (VLBA, Effelsberg, SMA, OAGH, NOT) and space-based (Swift, Fermi) facilities to obtain an unprecedented coverage of spectral energy distribution (SED) of two archetypical radio-loud quasars 3C273 and 3C279 and follow evolution of the SED on monthly timescale. The wide wavelength coverage of the Herschel instruments PACS and SPIRE will allow us to sample the region of the synchrotron peak of the SED in these sources and monitor its variability, which provides a way to distinct between various emission components expected in this region (one or more synchrotron components, thermal emission from dust). The combination of the Herschel data with the other facilities will provide almost completely sampled SEDs that will put strong constraints on the blazar emission models.

Unveiling the dark side of the Gamma-Ray Bursts with Herschel Far Infrared Photometry

Proposal ID: OT1_vd_1

Principal Investigator: Valerio D'elia

Time: 28.1 hours priority 1

Category: Extra-Galactic Other

Summary:

Dark gamma-ray bursts (GRBs) are bursts with a detected X-ray afterglow but not detected optical afterglow in spite of deep follow-up observations. Approximately 40% of all bursts belong to this category. Possible explanations for the lack of an optical detection are a high redshift (z>7), which however can not account for the whole dark population, and extinction due to the host galaxy dust. We plan to take advantage of the Herschel capabilities to spot for the first time these objects in the far infrared band, using PACS. The requested observations will shed light on the nature of dark GRBs, allowing us to put constraints on the dust content, on the afterglow physics and to search for the host galaxies of these elusive sources.

Molecules in the Distant Universe: Herschel Spectroscopy of Damped Lyman-alpha Quasar Absorbers

Proposal ID: OT1_vkulkarn_1

Principal Investigator: Varsha Kulkarni

Time: 36.8 hours priority 1

Category: Extra-galactic ISM

Summary:

Observations of interstellar molecules in distant galaxies are essential for investigating the chemical evolution of galaxies. Absorption line systems in quasar spectra, especially the damped Lyman alpha (DLA) absorbers, provide excellent venues for directly studying the interstellar matter (ISM) in distant galaxies, selected independently of the galaxy luminosities. A few cold, dusty absorption systems have been discovered using radio surveys and the Sloan Digital Sky Survey. These absorbers, far richer in dust/molecules than the general DLA population, give us rare opportunities to probe molecular clouds at high redshift. Here we propose Herschel observations of 4 quasars with such DLAs at z < 1.5 to further observe their molecular content. These DLAs exhibit H I 21-cm absorption and other signatures of cold ISM such as the 2175 A bump from carbonaceous dust or low spin temperature. Furthermore, we have detected 9.7 micron silicate absorption toward two of these DLAs with Spitzer IRS. We request HIFI spectroscopy to observe absorption lines of CO, CN, NH, H2O, and SPIRE photometry of the 4 quasars to determine the continuum accurately. In addition, we request SPIRE photometry of 10 other quasars with strong absorbers rich in dust/metals, in order to identify bright targets for future Herschel spectroscopy. Our overall science goals are: (1) to estimate molecular abundances and kinematics of the absorbing gas; (2) to constrain isotopic ratios such as 12C/13C from 12CO/13CO or 12CN/13CN; (3) to estimate the cosmic microwave background temperature at the absorber redshifts. Finally, (4) the proposed program will help to further constrain the cosmic variation of fundamental constants such as the electron-to-proton mass ratio.

Major-merger, starburst.... what next?

Proposal ID: OT1_vwild_1

Principal Investigator: Vivienne Wild

Time: 4.7 hours priority 1

Category: Low-z galaxies

Summary:

A popular scenario to explain the increase in number of quiescent, elliptical galaxies over cosmic time is one in which gas-rich major mergers lead to strong starbursts which exhaust fuel supplies and transform the morphology of galaxies from disks to spheroids. In this proposal we describe how PACS+SPIRE photometry can directly test this scenario. We present a unique sample of massive starburst-to-post-starburst galaxies in the local Universe (z<0.05), which have undergone a starburst between 10Myr and 1Gyr ago. The sample is drawn from a statistically complete sample of Sloan Digital Sky Survey (post-)starburst galaxies, i.e. they have experienced the same strength starburst. Together with CO molecular gas masses (already obtained), we will use the Herschel photometry to track the evolution of dust mass, dust temperature and dust-to-gas ratios for 1Gyr following the starburst. This will allow us to directly test (1) how star formation is quenched following a starburst: gas exhaustion, expulsion or change of gas state; (2) whether massive starburst galaxies are the progenitors of red-sequence galaxies. Additionally, we will use our accurate starburst ages to test whether supernovae or post-AGB stars contribute significantly to the enrichment of the interstellar medium (ISM) with dust. By combining with results from similar studies of local merger- or IR-selected galaxy samples we will calculate a "duty-cycle" for IR bright galaxies, crucial for understanding the selection of high-z galaxy samples. By combining our (post-)starburst galaxy sample defined upon the physical properties of starburst age and strength, with the diagnostic capabilities of CO and dust emission for probing the physical state of the ISM, this dataset will provide the best observational constraints to date on the merger+starburst evolutionary pathway from star-forming spiral to quiescent elliptical galaxy.

Keeping the cool gas in galaxy clusters warm.

Proposal ID: OT1_wjaffe_1

Principal Investigator: Walter Jaffe

Time: 24.9 hours priority 1

Category: Extra-galactic ISM

Summary:

We propose SPIRE FTS spectra to determine the source of heating of the cool/warm (100-300 K) gas in the Brightest Cluster Galaxy NGC-1275, the brightest of all cluster cool-core galaxies. The heating mechanism in BCGs is unknown and crucial to understanding analogous "negative feedback" processes in star-forming galaxies at high redshift. Our current mm-CO, PACS, nearIR and optical data on this cluster indicate that the SPIRE measurements will detect many CO lines and possibly H2O+ and OH+ lines that will determine the temperature, and density of the most important component of this warm gas. The ratios of the CO lines, and the presence or absence of the ionized lines, and the dependence of these lines with distance from the central AGN should allow us to choose between the several possible heating and excitation mechanisms: soft X-rays, cosmic ray ionization, and C- and J- shocks from AGN induced turbulence.

Spectroscopy of a Highly Magnified Galaxy Behind the Bullet Cluster

Proposal ID: OT1_agonza02_1

Principal Investigator: Anthony Gonzalez

Time: 12.8 hours priority 1

Category: High-z galaxies

Summary:

Initial Herschel results have demonstrated the power of the observatory for characterizing the properties of ultraluminous, star-forming galaxies during the peak era of star formation. Even with Herschel; however, the only way to spectroscopically study the properties of more typical, lower luminosity systems is by using gravitational lensing to augment the capability of the telescope. We request 12.8 hrs to obtain PACS and HIFI spectroscopy for a single, exceptionally magnified luminous infrared galaxy at z=2.791 that is lensed by the Bullet Cluster. This system, a dusty luminous infrared galaxy, is magnified by a factor of 100 and has a star-formation rate of 100 solar masses per year. It is the lowest stellar mass, lowest intrinsic luminosity galaxy known at z>2 that is magnified sufficiently to enable Herschel spectroscopy, providing our best chance of studying in detail a typical star-forming galaxy at this epoch. The primary goals with the current observations are (1) to obtain a high-fidelity determination of the warm gas mass in this sytem via molecular hydrogen rotational lines, and (2) to constrain the properties of the HII and photodissociation regions via fine structure lines, including the [CII] cooling line. The global objective is to obtain a detailed view of the ISM in this galaxy -- which is likely to yield the best information that we will have for any low mass galaxy at this epoch.

Tracing the Evolution of Star Formation Activity in High Redshift Galaxy Clusters

Proposal ID: OT1_apope_1

Principal Investigator: Alexandra Pope

Time: 54.7 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

Recent observations suggest a reversal in the star formation rate density relation at z>1 such that the average star formation rate in galaxies increases with increasing local galaxy density; the epoch at which this transition occurs is poorly constrained. Two high redshift clusters have shown an increased fraction of actively star forming galaxies towards the center of the cluster, albeit with small number statistics. We propose a statistical study of the dust-obscured star formation activity in a mass limited sample of 12 clusters from z=1.1-1.8 with PACS imaging at 100/160 microns. With 54.7 hours of observing time, we will detect ~150 cluster galaxies down to 100 solar masses per year and many more field galaxies. Our sample spans the fundamental redshift range during which massive clusters show signs of transitioning from a stage of active formation to passive evolution. We will determine the role of the cluster environment on the evolution of infrared luminous galaxies as a function of redshift. These Herschel observations will allow us to map out the star formation activity in galaxy clusters and constrain their mass assembly epoch.

Probing the Interstellar Medium of ULIRGs/SMGs at high redshift

Proposal ID: OT1_AVERMA_2

Principal Investigator: Aprajita Verma

Time: 77.3 hours priority 1

Category: High-z galaxies

Summary:

Early results from Herschel have shown we are entering a new and exciting era in the study of the interstellar media of galaxies. Using the far-infrared cooling lines, we have demonstrated the capability of the PACS spectrometer in deep integrations reaching line sensitivities of 3 sigma sensitivities of 3e-18 W/m/m in <~2 hours exposures on resolved lines, reaching as low as 1e-18 W/m/m in ~7 hours with the red detector allowing us to probe the ISM of galaxies in place at the peak of star-formation and AGN activity in the Universe (Sturm et al. 2010). This proposal builds on these first studies by performing PACS spectroscopy of a sample of bright and strongly lensed infrared/sub-mm galaxies at moderate to high redshift. By virtue of the magnification due to lensing we are able to probe intrinsically lower luminosity galaxies which would normally be beyond the reach of the Herschel spectro- meters, and, for the first time, constrain the physical processes and state of the ISM in these high-redshift galaxies.

Herschel Observations of the Coma Cluster

Proposal ID: OT1_csimpson_1

Principal Investigator: Chris Simpson

Time: 27.2 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to make deep PACS observations of a 1.75-square degree region of the Coma cluster which encompasses both the dense core and the southwest infall region, and covers a factor of 100 in galaxy density. In combination with SPIRE data from the Herschel-ATLAS Key Project, these data will provide the first reliable measurements of the dust properties in a rich galaxy cluster. We have assembled a vast multi-wavelength dataset over this region of Coma that has allowed us to compute reliable stellar masses for nearly 2,000 spectroscopically-confirmed cluster members. We will (i) measure the far-infrared luminosity function and determine whether the turnover seen in Virgo is also present in Coma; (ii) measure the dust masses and temperatures of all galaxies brighter than this turnover; (iii) derive reliable *total* star-formation rates for all galaxies from a combination of UV, H-alpha, and far-IR imaging, and hence address the controversy surrounding optically-classified "post-starburst" galaxies; (iv) relate these important properties of the cluster galaxies to quantities such as stellar mass, galaxy morphology, local galaxy density, and the density of the intra-cluster medium, to determine which physical processes are responsible for the transformation of galaxies from late-type to early-type. We will also search for intra-cluster dust which is expected to be produced via stripping of material from infalling galaxies.

SPIRE Spectroscopy of the Brightest High-Redshift Submillimeter Galaxies

Proposal ID: OT1_dmarrone_1

Principal Investigator: Daniel Marrone

Time: 4.1 hours priority 1

Category: High-z galaxies

Summary:

The South Pole Telescope has conducted a large survey of the southern sky at millimeter wavelengths and discovered a population of high-redshift strongly-lensed dusty star forming galaxies. Both the lensing and the long wavelength selection biases these sources to the highest redshift and their apparent luminosity makes them the most best possible candidates for SPIRE FTS spectroscopy. By combining the unique capabilities of SPT as a survey machine and Herschel as a followup spectroscopy machine, we propose to obtain spectra for five of the brightest lensed sources in the sky. These observations will open a new astrophysical window into the study of young star forming galaxies. The ratios of far-IR lines will provide ground-breaking physical information about this earliest stage of galaxy evolution, including the best measures of how star formation is proceeding, dust emission and absorption properties, the detailed physics of the ISM, and also the quantitative contribution of the emission that comes from black hole accretion in an obscured AGN for these high redshift sources.

Characterizing the Interstellar Medium in 'Normal' High Redshift Galaxies

Proposal ID: OT1_driecher_1

Principal Investigator: Dominik Riechers

Time: 24 hours priority 2

Category: High-z galaxies

Summary:

One of the most astounding recent discoveries is that 'normal' high-z star-forming galaxies are very gas-rich, and often dominated by a massive, cold molecular interstellar medium (ISM) component. The extended morphology, low gas excitation and low star formation efficiency in these galaxies suggest that they maintain widespread, long-lasting star formation. Thus, the overall conditions for star formation are consistent with nearby spiral galaxies, although scaled up by 1-2 orders of magnitude in gas mass and star formation rate. Building upon our comprehensive study of the molecular ISM in these galaxies, we here aim to explore a new regime of star formation diagnostics in the brightest galaxy in our sample with Herschel, exploiting the unprecedented spectral line sensitivity in the widely unexplored far-infared wavelength regime that is inaccessible from the ground. Using PACS and SPIRE, we aim to detect, for the first time, the seven brightest neutral and low ionization state fine structure ISM cooling lines of C, N, and O in a 'normal' high-z galaxy. These lines will provide a critical piece of evidence for the scenario that the ISM properties in these galaxies are indeed comparable to nearby spirals (rather than extreme starbursts) by constraining the UV radiation field, densities, temperatures, and composition (atoms/ions/molecules) of the gaseous component in our target. Such Herschel data are the last missing piece in a full characterization of the ISM in 'normal' star forming galaxies during the peak epoch of galaxy formation. Together with our extensive ground-based dataset, this will provide a unique template for studies of such galaxies at z>3 with ALMA (where a few of the targeted lines become accessible from the ground).

SPIRE Snapshot Survey of Massive Galaxy Clusters

Proposal ID: OT1_eegami_4

Principal Investigator: Eiichi Egami

Time: 27 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

For deep imaging longward of 100 um, confusion noise sets the fundamental sensitivity limits achievable with Herschel, and these limits cannot be improved by integrating longer. To penetrate through this confusion limit and detect faint high-redshift galaxies, gravitational lensing by massive galaxy clusters offers a very powerful and yet cheap solution. For this reason, we are currently conducting a PACS/SPIRE imaging survey of ~40 massive lensing clusters as one of the Herschel Key Programs, "The Herschel Lensing Survey" (PI: Egami, 292.3 hrs). Although this program is producing many exciting results as reported in our 5 Herschel special-issue papers, one thing is becoming clear: it is extremely difficult to find lensed galaxies that are bright enough (> 200 mJy in SPIRE bands) to perform spectroscopy with PACS/SPIRE. This disappointment, however, was quickly overcome by the serendipitous discovery of an exceptionally bright (~500 mJy@350 um) z=2.3 galaxy lensed by a massive cluster at z=0.325. This discovery suggests that if we survey a large enough cluster sample, we will find similarly bright lensed sources that make all kinds of exciting follow-up observations possible. Here, we propose to conduct such a survey by taking advantage of the Millennium Cluster Sample constructed from the ROSAT All-Sky Survey with many years of extensive follow-ups. More specifically, we will conduct a SPIRE snapshot survey of 279 X-ray-selected clusters. SPIRE's great sensitivity and observing efficiency means that we can complete this program in only 27 hours while achieving a nearly confusion-limited sensitivity of 10 mJy (1 sigma). Such a depth will allow all kinds of secondary science projects as well. Although SPIRE wide-area surveys like H-ATLAS will also discover many bright lensed galaxies, these sources are mostly lensed by galaxies and not clusters, which makes our approach an economic alternative to investigate a different type of lensed systems.

A PACS Redshift 1-2 Oxygen Survey: Leveraging the ZEUS [CII] Detections

Proposal ID: OT1_gstacey_3

Principal Investigator: Gordon Stacey

Time: 45.7 hours priority 1

Category: High-z galaxies

Summary:

We propose to use PACS spectroscopy to observe the [OI] 63 um, [OIII] 88 and 52 um, and [OIV] 26 um fine-stucture lines, and PACS/SPIRE photometry to measure the far-IR continuum from 12 IR-bright galaxies in the z = 1 to 2 redshift range. These are galaxies from which we have detected emission in the 158 um [CII] line using our grating spectrometer, ZEUS, on the CSO. We have found that the most luminous starburst-dominated systems in this epoch are characterized by kpc-scale moderate intensity star formation, while the AGN-dominated systems host similarly extended, but much more intense starbursts. The proposed oxygen survey addresses two key questions stimulated by our [CII] results: (1) To what extent are luminous star-forming galaxies at z = 1 to 2 simply scaled-up versions of local starbursts? (2) Why are the starbursts in AGN-dominated systems so much more intense? The oxygen sequence combined with our [CII] detections will have powerful diagnostic capabilities, yielding the strength and hardness of the ambient UV radiation fields, and the density, pressure, and mass of the ionized and neutral atomic components. This data will allow us to characterize the size and age of the starburst, and the importance of the central engine. The ultimate goal is to understand what drives the apparently galaxy-wide starbursts in both star-formation-dominated and AGN-dominated systems, and help identify the connection between starbursts and AGN in the early Universe. This survey is important and unique. We cover the redshift interval from 1 to 2 near the peak of the star formation per unit co-moving volume in the Universe, and it is within this redshift interval that the ZEUS and PACS sensitivities are well matched to enable the detection of the [CII] line together with the oxygen sequence in a wide variety of systems.

Measuring the Epoch of Reionization

Proposal ID: OT1_jcarls01_3

Principal Investigator: John Carlstrom

Time: 79 hours priority 1

Category: Cosmology/Extra-galactic surveys

Summary:

We propose to take advantage of the unique capabilities of both SPIRE and SPT to measure for the first time the ``kinetic SZ contribution'' to the CMB power spectrum. By doing so we will be able to detect, or severely constrain, a signal arising from the scattering of CMB photons off bubbles of ionized IGM during the epoch of reionization, thus providing a first glimpse of the universe as it emerged from the dark ages. To make this measurement we will map the 100 sq. deg. SPT Deep Field with SPIRE and conduct a joint CMB-style analysis of the SPIRE and SPT maps. The high-precision measurements of the CIB fluctuations provided by SPIRE are essential to isolate of the reionization signal. By adding SPIRE observations to the already-reduced SPT data, we will improve the existing constraints on this signal by an order of magnitude. Comparable constraints on the epoch of reionization are unlikely to come from any other combination of facilities prior to the next generation of 21 cm surveys. The combination of the SPT and proposed SPIRE maps will also enable numerous auxiliary studies.

Resolved Herschel photometry and line spectroscopy for the brightest lensed galaxy at z~2

Proposal ID: OT1_jrigby_1

Principal Investigator: Jane Rigby

Time: 19.2 hours priority 1

Category: High-z galaxies

Summary:

We propose to obtain deep, spatially--resolved Herschel PACS and SPIRE photometry and PACs and HIFI spectroscopy of the brightest (in the rest-UV) lensed galaxy yet discovered, RCS0327 at z=1.7038. The goal is to characterize the dust--reprocessed spectral energy distribution (SED) of a typical star--forming galaxy at the epoch when half the Universe's stars formed. Because RCS0327 extends across 38 arcsec, Herschel will spatially resolve it, and thus will measure spectral energy distributions in multiple spatially--distinct regions. The resulting SED will serve as one of very few templates of low--extinction star forming galaxies beyond the local universe. We will measure the far-infrared luminosity and thus infer a star formation rate, which we will compare to rates measured from the optical/nIR. Finally, we will measure the luminosities of the [O I] 63 and [C II] 158 micron lines, which with the far-IR luminosity constrain the densities, pressures, and radiation fields of the photo-dissociation regions. Such observations are impossible for Herschel in the distant universe without lensing amplification.

Revealing the most luminous dusty star forming galaxies

Proposal ID: OT1_jvieira_4

Principal Investigator: Joaquin Vieira

Time: 25.6 hours priority 2

Category: High-z galaxies

Summary:

The South Pole Telescope has surveyed 1000 square degrees at millimeter wavelengths down to milli-Jansky levels with the aim of constraining cosmological parameters. One of the most interesting and unanticipated results of this survey was the discovery of a population of high redshift strongly lensed sub-millimeter galaxies (SMGs). The magnification of these objects and the long-wavelength selection makes these source the best window we have to directly investigate massive galaxy formation in the early universe. Here we propose to observe a flux-limited sample of 65 of these sources with PACS and SPIRE for a total of 25.6 hours. These observations will span the peak of the SEDs at all redshifts, determine the redshift distribution and temperatures for these sources, and enable detailed study of molecular and fine structure lines of high-redshift galaxies. These observations are the best method for constraining the properties of the highest redshift SMGs, and we expect to find a minimum of 3 sources at z>5. As these sources are in the southern hemisphere they are ideal targets for ALMA early science observations and will provide an invaluable sample of sources for the community.

Unveiling the dust mass in the host galaxies of Gamma-Ray Bursts

Proposal ID: OT1_lhunt_2

Principal Investigator: Leslie Hunt

Time: 28.1 hours priority 2

Category: High-z galaxies

Summary:

Gamma-Ray Bursts (GRBs) are so luminous that they can shine through highly obscured galaxies, nearby and in the remote universe. GRBs enable identification of galaxies independently of their luminosity, thus singling out a population that is a potentially powerful probe of galaxy evolution. Only a minority of the host galaxies of GRBs (GRBHs) have been so far detected at sub-millimeter (submm) or mid-infrared (mid-IR) wavelengths; however, in this minority the inferred star-formation rates (SFRs) can be as high as ~500 Msun/year, implying that they are similar to submm galaxies. On the other hand, the frequent non-detections argue against a population dominated by massive and strongly starbursting galaxies. One way to resolve this dilemma would be warm dust. At redshifts 2-4, warm dust (40-50K) would be difficult to detect in the submm bands because its peak would be too blue, and also in the mid-IR, because its peak emission would be far too red. We propose to break this possible dust-temperature redshift "conspiracy" with Herschel PACS+SPIRE photometry of 14 GRBHs with redshifts reaching 4.4. The sample was selected on the basis of prior Spitzer IRAC (or MIPS) detections. We already have in hand a large amount of ancillary multiwavelength data with which we can determine stellar ages and masses. We will construct spectral energy distributions from the UV to the far-IR and use them to derive bolometric luminosities and SFRs, and constrain dust mass, dust temperature, and grain properties. We will compare the dust properties with the stellar component of the galaxies, and analyze the GRBHs in the context of other high-z galaxy populations. Such a program is now possible thanks to the unique ability of Herschel to study dust emission in galaxies over a wide range of redshifts. Ultimately our proposed study of GRBHs will open a new window on the study of galaxy formation and evolution.

Dissecting the nature of the Planck-HFI high-z blobs

Proposal ID: OT1_lmontier_1

Principal Investigator: Ludovic Montier

Time: 11.6 hours priority 2

Category: High-z galaxies

Summary:

Ultra luminous dusty galaxies radiating most of their energy in the far IR are now known from Spitzer IR and submillimeter observations to dominate the integrated luminosity at redshift 2 to 3. The behavior of this population at higher redshifts remains poorly constrained. This proposal is based on the use of the Planck all sky survey at millimeter and submillimeter wavelengths to find new and rare high-z candidate sources. The limited angular resolution requires a specific data processing to extract good candidates. The Cosmic Infrared Background (CIB) is observed with high signal to noise by Planck after a specific component separation. An algorithm detecting cold spots on the CIB (thus potentially high z dominated) compatible with point sources has been developed. These high z blobs have been shown to be a mixture of different type of objects. Among these, new high z ULIRGS at the high end of the luminosity function or lensed, or high z large scale structures are very interesting for galaxy evolution. We performed comparison of the Planck data with new unidentified sources found by SPT near the upper end of their luminosity function and we detected a few of them. Furthermore, the stacking in Planck of 34 of these SPT sources is easily detected in Planck and gives a typical SED in the Planck bands for these sources. We thus selected sources with this type of SED in the Planck data and produced a list of 10 candidates proposed in this program for observations with SPIRE and PACS. We propose an observation allowing to study the nature of these 10 cold blobs in three cases covering well the possible contributors to this Planck detected high z blobs (single source, cluster of 10 to 20 sources, structure of the cold CIB spot if a small number of sources has not been found). This should be a very interesting contribution to the study of this new emerging population. Furthermore this program should allow us to use best the Planck all sky survey later to find more candidates.

The Last of the Titans: The Nature of Super-Starbursts at z~1.5

Proposal ID: OT1_mswinban_1

Principal Investigator: Mark Swinbank

Time: 6.7 hours priority 1

Category: High-z galaxies

Summary:

We have recently discovered a population of 'super-starbursts' at z~1-3-1.5. These rare galaxies are selected from the zWiggles spectroscopic survey, and rest-frame UV and H-alpha spectroscopy suggests star-formation rates 100-500Mo/yr. These apparently high-luminosity, but low stellar mass (log(Mstar)~10Mo), gas rich (f_gas~60%) galaxies forming extremely quickly in an extended starburst are suggestive of late time proto-galaxies, but uniquely, are selected from their nebular emission lines. We have obtained three dimensional spectroscopy of 13 galaxies and mapped the two dimensional dynamics on ~kpc scales. The galaxies show extended star-formation on 4--16kpc scales, with dynamics which may resemble rotating systems and clumpy and intense star-formation which may indicate bulge formation. However, the impact of dust obscuration is unknown, and if these galaxies are confirmed as high luminosity ULIRGs, it would argue that these are instead mergers with structures dust, and instead comprise the low-redshift tail of the 'archetypal' high-z ULIRGs and SMGs seen at z~2.3. We propose short Herschel SPIRE observations of this sample of 13 galaxies. We conservatively predict 250um fluxes >12mJy, which should yield detections viable in just ~7mins each. Our total request 6.7 hours.

The Most Luminous Obscured Galaxies and Quasars Revealed by WISE

Proposal ID: OT1_peisenha_1

Principal Investigator: Peter Eisenhardt

Time: 10.0 hours priority 1 and 20.4 hours priority 2

Summary: High-z galaxies

In the past week, the Wide-field Infrared Survey Explorer (WISE), has completed its first coverage of the entire sky at 3.4, 4.6, 12 and 22 microns (W1, W2, W3, and W4), reaching sensitivities hundreds of times deeper than IRAS. Also in the past week, we have obtained spectroscopy of over 50 WISE sources with unusual colors, including 14 with z > 1.8. Nine of these 14 sources were selected by requiring strong W4 detection combined with insignificant W1 and W2 detection: W1/W2 drops. After rejecting optically bright W1/W2 drops, only 4 sources at z < 1.8 are present. These sources have in excess of 1E13 solar luminosities, and possibly 1E15. We request 64.1 hours of Herschel time to observe a sample of 88 W1/W2 drops, augmented by 5 other WISE sources at z > 1.8, from 70 to 500 microns with PACS and SPIRE. The resulting SEDs will enable us to extend the obscurations, luminosities, and star formation rates associated with ultra-luminous infrared galaxies (ULIRGs) into uncharted terrain.

A Star formation oasis in the middle of a cluster desert

Proposal ID: OT1_ppopesso_1

Principal Investigator: Paola Popesso

Time: 97.4 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

One of the most fundamental correlations between the properties of galaxies in the local Universe is the so-called morphology-density relation. In the local Universe late type star forming galaxies favor low density regimes and giant ellipticals reside in the cluster cores. Much of the debate centers on whether the relation arises early on during the formation of the object, or whether it is caused by environment-driven evolution. To shed ligth on this issue, we propose to map with PACS at 100 and 160 um the field of 8 clusters in the ``cluster desert'' at 1.4 < z < 1.8, at the epoch when clusters are accreting galaxies and galaxies are still undergoing their own formation process. Our goal is to observe each system down to log(LIR)=11.5 to observe almost the entire LIRGs and the complete ULIRGs population and to sample the bulk of the star formation. The 8 systems are all X-ray detected, spectroscopically confirmed and with large amount of multi-wavelength ancillary data. The X-ray detection ensures that these are well established, bound structures, which represent the missing link between the protoclusters at z > 2 and the well formed clusters in the local Universe. Our sample spans almost a decade in X-ray luminosity and dynamical mass, comprising relatively young systems and already old and relaxed clusters. This hetereogenity allows us to link the level of star formation activity to the global properties of the systems to shed light on which environmental process, if any, can affect the galaxy star formation activity. All systems are covered by medium-deep and deep XMM and Chandra data, crucial to reveal X-ray faint AGNs, and to study the connection between AGN feedback and star formation activity. The availability of accurate stellar mass estimates allows to relate the SF activity to the environment in different mass bins, thus disentangling the mass- from the environment-driven galaxy evolution.

Unveiling the nature of strong galaxy activity in an X-ray detected galaxy cluster at z=2.07

Proposal ID: OT1_rgobat_1

Principal Investigator: Raphael Gobat

Time: 17.7 hours priority 1

Category: High-z galaxies

Summary:

We have recently discovered the most distant X-ray luminous galaxy cluster known to date, a z=2.07 strong overdensity of red passively evolving ellipticals with extended X-ray emission seen by XMM-Newton. Several cluster members are detected by MIPS at 24 micron with fluxes above 100 microJy, implying high luminosities in the mid-IR rest frame. If due to star formation activity this would correspond to ULIRG-like luminosities, and would imply a very high degree of forming activity in the cluster core. However, the MIPS detected galaxies have elliptical like morphologies and SEDs, suggesting in turn that the mid-IR emission is due to a huge amount of heavily obscured AGN activity. We propose deep imaging with PACS and SPIRE in the cluster that will clarify the AGN or SF nature of the activity in the cluster. Our results will have important implications on the understanding of the early phases of cluster galaxy assembly. This project will push the study of galaxy activity in established clusters to the highest possible redshifts.

SPIRE and the formation and evolution of galaxy clusters

Proposal ID: OT1_rhuub_1

Principal Investigator: Hubb Röttgering

Time: 16.7 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

The progenitors of local galaxy clusters ("proto-clusters") are powerful laboratories for tracing the emergence of large scale structure and studying the evolution of galaxies in dense environments.

We propose to use SPIRE's excellent sensitivity and survey speed to obtain, for the first time, a large sample of dust-obscured, star forming, proto-cluster galaxies in an area encompassing the entire proto-cluster and its environment.

The 8 proto-clusters in the sample cover the key redshift range 2 < z < 4 and have a wealth of existing, multi-wavelength data and a large number of spectroscopically confirmed proto-cluster galaxies. The masses of the proto-clusters are typically a few times 10^14 - 10^15 solar masses and the cores are up to 40 times denser than the field.

Matching the SPIRE sources with upcoming LOFAR and EVLA radio observations, we will constrain the photometric redshifts to better than 0.3, resulting in a complete sample of dusty proto-cluster galaxies with very low (<5%) contamination.

The proposed SPIRE observations will be compared to our extensive simulations of forming proto-clusters, allowing us to: (i) unveil and characterize the (dust-obscured) star-forming galaxies in the proto-clusters and constrain their star formations rates and dust temperature; (ii) relate these properties to their optical morphologies, stellar masses and location in the proto-cluster and investigate the differences between proto-cluster galaxies and field galaxies; (iii) ascertain whether red proto-cluster galaxies are passive galaxies or dusty starbursts; (iv) determine the structure and size of the proto-clusters, in particular, distinguish whether galaxies are distributed homogeneously or in filaments; (v) trace the evolution and contraction of large-scale structures from z=4 to z=2.

The proto-cluster targets are ideally located for follow-up spectroscopy and high-resolution imaging with submm observatories such as APEX and ALMA.

Characterising the ISM of bright, lensed star-forming galaxies across cosmic time with the SPIRE FTS

Proposal ID: OT1_rivison_1

Principal Investigator: Rob Ivison

Time: 94.1 hours priority 1

Category: High-z galaxies

Summary:

We have shown that Herschel is capable of exploring high-redshift galaxies spectroscopically, provided those galaxies are sufficiently bright.

Here, we propose to exploit the wide wavelength coverage of the SPIRE FTS to study the powerful diagnostic rest-frame FIR cooling lines from a unique and complete sample of 25 bright, gravitationally-lensed - but intrinsically typical - submm galaxies (SMGs). We can thus perform the first detailed analysis of their ISM, tracing their density structure and searching for variations in line strengths compared to local counterparts.

Our targets span 1 < z < 3.1 (where [C II] is not accessible to ALMA) and a good range of L(FIR) (12 < log L(FIR) < 13.5), and are selected from panoramic Herschel imaging surveys that are uniquely capable of providing a large, reliable sample at S(350um) > 200mJy, with excellent ancillary data.

We will detect or place sensitive limits on the key atomic cooling lines, e.g. [C II], [O I], [O III], and combine these with ground-based observations of 12CO, 13CO, C I and dense-gas tracers to model their ISM and thence understand their energetics and evolution. Using these data we will:

1) map the evolution of the gas content as a function of redshift, via the sensitivity of [C II]/L(FIR) to M(H2); 2) search for changes in the properties of the star-forming gas as a function of redshift and L(FIR); 3) coadd the spectra in the rest frame to delve up to 5x deeper still, to search for faint lines, e.g. H2O and [O I]145.5, allowing a complete characterisation of the average emission; 4) conclusively address the issue of the contribution of AGN to the immense luminosities of submm galaxies.

Goals 1-3 drive the requirement for a sample of 25 SMGs. All our goals require Herschel and cannot be addressed by other facilities.

We stress that the scientific legacy of ISO and Spitzer has in large part been based on the wealth of data in their spectroscopic archives and the same is likely to be true for Herschel.

Measuring the PAH emission in a z=6.1 star forming Submillimetre Galaxy

Proposal ID: OT1_schapman_1

Principal Investigator: Scott Chapman

Time: 4.8 hours priority 1

Category: High-z galaxies

Summary:

We have discovered a z=6.1 Submillimetre Galaxy from a detailed survey of 0.5 sq deg in GOODS-N, FLS, and LockmanEast. HDF259 was originally detected by SCUBA and the VLA, but recently constrained through Herschel-SPIRE detections. The redshift is confirmed through a Keck spectroscopic redshift, an optical-near/mid-IR photo-z (as an I-band dropout with a rising stellar bump at 1.6um), and through template fitting with a most likely T_dust in the SPIRE through 1.2mm wavelengths. Even if the optical data incorrect redshift, an extreme range of T_dust secures the redshift as lying from z=4-8.

This SMG represents the first opportunity yet to study the rest-frame 7.7um region PAH features in a z>6 star forming galaxy, using the PACS spectrometer (where the 7.7um strong PAH feature comes into the PACS 51-70um and 70-105um bands only at z>5.9).

The strength of the PAH, estimated both from extrapolated flux measurements from Spitzer-MIPS, and from the z~2 L_IR-L_PAH relation (Pope et al. 2008) ensures that a typical PAH in this SMG will be well detected in 4.8hrs total programme duration.

THE HERSCHEL-AKARI NEP DEEP SURVEY: the cosmological history of stellar mass assembly and black hole accretion

Proposal ID: OT1_sserje01_1

Principal Investigator: Stephen Serjeant

Time: 73.5 hours priority 2

Category: High-z galaxies

Summary:

We propose a far-IR and submm mapping survey of the premier AKARI deep field in the North Ecliptic Pole, in PACS/SPIRE parallel mode. This is the only major deep infrared field not yet covered by Herschel guaranteed or open time key projects. The outstanding and unparalleled continuous mid-IR photometric coverage from AKARI, far better than equivalent Spitzer surveys, enables a wide range of galaxy evolution diagnostics unachievable in any other survey field (including Herschel HerMES/PEP fields), by spanning the wavelengths of redshifted PAH and silicate features and the peak energy output of AGN dust tori. The investment by AKARI in the NEP represents ~10 percent of the entire pointed observations available throughout the lifetime of AKARI. Our proposal remedies the remarkable omission from Herschel's legacy surveys of the premier extragalactic deep field from another IR space telescope.

We will simultaneously identify and find photometric redshifts for the Herschel point source population, make stacking analysis detections of the galaxies which dominate the submm extragalactic background light as a function of redshift, determine the bolometric power outputs of the galaxies that dominate the submm background, compare the UV/optical/mid-IR continuum/PAH/far-IR/submm/radio star formation rate estimator in the most comprehensive IR survey data set to date, and track the coupled stellar mass assembly and black hole accretion throughout most of the history of the Universe.

Dust in the wind: the role of dust in ram-pressure stripped gas and intracluster star formation

Proposal ID: OT1_ssivanan_1

Principal Investigator: Suresh Sivanandam

Time: 10.4 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to detect dust associated with ram-pressure stripping through deep Herschel PACS/SPIRE imaging of a carefully chosen set of cluster galaxies that show strong signs of on-going stripping and intracluster star formation. Several lines of evidence, such as the existence of cold molecular gas and intracluster star formation in ram-pressure stripped tails, strongly point towards the existence of dust in these tails. Herschel is the only telescope that has the sensitivity to detect the emission from dust blown out into the intracluster medium (ICM). With our proposed observations we aim to: 1. quantify the temperature, mass, and lifetime of dust blown out into the ICM; 2. understand the role dust plays in the existence of molecular hydrogen in the ICM and intracluster star formation. Our program will carry out deep Herschel observations of five galaxies in high pressure environments with highly extended (~20-80 kpc) multi-phase gaseous tails. The Herschel observations will expand our already large multi-wavelength dataset and finally provide complete inventory of the gas and dust associated with ram-pressure stripping. This will provide a more complete picture of the impact of ram-pressure on galaxy evolution.

Cold Gas and Dust in the Filamentary Complexes of Cluster Cooling Flows

Proposal ID: OT1_sveilleu_1

Principal Investigator: Sylvain Veilleux

Time: 7 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to obtain deep PACS + SPIRE far-IR photometry and 2D PACS [C II] 158 um spectroscopy of 7 cooling-flow clusters with extended Halpha filaments to constrain the properties of the dust and cooling gas in these systems. Our targets are part of a large sample of clusters that were imaged at Halpha using the Maryland Magellan Tunable Filter (MMTF) as part of a comprehensive multiwavelength survey. The superb sensitivity and resolution of the MMTF data have uncovered, often for the very first time, spectacular filaments of warm ionized gas extending as far as 50 kpc from the cluster core. The origin and heating source of these filaments remains a mystery. Our MMTF images have served as a guide to extract on-filament X-ray and optical spectra for a large sample of clusters, leading to the discovery that the X-ray ICM is cooling at a highly accelerated rate in the vicinity of these filaments. This direct link between the warm and hot phases may be the first direct evidence for the purported cooling flow. Given the high FIR fluxes detected in cluster cores, it is possible that dust grain cooling plays an important role in the cooling flow process. However, it remains unclear whether the observed dust is associated with the warm filaments or limited to the center of the brightest cluster galaxy (BCG). Current key programs cannot address this question given their lack of information on the Halpha filaments. Our proposed Herschel observations of the 7 cooling-flows clusters from our sample with the most extended Halpha filaments will directly address this question and help us determine: a) the role of dust cooling in the cooling-flow process, b) whether the observed dust is associated with the BCG or the warm filaments, and c) whether gas is cooling below 10^4 K, the temperature probed by Halpha. Providing answers to these questions will improve our understanding of the cooling processes in galaxy clusters and constrain the role of heating processes, such as AGN feedback, in preventing such cooling.

A deep PACS survey of AKARI-Deep field south: Revealing the connection between AGN and star formation

Proposal ID: OT1_ttakagi_1

Principal Investigator: Toshinobu Takagi

Time: 34.5 hours priority 1

Category: High-z galaxies

Summary:

We propose a deep PACS imaging survey of a prestigious far-IR survey field, AKARI-Deep field south, which has the lowest cirrus background in the sky and has been observed with most of the major IR and submm telescopes, such as AKARI, Spitzer/MIPS, BLAST and Herschel/HerMES, covering 7-12 deg^2. We also conducted one of the widest and deepest millimetre survey using ASTE/AzTEC within this field, covering 0.25 deg^2. Although there are many (sub)mm survey fields in different parts of the sky, ADF-S has a unique data set from AKARI/IRC at 2.4, 3.2, 4.1, 7, 11, 15 micron, i.e. filling the wavelength gap between Spitzer/IRAC 8 micron and MIPS 24 micron. We utilize this comprehensive mid-IR coverage to identify obscured AGNs and derive the bolometric AGN luminosity, based on the type-independent X-ray-to-mid-IR luminosity relation. PACS photometry is necessary to derive accurate star formation rate (SFR) in starburst-AGN composite system. We investigate the relative importance of AGN in SMGs and other mid-IR selected ULIRGs, as a function of SFR, stellar mass, and redshift. Ultimately, we will determine the role of AGN in galaxy formation and the regulation mechanism for co-evolution of stellar mass assembly and central black hole. Also, deep PACS images allow us to identify millimeter-selected SMGs at very high redshifts, which will be prime targets of ALMA.