- SOFIA Overview
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SOFIA Cycle 5 Approved Programs
Proposal ID: 05_0002
Principal Investigator: Charles Woodward (University of Minnesota - Twin Cities)
Title: Comet NEOs 41P and C/2015 V2 - The FORCAST Story
Abstract: Solar system formation is a process that simultaneously preserves and transforms ISM ices, organics, and dust grains into cometesimals, planetesimals and, ultimately, planets. Cometary dust contains remnants of both primordial material in the comet-formation zone as well as processed material transported from hotter regions closer to the Sun. They are primitive bodies, detritus from the epoch of planet formation. Why study comets? They can advance our understanding of both "How do circumstellar disks evolve and form planetary systems?" and "What are the initial stages, conditions and processes of solar system formation and the nature of the ISM that was incorporated?" We propose to observe (FORCAST/FPI+) comets 41P/Tuttle-Giacobini-Kresak and C/2015 V2 (Johnson), both “Near Earth Objects” coming within 0.2 - 0.8 AU of the Earth during their perihelion passage, to determine the coma grain properties and to characterize these bodies. Our SOFIA program addresses three questions: What information do the cometary grains provide us concerning the evolution of the early solar system? What are the fundamental differences between comets originating from different regions and times of the solar system? What is the connection between the properties of cometary grains derived from scattered light versus thermal emission?
Proposal ID: 05_0005
Principal Investigator: Robert Gehrz (Minnesota Institute for Astrophysics; University of Minnesota)
Title: SOFIA Target of Opportunity Observations of Galactic Supernovae and Supernovae in Nearby Galaxies
Abstract: We propose to conduct repeated SOFIA FLITECAM and FORCAST grism Target of Opportunity (ToO) observations of Galactic supernovae and supernovae in nearby galaxies that may occur during the SOFIA Cycle 5 observing period. Many of our FLITECAM objectives can be met for SNe with M_v < 14.0, while FORCAST objectives will require SNe in galaxies less than ~1 Mpc distant. The scientific focus of the proposed observations is the determination of the temporal development of the ejecta and the nature of the interaction of the supernova radiation, ejecta, and blast wave both with each other and with the surrounding material.
Proposal ID: 05_0008
Principal Investigator: James De Buizer (Universities Space Research Association)
Title: Revealing the Embedded Structures and Sources within Giant HII Regions: Wrapping up the Survey
Abstract: Most studies concentrate on the processes of isolated low-mass star formation while little is known about massive star formation and clustered star formation, despite the fact that the vast majority of stars are formed within OB clusters. Giant HII regions harbor the most active areas of OB star formation in the Galaxy, and as such are fantastic laboratories for the study of massive star formation as well as clustered star formation. However, most of these GHII regions are optically obscured and far away, requiring them to be studied in the MIR/FIR with adequate spatial resolution. SOFIA 19.7 and 37.1um imaging with approximately 3 arcsecond resolution well-suited for revealing the embedded structures and sources within these regions. These SOFIA observations will be combined with data taken at other wavelengths to quantify the detailed physical properties within GHII regions individually and as a population. The observations will also expose the areas of the youngest stages of massive star formation within the GHII regions and allow for the confirmation or confrontation of the recently proposed evolutionary sequence of GHII regions. GHII regions are a dominant source of emission contributing to the bolometric luminosity that we see from galaxies in general. Therefore, understanding the global and detailed properties of GHII regions in our own Galaxy can be used as a template for interpreting what we observe in galaxies far away.
Proposal ID: 05_0010
Principal Investigator: Aneurin Evans (University of Keele)
Title: The long wavelength view of stellar mergers
Abstract: We will use SOFIA to look at the aftermath of stellar mergers, the so-called Luminous Red Variables (LRVs). Other than Type Ia supernovae, these are the most energetic phenomena associated with low-mass stars. Their circumstellar environments can tell us a great deal about fossil remnants remaining from the common envelope phase that preceded the merger, and about the merger event itself. These events (exemplified by V838 Mon) produce a large amount of dust during the merger and thus offer the rare opportunity to study and validate theories for the mineralogical condensation sequence in freshly formed dust.
Proposal ID: 05_0012
Principal Investigator: David Neufeld (The Johns Hopkins University)
Title: Terahertz water masers
Abstract: Using the GREAT instrument, we will observe terahertz water masers toward seven oxygen-rich evolved stars with circumstellar envelopes that emit maser radiation in the 22 and 321 GHz water transitions: o Cet, U Ori, R Leo, R Crt, RS Vir, S CrB and R Cas. Our primary target will be the 8(27)-7(34) line of water vapor at 1296.411 GHz, a transition that our models predicted would be a strong maser - a prediction recently confirmed by our Cycle 4 observations of W Hya and U Her. This transition, which was not accessible with Herschel/HIFI, has a significantly higher frequency than any water maser transition observed to date. In combination with ground-based maser observations at lower frequencies, the proposed observations will provide new constraints on the conditions of gas temperature, gas density, and IR radiation field within the maser-emitting region, providing important information about the maser pumping mechanism.
Proposal ID: 05_0014
Principal Investigator: Philip Appleton (California Institute of Technology)
Title: Mapping extended [CII] emission in shock-dominated Seyfert galaxies with likely radio jet/ISM interactions
Abstract: We propose to observe [CII] emission in NGC 4258 and NGC 7319, two nearby low-luminosity AGN, which have unusually powerful mid-IR-detected warm molecular hydrogen emission indicative of powerful shocks. Both galaxies show evidence for radio jets interacting with the ISM of the host galaxies on extended scales. Our proposal aims at exploring how H2, heated by shocks, can potentially boost the strength of [CII] emission at the jet-ISM interface. In one case, NGC 4258, a single SOFIA leg was completed (Cy-4) which led to the discovery of unexpected large-scale minor-axis [CII] emission, and enhanced velocity dispersion associated with regions of warm H2 emission. We propose to extend the mapping to larger distances from the AGN where the jet may be further interacting with the disk. NGC 7319 is Seyfert galaxy in Stephan's Quintet that shows a collimated radio structure and bow shock at the base of a CO-emitting filament. Previous (incomplete) mapping of the Stephan's Quintet group by Herschel in [CII] missed the region around NGC 7319, but showed kinematic evidence on group-wide scales for a possible outflow from the AGN. Both observations have relevance to understanding the importance of shock boosting of [CII]/L(IR) ratios in galaxies at high-z, where ALMA observations are begining to uncover [CII] outflows associated with AGN.
Proposal ID: 05_0015
Principal Investigator: William Langer (Jet Propulsion Laboratory)
Title: Structure and Dynamics of Cloud Boundaries as Seen in the Far-IR Emission Lines of [O I], [C II], and [N II]
Abstract: We propose to observe and analyze the envelope in interstellar clouds where the transition takes place from the ionized boundary layer (IBL) to the Photon Dominated Region (PDR) surrounding the dense star forming molecular cores. These layers produce most of the far-infrared emission in the Galaxy and are regions where not only does the UV and EUV produced by stars get absorbed, but also where cloud growth takes place by a variety of agglomeration and collisional process. We will use SOFIA GREAT to observe the [O I] 63 micron line of neutral oxygen at high spectral resolution in nine lines of sight containing over 30 cloud components observed with Herschel HIFI in the [C II] line of ionized carbon, C+, and the [N II] line of ionized nitrogen, N+. We will combine the [O I] spectra with data in hand from Herschel HIFI observations of [C II] and [N II], and ground-based HI and CO isotopologues, and [C I] where available, and use them to separate out the contributions from different layers. The results can test static and dynamic models of the IBL and PDR transitions, inform models of cloud growth, and evaluate the contributions of various layers to Galactic FIR line emission.
Proposal ID: 05_0016
Principal Investigator: David Neufeld (Johns Hopkins University)
Title: Probing the molecular hydrogen fraction in diffuse molecular clouds with observations of HCl+
Abstract: Using the GREAT instrument, we will observe the Doublet Pi 3/2 J = 5/2 - 3/2 transitions of the H-37Cl+ and (where not already observed in Cycle 4) the H-35Cl+ molecular ions at 1.442 and 1.444 THz, in absorption, toward the bright continuum sources Sgr B2 (M), W31C (G10.6-0.4), W49N, and W51. The observations will yield robust estimates of the HCl+ column densities in diffuse clouds lying along the sight-lines to those sources. Because HCl+ reacts rapidly and exothermically with H2 to yield H2Cl+, the abundance ratio HCl+/H2Cl+ is sensitive to the H2 abundance in the interstellar gas; combining the HCl+ measurements with ones already available for H2Cl+ will thus permit independent estimates of the molecular hydrogen fraction along the proposed sight-lines. This proposal follows up on a successful detection of HCl+ obtained in a pilot program performed in Cycle 4.
Proposal ID: 05_0018
Principal Investigator: David Chuss (Villanova University)
Title: A Polarimetric Survey of the Cold Dust in the Central Molecular Zone of the Milky Way
Abstract: We propose a 214 micron polarimetric survey of the Central Molecular Zone (CMZ) of the Galaxy using the HAWC+ polarimeter. This survey will provide an unprecedented combination of coverage, sensitivity and angular resolution of the magnetic field geometry in the cool dust component of the Galactic center. The new data, which will consist of a map of thousands of independent polarization measurements across the CMZ, will help to determine the geometry and strength of the magnetic field in this complex region. It is known that the Galactic center contains strong magnetic fields, but their role in the dynamics of the region is not well understood. HAWC+/SOFIA is uniquely positioned to provide the most complete picture of the field in the cool dust to date, and will undoubtably help answer this important question.
Proposal ID: 05_0019
Principal Investigator: Kate Su (University of Arizona)
Title: Mineralogical Evolution in Extreme Debris Disks II
Abstract: Young (10-200 Myr), luminous (fractional infrared luminosity on the order of 1E-2) extreme debris disks provide a unique opportunity to explore exo-asteriod and exo-planetesimal collisions during the oligarchic and chaotic phases of terrestrial planet-building. We propose to obtain low-resolution grism spectra of two extreme debris disks to document and characterize the mineralogy evolution in the mid-IR region where strong peaks originating from silica and forsterite dust can be easily identified. The proposed observations will supplement our on-going warm Spitzer monitoring program studying disk variability at 3.6 and 4.5 microns, provide immediate insights on the long-term mineralogical evolution in comparison with the existing Spitzer IRS spectra, and will bridge to similar studies that JWST will provide in the near future.
Proposal ID: 05_0020
Principal Investigator: Jiangtao Li (Department of Astronomy; University of Michigan)
Title: Neutral and Ionized Gas from the Most Energetic Extragalactic Nuclear Superbubble in NGC 3079
Abstract: Superbubbles produced by nuclear starbursts or the AGN in the center of galaxies play a key role in exchanging energy and mass between galaxies and their environments. Far-IR band contains principle atomic and ionized ISM cooling lines which are critical in understanding the superbubble structure and the physical processes involved in producing them. We propose SOFIA/FIFI-LS spatially resolved spectroscopy studies of the 1.3kpc-diameter nuclear superbubble of NGC3079. We will search for [O III] 52,88 micron, [N II] 122 micron, [C II] 158 micron lines, and compare their spatial distributions to the multi-wavelength archival data tracing different ISM phases. We will model the lines and the IR continuum in order to estimate some physical parameters of the neutral and ionized gas. This will help us to constrain if the lines are produced from the diffuse gas or belong to PDRs at the surface of molecular cloudlets entrained in the outflow. Combining with the outflow velocity measured from the line shift, we will also estimate the kinematic energy contained in the cool gas and compare the energy budget among different gas phases of the superbubble.
Proposal ID: 05_0021
Principal Investigator: Sarah Ragan (University of Leeds)
Title: Cooling and kinematics in the Central Molecular Zone
Abstract: The Central Molecular Zone (CMZ) of the Milky Way contains a huge reservoir of molecular gas, and yet its star formation efficiency appears to be significantly lower than expected from standard star formation relations. This suggests that additional physics must be considered in order to understand the regulation of star formation in the CMZ. We propose GREAT observations of the [OI] and [CII] transitions toward three compact clouds residing in the so-called 100 pc ring surrounding the Galactic Centre. These lines are predicted to be the primary coolants of molecular clouds in this harsh environment. Measuring the strength of the [CII] and [OI] line emission produced by the clouds will therefore allow us to constrain their total cooling rate, while the [OI]/[CII] line ratio and the ratio of both lines relative to the measured FIR emission will allow us to constrain the density and temperature of the clouds, and hence the intensity of the cosmic ray ionization rate in their vicinity. We can test models that predict that the CMZ is a unique environment in which oxygen dominates carbon as a coolant. The superb velocity resolution of GREAT will also allow us for the first time to study the kinematics of the warm gas in the clouds, which we expect to fill much of their volume. Finally, by comparing clouds at different locations within the 100 pc ring, we will be able to study whether the age of the clouds increases as we move away from Sgr A*, allowing us to test the idea that the formation of the clouds may have been triggered by the tidal influence of the Milky Way's central black hole and nuclear star cluster. These ground-breaking observations are only possible with SOFIA and offer several different pathways to high-impact science.
Proposal ID: 05_0022
Principal Investigator: Andrew Harris (University of Maryland)
Title: Joint Impact Proposal: Mapping C+ Across the Galaxy's Central Molecular Zone
Abstract: We will produce a velocity-resolved C+ data cube covering the inner 220 x 44 pc of the Galactic center's Central Molecular zone. It is not only very important to study the Galactic center in the context of its role in Galactic structure and evolution, but also because studies of our own Galactic center form the basis of our understanding of all other “normal” galactic nuclei. The data products will be useful to many researchers; our own main science interests are to trace the C+ mass fractions associated with dense neutral gas, and to separate different gas components and flows to study the connections between regions. Only upGREAT on SOFIA can add this key information for our detailed understanding of our Galactic center and other galaxies: this will be a true SOFIA legacy data product of value to a broad group of researchers.
Proposal ID: 05_0029
Principal Investigator: Leslie Looney (University of Illinois)
Title: Far-Infrared Polarization of the Disks around HL Tauri and DG Tauri down to 0.9% Fractional Polarization
Abstract: With HAWC+ we have the sensitivity to detect circumstellar disk dust polarization in the FIR for the first time. The best observational limits to date place upper limits of 1.7% for the fractional polarization in the FIR, but recently HL Tauri was detected in the 1.3 mm dust emission with an average fractional polarization of 0.9%, suggesting that we have to push the observations deeper. HAWC+ can detect 0.9% fractional polarization to >3-sigma in the 2 FIR brightest disks (HL Tauri and DG Tauri) in a moderate amount of total observing time. For the case of HL Tauri, we will observe the polarization in all 5 bands, and for DG Tauri, we will observe the polarization only in the shortest and longest bands since polarization has not yet been detected in this source. Since DG Tauri B is in the DG Tauri field, we will also expect 3-sigma polarization detection for its disk. The millimeter polarization observations have a discrepancy with simple models that we can directly address with FIR observations. With these HAWC+ observations, we will be able to discern if more complex magnetic field morphologies (beyond simple toroidal/poloidal) are needed in our models, or if the polarized emission has components from scattered light as well as dust grain alignment, or if the dust grain alignment and misalignment in the dynamic disk environment is not well understood.
Proposal ID: 05_0033
Principal Investigator: Rolf Guesten (Max-Planck-Institut fur Radioastronomie Bonn)
Title: Joint Impact Proposal: Mapping C+ Across the Galaxy's Central Molecular Zone
Abstract: We will produce a velocity-resolved C+ data cube covering the inner 220 x 44 pc of the Galactic center's Central Molecular zone. It is not only very important to study the Galactic center in the context of its role in Galactic structure and evolution, but also because studies of our own Galactic center form the basis of our understanding of all other ``normal'' galactic nuclei. The data products will be useful to many researchers; our own main science interests are to trace the C+ mass fractions associated with dense neutral gas, and to separate different gas components and flows to study the connections between regions. Only upGREAT on SOFIA can add this key information for our detailed understanding of our Galactic center and other galaxies: this will be a true SOFIA legacy data product of value to a broad group of researchers.
Proposal ID: 05_0036
Principal Investigator: Dan Clemens (Boston University)
Title: The Magnetic Fields of the Dense and Diffuse Cores in L1544
Abstract: We propose higher angular resolution (HAWC+ D-band) and deeper polarimetric observations (twice the integration time) than the tabulated ROC plan for the dense core of the nearby (140 pc) dark cloud L1544. We will use these data to test ambipolar diffusion models of this pre-stellar core and to critically compare HAWC+ polarimetric maps to our near-infrared background starlight polarimetry and reprocessed SCUPOL map of the B-field of this cloud. Further, we propose sensitive HAWC+ E-band polarimetric observations of the outer, more diffuse pair of cloud cores (L1544 E and L1544 W) located outside the ROC FOV. These HAWC+ data will permit comparing how the B-field strengths (from the Chandrasekhar-Fermi method) vary with radial offset for the diffuse and dense cores. All of these data, taken together, will permit quantitative comparisons of position angle structure functions to assess the ratio of random to uniform B-field strengths in each core.
Proposal ID: 05_0038
Principal Investigator: John Vaillancourt (Massachusetts Institute of Technology; Lincoln Laboratory)
Title: Characterizing the FIR polarization spectrum in Galactic Clouds
Abstract: Magnetic fields permeate the Galactic ISM and have a significant influence on the formation of molecular clouds and stars. Far-infrared polarization from thermal dust grains aligned with the fields provides the strongest method for mapping the magnetic field strength and orientation. However, the exact method of grain alignment is still a matter of debate that thus leaves ambiguity in determination of where along the line-of-sight polarization can reliably trace the field. The observations proposed here aim to improve that degeneracy by testing models of grain alignment, which can then identify environmental conditions in which the field measurements are most reliable. Key predictions of grain alignment models lead to characteristic spectral shapes with strong variations in the FIR. We propose to test these predictions with multi-wavelength observations of the total polarized and unpolarized intensity in numerous environments (e.g., HII regions and hot proto-stellar cores). The primary measurements are multi-wavelength maps of total intensity, polarized intensity, and polarization position angle in three Galactic molecular clouds on scales of several arcminutes with high resolution (5-19 arcsec). From the multi-wavelength maps, this work will generate polarization spectra at point-by-point locations in each cloud. At a minimum this will characterize the FIR polarization spectra as a function of environment for the first time and, more broadly, provide input to test models of grain alignment. The maps will also measure the magnetic field morphology in cloud regions of the hottest dust, complementing longer wavelength measurements in cooler dust.
Proposal ID: 05_0039
Principal Investigator: Min-Young Lee (Commissariat a l'Energie Atomique (CEA))
Title: Unraveling the Physical Processes of Molecular Gas Excitation in N159W with SOFIA FIFI-LS
Abstract: In recent years, there have been an increasing number of detections of high-J CO transitions in a wide range of galaxies, suggesting the prevalence of warm molecular gas. Various excitation mechanisms including UV photons, X-rays, cosmic-rays, and shocks have been invoked to explain the observations. However, poor spatial resolutions and a lack of critical complementary data (e.g., PDR (photodissociation region) tracers and characteristics of X-ray sources) have hindered the examination of relative contributions from different energy sources and their spatial variations. Aiming at addressing this critical issue, we propose to observe the [CII] 158 micron and [OI] 145 micron fine-structure lines in N159W using the SOFIA FIFI-LS instrument. N159W is a region of particular interest in the Large Magellanic Cloud due to the presence of active star formation, a strong X-ray source, and shocks. In combination with our Herschel FTS observations of CO transitions up to J=12-11, we will confront the state-of-the-art theoretical models of the interstellar medium to investigate: (1) Relative contributions from different mechanisms (UV photons, X-rays, cosmic-rays, and shocks) of CO excitation and how they spatially vary across the star-forming region; (2) Properties of small-scale (driven by stellar outflows) and/or large-scale (driven by cloud-cloud collision) shocks. The high spatial resolution, excellent sensitivity, and fast mapping speed of FIFI-LS are crucial to achieve our science goals, enabling us to perform for the first time the spatially-resolved study of the physical processes of molecular gas excitation in an external galaxy on ~10 pc scales.
Proposal ID: 05_0041
Principal Investigator: Alexander Tielens (Universiteit Leiden)
Title: EXES Survey of the Organic Inventory of Hot Cores
Abstract: We propose an Impact Program to measure the 5.4-8 micron spectra of Hot Cores around massive protostars at high spectral (R=50,000) resolution and high sensitivity (S/N~100) with the goal of determining the organic inventory of these regions. These data will be combined with existing and to be requested ground based studies of the M and N bands to provide complete spectra from 4.5 to 13 micron. Hot Cores are chemically very diverse as many chemical and physical processes contribute to their molecular content. This spectral region contains the ro-vibrational transitions of many molecules known or expected to be abundant. The absorption line depths and profiles are unique signatures of the absorbing species and the data will be analyzed to determine column densities and abundances relative to CO, as well as the kinematics and the physical conditions in the absorbing gas. Derived abundances can also be directly compared to abundances of interstellar ice components obtained along the same sight-lines. These observations will provide an unprecedented data set, offering a unique view of the molecular content and physical conditions in regions of massive star formation and the physical and chemical processes that play a role in the origin and evolution of Hot Cores. In addition, this survey will provide a benchmark for the interpretation of much lower spectral resolution studies of Hot Corinos and protoplanetary disks around low mass stars to be obtained with MIRI/JWST.
Proposal ID: 05_0042
Principal Investigator: Terry Jones (University of Minnesota - Twin Cities)
Title: Multiple Generations of Massive Star Formation in the LMC
Abstract: We propose an infrared census of extremely young, luminous stars in the HII region N158 in the Large Magellanic Cloud (LMC). Imaging with FORCAST from 25 to 37 microns will allow us to resolve cooler sources that are bright at mid- to far-infrared wavelengths, but are conspicuously absent in the near-infrared Spitzer/IRAC images. These observations are a complement to FORCAST data taken during Cycle 3 on the nearby complexes N159 and N160 (Gordon et al. 2016). While N159 and N160 each contain a very recent generation of massive, young stellar objects (YSOs), N158 is sufficiently evolved to have potentially triggered a second generation of star-formation, whose cooler population will dominate the 24 to 40 micron emission. By imaging N158 in the mid-infrared with FORCAST, we can take a census of luminous stars in all stages of massive star evolution. We can compare the results of the proposed survey with the results of the N159/N160 survey to draw comparisons between the three LMC complexes and with complexes in regions of massive star formation in the Milky Way.
Proposal ID: 05_0043
Principal Investigator: Naseem Rangwala (NASA Ames Research Center/USRA)
Title: An EXES High-Resolution Molecular Line Survey towards Orion IRc2
Abstract: High spectral resolution molecular line surveys provide a chemical inventory for star forming regions and are essential for studying their chemistry, kinematics and physical conditions. Previous surveys have been limited to radio, sub-mm and FIR wavelengths. In the mid-infrared (MIR), there has not been any line survey with high spectral resolution. MIR missions such as ISO and Spitzer had low to moderate resolving power that were only able to link broad features with particular molecular bands and could not resolve the individual rovibrational transitions needed to identify specific molecules with certainty. The EXES instrument is currently the only available (airborne or spaceborne) spectrograph that provides high spectral resolution in the MIR region. We propose to use EXES to conduct an unbiased molecular line survey towards Orion IRc2 from 6 - 28.5 microns with a S/N of better than 70 over 90% of the proposed bandpass. The survey (due to its higher resolving power; R = 50,000) will do 5 - 50 times better than ISO in detecting isolated, narrow lines. This will allow us to (a) resolve the rovibrational structure of the gas phase molecules in order to identify them, (b) resolve their kinematics, (c) detect new gas phase molecules that were missed by ISO, and (d) provide useful constraints on Orion's hot core chemistry as sampled by IRc2. The proposed observations will provide the best infrared measurements (to date) of molecular column densities and physical conditions - providing strong constraints on the current chemical network models for star forming regions. This survey will greatly enhance the inventory of resolved line features in the MIR, making it an invaluable reference to be used by the JWST and ALMA scientific communities. By waiving the proprietary period, this program will allow astronomers to exploit these data as soon as they become available.
Proposal ID: 05_0048
Principal Investigator: B-G Andersson (SOFIA Science Center; USRA)
Title: Why are carbonaceous grains unaligned in the ISM? - HAWC+ polarimetry of IRC+10216
Abstract: Polarization due to aligned dust grains is a well-known tool for probing interstellar magnetic fields. The detailed physics of the grain alignment mechanism has, however, been poorly understood and it's only in the last decade that the promise of a quantitative, observationally supported, theory has emerged. A well-tested alignment theory would allow dust polarimetry to more securely probe the magnetic fields, but also to address issues of grain size distributions, mineralogy, and environmental parameters. Radiative Alignment Torque (RAT) theory predicts that asymmetric dust grain are spun up and, if paramagnetic, aligned with the magnetic field, through interaction with the radiation field. The theory provides a number of quantitative predictions, many of which are supported by observations. One - as of yet untested - prediction would resolve the conundrum of why carbonaceous dust does not contribute to ISM polarization. Under RAT alignment carbonaceous grains are spun-up by the radiation but, because such dust is diamagnetic, does not align with the magnetic field. The theory, however, also predicts that for an intense, highly anisotropic radiation field, the grains will align with the radiation. We will test this prediction by performing HAWC+ polarimetry of the carbon rich circumstellar envelope of IRC+10216. This is re-submission of an accepted ("Must Do") Cy 4 program, which is unlikely to be scheduled due to delays in the HAWC+ commissioning. The scientific background and justification has been updated.
Proposal ID: 05_0050
Principal Investigator: Mikako Matsuura (Cardiff University)
Title: A SOFIA study of SN 1987A's dust components
Abstract: Supernova (SN) 1987A is the closest SN explosion detected in 400 years. It has provided a unique opportunity to understand how dust is formed in supernova ejecta, and how dust in the circumstellar material is impacted by the interaction with the SN blast waves. However, there are still some gaps in our understanding of this dust, which can be filled by the proposed SOFIA observations. Within the system of SN 1987A, there are three components of dust, each with distinct origins and physical properties. One is cold (20K) ejecta dust, formed from newly synthesised and ejected elements after the explosion. The other components are hot (~400K) and warm (~180K) dust, both of which are associated with the ring and formed when the progenitor star was in the red supergiant phase. The fast (up to ~10000 km s-1) blast waves from the SN explosion is now colliding with this progenitor dust, heating it and potentially destroying the dust collisionally. The emission from the hot dust component, which we are monitoring with Spitzer at 3.6 and 4.8 microns, has begun to decline, consistent with on-going destruction of this dust. However, the warm ring dust component has not been monitored since 2009, after Spitzer full operation was over. Following the cycle 4 approved program of 11.1 and 19.7 micron observations, we propose a FORCAST monitoring program at 11.2, 19.7 and 31.5 microns to determine if the warm ring dust component is indeed being destroyed. Our Herschel observations found an excess at 70 micron on top of the cold dust emission, however, the detection at a single wavelength makes further analysis difficult. The excess, if confirmed by the SOFIA, suggests the presence of small dust grains with higher temperatures than the larger dust grains. Our proposed HAWC+ observations at 31.5 micron, 53 micron and 63 micron can show the full picture of the spectral energy distribution, enabling a more precise determination of the temperature and the mass of ejecta dust.
Proposal ID: 05_0052
Principal Investigator: B-G Andersson (SOFIA Science Center; USRA)
Title: Testing the Physics and Chemistry of Radiation Driven Cloud Evolution - [C II] Mapping of IC 59 and IC 63
Abstract: The interaction of newly formed stars with their natal clouds give rise to a number of dynamical and chemical effects, forming H II regions, injecting energy in the surrounding ISM and, potentially giving ride to triggered star formation. When an expanding H II region encounters density enhancements, Bright Rimmed Clouds (BRC) are formed, containing photo-dissociation regions (PDR). These provide valuable laboratories of radiation driven dynamics both for cloud dynamics and the physical and chemical evolution of the gas and dust. We propose to map the near-by pair of BRCs IC59 and IC 63, in the [C II] line, a well-known PDR tracer, with the upGREAT LFA array. These observations will complement a significant amount of existing data tracing the molecular gas and dust in the clouds. The parallel CO (J=11-10) data from the L1 channel will provide important information about the dense warm molecular gas to be compared e.g. to existing low-J CO transitions. Although at similar distance from the illuminating star gamma Cas, the two nebulae show dramatic differences in their structure. Because of their relative vicinity (~190pc), the clouds provide a unique environment to acquire high spatial resolution observation of BRC and PDRs. Because of the high spectral resolution of upGREAT, our observations will provide detailed information about gas flows and turbulent motions, providing important constraints and test for models of radiation driven cloud evolution and the chemistry and physics of PDRs.
Proposal ID: 05_0054
Principal Investigator: Steve Ertel (University of Arizona)
Title: The nature and origin of the Solar system scale disk in the Helix Nebula
Abstract: We aim to determine the nature and origin of the Solar system scale, dusty disk around the central star of the Helix nebula, the closest planetary nebula (PN, d=152 to 219pc). There are three scenarios for its origin: a Kuiper belt that survived the stellar post-main sequence (post-MS) evolution, a large cloud of eccentric comets resulting from a disrupted Kuiper belt, or a remnant post-Asymptotic Giant Branch (pAGB) disk that formed from material ejected by the star during that phase. Our SOFIA observations will pinpoint the peak location of the spectral energy distribution (SED) of the dust, characterize its shape, and determine the slope of the SED toward longer wavelentghs. We will combine our SOFIA data with our scheduled ALMA observations that will resolve the disk and measure its flux at 1.3mm. The grain properties (dominating size, size distribution) derived from the well sampled SED will be critical to distinguish between the three scenarios. The primordial Kuiper belt case: This will be the first Kuiper belt confirmed around a star that went through the post-MS evolution and critical, direct evidence that planetary systems survive this phase. We will investigate the effects of this phase on planetary/planetesimal systems for the first time through observations. The comet cloud: This will be the first direct evidence of the fate of a planetary system during the stellar post-MS phase. The remnant post-AGB disk case: We will measure the grain size and thus constrain grain growth in the pAGB disk. We will investigate whether second-generation planet(esimal) formation is possible there. The Helix is a bipolar PN (almost seen pole-on) but no binary companion is known to its central star. Thus, our observations will provite great insight into the evolution of post-MS stars and their disks and on the binary hypothesis of PN formation.
Proposal ID: 05_0058
Principal Investigator: Hans Olofsson (Dept. of Earth and Space Sciences; Chalmers)
Title: The carbon budget of the detached gas shell around the AGB star R Scl
Abstract: Asymptotic giant branch (AGB) stars play a fundamental role in the enrichment of the interstellar medium (ISM). Yet, the rate at which they do this remains uncertain and the details of the mechanism behind the matter return are still not fully understood. The geometrically thin gas/dust shells that surround some AGB stars have proven to be of particular interest in this context. The formation of the shells are most likely connected to the astrophysically important process of thermal pulsing, and hence a clear relation between mass-loss characteristics and stellar behaviour during this process can be identified. This may lead to a deeper understanding of the mass-loss mechanism. The detached gas/dust shell around the carbon star R Scl has been particularly well studied in CO lines and dust scattered and thermal radiation using various methods. In addition, it has been detected in the CI line at 492 GHz. The CI detection indicates that the photodissociation of CO has not started (the C comes from the photodissociation of all other carbon-bearing species), but this rests on the assumption that photoionisation of CI is still limited. We aim now to close the loop by detecting the CII line at 158 micron in the detached gas shell of R Scl. This will add the crucial constraint on the photoionisation of CI, and it will improve our estimates of the physical and chemical characteristics of the detached shell, that can be confronted with models of mass loss during a thermal pulse.
Proposal ID: 05_0060
Principal Investigator: Paola Caselli (Max-Planck-Insitut fuer extraterrestrische Physik)
Title: OD and the origin of water in protostellar cores
Abstract: We propose to observe with SOFIA the ground-state rotational line of OD at 1.39 THz ( 216 micron) towards low-mass and intermediate-mass protostars with massive, cool envelopes. The line is predicted to be detected in absorption against the strong far-inrared continuum from the central source. The OD data will be combined with HDO observations, with the goal of disentangling grain-surface and gas-phase production pathways of OH and H2O, which form in similar reactions as OD and HDO. Water and the hydroxyl radical are at the heart of the oxygen chemistry, and important for the production of complex organic molecules. Our chemistry model predicts that the OD/HDO abundance ratio obtains much smaller values on grain-surfaces than in the gas-phase. Therefore, the OD/HDO ratio can be used to infer the origin of OH and H2O detected in protostellar envelopes, i.e. whether they are primarily produced by gas-phase chemistry or by desorption from the icy mantles of grains.
Proposal ID: 05_0061
Principal Investigator: Loren Anderson (West Virginia University)
Title: HII Region Dynamics Revealed by [CII] Emission
Abstract: Understanding HII region dynamics is key to estimating their ages and three-dimensional structures. However, the dynamics of HII regions are poorly constrained due to a previous lack of good spectroscopic tracers. The 158 micron [CII] fine structure line, tracing the ionized gas component as well as photodissociation regions, can now easily be mapped in bright HII regions with upGREAT on SOFIA, and thus opens a new window into the study of HII region dynamics. We propose to map the [CII] emission toward the well-studied HII regions S235 (for a northern deployment) and RCW120 (for a southern deployment). These observations will allow us to estimate the age of these two regions, and will highlight the importance of the [CII] line as a probe of HII region dynamics. They will also help us to understand the contribution of "normal" HII regions to a galaxy's [CII] emission.
Proposal ID: 05_0063
Principal Investigator: Lizette Guzman-Ramirez (Leiden Observatory)
Title: Understanding the Nebular Abundance Discrepancy Problem with SOFIA
Abstract: The abundance discrepancy between recombination and collisional lines is a long-standing open question for planetary nebulae and HII regions. For planetary nebulae (PNe), C, N, O, and Ne abundances as derived from optical recombination lines (ORLs) are typically a factor of ~5 or more higher than the values inferred from collisional lines. This ratio is called the abundance discrepancy factor (adf). A promising proposition to explain this long-standing nebular abundance problem posits that these nebulae contain (at least) two distinct media - 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. These clumps have eluded direct detection thus far, but this year Garcia-Rojas et al. (2016) found evidence of these clumps in the PN NGC 6778. On the other hand, there is mounting circumstantial evidence for their existence, Yuan et al. (2011) modelled the high-adf PN NGC 6153 using a 3-D photoionization code. The models that included the low Te, H-deficient clumps fit most observations far better than did those models without the clumps. It has been shown that the adf varies with position in a PN and is highest close to the central star. The very low Te clumps must be cooled predominantly by FS mid-IR lines. We propose to use FORCAST grisms to map mid-IR FS lines in a sample of PNe to compare the co-spatial optical and IR CELs where the adf peaks.
Proposal ID: 05_0064
Principal Investigator: Nathan Smith (University of Arizona)
Title: The Mass and Age Dependence of Dusty Red Supergiant Winds, and Their Impact on Supernova Progenitors
Abstract: The dusty winds of red supergiants (RSGs) have a tremendous impact on the evolution of stars of 8-40 M_sun. Wind strength determines whether a star can shed its H envelope or not, thus determining the type of resulting SN, and these dusty winds create the circumstellar medium (CSM) at the end of the stars life. However, RSG mass-loss rates are very uncertain, which hampers the predictive power of stellar evolution models. RSGs are expected to end their lives as Type II-P supernovae. Many RSGs are observed with initial masses well above 20 M_sun, but from Type II-P progenitors directly detected so far it seems that the stars that explode are of relatively low mass, with all progenitor mass estimates below 16-17 M_sun. This is known as the Red Supergiant Problem, prompting suggestions that the massive RSGs collapse to black holes with undetectably faint SNe. Alternatively, it has also been suggested that the more massive RSGs evolve to yield other types of SNe or that dusty CSM could cause the progenitor to faint, underestimating its mass. One expects that the most massive and most evolved RSGs would also have the highest extinction or would be the most likely to evolve to a H-free star --- this is qualitatively what is needed to explain the missing high-mass RSGs. To test this idea, we propose to use FORCAST to obtain mid-IR photometry for RSGs in three coeval star clusters with known ages(and different turnoff masses of 12, 18, and 35 M_sun). By modeling CSM dust emission, we will derive mass and age dependent mass-loss rates and CSM extinction, below and above the derived cutoff mass for Type II-P progenitors, thereby determining whether this effect is large enough to solve the Red Supergiant Problem.
Proposal ID: 05_0067
Principal Investigator: Volker Tolls (Smithsonian Institution Astrophysical Observatory)
Title: [OI] and Why Outflows Under-Produce Water
Abstract: Extensive observations of H2O from outflow sources by SWAS, Odin and, most recently, Herschel have consistently shown discrepancies with the predictions of current shock models, which were developed assuming the presence of no external far-ultraviolet radiation. In response, we have developed a non-dissociative shock code that takes full account of the effects of external radiation and can be tested with data provided by SOFIA. We propose to use the GREAT instrument to observe the [OI] 63.1837 um line toward the outflow regions associated with the young stellar objects AFGL 2591, L1551-IRS5, and Serpens-SMM1, for which we have Herschel/HIFI H2O, CO, and OH data. Velocity-resolving the [OI] line, which was clearly detected by Herschel/PACS toward these sources, but was not possible with Herschel/HIFI, will provide the intrinsic line profile - any broad component to the [OI] line is assumed to be due to shock excitation, as with the H2O, CO, and OH lines. The line flux from these key shock tracers will be used to test this new shock model, which, if successful, would have broad applicability to a wide variety of outflow sources.
Proposal ID: 05_0068
Principal Investigator: Anthony Remijan (National Radio Astronomy Observatory)
Title: Confirmation of Interstellar SiH
Abstract: In 2001, Schilke et al. presented a tentative detection of SiH toward the Orion KL hot core. SiH has been proposed as a counterpart of sorts to the well-known shock-tracer molecule SiO, with both Si and SiH reacting with molecular oxygen to form SiO. The presence of SiH therefore indicates a distinct lack of molecular oxygen in a source, making it an excellent probe for molecular oxygen which is a difficult to constrain but critical species. Since the original report of a tentative detection, no confirming transitions have been reported in the literature. We propose to detect a higher-frequency transition of SiH in the same source as the original, Orion-KL, and in IRC+10216, for independent confirmation. The detection will both confirm the status of SiH as an interstellar molecule, and constrain its excitation, providing valuable information about its formation conditions.
Proposal ID: 05_0073
Principal Investigator: Graham Harper (University of Colorado at Boulder)
Title: Spectrally-resolved forbidden emission lines: Part B - EXES constraints on accelerating flows from cool evolved stars
Abstract: Mass loss from cool evolved stars is important for both stellar evolution and galactic chemical evolution, but it still remains poorly understood. Early-M supergiants are important for mass loss studies because they have little dust and molecules in their winds and yet still are able to drive high mass-loss rates like their dusty cousins of later spectral-types. We propose to use SOFIA-EXES to spectrally-resolve with R=50,000 two 25 micron forbidden emission lines from the ground terms of [Fe II] and [S I] in order to trace the wind acceleration and turbulence in the outflows of cool evolved M stars. For early-M supergiants these species will be the dominant ionization stages and trace the outflow mass, and the emission diagnostics can be used to test theoretical models in the crucial wind acceleration region. We also seek to refine the intrinsic wavelength of the [S I] 25.249 micron line so that it can be used as a new astrophysical velocity diagnostic.
Proposal ID: 05_0076
Principal Investigator: John Bally (University of Colorado; Boulder)
Title: Impact Program: The Outer CMZ C+ Survey
Abstract: The Central Molecular Zone (CMZ) contains the densest, most turbulent, and highest pressure clouds in our Galaxy. Although the CMZ extends to a radius of R~250 pc from the Galactic Center, most star formation occurs within R~100 pc. The CMZ is asymmetric; more than two-thirds of the dense gas is at positive longitudes while the majority of massive stars traced by compact 24 um emission are at negative longitudes. This program will test the hypothesis that the positive-longitude part of the CMZ up-plane from Sgr B2 is pre-star-forming while the negative longitude portion down-plane from Sgr C is post-starburst and has disrupted its natal clouds. The observations will search for mass outflow from the CMZ starburst regions that could mass-load and fuel the Fermi-LAT bubbles. We will obtain seven strip-maps and target sixty compact 24 um sources in three fields in [CII] with the upGREAT LFA and [NII] and CO with the L1 channel. Field 1 extends from Sgr B2 to longitude l=2 to study the dense complexes at positive longitudes to determine if they are condensing to form future star forming CMZ clouds. Field 2 probes negative longitudes to investigate the nature of the compact 24 micron sources and to determine if massive star feedback had disrupted this portion of the CMZ dense cloud population. Field 3 probes the kinematics of ionized and atomic gas above and below the molecular layer to see if star formation feedback is fueling and mass-loading the Fermi-LAT bubbles. SOFIA upGREAT is the best facility to address these issues. The proposed 35 hour program complements the 20 hours of observations in the ROC by investigating the outer CMZ and its vertical structure to answer fundamental questions about dynamics, the formation and destruction of the dense clouds, the recent star-formation history, the role of feedback, and the origin of the kpc-scale Fermi-LAT bubble.
Proposal ID: 05_0077
Principal Investigator: Bernd Husemann (European Southern Observatory - Germany)
Title: How accurate is [CII] tracing star formation in nearby luminous AGN?
Abstract: We propose [CII] line mapping with FIFI-LS to complete observations for 4 nearby luminous AGN as part of our Close AGN Reference Survey (CARS) unobserved in Cycle 4. Our aim is to create a spatially-resolved multi-wavelength dataset to understand whether and how AGN can control star formation in their hosts. We already obtained wide-field optical IFU spectroscopy with MUSE to disentangle emission from HII regions and photoionized gas by the AGN across the galaxies. Currently, there is a high pressure to understand the impact of AGN especially at the peak of cosmic star formation beyond z>2 where measuring the SF is diffcult. The [CII] line at 158microns has become an important diagnostic for SF in high-redshift galaxies with the advent of ALMA. However, the line can be excited by various mechanisms in a multi-phase ISM. In particular the hard radiation field of AGN is a major concern which can only be quantified in nearby galaxies. FIFI-LS aboard SOFIA is currently the only way to perform follow-up observations of FIR emission lines. By uniquily combining MUSE and FIFI-LS we will be able to 1. test if the empirical [CII]-SFR scaling relation hold for luminous nearby AGN, 2. quantifiy any deviation as a function of AGN luminosity, 3. test if the [CII] line kinematics are strongly affected by outflows or trace solely the kinematics of the cold gas disc. Those observations for nearby galaxies with FIFI-LS are crucially needed to establish a reference frame for interpreting high-redshift observation with ALMA at similar physical resolution.
Proposal ID: 05_0081
Principal Investigator: Fabio Pereira Santos (Northwestern University)
Title: Magnetic Field Structure in Perseus at 0.01 pc Scale
Abstract: The ion-neutral decoupling scale is one of the fundamental quantities governing the physics of the star formation process. For a weakly ionized gas, such as that encountered in star-forming regions, this scale corresponds to the smallest scale at which the magnetic field is frozen to the mostly-neutral gas. Beneath this scale, turbulence in the magnetic field will be significantly damped and MHD waves will be unable to propagate. Although some observational evidence has been obtained for this diffusion scale, all consistent with expectations from theoretical and simulation studies, a direct and definitive detection has yet to be realized. We thus propose to use the newly commissioned HAWC+ polarimeter on SOFIA to perform observations at high sensitivity and angular resolution on three distinct regions in the nearby Perseus molecular cloud. These measurements in the C, D, and E bands will allow the detection of several hundred polarization vectors at resolutions of, respectively, 11 mpc, 20 mpc, and 27 mpc at the distance of Perseus. We will then be able to resolve the expected ion-neutral decoupling at the expected scale (around 45 mpc) for the densities probed by our observations (approximately 10000 particles per cubic cm). Analyses of these data using state-of-the-art methods (e.g., the angular dispersion and the Histograms of Relative Orientations methods) will allow us to characterize the turbulence power spectrum and provide the magnetic field information necessary to test the results and predictions from both numerical simulations and analytical studies.
Proposal ID: 05_0082
Principal Investigator: Janet Simpson (SETI Institute)
Title: Using SOFIA to Unveil the Star Formation History of the Massive Galactic Center H II Region Sagittarius B1
Abstract: The proximity of the center of our Galaxy enables us to study star formation under conditions commonly found in other galaxies, but at spatial resolutions unachievable elsewhere. In the past few years, numerous large scale surveys of the inner regions of the Galaxy (~100 pc) have helped to create a possible unified picture of star formation in the Galactic Center (GC) as arising from streams of gas passing near the super massive black hole, Sgr A*, located at the center. The proposed model envisions sequential star formation within the streams, with age a function of time since closest approach to Sgr A*. The ~15 pc diameter H II region, Sgr B1, long thought to be associated with the more active and embedded region Sgr B2, however, does not fit well within this emerging picture, being either too old or in the wrong place. We propose to expand our ongoing investigation of star formation within Sgr B1 by adding additional FIFI-LS spectroscopy to our Cycle 3 FORCAST and Cycle 4 FIFI-LS observations of the region. By combining observations of the [O III] (52 and 88 micron), [O I] (146 micron), and [C II] (158 micron) lines, with spectra of other emission lines available from the Spitzer Space Telescope archive and our Cycles 3 and 4 SOFIA observations, we will be able to create a complete picture of the stellar population within this problematic region. We will therefore be able to address outstanding questions on the age and nature of Sgr B1, and its role in the large star formation history of the GC.
Proposal ID: 05_0084
Principal Investigator: Fiorella Polles (Commissariat a l'Energie Atomique (CEA))
Title: Modeling the ionized gas in low-metallicity environments: the nearby dwarf galaxy IC10
Abstract: The Herschel Dwarf Galaxy Survey opened the study of the physical properties of the interstellar medium (ISM) in low-metallicity environments demonstrating the importance of the diffuse ionized gas phase for these galaxies. However this analysis was done on global galaxy-wide scales, without distinguishing the different ISM phases spatially (Cormier et al 2015). Aiming to understand how low-metallicity environments affect the propagation of radiation in different ISM phases, we are zooming into the Local Group galaxy, IC10. We have mapped IC10 completely with spectroscopy and continuum with Spitzer and Herschel, to study the dust properties and the neutral and ionized gas properties. The values of targeting IC10 for this experiment are its proximity (d=800 kpc), its metallicity falling between the two Magellanic Clouds, and its elevate starburst activity. With these SOFIA observations we seek to characterize the density distribution of the ionized gas, which we have already mapped in [OIII] 88 micron line with Herschel/PACS, by now observing the [OII] 52 micron line with FIFI-LS. The detection of the [OIII] 52 micron line, only achievable with SOFIA, combined with our Herschel [OIII] 88 micron map and other Herschel and Spitzer data already in hand, will give us the unique possibility to model and characterize the low metallicity ionized gas at 23pc scales.
Proposal ID: 05_0087
Principal Investigator: Asantha Cooray (University of California - Irvine)
Title: Mid-Infrared Flux Densities of z=1-2.5 Gravitationally Lensed Starburst Galaxies
Abstract: We propose SOFIA/HAWC+ Band A and C (53 and 89 micron) total intensity imaging of three of the brightest (S500 > 400 mJy), distant (z=1-2.5), and gravitationally lensed dusty star-burst galaxies. The proposed sample represents some of the most (apparent) luminous distant galaxies that Herschel has discovered in extragalactic legacy surveys of HerMES and H-ATLAS over an area of 1200 sq. degrees. Due to their high brightness, they have been followed-up and studied with a wide range of ground and space-based facilities, allowing redshifts with CO molecular gas lines, certain physical properties of their interstellar medium, and accurate modeling of the lensing magnification. However, the contribution from active galatic nuclei (AGN) to the total IR luminosity remains uncertain. This is due to the missing or uncertain mid-infrared flux density measurements, especially between 50 and 100 microns. With SOFIA/HAWC+, we will improve the overall SED and increase our confidence in constraining the contribution from an active galactic nuclei (AGN) to the total infrared luminosity, and thus to the inferred star-formation rate of these galaxies.
Proposal ID: 05_0089
Principal Investigator: Patrick Morris (California Institute of Technology)
Title: Measuring Changes in the Distribution, Mass, and Composition of Dust in the Eruptive LBV Eta Carinae
Abstract: The luminous, massive binary system eta Carinae is both one of the nearest and most unstable objects in a class of evolved massive stars, near the end of its lifetime before expected destruction in a supernova. It experienced a major outburst in 1843, producing the well-known Homunculus nebula, containing some 15 to 40 Msun in warm (~170 K) and cool (90-110 K) dust and gas, according to mid-infrared ISO spectroscopy. The location of these thermal components has been uncertain due to large apertures. In Cycle 3 we were approved for 10 hours to use the FORCAST imager with long wavelength filters to better locate and estimate the mass in thermal components of this material that may be resolved, constraining it to the interior regions or bipolar lobes of the Homunculus nebula, or in outer ejecta that would support the hypothesis of a major event prior to the 1843 eruption. About 40% of the program is planned for completion in Cycle 4. We are proposing in Cycle 5 to carry out spectroscopy of the dusty Homunculus nebula at two positions and one reference sky position, using the FORCAST grism with all four filters, in order to characterize changes in mass, composition, and grain properties of especially the cool dust containing >80% of the dust mass, and comparing the results to our spatially integrated ISO spectra taken in 1996/1997, and to 8-13.5 micron data of the warm dust obtained with VLTI/MIDI in 2002/2003 by Chesneau et al. (2005) . These changes may result from the ongoing production of dust in the colliding winds of the 5.5 year period eccentric binary system, particularly during periastron which has occurred three times since 1997. The proposed spectroscopy of especially the cool dust cannot be accomplished from the ground.
Proposal ID: 05_0093
Principal Investigator: Tanio Diaz-Santos (Universidad Diego Portales)
Title: The Effect of AGN Feedback on the [CII] Emission in NGC 1365
Abstract: One of the most exciting results obtained with the Herschel Space Observatory has been the detection of massive molecular gas outflows likely associated to AGN feedback in nearby, very luminous infrared galaxies (LIRGs). However, the impact of AGN-driven winds on the ionized gas traced by far-IR, fine-structure emission lines (in particular [CII]158um) in less luminous galaxies is not as clear, with mechanical heating due to turbulence potentially playing a key role in boosting the line intensity and dispersion. NGC 1365 hosts a Sy1.8 nucleus and is the most nearby (z = 0.0055) low-luminosity LIRG with evidence for an outflow in our far-IR Herschel/PACS spectroscopy obtained for the Great Observatories All-sky LIRG Survey. However, while the existing [CII] data suggests the presence of enhanced turbulence perpendicular to the rotation plane of the galaxy, the field of view is constrained to the inner <~ 2 kpc. Here we propose to obtain SOFIA/FIFI-LS observations of the [CII] emission line in 4 key regions in NGC1365 not covered by our Herschel data with the goal of (1) map the wind observed in [CII] out to larger distances from the galaxy nucleus, and to estimate the outflow terminal velocity and mass as well as its loading factor (Moutflow/SFR); (2) identify the presence of shocked gas at the leading edge of NGC 1365's bar associated to the compression of the gas due to the interaction between the bar and the underlying, diffuse ISM of the galaxy.
Proposal ID: 05_0094
Principal Investigator: Eric Omelian (Logyx/NASA/SOFIA)
Title: Probing Accretion in the Symbiotic Mira, R Aquarii
Abstract: R Aqr is one of the nearest and brightest symbiotic stars. It is a dusty symbiotic, consisting of a mass-losing Mira variable and a hot accreting White Dwarf (WD). It is surrounded by extended shells caused by nova-like explosions that happened several hundred years ago, and contains a spectacular jet fueled by the accretion onto the WD. The accretion mechanism is not well understood. One scenario is that the binary is in a highly eccentric orbit and remains detached most of the time except near periastron when Roche Lobe overflow occurs. The competing scenario is that the orbit is not highly eccentric but that the accretion is enhanced during phases around periastron when the AGB wind fills the Roche Lobe and is focused into an accretion stream. R Aqr is also an eclipsing system with periastron occuring during the eclipse of the Mira by the WD. The system is currently approaching its widely anticipated eclipse and periastron. During the coming years, R Aqr is visible at phases close to the Mira pulsation minimum, giving us an excellent opportunity to probe the effects of the enhanced binary interaction and the effects of the WD heating on the material being accreted, and thereby to determine the physical conditions in the accretion stream and unravel the underlying accretion mechanism. We propose to obtain photometric measurements at several wavelengths between 5 and 214 microns by imaging R Aqr using FORCAST and HAWC+ and to obtain the shape of the silicate emission features at 10 and 18 microns using FORCAST grisms. The differences between the spectral energy distributions obtained in this epoch and obtained earlier, near apastron, will directly trace the enhanced binary activity. This proposal is the second in a series (following our successful Cycle 4 proposal) to monitor the mid- and far-IR emission from R Aqr through the upcoming eclipse and periastron passage.
Proposal ID: 05_0097
Principal Investigator: John Carr (Naval Research Laboratory)
Title: Molecular Absorption in the Disk of GV Tau
Abstract: High resolution MIR spectroscopy with SOFIA offers the opportunity for unique insights into the chemical evolution of disks (e.g., the origin of prebiotic molecules) and planet formation processes. We propose to use EXES to measure molecular absorption in the edge-on protoplanetary disk of GV Tau N. The proposed observations will search for and characterize several molecules of astrobiological importance: water, formaldehyde (H2CO), and formic acid (HCOOH). The latter two simple molecules are potential chemical starting points for the synthesis of sugars, amino acids, and RNA. We will also search for SO2, which may be the dominant gas phase carrier of sulfur in disk atmospheres. Our observations will constrain the (poorly known) degree of sulfur depletion in disks, which bears on our understanding of the differentiation of the Earth's core. With the exception of water, little to nothing is known about these molecules in inner protoplanetary disks. Molecular column densities and relative abundances will be determined for comparison with chemical disk models and abundances in comets and the interstellar medium. In addition to lending new insights into the chemical evolution in the planet formation regions of protoplanetary disks, the observations will also serve as valuable pathfinder observations for JWST.
Proposal ID: 05_0098
Principal Investigator: David Koerner (Northern Arizona University)
Title: Exo-Kuiper Belts around Sun-like Stars
Abstract: We propose SOFIA/HAWC+ observations of debris disks around two nearby G-type stars. Our goals are to characterize the spectral distribution and temperature of circumstellar dust with photometric observations at wavelengths of 53, 89, 154, and 214 microns (HAWC+ bands A, C, D, and E) and to resolve the dust morphology in the smaller beams of the two shortest wavelengths. Spitzer/MIPS observations of each target revealed strong excess infrared emission (> 200 mJy) at 70 microns but none at 24 microns. These properties strongly indicate that each star is surrounded by a cold outer disk. Neither target was observed at longer wavelengths or with higher resolution by Herschel Space Observatory, so details about ring dimensions and thermal properties are lacking. The cold temperature of the dust (T < 70 K) and proximity of the targets (d < 25 pc) suggest they each possess a large outer ring that could be resolved by SOFIA at 53 and 89 microns. If so, the rings may show evidence of the gravitational influence of an outermost giant planet by analogy with the Kuiper Belt in our solar system and offset rings seen around a small number of other stars with Hubble Space Telescope. HAWC+ is the only instrument currently available to image thermal emission from the rings at wavelengths of peak dust emission and with angular resolution needed to identify spatial structure.
Proposal ID: 05_0100
Principal Investigator: Melanie Chevance (Commissariat a l'Energie Atomique (CEA))
Title: Probing the large scale multiphase ISM in an extreme starforming low-metallicity environment: 30 Doradus in the LMC
Abstract: We propose to use FIFI-LS on board the SOFIA Observatory to study the extreme environment of 30 Doradus in the Large Magellanic Cloud in the far-infrared fine structure lines. The proximity of this powerful starburst region provides a unique testbed for investigating the impact of a super star cluster (SSC) on the surrounding interstellar medium. Not only does the SSC R136 in 30 Doradus allow us to probe an important mode of star-formation during the time of galaxy assembly, it also evolves in a relatively low-metallicity environment that may be reminiscent of physical ISM conditions in younger high-z galaxies. With [CII] and the dust emission already observed with SOFIA, Herschel and Spitzer, [OI] 145 mu is now the missing diagnostic to model the multi-phase ISM around 30 Doradus, as we have been doing thus far with the limited PACS observations, to unveil the full structure of the photodissociation regions and quantify the local conditions controlling the fraction of CO-dark gas. A large map (6'x5'), only achievable with SOFIA, is required to cover the extended PDR affected by the R136 luminous star cluster and will probe the gradient of physical conditions over a contiguous ~100 pc region. This study will result in the construction of a three dimensional view of the region as well as provide a template for unresolved starbursts in distant gas-rich galaxies.
Proposal ID: 05_0101
Principal Investigator: Michael Kaufman (San Jose State University)
Title: A GREAT Map in M20: Spatially and Spectrally Resolved [OI] and [CII] in a Young Star Forming Region
Abstract: We propose to use GREAT on SOFIA to make a fully-sampled, velocity-resolved small map in the young Galactic star-forming region M20, using the principal cooling lines of the interstellar medium, [CII] 158m and [OI] 63m. We will: 1.separate PDR emission from other sources of FIR line and continuum emission, including outflows and embedded young stars. The map focuses on a region that includes an edge-on PDR, a star-forming clump, several cometary globules, outflows, and Infrared Dark Clouds (IRDCs). The velocity-resolved emission lines will allow us to separate PDR emission from other sources of emission. 2.compare PDR emission with PDR models in a region where the FUV field is well described, providing a unique calibrator for PDR line emission in a young star-forming region. The fragmented molecular cloud structure at the edge of the HII region provides a small menagerie of structures on which to test our models. 3.provide a data product to the community that can be used as a template for Galactic and extragalactic PDR observations. This will be particularly useful for comparison with PDR emission from high redshift systems with similar young star forming regions.
Proposal ID: 05_0102
Principal Investigator: Mark Morris (University of California; Los Angeles)
Title: Characterizing Neutral Gas in the Central Parsec of the Galaxy
Abstract: The central black hole of the Galaxy is surrounded by a massive circumnuclear disk that has an inner cavity with a radius of about 1 parsec. Various lines of evidence indicate that there are several hundred solar masses of neutral gas within that cavity, but the origin and dynamics of that gas have not been well characterized. This gas will likely participate in, and perhaps ultimately dominate, the accretion flow onto the central black hole so it is important to characterize its present state, its dynamics, and its total mass. We propose to use the GREAT instrument to map the distribution and the dynamics of the 63 micron line of neutral oxygen, which is known to be relatively strong within the inner cavity of the circumnuclear disk, and within the disk itself. The spatial and velocity resolution with GREAT on SOFIA will provide a much clearer picture of the neutral gas motions there than we now have with any other probe.
Proposal ID: 05_0106
Principal Investigator: Lars Kristensen (Niels Bohr Institute; Copenhagen University)
Title: Where is the oxygen in protostellar outflows?
Abstract: Oxygen (O) is the third-most abundant element in the Universe after hydrogen and helium. Despite its high elemental abundance, a good picture of where oxygen is located in low-mass protostellar outflows and jets is missing: we cannot account for > 60% of the oxygen budget in these objects. This hole in our picture means that we currently do not have a good understanding of the dominant cooling processes in outflows jets, despite the fact that [O I] emission at 63 micron is one of the dominant cooling lines, nor how cooling processes evolve with protostellar evolution. To shed light on these processes, we propose to observe the [O I] 63 micron line with SOFIA-GREAT toward seven low-mass protostars. As a first step, the velocity-resolved line profile will be decomposed into its constituent components to isolate the relative contributions from the jet and the irradiated outflow. Second, the [O I] line profile will be compared to those of H2O, OH and CO to obtain the relative atomic O abundance with respect to CO, H2O, and OH. Third, the effects of evolution will be examined by observing protostars at different evolutionary stages. These three approaches will allow us to quantify: the oxygen chemistry in warm and hot gas, the relative amounts of material in the outflow and the jet, and finally to start tracing the evolutionary sequence of how feedback evolves with time.
Proposal ID: 05_0107
Principal Investigator: Maria Kirsanova (Institute of Astronomy of the Russian Academy of Sciences)
Title: Properties of photon-dominated regions around O and B-stars in S235East1
Abstract: We propose to observe [OI] at 63mkm and [CII] at 158mkm lines in heated gas close to young massive stars known as photon-dominated regions (PDRs hereafter) to understand the energy balance of PDRs and their dynamics. We plan to assign the emission of the [OI] and [CII] lines to the two different PDRs excited in the same gas: the 20 solar masses O-type main exciting star of S235 illuminates molecular cloud S235East1 from the western side and a 10 solar masses B-type star illuminates it from the eastern side. We expect to see different intensities of the fine-structure lines at the east and west sides of S235East1 and exclusively study the role of the UV field, differing by a factor 8, from opposite sides of the cloud. Velocity resolved observations will help to distinguish velocity components from the different PDRs with different physical conditions.
Proposal ID: 05_0109
Principal Investigator: Ian Stephens (Smithsonian Institution Astrophysical Observatory)
Title: The Role of Magnetic Fields in High-Mass Star-Forming Filaments
Abstract: Filaments are ubiquitous in the star formation process. Planck has revealed that magnetic fields are perpendicular to the densest filaments, which are the birthplace of high-mass stars, suggesting that fields help funnel gas into the filaments. However, the resolved field morphologies and strengths in the dense filaments are unknown. We propose HAWC+ 53 and 214 um polarimetric observations toward two filaments, the Snake (G11.1) and G18.6, to unveil the field morphology. Such observations will probe the filament field morphology at the subarcminute scale over the largest spatial extent to date: 25 and 9 pc respectively. We expect to have over 400 independent beams worth of detections. From the field morphology, we will test the hub-filament theory and investigate how the magnetic field strength and morphology changes with evolution and size-scale.
Proposal ID: 05_0110
Principal Investigator: Els Peeters (SETI Institute)
Title: Calibrating the response of the PAH emission to changes in PDR conditions.
Abstract: The mid-IR spectra of almost all objects are dominated by strong emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 micron due to Polycyclic Aromatic Hydrocarbon molecules (PAHs). It is now well established that these mid-IR bands show clear variations in intensity, shape and peak position. Although these variations are known to depend on the local physical conditions, their detailed quantitative origin is yet to be determined. Consequently, a firm calibration of the response of the PAH molecules to their environment is still lacking. Efforts thus far have been hampered by insufficient knowledge of the physical conditions of the regions in which the PAH molecules reside, rendering existing calibrations rather uncertain. We propose to use SOFIA's unique capabilities to observe the dominant PDR cooling lines ([OI] 63, 146 micron and [CII] 158 micron) with FIFI-LS for a sample of PDRs. Combined with existing data, this allows us to compile a coherent dataset of mid- and far-IR mapping observations for a sample of PDRs spanning a wide range of physical conditions. We will then apply PDR models to this dataset to determine the physical conditions at the same locations where PAH emission has been observed and quantify the interplay between the spectral PAH characteristics and the local environment. Given their omnipresence, this will enable their use as a tracer of physical conditions at cosmological distances. Hence, the outcome of this proposal is very timely in view of the imminent launch of JWST.
Proposal ID: 05_0111
Principal Investigator: Gordon Stacey (Cornell University)
Title: FIFI-LS [OIII] Spectrosopy of Nearby Infrared Bright Galaxies: Tracing Stellar Populations, the O/N Abundance Ratio, and absolute abundances
Abstract: We propose to map the [OIII] 52 um line emission from the central regions of five infrared bright, nearby star forming galaxies, NGC 1808, NGC 1365, NGC 3256, NGC 4945, and Arp 299. These data will be used together with publically available [OIII] 88 um, [NII] 122 um, and [NIII] 57 um line detections from Herschel/PACS and H radio recombination line interferometric observations to constrain the ionized gas density and mass, the hardness of the stellar radiation fields (hence most massive star on the main sequence), the O/N ratio (reflecting the numbers of cycles for star formation) and the ionized gas phase N/H and O/H abundances which measure the star formation efficiency integrated over time. We will also use the Herschel archival [OI] 63 and 146 um, and [CII] 158 um imaging to characterize the neutral ISM and the strength of the FUV (6-13.6 eV) stellar radiation fields. Together we will have a continuous measure of the stellar UV radiation fields from 6 to 54 eV thereby constraining the numbers of upper main sequence stars. The proposed FIFI-LS [OIII] 52 um line observations are the lynch-pin that holds the technique together. These measurements provide a local benchmark for our line-ratio techniques that can be applied to similar studies of high-z galaxies where it is expected that stellar radiation fields will be harder, and the O/N radio will be larger for the lowest metallicity galaxies. Therefore, the proposed observations are fundamentally important to our understanding of the star formation process over cosmic time.
Proposal ID: 05_0120
Principal Investigator: Jonathan Tan (University of Florida)
Title: Joint Impact Program: The Timescale of Star Formation from para-H2D+ - II. Colder and Lower Luminosity Sources
Abstract: The timescale of star formation is of fundamental astrophysical importance, but is currently very uncertain. The SOFIA discovery of para-H2D+ in the accretion envelope of a forming Sun-like star (Brunken et al. 2014, Nature, 516, 219) and the fact that the ortho-to-para ratio (OPR) of H2D+ can be used as a proxy of the OPR of H2, which is the best chemical clock of molecular clouds, enabled an age estimate of >1Myr. This ground-breaking result has motivated this Joint Impact Program, approved in a pilot phase in Cycle 4, to extend such studies throughout the Galaxy. The program aims to measure para-H2D+ with GREAT at 1.37 THz in absorption toward a large sample of high- & intermediate-mass protostars. Lines of sight to these sources probe protostellar/protocluster envelopes in a variety of environments relevant to the bulk of star formation in the Milky Way. These protostars are already the subject of SOFIA-FORCAST observations, which, combined with radiative transfer modeling, enable estimation of envelope density & temperature profiles needed for the astrochemical analysis to derive ages. The para-H2D+ absorption line data will then be utilized together with observations of ground state ortho-H2D+ to measure OPR of H2D+ and thus, in comparison with astrochemical models, the OPR of H2. Measurement of OPR of H2 allows estimation of the age of the molecular gas, i.e., the time since the H2 formed from HI. We will thus measure for the first time the ages of a statistically significant sample of star-forming molecular clouds and put stringent constraints on theories of the dynamics of star & star cluster formation. Here in Cycle 5, guided by preliminary results from observations of several luminous protostars in the sample, we next focus on colder and lower luminosity sources.
Proposal ID: 05_0121
Principal Investigator: Harriet Dinerstein (University of Texas at Austin)
Title: Probing Chemical Enrichments in Planetary Nebulae with EXES on SOFIA
Abstract: One of the major goals in astrophysics today is to understand the origin and buildup of elements that are synthesized in stars and returned to the environment by outflows towards the ends of stellar lives. Planetary nebulae (PNe) provide a real-time view of low and intermediate-mass stars acting as agents of element enrichment. The compositions of PNe challenge our understanding of stellar evolution (particularly the Asymptotic Giant or AGB phase, when many reactions occur) and can be used to quantify the contributions of these stars to galactic chemical evolution. We propose to use EXES on SOFIA to observe three mid-infrared emission lines (including two never previously detected) of F (Z = 9) and Na (Z = 11) in PNe. These observations will provide new insights into the synthesis of these elements, for which the main astrophysical and nuclear sources are uncertain. Measurements of F and Na abundances in late AGB stars are difficult to make; PNe offer an alternate approach. Models predict that F can be enhanced by up to an order of magnitude and Na by factors of a few, but different models disagree on exact values. Since F and Na production depend on uncertain physical conditions and processes (e.g. mixing), empirical constraints are essential. This study will build on previous work by the proposers on trans-iron elements enriched by neutron-capture reactions that also occur during the AGB. In the past 15 years two of us (HD, NS) made new identifications of IR lines from 6 such elements in PNe, measuring enrichments and comparing to evolutionary models, and one of us (AK) is a leader in state-of-the-art simulations of AGB evolution.
Proposal ID: 05_0122
Principal Investigator: James Jackson (Boston University)
Title: Infall toward High-Mass Star-forming Clumps and Cores: The [O I] 63 um Line
Abstract: Although the 63 um line has often been used as a diagnostic of photodissociation regions, toward cold, dense infrared dark cloud clumps it is often seen in absorption. We aim to exploit this high optical depth in IRDCs to probe the infall velocities and mass accretion rates of high-mass star-forming clumps and cores. We will use "blue asymmetric" self-absorbed line profiles or redshifted absorption against the protostellar dust continuum to measure infall rates. We will target 8 IRDC clumps in NGC6334 and "Nessie" to probe how the infall rates may change with evolutionary stage.
Proposal ID: 05_0123
Principal Investigator: Goran Sandell (SOFIA-USRA)
Title: Origin of [OI] and [CII] emission in Young Stellar Objects
Abstract: Observations with Herschel/ PACS show that [OI] 63 micron is ubiquitous in young stellar objects (YSOs). In Class II sources the emission is mostly unresolved, whereas it can be quite extended in deeply embedded Class 0 sources powering highly collimated molecular outflows. Since [OI] can be excited in both photon dominated regions (PDRs) and in shocks, and because the Herschel/ PACS [OI] observations do not resolve the [OI] emission, it is uncertain what fraction of emission originates in PDRs (disks) versus shocks. [CII], when detected, is often spatially extended, and likely to originate from PDR emission in the surrounding cloud. Since extended [CII] emission seems to correlate with extended [OI] emission, it is often assumed that the emission originates from the same region. This assumption is almost certainly false. [CII] is not excited in shocks, nor does it seem to trace emission from disks.Here we will use GREAT in the L2/H configuration to obtain velocity resolved spectra of a small sample of YSOs from the Herschel GASPS and DIGIT sample to investigate whether [OI] is primarly is excited from dissociative J-shocks or irradiated J/C shocks and how [CII] relates to [OI].
Proposal ID: 05_0125
Principal Investigator: Michael Person (MIT)
Title: A New Look at Triton's Atmosphere
Abstract: When it was first examined with stellar occultations in the 1990s, Triton's atmosphere was seen to undergo global expansion during the period from 1993 to 1997. This expansion was confirmed as a continuing phenomenon with a stellar occultation observation in 2001 . Unfortunately, as Triton started to pass through a fairly sparse star field, occultation observations have been much more difficult to make. There have been no published occultation data on Triton's atmosphere since the 2001 event, and reported observations in early 2007 had too low of a signal-to-noise ratio to say anything about the atmospheric profile. Thus, it has been over 15 years since the last direct measurement of Triton's expanding atmosphere was made, leaving wide open the question of Triton's current atmospheric state. Is the atmosphere still expanding or is it now collapsing? Are the haze layers seen by Voyager still present? Are the variations seen in the 1990s seasonal or cyclic on shorter time scales due to Triton surface processes? The observation of stellar occultations remains the only way to gain current data on Triton's atmosphere from Earth, and SOFIA's unique ability to be reliably placed in the central flash region of occultation events where the richest dataset is available, and its immunity to low-level weather disturbances make it the ideal platform for updating our knowledge on Triton and beginning to answer these many outstanding questions. We therefore propose to use SOFIA with HIPO, FLITECAM (FLIPO), and the FPI+ to measure temperature, pressure, and particulate haze radial profiles of Triton's atmosphere by observing a stellar occultation which will be visible over the eastern portion of North America in October of 2017. We expect to use FLITECAM/HIPO (FLIPO) Guaranteed Time Observing (GTO) hours for the included observations with the agreement of the FLITECAM and HIPO instrument teams.
Proposal ID: 05_0128
Principal Investigator: Imke de Pater (University of California - Berkeley)
Title: Jupiter's Tropospheric Dynamics from SOFIA Mapping of Temperature, Para-Hydrogen, and Aerosols
Abstract: We request time with FORCAST to observe Jupiter at mid-infrared wavelengths using 8-37 micron grism spectroscopy of the collisionally-induced H2-He continuum to derive the zonal mean tropospheric temperatures and para-H2 distribution. In addition, we request imaging in discrete filters between 5 and 37 micron to provide spatial context for the spectroscopy. This proposal is a follow-up of our successful observations in May 2014, where we confirmed the N-S polar asymmetry in the para-H2 fraction detected by Voyager 1, also during late summer in Jupiter's northern hemisphere. In spring 2017, during a world-wide campaign in support of the Juno mission, it gets close to southern summer solstice. This timing is ideal to assess seasonable variability on the planet.
Proposal ID: 05_0129
Principal Investigator: Christy Tremonti (Univeristy of Wisconsin Madison)
Title: Probing Dust-obscured Star Formation and AGN Activity in Massive Ultra-compact Galaxies
Abstract: We have discovered a rare population of extremely compact massive galaxies at z~0.6 that have extraordinarily high star formation surface densities. The galaxies are in the final stages of highly dissipational mergers and they host powerful ionized and molecular gas outflows. Based on the existing optical and mid-infrared data, we hypothesize that the outflows are powered by star formation, but constraints on the far infrared spectral energy distributions (SEDs) are needed to conclusively rule out contributions from obscured AGNs. We propose to use HAWC+ in total intensity mode with the A, C, and E filters to measure the SEDs of five galaxies from 30-130 um in the restframe (50-200 um observed). We will combine this data with our existing 0.1-14 um observations to measure the bolometric output of these systems, decompose their SF and AGN activity, and test whether the winds can be driven by star formation. The galaxies are excellent lower redshift analogs of the z > 3 progenitors of today's massive early-type galaxies and they provide us with an unprecedented opportunity to study star formation and feedback at its most extreme. Notably, no objects of this nature have existing measurements in the far-IR, so HAWC+ will enable entirely new science.
Proposal ID: 05_0130
Principal Investigator: Miguel Chavez (Instituto Nacional de Astrof_sica; _ptica y El_ctronica (INAOE))
Title: Constraining the Properties of the Warm Dust Around the Dustiest Main Sequence Star V488 Per
Abstract: The study of warm dust disks around mature stars is a fundamental piece in under-standing the evolution of circumstellar material and planetary systems. Explaining their origin, their large masses and their recently discovered rapid variability (Melis et al. 2012) is a strong theoretical challenge not yet overcome. We want to characterize and quantify the hot and warm circumstellar material around V488 Per, which is claimed to be the dustiest main sequence stars, and to study its variability. We will use unique SOFIA photometric observations to have a (almost) simultaneous sampling of the whole mid- and far-IR SED of V488 Per that will allow a precise estimation of the total amount of dust in the system. These data will also be essential in the discussion of the variability of the IR emission, for which we found hints in multi-epoch WISE observations. We will carry out prompt data analysis and any result will be immediately publishable, since both detections (which allow to determine the properties of the circumstellar dust) and non-detections (which will pose very strong constraints on the source variability) will provide valuable information.
Proposal ID: 05_0133
Principal Investigator: Giles Novak (Northwestern University)
Title: Joint HAWC+/ALMA study of magnetic fields in Ophiuchus
Abstract: Using ALMA, the superb new international astronomical facility in Chile, astronomers are at the threshold of directly observing the process of planet formation, thereby stimulating intense research activity by theorists and observers worldwide. However, stubborn puzzles remain, including the "magnetic braking catastrophe" which refers to our failure to understand what stops magnetic forces from funneling all disk material directly into the nascent star. Proper tests of theories that address this puzzle will require observations of magnetic fields over a very wide range of spatial scales. The nearby stellar nurseries in Ophiuchus, just 125 parsecs away, provide a unique opportunity to carry out such tests. By combining polarimetry data from the Planck satellite, the HAWC+ far-IR polarimeter on SOFIA, and ALMA, we can trace magnetic fields nearly continuously over more than four orders of magnitude in spatial scale. Here we propose to observe 11 protostars with HAWC+/SOFIA, out of 32 targets which have already been approved for observation with ALMA. Our results will test whether magnetic field misalignment is important for disk formation and allow field strength estimates, both of which are key unknown factors that strongly affect the formation of disks around protostars.
Proposal ID: 05_0138
Principal Investigator: Ralph Shuping (Space Science Inst.)
Title: Short-term variability in pre-transtional disks around high-mass pre-main sequence stars
Abstract: We propose multi-epoch mid-infrared observations of 3 known pre-transitional disks around young high-mass stars (HAeBe and Be type). Transitional and pre-transitional disks are thought to represent stages in disk evolution from optically thick evolved disks to optically thin debris disks, during which central holes and gaps are created, possibly due to the planet formation process. The mid-infrared ``see-saw'' variability in pre-transitional disks is thought to be caused by vertical perturbations in the inner-disk, possibly due to the interaction between an unseen planetary companion and the inner disk wall. However, this model has only been tested/confirmed for low-mass young stellar objects (YSOs). Our aim is to further test this model by observing higher-mass pre-main sequence objects with known pre-transitional disks to look for variability on week to month-long timescales. If the vertical perturbation model is correct, then we expect to see the ``see-saw'' variability shift from weekly to monthly (or longer) timescales, due to the increased physical size of the circumstellar disk for high-mass stars. If the ``see-saw'' variability is observed on weekly timescales, then the model may need to be revisited and additional explanations explored. If the observed variability is different---or absent---this would indicate that the dynamics and energetics associated with pre-transitional disks around hot stars is quite different than for their low-mass cousins, despite the fact that they share very similar architectures.
Proposal ID: 05_0144
Principal Investigator: Pasquale Temi (NASA - Ames Research Center)
Title: The AGN Feedback Cycle in Massive Galaxies
Abstract: We propose SOFIA/FIFI-LS [CII] observations of three Elliptical galaxies selected from the MASSIVE survey sample. Our investigations are aimed to clarify the formation and evolution of multiphase gas in the atmospheres of massive galaxies. Cold gas has a pivotal role in activating the feedback process. It likely dominates both the Black-Hole accretion process and possibly also the outflow rate. This study will investigate in details the content, distribution, and kinematics of the cold gas phase associated with [CII] emission. FIFI-LS observations in the [CII] line will probe the presence and physical condition of the cold gas and are aimed to clarify if the spatially extended [CII] emission observed in massive elliptical galaxies is associated with molecular gas in PDRs or is emitted by the warm gas, quite unrelated to molecules. These investigations are complemented with theoretical studies and the use of 3D high-resolution magnetohydrodynamic simulations via high-performance supercomputing.This program is strongly tied with the growing availability of ALMA data and studies. We will complement the SOFIA data with our own ALMA observations on the measured CO in Ellipticals.
Proposal ID: 05_0145
Principal Investigator: Angela Cotera (SETI Institute)
Title: Star Formation in the Galactic Center: Massive stars and the ISM in Sgr B
Abstract: Our Galactic Center (GC) is a unique region that enables detailed studies of a mild starburst nucleus at resolutions unapproachable in other galaxies. The GC provides unparalleled opportunities to test theories of the interrelationship of massive stars, molecular and ionized gas, dust, turbulent giant molecular clouds, large-scale magnetic fields, and a black hole; all under extreme conditions. We propose to use FLITECAM to obtain a Paschen-alpha map extending east from the Radio Arc region (previously observed in Paschen-alpha with HST) out to Sgr B. Made up of two distinct regions (Sgr B1 and Sgr B2), Sgr B is one of the most complex star-forming regions in the Galaxy, containing a massive molecular cloud, dozens of HII regions, and numerous young stellar objects (YSOs). Although much of Sgr B2 is unobservable at IR wavelengths due to extinction, Sgr B1 and the periphery of Sgr B2 have lower extinction making the proposed observations possible in these regions. We further propose to complete our Cycle 3 FORCAST observations of the peak mid-infrared emission in Sgr B1 to investigate the temperature and dust structure within these regions which contain known massive stars and massive YSOs. When combined with existing multi-wavelength observations, we will be able to address crucial questions such as: Where are the young massive stars currently located? Is star formation in our Galactic nucleus fundamentally different due to the extreme conditions in the central 400pc? How does the stellar feedback from massive star formation impact turbulence in giant molecular clouds?
Proposal ID: 05_0146
Principal Investigator: Ranga-Ram Chary (Caltech)
Title: Planck's Dusty GEMS: Measuring the AGN Contribution in the Brightest z~3 Star-Forming Galaxies in the Sky
Abstract: Hyperluminous (>1E13 Lsun) infrared galaxies detected at submillimeter wavelengths are among the most intense, star-forming galaxies in the Universe. Although they show signs of AGN activity in the X-rays and the mid-infrared, it is generally thought that their bolometric luminosity, most of which is emitted in the far-infrared, is dominated by star-formation and not by the AGN. Here, we propose to measure the AGN contribution in a population of high redshift (z~3) submillimeter galaxies detected through the Planck all sky survey which have been greatly amplified through gravitational lensing by a foreground galaxy. The SOFIA data bridge the gap in wavelength coverage that exists between the WISE 22 micron and Herschel 250 micron data - this is crucial for sampling the hot dust emission from a buried AGN and deriving robust bolometric luminosities. Our observations will also characterize the multiple components of thermal dust emission to critically assess the canonical view that high redshift starbursts appear to show a limited range of spectral energy distribution (SED) shapes in the far-infrared that is distinct from the SED of main-sequence star-forming galaxies. Since these SEDs have been the benchmark for characterizing the unlensed star-forming, submillimeter galaxy (SMG) population, the proposed observations will have an impact not just on our target sample but on the derived properties of the SMG population as a whole, such as their star-formation rate and gas/dust mass.
Proposal ID: 05_0153
Principal Investigator: William Sparks (STScI)
Title: Confirmation of Water Plumes on Europa
Abstract: Evidence was found for plumes of water ice venting from the polar regions of Europa (Roth et al 2014a) - FUV detection of off-limb line emission from the dissociation products of water. We find additional evidence for the presence of ice plumes on Europa from HST transit imaging observations (Sparks et al 2016). The evidence for plumes remains marginal, 4-sigma, and there is considerable debate as to their reality. SOFIA can potentially resolve this issue with an unambiguous direct detection of water vapor using EXES. Detection of the fundamental vibrational mode of water vapor at ~6 micron, as opposed to the atomic constituents of water, would prove that the plumes exist and inform us of their physical chemistry through quantitative consideration of the balance between water vapor and its dissociation products, hydrogen and oxygen. We propose to obtain spectra of the leading and trailing hemispheres separately, with trailing as the higher priority. These provide two very different physical environments and plausibly different degrees of activity. If the plumes of Europa arise from the deep ocean, we have gained access to probably the most astrobiologically interesting location in the Solar System, and clarify an issue of major strategic importance in NASAs planning for its multi-billion dollar mission to Europa.
Proposal ID: 05_0165
Principal Investigator: Dominik Riechers (Cornell University)
Title: Dissecting an AGN-Starburst System at Redshift 4 with SOFIA
Abstract: Studies of AGN-starburst systems at high redshift over the past decade have revealed massive dust reservoirs in many of them, suggesting dust-obscured star formation rates in excess of 1000 Msun/yr if heated by massive star formation. However, due to lack of constraints at observed-frame far-infrared wavelengths, the contribution of AGN to the dust heating is still an active subject of debate. We here propose a demonstration of the utility of SOFIA/HAWC+ to significantly improve our understanding of this issue in the early universe by decomposing the dust SED of a luminous AGN-starburst system at redshift 4. Our target, the unique lensed galaxy APM 08279+5255, is the apparently most luminous galaxy in the universe, with an apparent bolometric luminosity of 7 x 10^15 Lsun, ~20% of which is radiated away at (far-)infrared wavelengths. The proposed inexpensive photometry at 53, 89, 153 and 214 micron (only 20min on source total) will yield dramatically improved constraints on the warm dust peak powered by the AGN compared to the original, moderate signal-to-noise ratio IRAS detection, enabling a detailed decomposition of the dust spectrum to measure the dust masses, temperatures and opacities of different components. This will establish SOFIA as a key probe of early cosmic epochs, back to ~1.5 billion years after the Big Bang.
Proposal ID: 05_0167
Principal Investigator: Sherry Yeh (Eureka Scientific Inc.)
Title: Mid-infrared Flux Variability in an Awakening AGN
Abstract: We propose FORCAST spectroscopic observations between 8 um to 40 um near the nucleus of NGC 660. NGC 660 underwent an AGN outburst 6 years ago, which is an ideal case for studying AGN astrophysics in a rather quiecent system. However, this rare event has not yet been monitored. Our immidiate goal is to verify the MIR spectroscipic variabilitiy in NGC 660, and to study the AGN effects on dust destruction and ISM. We will compare the FORCAST spectra with the Spitzer IRS spectra (taken before the AGN outburst), including dust continuum, PAH emission, and high- and low-ionization emission lines. FORCAST's slit width is a close match to the IRS slit width, allowing a direct comparison of the spectra between FORCAST and IRS. Our single-slit Subaru COMICS spectrum taken after the outburst shows significantly weakened PAH emission and dust continuum, suggesting dust destruction. However, it is difficult to draw robust intepretations due to systematic uncertainties in the Subaru data. If dust destruction is confirmed in the post-outburst FORCAST observaitons, we will evaluate the energy budget using the MIR line ratio diagnostics, with archival X-ray and radio data. We will then propose cadence observations of MGC 660's nucleus to monitor the MIR flux variability, and employ the reverberation mapping technique to study NGC 660's AGN.
Proposal ID: 05_0171
Principal Investigator: Matthew Richter (University of California - Davis)
Title: H2O absorption toward Orion KL: Improving on ISO
Abstract: The ability to observe H2O is a primary benefit of SOFIA. Because of interference from Earths atmosphere, much of what we know regarding H2O absorption and emission in celestial objects comes from the limited number of previous space missions such as ISO. Therefore, our knowledge of even very well-studied environments such as the Orion BN/KL IRc region is limited by the constraints imposed by those observatories. With SOFIA/EXES, we can drastically improve on aspects of ISO observations. We propose to map the BN/KL region at the spatial resolution limit of SOFIA to examine in detail rotational H2O lines at 26 and 27 microns seen in a single spatial pixel by ISO. With these data, we can study the spatial distribution of the lines, look for line profile variations, and investigate the abundance and temperature variations that are likely present across such a complicated region.
Proposal ID: 05_0176
Principal Investigator: Raghvendra Sahai (Jet Propulsion Laboratory)
Title: Shocked and Scorched: A GREAT Investigation of [CII] and [OI] emission from free-floating Evaporating Gas Globules in Massive Star Formation Regions
Abstract: We propose to use GREAT in order to observe [CII]158 micron and [OI]63 micron emission towards 3 select members of a new class of tadpole-shaped free-floating evaporating gas globules (frEGGs) in two massive star-formation regions. Since discovering the most prominent member of this class in an HST imaging survey, we have now identified substantial populations of such objects in several massive star-forming regions using Spitzer IRAC 8 micron images. By virtue of their distinct, isolated morphologies, frEGGs are ideal astrophysical laboratories for probing star formation in irradiated environments. Our molecular-line observations (CO, 13CO J=2-1 & HCO+ J=3-2) reveal the presence of dense molecular cores associated with these objects, with total masses of cool (~15 K) molecular gas exceeding 0.5-3 Msun, and our radio continuum imaging reveals bright photo-ionized peripheries around these objects. This pilot study will allow us to determine the mass of warm (few 100 K) atomic gas which must exist in photodissociation regions surrounding the molecular gas in frEGGs. The line profiles will be used to probe the photoevaporative flow that is expected to drive the evolution of these objects. We will use sophisticated 3-D numerical simulations of dynamical and chemical evolution of dense, irradiated globules to reproduce our SOFIA data and additional existing multiwavelength data on frEGGs. Our proposed study will pave the way for a larger [CII] survey of frEGGs that will lead to new insights into the complex star formation process under the influence of the harsh ionizing radiation from massive stars.
Proposal ID: 05_0180
Principal Investigator: Eiichi Egami (University of Arizona)
Title: FLITECAM H-alpha Spectroscopy of the 1 Jy Gravitationally Lensed Galaxy at z=3
Abstract: An exceptionally bright z=3.005 gravitationally lensed submillimeter galaxy (SMG) was discovered last year using the Planck all-sky survey data. Having a peak flux density of ~1.1 Jy at ~300 microns, this SMG is by far the most luminous among many tens of similar objects discovered so far. Even taking into account the effect of lensing amplification, this galaxy must be extremely luminous intrinsically. Therefore, we would like to understand the origin and nature of this exceptional object. Here, we propose to use the FLITECAM grism spectroscopy mode to observe the redshifted H-alpha emission at z=3.005. Our main goal is to detect H-alpha emission from this galaxy and to find out (1) how much H-alpha emission is attenuated by dust (by comparing SFR(H-alpha) and SFR(LIR)), and (2) if there is any sign of a luminous AGN (e.g., a broad H-alpha component, high [N II]/H-alpha ratio). A large dust extinction (e.g., non-detection of H-alpha) would indicate that star-forming regions are concentrated in a small volume (within a few-hundred pc scale), and that the galaxy is undergoing a phase of violent starburst. On the other hand, a modest dust extinction would suggest that star-forming regions are distributed over large scales (> kpc), and that the galaxy is undergoing a phase of secular evolution (i.e., on the main-sequence of star-forming galaxies). If there is a luminous AGN harbored in this object, we should also be able to see its sign.
Proposal ID: 05_0182
Principal Investigator: Diane Wooden (NASA Ames Research Center)
Title: FORCAST Observations of a ToO Comet
Abstract: With this CY5 Target-of-Opportunity (ToO) proposal, we propose to measure the dust and organic grains of a yet-to-be-discovered comet or a comet that outbursts. A 5-27 micron spectrum coupled with 11, 19, and 31 micron dual-band photometry of a ToO comet with FORCAST will address our two primary goals: 1) characterize the coma dust mineralogy; and 2) identify organics in the critical 5-8 micron region. Observations of cometary organics probe the unknown precursor materials that were transformed by heat into macromolecular carbon found ubiquitously in carbonaceous chondrite samples from primitive asteroids. Thermal models fitted to FORCAST observations of a ToO comet determine the dust properties and the comet's dust properties link to the physical and chemical conditions in the solar nebula, and help to fulfill the SOFIA Science Case for Evolution of Our Solar System. The crystalline fraction of comet dust has become a benchmark for models of heating and radial transport in our protoplanetary disk. By measuring the wavelengths, relative intensities, and feature asymmetries of crystalline peaks at 11.1, 19, and 23.5, 27.5, and 33 micron, the shapes of forsterite crystals can be constrained and their condensation temperatures inferred by comparison with theoretical and experimental data. We impose the requirement that a CY4 ToO comet have an expected surface brightness of 430 mJy/arcsec-squared, such as from helio- and geo-centric distances of 1 and 1.2 AU and with an Afrho~3000 cm; that is, a relatively bright comet. From 1995 through 2015, there were ten comet apparitions with V<6 mag, where three were naked-eye within 2 months of discovery. FORCAST 5-31.5 micron observations of a ToO comet will enable the study of dust mineral compositions and organic materials, will enable the search for controversial species including PAHs, phyllosilicates and carbonates, and will add to the sample of less than 2 dozen comets with good SNR spanning mid- to far-IR wavelengths.
Proposal ID: 05_0184
Principal Investigator: Francisco Muller-Sanchez (University of Colorado at Boulder)
Title: Testing Unification Models in Dual Active Galactic Nuclei
Abstract: Dual active galactic nuclei (AGNs), which are kpc-scale separation AGN pairs in galaxy mergers, are ideal targets for testing unification models and models of galaxy evolution. By definition, the AGN nature of the two nuclei suggests that they must be consistent with standard unification models (i.e, a dusty torus obscures the central engine in type 2 AGN). At the same time, they are the result of merger-induced nuclear activity. Galaxy evolution models suggest that merger-induced AGNs are heavily obscured for long periods by the high gas densities powering them. Eventually, feedback drives away material, creating a brief window in time in which the AGN is not obscured. Therefore, in these models, there is no need for a small-scale torus. We are constructing for the first time the spectral energy distributions (SEDs) of the two AGNs in dual AGN systems using data from Hubble and Chandra telescopes, in combination with VLA, Keck and VLT data. However, a critical missing component is dust emission at 30-40 microns, which can only be achieved by SOFIA. We propose FORCAST 31.5 and 37.1 microns observations of the complete sample of 5 confirmed dual AGNs with angular separations >3.5". As suggested by current models, the best wavelength to detect thermal emission from a torus would be between 30-40 microns, where both the non-thermal core and the stellar emission sharply decline, and the torus emission peaks. Thus, FORCAST provides 1) the best angular resolution between 30-40 microns of the current suite of instruments, crucial to separate the emission from the two AGNs, and 2) the largest constraining power for torus models, crucial to characterize the properties of the torus in AGNs.
Proposal ID: 05_0189
Principal Investigator: Robert Brauer (Institut fur Theoretische Physik und Astrophysik der Universitat)
Title: Bok globules in the far infrared: Constraining the origin of polarization holes
Abstract: Polarimetric observations of Bok globules at submm/mm wavelengths frequently show a decrease in the degree of polarization towards their central dense regions ("polarization holes", Henning et al. 2001; Vallee et al. 2003; Wolf et al. 2003). This behavior can be explained by multiple physical conditions and effects (Brauer et al. 2016). For instance, a high optical depth in the core of Bok globules is expected to significantly reduce the degree of polarization. However, the relative importance of the various effects has not been confirmed quantitatively. We investigate the influence of the optical depth on the occurrence of polarization holes in observations of Bok globules at 850 microns by comparing these with polarimetric observations at 154 microns and 214 microns. We will make use of HAWC+ polarimetric observations at 154 microns (D) and 214 microns (E) to obtain the orientation and degree of linear polarization in the central regions of the Bok globules CB199 (B335), CB68, and CB54. We will obtain the Stokes parameter I, Q and U of the central regions of the Bok globules B335, CB68, and CB54 to calculate the orientation and degree of the linear polarization. Taking these polarization observations and those already obtained at 850 microns into account, the relative importance of the optical depth effect can be estimated. In addition, we will compare the direction of the polarization vectors with observations of dichroic extinction of background stars to enhance our constraints on the optical depth (Bertrang et al. 2014).
Proposal ID: 05_0190
Principal Investigator: Robert Simon (I. Physikalisches Institut der Universitaet zu Koeln)
Title: Spatial and velocity variations of [CII] optical depth towards S106 IR
Abstract: The [CII] 158 micron fine structure line is one of the most important cooling lines of the interstellar medium, in particular in lower density UV illuminated regions (Photon Dominated Regions, PDRs). It is commonly used, together with chemical modelling, to study the physical conditions in high-mass star forming regions of our Milky Way and external galaxies. PDR models predict a [CII] optical depth of about unity. Velocity resolved [CII] observations of nearby Galactic sources, however, often show broad and complex line profiles, suggesting multiple velocity components or higher optical depths. To investigate the effects of high optical depths in the [CII] line, we have started a program dedicated to deep integrations of the [13CII] hyperfine structure, which is observed simultaneously with the [12CII] line and thus allows a precise determination of the optical depth of the main line. Recent first observations with GREAT/SOFIA at very high velocity resolution towards the well-studied bipolar nebula S106 have confirmed optical depths in the range from 1 to >5, larger than what is predicted by models, and at least two velocity components with surprising variations in opacity. Line ratios of fine structure lines, to derive physical properties such as UV-intensity and density, will thus have to take optical depths in the main line into account to avoid questionable results. An accurate determination of the [12CII] optical depths critically depends on a high signal to noise of the weaker (typically by a factor of ~100 in S106) [13CII] hyperfine satellites and thus requires long integrations. We here propose to obtain a small map (9 settings of the upGREAT LFA array) around the central star S106 IR to characterize the effects of self-absorption, the length scale of the foreground variation, and the rapid change in the source instrinsic composition (e.g., disk, outflow cavity walls, etc.).
Proposal ID: 05_0192
Principal Investigator: Rodrigo Herrera-Camus (Max-Planck-Institut fur extraterrestrische Physik Garching)
Title: Far-Infrared in the EDGE/CALIFA Sample of Galaxies
Abstract: We propose to obtain [CII], [OI], and dust continuum information in 31 galaxies from the EDGE/CALIFA survey of local galaxies, a representative sample of normal z=0 galaxies with full optical IFU spectroscopy and CO interferometric information. This represents a substantial addition to Herschel KINGFISH spectroscopy (50 galaxies), in a sample with exceptional optical and mm-wave ancillary data. We will use these observations to study the relation between [CII] emission, cooling, and SFR, the "[CII] deficit", and the relation betweed dust, extinction, and molecular gas.
Proposal ID: 05_0196
Principal Investigator: Silvia Leurini (Max Planck for Radio Astronomy)
Title: The warm atomic and molecular gas in protostellar jets
Abstract: Collimated and high-velocity mass ejections are often associated with young stellar objects (YSOs) as a natural outcome of the protostellar accretion process. In the earliest phases of evolution, jets are detected as collimated high-velocity emission in low excitation CO and SiO lines in the submillimeter. However, observations of this high-velocity molecular component is challenging for current instrumentation. In this proposal, we want to search for the atomic counterpart of the high velocity gas in the form of a jet in the OI at 63 m in two YSOs and study its relation with hot gas traced by high-J CO lines with GREAT and upGREAT. The high spectral resolution provided by GREAT and upGREAT is essential to study the kinematics of the atomic jet in comparison with the molecular component and verify if OI coexists with CO or if it originates in a different and faster jet component. We will probe whether the role of atomic gas in the jet increases with evolution as suggested by previous observations with PACS with no velocity information. We will also verify whether the relative contribution of high-velocity shock emission and emission from low-velocity photo dissociation regions changes from Class 0 to Class I YSOs as suggested by previous observations with ISO and Herschel. Our observations will open the way towards a better understanding of oxygen chemistry in outflows and jets based on observations of CO, H2O, OH (this proposal) and OI at high spectral resolution.
Proposal ID: 05_0197
Principal Investigator: Silvia Leurini (Max Planck Institut for Radio Astronomy)
Title: Far-IR cooling in massive YSOs
Abstract: Models and observations show that the cooling budget of low- and high-mass star forming regions is dominated by OI, CO and H2O lines at far-IR wavelengths. However, our knowledge about these lines is still very limited because of the very poor angular resolution and velocity information provided by observing facilities such as ISO, KAO and even Herschel. This renders the interpretion of the observations difficult especially for distant objects in our Galaxy and even more for external galaxies. In this proposal we aim to study the evolution of the main contributors of the far-IR line cooling with time during the formation of massive stars and to separate the contribution of outflow/jets from the low-velocity emission or absorption in each tracer. How does the contribution of the main species (OI, H2O, CO) to the far-IR line cooling evolve with time during the formation of massive stars and which environment do they trace? Is water an important coolant at least at high-velocities in outflows? Which is the contribution of warm atomic gas traced by OI on the overall jet/outflow system? These questions can be answered only with spectroscopically resolved observations of OI, CO and H2O of a sample of massive sources in different evolutionary phases. Our team was awarded HIFI/Herschel time to study water in the proposed sample of sources. High-J CO lines were already collected towards the vast majority of our sources during previous SOFIA cycles. We now need GREAT observations of OI to obtain a complete view of the far-IR line cooling budget in our sample of sources.
Proposal ID: 05_0198
Principal Investigator: Christof Buchbender (I. Physikalisches Institut; Universitaet zu Koeln)
Title: Velocity resolved [CII] and [NII] observations in M33
Abstract: We propose to observe the emission of some of the major gas cooling lines of the interstellar medium (ISM), [CII] 158um and [NII] 205um in six giant HII region complexes of the nearby galaxy M33, using GREAT. These spectra will be combined with existing 12CO, 13CO, and HI spectral line cubes, and with maps of the far-infrared continuum. The aim is to use the intensity and velocity information of the FIR lines to study the origin of [CII] emission, i.e. to measure the fraction of [CII] emission from the different phases of the ISM, the diffuse ionized gas, the atomic cold neutral medium, CO-dark molecular gas, diffuse CO-bright clouds, and dense cloud cores. This will allow to establish the relations of [CII] with the FIR continuum as measure of the star formation rate (SFR) and of the star formation efficiency (SFE), which will help to interpret the unresolved emission of objects at much larger distances.
Proposal ID: 05_0200
Principal Investigator: Jochen Eisloeffel (Thuringer Landessternwarte - Karl-Schwarzschild-Observatorium Ta)
Title: Probing the hidden atomic gas in Class I jets
Abstract: We request FIFI-LS spectroscopic maps of three prototypical collimated bipolar outflows driven by Class I protostars in the 63mu and 145mu transitions of [OI]. These maps will enable us to study the extent of warm low excitation atomic gas in these flows, to derive the mass flux rate in the atomic jet, measure the ionisation fraction of the gas to get more insight into its excitation mechanism, and measure the accretion/ejection ratio of matter in Class I sources. In a feasibility study we have detected the [OI] 63mu line in two Class I sources. The proposed observations will help to bridge the existing gap of knowledge between Class 0 and Class II sources that remains after HERSCHEL by creating a small but meaningful sample, and will thus allow us evolutionary studies of the derived flow characteristics.
Proposal ID: 05_0201
Principal Investigator: Sarah Sadavoy (Max Planck Institute for Astronomy)
Title: Testing the Response of Dust Grains to Magnetic Fields in Perseus B1
Abstract: Magnetic fields in our Galaxy are often traced by polarized emission from dust grains. Nevertheless, dust grains are not homogenous, and different dust grain properties can change the observed polarization. To test the how measurements of the magnetic field are affected by dust grain properties, we will observe the B1 clump in the Perseus molecular cloud in dust polarization with HAWC+ in Band E (214 um). The B1 clump shows evidence of dust grain growth toward its dense cores, providing the means to compare how both density and grain size affect polarization. We will also characterize the magnetic field structure across the diffuse cloud material over ~300 independent beams. From these observations, we will determine how different dust grain properties affect the observed polarization. This proposal represents a pilot study to compare dust polarization with dust grain properties in other star-forming regions.
Proposal ID: 05_0202
Principal Investigator: Bringfried Stecklum (Thuringer Landessternwarte - Karl-Schwarzschild-Observatorium Ta)
Title: Tracing the heat wave of an accretion outburst from a high-mass young stellar object
Abstract: Recently, we obtained first epoch FORCAST and FIFI-LS observations of the burst of the high-mass young stellar object S255IR-NIRS3. They are revealing a dramatic change of its spectral energy distribution (SED). This suggests the presence of a heat wave, caused by the burst, which propagates outward in the disk as it is cooling. Since SOFIA is the only facility capable of tracing the implied spectral evolution of the SED, we request second epoch measurements using the same instruments. Using time-dependent radiative transfer modeling, this will allow us for the first time to study the response of a circumstellar disk to the transient heating by an accretion burst. The results will be shedding light on the formation mechanism of massive stars as well as delivering new insights on the physics of circumstellar disks.
Proposal ID: 05_0205
Principal Investigator: Karl Menten (Max-Planck-Institut fuer Radioastronomie Bonn)
Title: Systematic Studies of the Diffuse ISM with SOFIA Observations of CH at 2 THz
Abstract: Recent measurements of widespread absorption in it ground-state fine structure lines near 535 GHz have established the CH radical as a an excellent tracer of the diffuse interstellar medium on a galaxy-wide scale. First SOFIA/GREAT observations of CH's 2.0 THz rotational transitions, also connecting to the ground-state, have shown the great potential of these lines. Even better than the 535 GHz lines, they will contribute key information on absorbing clouds in spiral arms along the lines of sight to distant massive star forming regions whose dust emission provides the continuum flux. Remarkably, combining data from both transitions can provide important constraints on the densities of the star forming regions.
Proposal ID: 05_0206
Principal Investigator: Thushara Pillai (Max-Planck-Institut fur Radioastronomie Bonn)
Title: Magnetic Fields in Massive Filaments
Abstract: Magnetic fields pervade galaxies, shaping them from the largest scales to the smallest star forming scales. A firm understanding of their role is crucial to our understanding of the physics of ISM. A dominant phase of the ISM that has received considerable attention is that of filaments which are ubiquitous and dominate the mass reservoir in molecular clouds. Enormous progress has been made recently towards understanding filament properties. The next major step should be to understand the role of magnetic fields in filaments. We propose to take advantage of HAWC+ dust emission polarimeter now available on SOFIA to launch a pilot polarization study towards three major classes of filaments: (i) Pristine (ii) Hub-Filament systems and (iii) Perturbed. HAWC+ will trace the connection between the star forming cores and the filaments enveloping them. By covering a vast range in parameter space from quiescent to active filaments, we will be constraining the initial conditions prior to star formation, during star formation and after star formation (feedback from newly formed stars on their parent clouds.) The interpretation of observations will be supported by extensive custom--made numerical simulations of magnetized clouds and subsequent dust radiative transfer with various grain alignment mechanisms, as provided by collaborators. Combined, these observations will provide the first panoramic view of the magnetized nature of massive filaments in the ISM.
Proposal ID: 05_0207
Principal Investigator: Miwa Goto (Max Planck Institute for Extraterrestrial Physics)
Title: The Deuteration Ladder of H3+
Abstract: We propose to use SOFIA/EXES to search for the strongest absorption line of D3+ (triply deuterated H3+) at 5.296 um. Deuteration of H3+ begins with an exothermic reaction H3+ + HD -> H2D+ + H2, and continues with similar reactions between deuterated products and HD until D3+ is produced. The exothermicities of these reactions are on the order of ~200 K, or 0.02 eV, which are diminutive in the standard of the laboratory. On the contrary, they have an enormous influence on the abundance the deuterated molecules in the cold ISM, making the molecules detectable at all against the odds of low elemental abundance of deuterium (D/H~1.5e-5). For the quantitative understanding of the deuterium fractionation, experimental data from the ISM are critically missing, as (for technical and astronomical reasons) there are no sightlines on which H3+ and its isotopomers (H2D+, D2H+, and D3+) have been observed simultaneously. When certain physical conditions are met, D3+, as the endpoint of the deuteration ladder, could be the most abundant isotopomer of H3+, including H3+ itself. We will measure D3+/H3+ ratio, or its upper limit, on a few sightlines in order to quantitatively understand the deuteration process in the ISM. The search for H2D+ infrared absorption lines are in progress on the ground-based facilities to be coupled with the SOFIA/EXES observations.
Proposal ID: 05_0208
Principal Investigator: Nicola Schneider (I. Physik. Institut Cologne; University of Cologne; Germany)
Title: The CII line in Draco as a tracer for CO-dark gas
Abstract: The Draco cloud can be considered as a template region for a colliding HI flow scenario in which H2 formation is partly triggered by the shock interaction between a high-velocity (HVC) and intermediate-velocity cloud (IVC). From Herschel dust maps, a double lognormal PDF is obtained, that we interprete as arising from the atomic and molecular hydrogen gas phase. Because the observed total hydrogen column densities are very low (<2 10^20 cm^-2), a large part of the H2 gas is CO-dark. Simulations predict that the CII 158 micron line is a good tracer for this gas phase, we thus propose to observe the CII emission towards two points in Draco with upGREAT. One point is located at the collision point of the HVC and IVC, the other one is found in a region without emission from the HVC. We will compare the intensities and kinematics of the CII with HI and CO and model predictions, and deduce how much CO-dark H2 is associated with the cloud. These observations will also allow us to refine theoretical models of molecular cloud formation and they will provide important constraints on numerical simulations of this process.
Proposal ID: 05_0209
Principal Investigator: Thomas Giesen (University of Kassel)
Title: First Time Detection of C13CC and Study of 13CCC in Dense Star Forming Regions
Abstract: Small carbon chain molecules play an important role in the formation of larger, complex molecules as well as in the destruction process of interstellar grains. Linear C3 was found in dense star forming regions and in shells of late type carbon stars. In the course of recent SOFIA cycle 4 observations we made a first time detection of the 13C-isotopologue 13CCC in space. Asymmetrically substituted 13CCC transitions were detected based on recent unpublished laboratory data. Following this detection we propose to look for the yet undetected C13CC isotopologue and to observe higher-J Q-transitions for both isotopologues. The measurements aim to determine the 13CCC/C13CC ratio which equals 2 for random 13C-incorporation during the C3 formation process. A non-random, chemically driven 13CCC/C13CC ratio will shed light on possible routes to C3-formation. Furthermore high level J-transitions are sensitive to the prevailing excitation conditions. Below 50K symmetrically substituted C13CC can only be cooled by collisions with the ambient gas, whereas asymmetrically substituted 13CCC is cooled by collisions AND radiation thanks to a small permanent dipole moment. Thus 13CCC/C13CC-intensity ratios of the Q(8) line will give insights into excitation mechanism and temperatures of C3. For the new measurements we choose SgrB2(M) as source in order to compare line strengths of C3 and its 13C-isotopologues at exactly the same conditions than we had in our previous CCC observations.
Proposal ID: 05_0210
Principal Investigator: Rodrigo Herrera-Camus (Max-Planck-Institut fur extraterrestrische Physik Garching)
Title: The GREAT [CII] Account of the Low-Metallicity ISM in the SMC
Abstract: We propose to use GREAT to observe in [CII] 158 um emission 7 diverse star-forming regions of the Small Magellanic Cloud. At a distance of 60 kpc and low-metallicity, the SMC is an ideal target to investigate the state of the ISM. Our proposal exploits the spectral resolution of GREAT (1 km/s) in order to determine conclusively whether the [CII] emission probes the column of molecular hydrogen (H2), potentially revealing star-forming gas that is not traced by CO emission. We can then apply the information from the [CII] profiles in specific regions to larger regions mapped with Herschel PACS in [CII] and [OI] to study the details of the low-metallicity ISM and how that relates to star formation. In combination with the ancillary datasets available on these sources and the ISM modeling expertise present in the team, these data will provide one of the best insights into the origin of [CII] emission and total amount of molecular gas (as compared to CO) at low metallicity, both of which are key to understanding high-z ALMA observations of those lines.
Proposal ID: 05_0212
Principal Investigator: Friedrich Wyrowski (Max-Planck-Institut fur Radioastronomie)
Title: Ammonia as a probe of infall in high-mass star forming clumps, Part III
Abstract: Infall is a fundamental process during star formation. While the number of studies towards high-mass star forming region of so-called ``blue-skewed'' line profiles as infall evidence is increasing, their interpretation offers many pitfalls. Detecting infall via redshifted absorption in front of continuum sources is a much more direct method but so far mostly restricted towards absorption in the centimeter towards strong HII regions. A novel approach is to probe absorption of a rotational ammonia transitions in front of the strong dust emission of massive star forming regions. This method was used successfully by us during science demonstration and Cycle 1 to determine infall rates towards six objects. Here we propose to continue this project to a larger range of stages to study infall through the complete evolution of massive star forming clumps and to investigate one of the brightest sources in more detail by imaging its velocity field.