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Program ID: 75_0001

Principal Investigator: R. T. Hamilton (SOFIA/USRA)

Title: Observations of a Bright Type Ia Supernova in M82

DDT Highlight, see webpage.

Abstract: While SNe Ia have been observed extensively at optical and radio wavelengths, only recently have they been the subject of NIR observations. Nevertheless, NIR data can provide significant constraints on SNe Ia physics by revealing information about progenitor composition and explosion products. NIR spectra reveal features from elements such as He, C, O, Mg, and Mn that are undetectable or obscured by line blending at other wavelengths. FLITECAM on SOFIA, with its suite of grisms and filters, provide access to wavelengths that are completely or mostly obscured from ground-based observatories and can thereby make a unique contribution to the study of nearby bright SNe.

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Program ID: 75_0002

Principal Investigator: Robert D. Gehrz (University of Minnesota)

Title: Probing the Ejecta and Surroundings of SN 2014J in M82

DDT Highlight, see webpage.

Abstract: We propose to conduct repeated long-term observations of SN2014J in M82 using SOFIA Director's Discretionary Time. The objectives of the FLITECAM and FORCAST grism and photometric imaging observations are to determine the temporal development of the ejecta and the nature of the interactions of the SN radiation, ejecta, and blast wave with the surrounding material.

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Program ID: 75_0003

Principal Investigator: W. Vacca (SOFIA/USRA)

Title: FORCAST Observations of a Bright Type Ia Supernova in M82

DDT Highlight, see webpage.

Abstract: While SNe Ia have been observed extensively at optical and radio wavelengths, and recently at near-infrared (NIR) wavelengths, there have been almost no observations of SNe Ia at mid-infrared (MIR) wavelengths. Nevertheless, MIR data can provide significant constraints on SNe Ia physics. The emission lines in the MIR are farther apart than in the optical, which mitigates line blending issues. This implies that kinematics can be determined directly and simply from the line profiles. The MIR lines also generally have lower optical depths and are often optically thin, which allows abundances to be determined in a far more direct manner. Since the MIR continuum is dominated by dust emission, MIR observations can also be used to place constraints on dust formation in the ejecta. FORCAST on SOFIA, with its suite of grisms and filters, can provide access to wavelengths that are completely or mostly obscured from ground-based observatories and thereby make a unique contribution to the study of nearby bright SNe.

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Program ID: 75_0013 and 75_0014

Principal Investigator: Jochen Eislöffel (Tautenberg)

Title: Catching the outbursting new FU Orionis object 2MASS J06593158-0405277 on the rise

Abstract: A new outbursting young stellar object of the rare FU Orionis type – 2MASS J06593158- 0405277 – has recently been discovered. Obtaining MIR and FIR photometry within the next months, while it is still on the rise of its burst, constitutes an unprecedented chance to learn more about where in the circumstellar disk such a burst starts, how it is triggered, and what its implications for planet formation may be. We are requesting FORCAST (45 min) and FIFI-LS (45 min) photometry to derive the spectral energy distribution of the source, while this burst is still on its rise.

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Program ID: 75_0015

Principal Investigator: Erick Young (SOFIA/USRA)

Title: [C II] Emission from the Horsehead Nebula

DDT Highlight, see webpage.

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Program ID: 75_0016

Principal Investigator: Melanie Chevance (CEA Saclay)

Title: The large-scale multi-phase ISM in the 30 Dor complex: A template for distant unresolved starburst regions

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], [OI] 145 mu and [OIII] 88 and 52 mu maps from FIFI-LS, along with other data already in hand, we will 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.

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Program ID: 75_0017

Principal Investigator: Bill Vacca (SOFIA/USRA)

Title: Mapping the Starburst in M82 with EXES

Abstract: At a distance of only ~3-4 Mpc, M82 is one of the nearest starburst galaxies, and therefore has been studied extensively across the entire electromagnetic spectrum. Although previous MIR observations of M82 exist with ISO and Spitzer, these have limited spatial information. The beam was huge for ISO (14" x 20" at the smallest; Foerster-Schrieber et al. 2001; Verma et al. 2003) and the Spitzer observations consist of only a few targeted regions on the galaxy (Beirao et al. 2008). Neither set of observations was obtained with very high spectral resolution, so they yield no velocity information for the emitting gas. The ground-based observations of Achtermann & Lacy (1995, hereafter AL95), however, combine high spectral resolution (R~10000) with spatial sampling similar to what can be achieved with SOFIA/EXES. AL95 used Irshell on the IRTF to map M82 in the lines of Brα, [Ar III] 8.99 microns, [S IV] 10.51 microns, and [Ne II] 12.8 microns at a spatial resolution of ~2". We propose to use EXES to map M82 in the lines of [Ar II] 6.99 microns and [S III] 18.71 microns. These data will have a spatial resolution of 2-3" and will be combined with the results of AL95 to generate spatial maps of the [ArIII]/[ArII] and [SIV]/[SIII] line ratios, which can be compared to the [Ne III]/[Ne II] line ratio (AL95). All three ratios provide constraints on the excitation of the emitting gas, which in turn yields constraints on the high mass stellar content (see e.g., Foerster-Schreiber et al. 2001), with relatively minimal corrections needed for extinction (compared to optical or NIR wavelengths). The proposed EXES observations will also allow us to examine the spatial variations in the abundance of Ar and S in M82. Interestingly, Verma et al. (2003) found that M82 was underabundant in S by a factor of 2 relative to the Ne and Ar abundances. It was not clear why this should be the case. The spatial distribution of the line flux can also be compared with the spatial maps of [O III] 52 microns made by FIFI-LS, which reveal strong emission from the nucleus and weaker emission extending along the minor axis of the galaxy, tracing the outflow. Finally, the high spectral resolution provided by the EXES observations can be used to trace the motion of highly ionized gas, and then compared with the AL95 and FIFI-LS results.

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Program ID: 75_0018

Principal Investigator: Bill Reach (SOFIA/USRA)

Title: EXES Spectroscopy of H2 in IC443

Abstract: To fill a gap in the flight plans for this EXES flight series, we propose to observe H2 from the supernova remnant IC 443, at locations where the shock front is impact a molecular cloud.

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Program ID: 75_0019

Principal Investigator: Pablo Fonfria

Title: Searching for C4 in the CSE of the AGB star IRC+10216

Abstract: We propose to observe the AGB star IRC+10216 around 1549 cm-1 (6:456 um) with the spectrograph EXES to confirm the existence of the fundamental band ν3 of the carbon chain C4, which would mean the first evident detection of this molecule in space. The ability of SOFIA to observe from high atmospheric layers joined to the high spectral resolution provided by EXES will give us the chance to discover this important molecule in a spectral window unavailable from ground.

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Program ID: 75_0020

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: Filler observations for dead legs

Abstract: Filler observations for dead legs

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Program ID: 75_0021

Principal Investigator: Maria Kirsanova

Title: Dust transformation under irradiation and shocks around massive B-type stars: from cold grains coated with water-ice mantles to small PAHs

Abstract: With the help of the FLITECAM instrument, SOFIA provides a unique opportunity to observe all three stages of the impact of massive stars on the dust, and study the dust transformation under irradiation and shocks from large cold grains covered by ice mantles to small PAHs. FLITECAM allows us to outline dust content in three basic phases: ionized, atomic and molecular gas near single B­ type stars. FLITECAM has a large enough field of view to get three compact bright HII regions in one image, while the 2' slit in the spectrographic mode makes it possible to obtain their spectra. First, using the Paα filter we will trace highly excited photo­ionized gas. Second, in order to study PAH distributions in these regions we intend to use the PAH filter centered at 3.3 μm. Small neutral PAHs have been found to be responsible for the generation of 3.3 μm band (Mulas et al., A&A, 2006). Using this filter, we will make a map of small neutral PAHs, which can survive only in the PDR, but not in the ionized region. The Spitzer 3.6 μm filter, which covers the PAH aromatic emission of 3.3 μm band, does not suit our purposes as it also includes other prominent features, like the water absorption band at 3 μm and the 3.4 μm aliphatic hydrocarbon emission band. We will map the distribution of ionized PAHs using archival Spitzer data at 8 μm. Third, observations of water ice absorption with the FLITECAM H2O ice filter towards infrared­bright regions will allow us to understand whether ice mantles on dust grains can survive in the PDR.

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Program ID: 75_0022

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: Mid-infrared spectral map of Orion

Abstract: The Orion BN/KL region, including the Trapezium and Orion Bar, is one of the most investigated areas of massive star formation in the Galaxy. This is because Orion is only about 400pc away, while most massive star forming regions are kiloparsec distances. Thus, we get a much more detailed picture of massive star formation processes, chemistry, and dynamics in Orion, than anywhere else. This program will use the FORCAST SLITSCAN mode to map the central ~3’x3’ area of the Orion Nebula, including the BN/KL, Ney-Allen, and Trapezium regions. We will create a spectral map of the area at spatial and spectral resolutions never before possible. These observations will generate a rich dataset for the general astronomical community at wavelengths and resolutions never before achieved.

This program was replaced as an inclusion in 76_0002

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Program ID: 75_0023

Principal Investigator: Daniel Angerhausen (U. Bern)

Title: SOFIA observations of TRAPPIST-1: spectrophotometry, stellar variability and transit timing variations

Abstract: Context: The nearby ultracool dwarf TRAPPIST-1 hosts at least seven transiting Earth-size exo- planets. At a distance of about 40 light years, the TRAPPIST-1 system is one of the most interesting and observationally accessible exoplanet hosts, and is a prime target for JWST. Now is the time to begin a detailed study of these planets and their host star. To fully realize the potential of JWST observations of this target, it is essential that we have precise ephemerides of the planets, and that we understand the host star variability during spectrophotometric observations. Aims: The science goals of this proposal are three-fold: (1) to collect broad-band spectrophotometry time-series observations of the innermost planet TRAPPIST-1b, (2) to study variability in preparation for spectrophotometry of exoplanets with ultra-cool hosts like TRAPPIST-1 with JWST, and (3) to obtain additional transit-timing measurements to refine the orbital ephemeris. Methods: We will observe a transit of TRAPPIST-1b using SOFIA's capability of simultaneous optical and infrared spectrophotometry. TRAPPIST-1b is our primary target, but our observing win- dows also include opportunities to observe multiple/overlapping transits of other planets in the system. Furthermore, we propose to repeat these very short time-series observations (∼ 30 min transit plus same amount of baseline) over the Fall 2017 FLITECAM campaign to track the variability of our results over different timescales. Synergies: The proposed observations are preparatory work for JWST observations that will take place beginning in 2019. TRAPPIST-1 is part of multiple JWST Guaranteed Time Observation programs and will be observed with multiple instruments (NIRSpec, NIRISS, MIRI) that cover a range of near- infrared wavelengths, so it is critical to characterize the system and its variability at multiple wavelengths now to assist interpretation of the upcoming JWST observations. Anticipated results: With regard to our three science objectives we anticipate the following science outcomes: (1) simultaneous spectrophotometric observations in z' and K band, (2) measurements of the variability of the host star and its impact on the repeatability of spectrophotometric observations, and (3) high-precision transit times for TTV analysis. Analyzing the variability of TRAPPIST-1 will provide essential input to the much anticipated observations with JWST.

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Program ID: 75_0024

Principal Investigator: Matthew Richter

Title: Molecules in NGC 7538 IRS 1 & 9

Abstract: High-mass young-stellar objects are particularly well suited for mid-infrared absorption studies focused on the molecular inventory of the region. The embedded star warms the dust around it creating a strong “background lamp” and enriches the surrounding gas with products of dust-grain chemistry. NGC 7538 IRS 1 and IRS 9 are frequent targets for this type of experiment both from the ground (Knez et al 2009 [K09]; Barentine & Lacy 2012) and space (Boonman & van Dishoeck 2003). Many molecules have been detected in the mid-IR, such as C2H2, HCN, NH3, CH4, CH3, CS, and HCNO (K09). From these data, K09 derive the temperature, abundance, velocity, covering factor, and estimate the age of IRS 1 via comparison with chemical models.

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Program ID: 75_0025

Principal Investigator: B-G Andersson (SOFIA/USRA)

Title: Confirming Radiative Atomic Alignment of C+ in IC 63

Abstract: In regions with ordered radiation and magnetic fields, but low collisional rates, atoms and ions can become aligned through optical pumping. This "ground state alignment" (GSA) provides a new way to determine magnetic characteristics in the diffuse interstellar medium (ISM) and similar environments. We propose to confirm a tentative detection of GSA-induced polarization in the [C II] 158μm line in the reflection nebula IC 63.

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Program ID: 75_0026

Principal Investigator: William Sparks

Title: SOFIA confirmation of Europa plumes in coordination with HST

Abstract: The presence of plumes on Europa is of extreme interest to NASA, as it develops a major flagship mission to a prime astrobiological Solar System target. A large amount of Hubble Space Telescope time is being invested in 2018 to confirm and characterize the plume events. SOFIA EXES can provide sensitivity comparable to HST, and has the advantage of certainty that any detections are unambiguously water. We request SOFIA EXES observations to be obtained of Europa during the period of the intensive HST campaign (any time during 2018), to provide sensitive detection limits and quantitative characterization of plumes on Europa, of interest to NASA, the scientific community and general public.

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Program ID: 75_0027

Principal Investigator: Kenneth Hinkle

Title: Measuring water in AGB circumstellar outflows. II. Extreme Cases

Abstract: Significant gaps remain in our understanding of mass loss on the AGB. The AGB Mira stage accounts for 90 percent of the mass loss in low mass stars. This mass flow contains the critical elements for life that are produced in these stars. We know how these elements are produced but we only know a framework about the process that transports them into the ISM (Höfner 2008). The cool outflow from Miras is molecular and low excitation lines are formed through the molecular envelope into the circumstellar gas expanding at terminal velocity. For oxygenrich stars H2O could be one of the most useful molecular probes. However, H2O is difficult to use because the telluric H20 spectrum is opaque for the most significant astrophysical transitions. Science verification observations with SOFIA demonstrated the ability of EXES to observe in stars the lowest excitation transitions of the strongest of the H2O vibrationrotation bands, the 6 μm (010)-(000) bending transition (Indriolo et al. 2015). We were granted time to observe these lines in the prototype Mira o Ceti to measure the acceleration of circumstellar gas and the abundance of water in the gas as it passes from the base of the circumstellar shell to the H2O maser region. These parameters will provide vital information on the role of grain mantels in transforming transparent grains into grains that can be pushed by radiation pressure.

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Program ID: 75_0028

Principal Investigator: Graham Harper

Title: Mass Loss Diagnostics for Core-Collapse Supernova Progenitors

Abstract: The goal of this proposal is to improve our understanding of the thermodynamic/dynamic conditions (density, temperature, and velocity) in the near-stellar environment of Aur (K5- M0 Iab-Ib) to help understand the structures resulting from the poorly understood mass-loss process (Arroyo-Torres et al. 2015, A&A 575, 50; Kervella, Le Bertre, & Perrin, G. (Eds), Betelgeuse Workshop 2012. The Physics of Red Supergiants: Recent Advances and Open Questions, EAS Pub. Ser, Vol 60, and references therein). This goal addresses multiple astrophysics problems including mass loss, and its effect on stellar and galactic evolution, and the interpretation of early-time supernova spectra.

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Program ID: 75_0029

Principal Investigator: Tomasz Kaminski

Title: Close Circumstellar Chemistry of Oxygen-rich AGB Stars

Abstract: In this DDT proposal, we would like to make use of the scheduling gaps of SOFIA/EXES to conduct an exploratory survey in the 14 m, 7 m, and 6 m regions towards the high-mass-loss AGB star TX Cam. The main goal of this project is twofold. First, we would like to detect the HCN v2 = 0 ! 1 absorption. Second, we would like to determine, or obtain direct observational constraint on, the abundance of CH4 in the inner CSE.

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Program ID: 75_0030

Principal Investigator: Curtis DeWitt

Title: Locating the Water Vapor in the Disk of the FU Ori object V1057 Cyg

Abstract: V1057 Cyg is an archetypal FU Ori object, a class of young solar-mass stars defined by massive accretion events causing 4-6 magnitude brightness increases. Because of the disk heating, these sources have a disk photosphere that dominates the system luminosity, with the observed effective temperature and absorption line width depending on the wavelength of the observation. FU Ori objects present a unique opportunity to probe young disk atmospheres because of their unusual disk vertical temperature profile. Using R=100 spectroscopy with IRS/Spitzer, Green et al. 2006 report the appearance of water vapor absorption in V1057 Cyg and in other FU Ori objects. We will confirm this identification with EXES in medium resolution mode and resolve individual water vapor lines, which will unveil the kinematics and temperatures of the absorbing gas, as well as yield clues to the way the chemistry of a particular circumstellar disk responds to FU Ori events.

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Program ID: 75_0031

Principal Investigator: Michael Mumma

Title: Volatiles in the Unique Oort Cloud Comet C/2016 R2 (PanSTARRS)

Abstract: The composition and structure of cometary nuclei are keys to understanding the formation and evolution of matter in the early Solar System (Mumma and Charnley 2011; Bockelee-Morvan etal. 2004). Compared with dust, the ices are more sensitive to changes induced by thermal and radiation processing, so their identities and abundances can provide central clues to those aspects of planetary heritage. For that reason, increasing emphasis has been placed on classifying comets according to the composition of native ices and dust (rather than orbital dynamics). Two hypervolatiles (CO2 and CS2) fall within the spectral grasp of EXES, but cannot be sensed from the ground. We propose to target these two important primary volatiles to further quantify the hypervolatile chemistry of this comet.

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Program ID: 75_0032

Principal Investigator: Archana Soam

Title: Do I sit in the sun or in the shade?

Abstract: We propose to use some of the remaining OC6E dead-legs to measure the gas temperature in IC 63 along the long EXES High-Medium slit, to quantify the gas-grain collision rate in gas directly exposed to the light from γ Cas and gas in the shade of the molecular clumps.

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Program ID: 75_0034

Principal Investigator: Paul Lucey

Title: Water abundance on the Moon from 6 μm observations

Abstract: DDT observations of the Moon

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Program ID: 75_0035

Principal Investigator: Dariusz Lis

Title: D/H Ratio in Cometary Water: Understanding the Origin of Earth’s Oceans

Abstract: Comets contain some of the most pristine materials left over from the formation of the solar system. Measurements of isotopic ratios, in particular the D/H ratio in cometary water, provide key constraints on the origin of Earth’s oceans. The newly commissioned 4GREAT instrument on SOFIA allows very accurate measurements of the D/H ratio in water through nearly-simultaneous observations of the low-energy 509 GHz HDO and the 547 GHz H218O lines. We will use this instrument to measure the D/H ratio in a TOO comet with a figure of merit >= 2E29 s^-1 au^-1 in Cycle 7, to complement the GT observations of comet 46P/Wirtanen in December 2018. The data analysis and interpretation will follow the procedures successfully applied to our Herschel observations of comet 103P/Hartley 2, the first Jupiter Family comet in which the D/H ratio was measured. The same well-tested excitation models will be used to convert the observed line intensities to molecular production rates. Only SOFIA allows nearly-simultaneous observations of the low-energy HDO and H218O in a very similar field of view. This significantly simplifies the analysis and decreases measurement uncertainties. Based on historical average, we expect about one comet per year to be bright enough for HDO to be detectable with SOFIA. Over its lifetime, SOFIA can thus double the number of existing D/H measurements, significantly improving the statistics and providing key observational constraints for understanding Earth’s habitability. This research is perfectly aligned with the strategic objective of the DISCOVER theme of the NASA 2018 Strategic Plan: “Understand the Sun, Earth, Solar System, and Universe.”

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Program ID: 75_0037

Principal Investigator: Bringfried Stecklum

Title: DDT Observation

Abstract: DDT Proposal

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Program ID: 75_0038

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: [OI] 63 micron Emission in the Trumpler 16 Region

Abstract: We will make fully-sampled [OI] 63 micron maps in the Trumpler 16 region of the Carina Nebula Complex. The [OI] maps for these DDT observations will be toward regions of strongest [OI] emission identified during observations of project 07_0028 (PI Goldsmith). The 07_0028 observations are optimized for [CII] observations, and the [OI] map obtained in parallel will be sparsely sampled. We will use the sparsely-sampled map as a 'finder chart' to identify regions of bright, extended [OI] 63 micron emission, and then design observations to map these regions.

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Program ID: 75_0039

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: Observation of X Her

Abstract: Filler observation.

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Program ID: 75_0040

Principal Investigator: Kate Su (University of Arizona)

Title: Constraining Planetesimal Collisions in the Terrestrial Planet Zone of HD 166191

Abstract: The newly discovered variable emission by luminous young (10–200 Myr) debris disks provides a unique opportunity to explore exo-asteroid collisions during the oligarchic and chaotic phases of terrestrial planet-building. Our multiyear Spitzer monitoring shows that the debris production in the terrestrial zone of HD 166191 has become very active since 2018, exhibiting a large-scale, year-long flux increase similar to that observed in the prototype of the variable system ID8 (Su et al. 2019). The infrared flux increase is consistent with the aftermath of two Vesta-sized asteroids colliding, located at 0.54 au from the stars, suggesting on-going collisions of rocky bodies in real time and signaling the final stages of planet construction. We have obtained a SOFIA/FORCAST grism spectrum of the HD 166191 system in 2017 during the quiescent state. The spectrum reveals the presence of abundant small grains of amorphous and Fe-rich crystalline silicates in the 0.2–1 au region, consistent with the material produced in high temperature events. New Spitzer observation obtained in July 2019 further shows that the disk flux at 3.6/4.5 μm has doubled since 2018, reaching to a record high level. A new mid-infrared spectrum of the system in such an active state can reveal the presence of newly generated and highly shocked material produced by hyperve- locity collisions, providing potentially highly diagnostic information about the violent events involved in planet building. We propose to obtain a new epoch SOFIA/FORCAST grism spectrum of the system when it is in such a highly active state. FORCAST grism-mode spectroscopy is well suited to study the mineralogical solid-state features, providing direct constraints on the dust composition of the newly produced debris. The proposed spectrum would enable a quantitative comparison in the debris properties – the amount and composition of small grains – between the quiescent and active states of the system.

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Program ID: 75_0041

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: S-DDT Program: The Far-Infrared Properties in the EDGECALIFA Galaxy Sample

Abstract: We propose to obtain [CII], [OI], and dust continuum information in up to 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 that uniquely leverages the [CII] and continuum science. Moreover, the galaxies are selected to fall in a poorly studied area of the SFR-[CII] relation, intermediate between "normal disks" and "starbursts", allowing us to study the onset of the "[CII] deficit". We will use these observations to study the relation between [CII] emission, cooling, and SFR, the "[CII] deficit", and the relation between dust, extinction, and molecular gas. Two of these galaxies were observed by FIFI-LS in cycle 5, confirming our estimates for the [CII] emission. All analysis expertise and ancillary data are in place to quickly publish the survey results, assuming we obtain about 15 objects.

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Program ID: 75_0042

Principal Investigator: Jochen Eisloeffel (Thueringer Landessternwarte Tautenburg)

Title: Catching the accretion burst in G24.33+0.14 on the rise

Abstract: A new outbursting high-mass young stellar object (HMYSO) - G24.33+0.14 - has been discovered on September 5. Observations of members of the Maser Monitoring Organization (M2O) are showing it flaring in the 22 GHz water line, several methanol lines, and other rare maser species in unprecedented detail. Obtaining MIR and FIR photometry is crucial to assess the consequences of the heatwave passing through the accretion disk and exciting these masers, and to derive the energy input it is delivering to the disk material. Because of the urgency we are requesting FORCAST (45 min) and FIFI-LS/HAWC+ (45 min) photometry with this DDT proposal to derive the spectral energy distribution of this unique source in the next weeks, while this burst is still on its rise.

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Program ID: 75_0043

Principal Investigator: Jochen Eisloeffel (Thueringer Landessternwarte Tautenburg)

Title: Deciphering the periodically outbursting masers in G107

Abstract: Recently, accretion bursts of massive young stellar objects (MYSOs) have been identified to cause flares of Class II methanol masers due to mid-IR pumping. This opens a new window to gain knowledge on protostellar accretion variability. It implies that periodic methanol masers hint at cyclic accretion, possibly caused in a YSO binary source. We derived the first IR light curve of a periodic maser host from NEOWISE data and the contemporary maser lightcurve with the Torun 32-m radio telescope. The source, G107.298+5.639, is an intermediate-mass YSO hosting methanol, water, and hydroxyl masers which are every ~ 34.5 days. A current first interferometric measurement at 3 mm with NOEMA shows clear indications for strong infall in the observed molecular lines. With this proposal to the DDT Flash Call for FIFI-LS we are requesting two flight legs of 48 min each, one towards the beginning, the second towards the end of the FIFI-LS flight series to derive the spectral energy distribution and its possible variability - as well as a few crucial emission lines tracing accretion and warm gas - of this prototypical source near its burst maximum and in quiescence. With these data we will derive the accretion rate and the energy input available to pump the maser emission. This will allow us new insights in the emerging field of using methanol masers as signposts to the dynamics of the accretion-driven growth of massive stars and compare to latest high-mass binary formation models.

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Program ID: 75_0045

Principal Investigator: Dario Fadda (SOFIA Science Center)

Title: Charting C+ in a Milky Way analog: NGC 7331

Abstract: We propose to obtain a map of the [CII] emission of the NGC 7331 galaxy. The far-infrared morphology of this local galaxy (cz = 800 km/s) is dominated by a central dust ring which hosts a third of the present star formation activity. The galaxy can be seen as an analog of the Milky Way because of similar morphology, mass, and star formation activity. Also they share the existence of a massive HI disk and a dusty ring which hosts a large fraction of the star formation activity. Method. A central strip of the galaxy has been already observed with PACS/Herschel showing intense [CII] emission. We will use FIFI-LS on SOFIA to extend the Herschel/PACS [CII] strip of NGC 7331 to a coverage matching the existent CO map (HERACLES survey). [CII] is the brightest far-infrared line emitting up to a few percent of the total infrared power. It is considered an excellent tracer of the molecular gas in the interstellar medium and a good star-formation indicator. Establishing the reliability of [CII] as star formation indicator is paramount for studies of high-z galaxies made with ALMA. By comparing the [CII] emission map with existing CO, HI, H-, and infrared maps from Spitzer and Herschel, we will be able to pinpoint the origin of the [CII] emission in the galaxy. This map, in conjunction with other complete [CII] maps obtained with SOFIA (M 51 and NGC 6946), will be used to constrain the relationship between star formation rate and global [CII] emission. Synergies. NGC 7331 has been completely mapped by several facilities: VLA (HI), IRAM (CO), Spitzer (mid-IR), Herschel (far-IR), GALEX (UV). All these data are publicly available from different projects (THINGS, HERACLES, SONGS, KINGFISH) and will allow a direct comparison with the SOFIA data. Also, the availability of all these data makes possible precise star formation rate estimates with different techniques. Anticipated results. We will produce the first complete [CII] map of NGC 7331. We will compare the distribution of the [CII] emission with those of atomic and molecular gas to pinpoint the origin of the [CII] emission in the different parts of the galaxy. Since this galaxy is a Milky Way analog, we can constrain the relationship between [CII] and total star formation rate obtaining an estimate valid for the majority of normal galaxies observed at high redshift.

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Program ID: 75_0046

Principal Investigator: Randolf Klein (SOFIA Science Center)

Title: Completing the FIFI-LS observations of DR21

Abstract: Context Massive star formation is a very energetic process. How the energy injected by the young massive stars affects the parental molecular clouds is of importance for star-forming theories and galaxy evolution. Aims This proposal aims at studying the feedback mechanisms in DR21, a massive hub in the DR21 molecular ridge. Especially the photodissociation regions (PDRs), where radiative processes erode the cloud, is the taregt of the proposed investigation. Methods FIFI-LS has already gathered data on DR21, but for a full analysis a few more transitions are needed. With the proposed observations of [OIII]52 μm and two high-J CO lines, the data set will be complete and modeling can provide maps of physical parameters like temperature, densities and UV radiation fields. Synergies This study is complementary to the FEEDBACK Legacy proposal which will provide high spectral resolution maps of the Cygnus X region to study the effects of winds on the star-forming regions, whereas the FIFI-LS observations provide many diagnostic lines suitable for a PDR analysis.

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Program ID: 75_0047

Principal Investigator: Elaine Winston (CfA Harvard Smithsonian)

Title: G104.52+01.24: Effect of Environment on Star Formation in the Outer Galaxy with FIFI-LS

Abstract: While the basic processes of high mass star formation are generally understood, the effects of environment on the formation of massive stars, the progression of star formation across a massive cluster, and on the evolution of the young low-mass stars forming therein has not been well characterized. In order to investigate the changes in the star formation process caused by the differing environment in the outer Galaxy (lower metallicity, temperature, density, etc.), we propose to use FIFI-LS on SOFIA to obtain integral field spectra of the region around the central source and walls of the outer Galaxy cluster G104.52+01.24. These observations will complement our recently proposed observations with SOFIA/FORCAST of the same region. They will further compliment our recently published Spitzer and near-IR study, and scheduled Chandra observation, and followup ground-based spectroscopic study of the YSOs. The combination of these data will allow us to measure the ionization in the environment of the central massive stars and in the associated ridge where we identified a number of embedded protostars. We will examine the effect that these stars have on their surroundings through outflows and radiation, and how it is shaping the molecular cloud and triggering subsequent generations of star formation.

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Program ID: 75_0048

Principal Investigator: Curtis De Witt (SOFIA/USRA)

Title: M8 III extension to 06_0056 "Water Absorption in Late-Type M Giants

Abstract: This is a short filler target for ~30 min, in a time where no other targets were available in the proper direction. The target and setting is valuable to the GO Kraemer, "Water Absorption in Late-Type M Giants", because it extends the spectral type range for their study from M4/M5/M6 to M8 III. The target was included in at at the outset of the developing of proposal 06_0056 but omitted from the final target list in order to sharpen the proposal's focus.

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Program ID: 75_0050

Principal Investigator: Graham Harper (University of Colorado)

Title: upGREAT: Probing the near-stellar environments of core-collapse supernova progenitors

Abstract: While the basic processes of high mass star formation are generally understood, the effects of environment on the formation of massive stars, the progression of star formation across a massive cluster, and on the evolution of the young low-mass stars forming therein has not been well characterized. In order to investigate the changes in the star formation process caused by the differing environment in the outer Galaxy (lower metallicity, temperature, density, etc.), we propose to use FIFI-LS on SOFIA to obtain integral field spectra of the region around the central source and walls of the outer Galaxy cluster G104.52+01.24. These observations will complement our recently proposed observations with SOFIA/FORCAST of the same region. They will further compliment our recently published Spitzer and near-IR study, and scheduled Chandra observation, and followup ground-based spectroscopic study of the YSOs. The combination of these data will allow us to measure the ionization in the environment of the central massive stars and in the associated ridge where we identified a number of embedded protostars. We will examine the effect that these stars have on their surroundings through outflows and radiation, and how it is shaping the molecular cloud and triggering subsequent generations of star formation.

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Program ID: 75_0051

Principal Investigator: Graham Harper (University of Colorado)

Title: EXES: Probing the near-stellar environments of core-collapse supernova progenitors

Abstract: We propose to use EXES to spectrally resolve [Fe II] 25.99 in Betelgeuse in its current historical minimum luminosity.

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Program ID: 75_0052

Principal Investigator: Graham Harper (University of Colorado)

Title: G104.52+01.24: FIFI-LS observations of Betelgeuse

Abstract: Observations of Betelgeuse in continuum and [OI] lines to see how the recent fading in the optical is reflected in the FIR

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Program ID: 75_0053

Principal Investigator: William Vacca (SOFIA/USRA)

Title: FORCAST Observations of Betelgeuse During a Dimming Event

Abstract: We are requesting FORCAST grism and imaging observations of Betelgeuse (alpha Ori) to monitor the behavior of the M supergiant during the recent dimming event.

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Program ID: 75_0054

Principal Investigator: William Reach (SOFIA/USRA)

Title: SOFIA Legacy survey of the distribution of lunar water

Abstract: Where is there water on the Moon? Water ice has been detected in portions of the lunar polar regions permanently shaded from sunlight that achieve extremely low temperatures, typically lower than 100 K. The LCROSS mission impacted an expended rocket booster to excavate buried ice at the shadowed polar crater Cabeus, where they found evidence of several weight percent ice in the ejecta. Indications from the neutron experiment on Lunar Prospector suggested the presence of Hydrogen from water in the upper several cm of the lunar surface. Near-infrared reflectance measurements from the M3 instrument on the Chandrayaan-1 spacecraft and UV observations by the LRO showed the locations of OH features in shadowed portions of crates near the lunar poles. The existing observations do not uniquely detect H2O but rather infer its presence from H and OH, based on H2O being a likely form. The 6.1 micron spectral feature of H2O, which at present can only be observed using SOFIA, uniquely detects H2O because it arises from an H-O-H bending mode that requires all 3 atoms of the molecule. SOFIA can therefore provide unique information confirming the prior inferences and leveraging the advantages of those other techniques, including the high spatial resolution available from in situ or large-telescope observations in the near-infrared.

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Program ID: 75_0055

Principal Investigator: William Vacca (SOFIA/USRA)

Title: Mapping the [CII] outflows in M82

Abstract: Observe outflows in M82.

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Program ID: 75_0056

Principal Investigator: Nicole Karnath (SOFIA)

Title: Investigating the Outflows and Shocks of HOPS 361

Abstract: We propose a HST near-IR + SOFIA far-IR study of NGC 2071, a system of at least two outflows from a small group of intermediate to low luminosity stars. Protostellar outflows are ubiquitous part of the star formation process. They provide a record of variable accretion onto stars, have significant impact on the surrounding molecular cloud, and may disrupt or trigger star formation in molecular clouds. Intermediate-luminosity (30 < L_bol < 1000L_sun) protostars bridge the gap between low- and high-mass star formation, forming stars with masses between 2 and 10 M_sun stars (Di Francesco et al. 1997; Mannings & Sargent 2000). Outflows from these systems of protostars have a significant impact on the surrounding ISM, may play an important role in cloud evolution, and are an important laboratory for understanding the origin of far-IR line emission from outflows. Shock-excited emission lines in the near- and far-IR can be used to study the energetics of outflows and their impact on the surrounding cloud. In this study, WFC3/IR images of [FeII] and Paschen beta lines will trace the shocks in the near-IR. A comparison of these data to WFC3/IR imaging in the F160W band from 2009 will be used to derive proper motions. The intensity of these lines will provide estimates of the mechanical luminosity of the line. SOFIA upGREAT will trace emission from far-IR transitions of [OI] and CO (J=16-15). These lines will provide both radial velocities of the shocked emission as well as measurements of the mass flow and heating by shocks and UV radiation. The combined data will provide 3D velocities of the shocks in the molecular clouds, shock velocities, and mass, energy momentum flows through the shocks, providing one of the most detailed measurements of the feedback from a system of protostars to date. The observations of this relatively nearby system (420 pc, Kounkel et al. 2017) will provide unique information on the outflows in a region that is being increasingly well studied through SOFIA FORCAST and HAWC+ observations, making it a well-characterized template for intermediate-mass star formation.

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Program ID: 75_0057

Principal Investigator: Steven Goldman (Space Telescope Science Institute)

Title: SOFIA and HST Multi-wavelength study of the Symbiotic Mira HM Sge

Abstract: To showcase the capabilities of evolved-star science using the instrument modes of SOFIA and the Hubble Space Telescope (HST), we propose to use FORCAST and EXES aboard SOFIA, and WFC3 and COS aboard HST to probe the quickly-evolving symbiotic system HM Sge. We will use SOFIA to probe the dust and the kinematics of the dense circum-stellar material, and HST to map the gas in the inner nebula and probe the shocked emission. These observations will provide a public dataset that can be used to anchor future observations of HM Sge, a post-outburst symbiotic Mira that displays a wide and diverse range of active astrophysical phenomena. The observations will also demonstrate the possibilities for future observations of other evolved-star systems.

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Program ID: 75_0058

Principal Investigator: Mark Siebert (University of Virginia)

Title: Further Investigation of the Tentative Detection of FeH Toward IRC+10216

Abstract: We propose re-observing IRC+10216 using GREAT with the same spectral setup in the 4G3 pixel as used in Siebert et al. (2020), with the objective of obtaining a definitive detection of this important new interstellar molecule. 

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Program ID: 75_0059

Principal Investigator: Martin Cordiner (NASA Goddard Space Flight Center)

Title: Is Phosphine Present in the Atmosphere of Venus?

Abstract:  The detection of phosphine (PH3) on Venus by Greaves et al. (2020) using ALMA and JCMT is one of the most significant developments in planetary science this year, generating major interest among the astrochemistry and astrobiology communities, as well as the public. However, the claimed detection is questionable due to: (1) the extremely weak absorption signature at 267 GHz, (2) bandpass calibration issues due to the brightness of Venus, (3) only a single spectroscopic transition has been detected, and (4) the lack of plausible chemical/geological synthesis pathways for PH3. We propose to search for phosphine on Venus by observing the spectrally-resolved J = 2 − 1 doublet at 534 GHz and J = 4 − 3 quadruplet at 1067 GHz using SOFIA GREAT. The predicted strengths of the target lines will enable a robust confirmation (or upper limit) on the presence of atmospheric PH3, providing crucial input for future Venus space-mission planning.

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Program ID: 75_0060

Principal Investigator: Greg Sloan (Space Telescope Science Institute)

Title: A high-resolution quick-look spectrum of Arcturus (α Boo)

Abstract: We propose to obtain spectra of the K giant α Boo (K1.5 III) using EXES in the fundamental SiO absorption band at 7.6–7.8 and 8.1–8.3 μm using Director’s Discretionary Time. These spectra will support the accepted JWST GO1 program 2050, “Mid-infrared molecular absorption in the atmospheres of K giants,” which will observe four K giants used as standard stars by the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. See the JWST proposal for a more detailed science background for the JWST program.

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Program ID: 75_0062

Principal Investigator: Kathleen Kraemer (Boston College)

Title: AGB Stars in the Far North

Abstract: We will obtain 17.8-37 micron spectra of the 4 dustiest M stars in the Flash Call observing region. Most stars on the asymptotic giant branch (AGB) in the Milky Way have atmospheres dominated by oxygen-rich chemistry, with the carbon-to-oxygen ratio less than unity C/O<1. Thus, in M stars, the dust features are primarily silicates, usually amorphous but sometimes crystalline in structure. However, the conditions under which crystalline silicates form are not yet understood. Further, dust is intimately linked to the mass-loss process, as the radiation pressure drives the grains away, but the effect of crystallinity on this mechanism is also unknown. To understand the crystalline silicates, their formation, and their effects on outflows and stellar evolution, we must find the sources in which they have formed. We will use the FORCAST grisms on SOFIA to characterize the dust in a set of the dustiest M stars in the northern sky. The 17.8-37 micron wavelength range contains the key diagnositics needed to determine which format the silicates are in, amorphous or crystalline. We request 1 hour to carry out this project.

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Program ID: 75_0064

Principal Investigator: Raghvendra Sahai (Jet Propulsion Laboratory)

Title: A FORCAST Study of the Cat's Eye Nebula

Abstract: When ordinary stars (with main-sequence masses 1-8 Msun) die, they eject half or more of their total mass in the form of nucleosynthetically-enriched material into the interstellar medium (ISM). This mass-loss dramatically alters the course of stellar evolution, seeding the ISM for future generations of stars and habitable planets, and driving galactic chemical evolution. Yet this crucial stellar evolutionary process is very poorly understood. Most notably, although one expects asymptotic red giant (AGB) stars to evolve into round planetary nebulae (PNe), such PNe are exceedingly rare, and aspherical PNe are quite common! There is now mounting evidence that the death of these stars is influenced by strong binary interactions which also, directly or indirectly, produce dense dusty waists and high-speed jets and may therefore be the primary cause behind the dazzling variety of observed PN shapes (mostly multipolar, bipolar and elliptical).

The Cat's Eye Nebula (NGC 6543), with a strikingly beautiful multipolar morphology in its central region, is one of the best-studied PNe. The proposed study will produce the first-ever high-resolution images and spatially-resolved spectra at ~20-40 micron, of a key object in the poorly understood late stages of stellar evolution. These data, together with existing optical and x-ray images, will set the stage for the use of SOFIA to provide new insights into the formation and shaping of planetary nebulae.

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Program ID: 75_0065

Principal Investigator: John Bally (University of Colorado Boulder)

Title: The birth environment of the HH199 and HH200 jets in Lynds 1228 (IRAS 20582+7724)

Abstract: We propose SOFIA FORCAST 31 and 37 micron observations of a far-northern low-mass star forming region, L1228, located at a distance of ~370 pc in the Cepheus Flare clouds. The region hosts two Herbig Haro jets (HH199 and HH200) and is associated with the low-luminosity IRAS 20382+7724 source (mid-infrared flux density of a few Jansky). We wish to study the known protostellar energy sources in the region but also discover new fainter young embedded sources all lying within a ~5 arcmin field of view, well suited for the FOV of FORCAST (two pointings, observing time about 2hours). This DDT proposal makes good use of the sensitivity and excellent spatial resolution (~3 arcsec, ~1000AU) of the diffraction limited mid-IR FORCAST-LW camera that is needed to resolve a small deeply embedded cluster of faint young protostars, likely to accompany the brighter dominant IRAS source.

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Program ID: 75_0067

Principal Investigator: Heinz-Wilhelm Huebers (DLR-Institute of Optical Sensor Systems)

Title: Observation of atomic oxygen in the mesosphere and thermosphere of Earth

Abstract: Atomic oxygen (OI) is an important component of the Earth's atmosphere. It extends from the mesosphere to the lower thermosphere (MLT). It is generated through photolysis of molecular oxygen by UV radiation. OI is important with respect to the photochemistry and energy balance of the MLT, because it is its main component and fuels exothermic reactions. An accurate knowledge of the concentration profile of OI in the MLT as well as diurnal and annual variations is therefore essential for understanding the MLT, in particular because global climate change also affect the MLT. OI is extremely difficult to measure, because it has only few optically active transitions. The observation of its ground state fine structure transitions at 4.74 THz and 2.06 THz is a very powerful method to determine the OI concentration, because contrary to other methods it does not involve photochemical models or reaction rates to derive the OI concentration from a measured spectrum. Recently, this method has been demonstrated using 4.7-THz OI observations made with GREAT/SOFIA. Here we propose to measure OI in the MLT during the SOFIA Tahiti deployment. The objectives of the proposal are to measure the influence of the 27-day solar cycle on the OI concentration. In addition, OI data from another geolocation at a different latitude compared to the SOFIA campaigns from Palmdale, Christchurch or Cologne wil be measured and because flying out of Tahiti possibly starts with a rather straight southbound flight direction it will be possible to measure OI along a wide range of latitudes. We therefore propose to use the unique opportunity of the Tahiti deployment for measurements of OI in the MLT.

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Program ID: 75_0069

Principal Investigator: Dariusz Lis (Jet Propulsion Laboratory)

Title: Search for extended water release in comet C/2021 A1 Leonard

Abstract: Comets contain pristine ices left over from the formation of the Solar System. Measurements of the D/H ratio provide key constraints on the origin and thermal history of water, and the contribution of comets to Earth’s oceans. Hyperactive comets have been suggested to have D/H ratios consistent with the terrestrial (VSMOW) value. However, this conclusion is based on a small number of measurements and has to be confirmed with observations of additional Oort cloud and Kuiper belt comets. Hyperactive comets require a secondary source of water vapor in their coma, explained by the presence of subliming icy grains expelled from the nucleus. The presence of such grains can be confirmed by measurements of the spatial distribution of the water emission in the IR.

Comet C/2021 A1 (Leonard) is an Oort cloud comet predicted to be very active in early December 2021, while at ~0.5 au from the Earth. SOFIA/4GREAT measurements of the D/H ratio in this comet were requested, but are not possible due to scheduling constraints. However, ground based observations of HDO will be carried out through an approved ALMA proposal. We request 2.1 hours of SOFIA EXES time to observe multiple water lines in comet Leonard. These observations will provide an accurate water production rate and determine whether an extended source of water emission is present. They will thus provide critical context for the approved ALMA observations of HDO and demonstrate the feasibility of future observations of water in active comets using EXES.

This research is perfectly aligned with the strategic objective of the DISCOVER theme of the NASA 2018 Strategic Plan: “Understand the Sun, Earth, Solar System, and Universe.” Vision and Voyages explicitly identified “determining the deuterium/hydrogen and other crucial isotopic ratios in multiple comets” as key measurements for understanding Solar System beginnings.

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Program ID: 75_0071

Principal Investigator: Asantha Cooray (University of California - Irvine)

Title: AGN vs. Starburst: What powers the infrared luminosity of HSLW01, the brightest z=2.9 Herschel-HerMES HyLIRG in the Lockman Legacy Field?

Abstract: We propose SOFIA/HAWC+ Band B, C, D and E (63 to 214 micron) total intensity imaging of the brightest Herschel-HerMES extragalactic source in the Lockman Legacy Field. The source location is consistent with the RA and Dec ranges requested for the filler DDT. The target is gravitationally lensed by a factor of 11-12 and presents a unique opportunity to study a z=2.9 galaxy with HAWC+, extending recent detections with HAWC+ of z=1 to 3 hyper-luminous lensed extragalactic targets that are also partly powered by an AGN. Due to its high brightness, the traget has been followed-up and studied with a wide range of ground and space-based facilities, allowing studies on 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. 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.

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Program ID: 75_0073

Principal Investigator: Robert Minchin (USRA)

Title: Investigating the dust emission of NGC 2276: a face–on, nearby, star–forming galaxy shaped by its surrounding environment

Abstract: Galaxy evolution is driven by the interplay between interstellar medium and stars, as well as by the interaction of the galaxy with the surrounding environment. Even in galaxy groups, the environment can play an important role in the evolution of a galaxy. The nearby galaxy NGC 2276, part of a small galaxy group centered on NGC 2300, is an ideal target to investigate these effects. NGC 2276 is a face-on, star-forming galaxy plowing through the gaseous medium of the group. The compressed western edge shows an arc with intense star formation. On the opposite side, the arms are deformed by the tidal interaction with NGC 2300 and a tail of stripped gas is visible in the radio data. To investigate the physical properties of this galaxy and how they are affected by the interaction with the surrounding environment, we propose to observe NGC 2276 with HAWC+ in three bands: band C (89μm), band D (154μm), and band E (214μm). Combining HAWC+ observations with public archival data, we will model the dust emission across the disk of the galaxy and derive the infrared luminosity, dust mass and temperature, as well as the star-formation history across the different regions of NGC 2276.

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Program ID: 75_0075

Principal Investigator: William Fischer (Space Telescope Science Institute)

Title: Far-IR Reconnaissance of a Binary Outbursting Protostar

Abstract: As a low-mass star forms, mass may be accreted either in episodic bursts of accretion or in steady flows. The fraction accreted in each mode has implications for understanding the time dependence of accretion onto protostars, the properties of stars as they transition from protostars to pre-main-sequence stars, and the evolution of disks being heated by the bursts. RNO 1B and 1C are a binary pair of protostars in the dark cloud L1287, separated by 6.2". Uniquely among protostellar binaries, both show evidence of an ongoing major accretion outburst. The RNO 1B burst occurred between 1978 and 1990, while the date of the 1C outburst is unconstrained. We propose to obtain HAWC+ Band A, C, D, and E photometry of the binary to construct its far-IR SED ten years after this was done with Herschel, which revealed the outbursts to still be in progress as of 2012. The angular resolution of Band A is fine enough to potentially allow the fluxes of each component to be measured for the first time in the far IR. The photometry will enable an estimate of the luminosity of the pair, potentially of each independent member, and a check of whether the outbursts are still in progress as of 2022. This will add to the developing understanding of whether the durations and luminosities of protostellar outbursts resemble better-understood outbursts in more evolved young stellar objects.

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Program ID: 75_0081

Principal Investigator: Susan Clark (Stanford University)

Title: The role of magnetic fields in the earliest stages of star formation: SOFIA HAWC+ Flash Call observations of the densest filament in the Polaris Flare

Abstract: Filamentary structure is ubiquitous in the interstellar medium (ISM), and has garnered substantial attention in recent years as a morphological tracer of interstellar magnetic fields and the physics of star formation. An emerging theoretical paradigm for star formation invokes the formation of elongated filaments that fragment into star-forming cores. The possible role of magnetic fields in regulating this process remains unclear. Well before the formation of a protostar, molecular clouds must condense out of the diffuse ISM, and their subsequent evolution is one of the least-well-understood steps in the formation of new stars. We propose SOFIA HAWC+ observations of the densest filament in the Polaris Flare, a nearby, non-star-forming, translucent molecular cloud. We will analyze the magnetic field structure of this dense filament and its starless cores in conjunction with ancillary data on the magnetic field and density structure of the Polaris Flare. Our observations will probe the role of magnetic fields in the formation and evolution of molecular clouds.

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Program ID: 75_0085

Principal Investigator: Robert Minchin (USRA)

Title: OTF Mapping of M101 with FIFI-LS

Abstract: This proposal will cover 25 square arcminutes of M101 using the OTF mapping mode of FIFI-LS to a 5-sigma [CII] sensitivity of 2.5E-16 W/m^2. Based on an earlier PACS strip through the galaxy, this should be sufficient to detect [CII] both in the center and in the disk.

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Program ID: 75_0087

Principal Investigator: Carl Melis (University of California San Diego)

Title: What causes R CrB-type stars to show mid-infrared spectral features?

Abstract: R Coronae Borealis (R CrB) stars are enigmatic variable stars which can rapidly fade by factors of 1000 or more and have atmospheres deficient in H but rich in He and C. R CrB stars are typically surrounded by an inner warm and an outer cold envelope of material that is responsible for the brightness dips. Mid-infrared spectra of R CrB-type stars are typically featureless, usually showing only broad features around 6-8 microns thought to be attributed to amorphous carbon dust. In rare cases they may show rich spectra of PAHs and fullerenes; what causes some R CrB systems to show such features is not known. In this proposal we seek to make use of the FORCAST Flash call to obtain a mid-infrared spectrum for an R CrB-type star serendipitously placed in one of the two available sky areas. The proposed FORCAST spectrum will allow us to explore the composition of the material around our target star and further explore under what conditions R CrB-type stars exhibit mid-infrared spectral features.

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Program ID: 75_0089

Principal Investigator: Michael Zemcov (Rochester Institute of Technology)

Title: Constraining the Primordial Abundance of Lithium through FIFI-LS Observations of High Velocity Clouds

Abstract: The primordial abundance of lithium (Li) is a well-understood prediction of Big Bang Nucleosynthesis. However, measurements of this quantity are consistently a factor of 4 below expectations from Standard Model processes, likely due to processing of Li in stars over cosmic history. This discrepancy is difficult to reconcile with our understanding of fundamental physics and the early universe. In this program, we propose to constrain the primordial lithium abundance by observing gas-phase LiH in emission at far-IR wavelengths. We will observe pristine material in the form of an ultra-compact High Velocity Cloud (HVC) in-falling into the Milky Way for the first time. This method skirts the problem of Li processing in stars, and provides a direct window into the properties of pristine gas in the cosmos. With 7.5 ks of on-source integration time, we will reach flux levels of 3 × 10^18 W m−2 (1σ) which should allow us to place interesting constraints on the abundance N(LiH)/N(H2). We will also observe an off-source field for 3.8 ks to provide a null test that will allow us to study systematics and understand our error budget. The total time required for this program is 8 hours. We will use radiative transfer codes to understand our results, and collaborate with astrochemists to help interpret the measurements. Our hope is that this investigation will be a precursor study that will enable future measurements of this type, consistent with the objectives of SOFIA DDT and this Flash Call.

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Program ID: 75_0090

Principal Investigator: Greg Sloan (Space Telescope Science Institute)

Title: High-resolution quick-look spectrum of alpha Boo and gamma Dra

Abstract: We propose to obtain spectra of the K giants alpha Boo (K1.5 III; Arcturus) and gamma Dra (K5 III) using EXES in the fundamental SiO absorption band at 7.6–7.8 and 8.1–8.3 μm using Director’s Discretionary Time. These spectra will support the accepted JWST GO1 program 2050, “Mid-infrared molecular absorption in the atmospheres of K giants,” which will observe four K giants used as standard stars by the Infrared Spectrograph (IRS) on the Spitzer Space Telescope.

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Program ID: 75_0093

Principal Investigator: Alberto Bolatto (University of Maryland College Park)

Title: A Complete Picture of the Interstellar Medium and Star Formation in NGC4303

Abstract: We request FIFI-LS mapping of the NGC4303 in [CII] and [OIII]. NGC4303 is one of a handful of galaxies that have the combination of proximity, complete coverage with optical integral field spectroscopy by MUSE and cold gas by ALMA and the VLA. These data will allow us to: 1) obtain a complete picture of the ISM in this galaxy from optical to radio waves, 2) study the cooling and thermal pressure of the gas in relation to its star formation activity, and 3) characterize the use of the FIR [OIII] 52 um transition to obtain metallicities that are independent of electron temperatures.

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Program ID: 75_0096

Principal Investigator: James Rhoads (NASA Goddard Space Flight Center)

Title: Physical Conditions in Green Pea Galaxies from FIR Lines

Abstract: We request SOFIA FIFI-LS time to observe the [CII] and [OIII] lines from four Green Pea galaxies. Green Pea galaxies are small yet extreme starbursts, with optical spectra dominated by strong line emission, characteristically compact sizes, extreme ionization parameters, and modest masses and metal abundances. They are the best low redshift analogs of high redshift Lyman-alpha galaxies. They are also frequently Lyman continuum leakers, and analogs of the early galaxies that reionized the universe. Vigorous star formation in Green Peas must be fueled by a cold gas reservoir; yet, Lyman alpha escape requires low column densities. The combination points to a complex multiphase interstellar medium (ISM). The subsample we have chosen for this proposal have been detected in both Lyman Alpha and 21cm, thus probing both ionized and neutral gas. Adding SOFIA observations of [CII] (158 micron) and [OIII] (88 micron) lines will probe molecular gas and photon-dominated regions (PDRs). We will use these results to build a more complete picture of the ISM in these fascinating small starbursts, and to help predict and interpret ALMA observations of similar sources at high redshifts.

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Program ID: 75_0103

Principal Investigator: Bringfried Stecklum (Thuringer Landessternwarte Tautenburg)

Title: Estimating the energy of the accretion burst of the massive YSO G323.46-0.08 from its FIR afterglow

Abstract: Accretion bursts are particularly well suited to study massive star formation. So far only six outbursts from massive young stellar objects (MYSOs) are known. They differ in duration and strength, possibly due to various triggering mechanisms. Analysis of archival NIR data from MYSO G323.46-0.08 (hereinafter G323) revealed an outburst with a Ks-band brightness peak in late 2013/early 2014. A crude estimate of its energy suggests that it is the most energetic MYSO accretion burst caught to date. This event has ended recently, as evidenced by the return of the NIR and 6.7GHz methanol maser emission to the preburst levels. However, the first time-dependent radiative transfer (TDRT) simulations performed by us suggest that, in mid-2022, the FIR afterglow still exceeds the preburst fluxes by ~15%. This prediction was obtained by modeling the response of the best model that fits the pre-burst spectral energy distribution (SED) to the temporal behavior of the accretion burst. Thus, we request SOFIA FIR observations to study the development of the afterglow of this archetype source. By measuring the FIR flux after the burst has ceased, we will be able to precisely determine its energy input. This is a prerequisite to obtain reliable estimates of the total accreted mass and the accretion rate. Thus, these SOFIA observations in mid-2022 are mandatory not only because of the unique wavelength coverage in the FIR but also to keep the chance of catching the region still in an elevated state. Comparing this analysis with the other outburst MYSOs observed so far (in particular, G358.93-0.03-MM1 and S255IR NIRS3) will help reveal whether similar or different processes of mass accretion mechanisms are required to explain the variety of outbursts. The data will be crucial to better understand high-mass star formation and the underlying processes of mass accretion.

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Program ID: 75_0104

Principal Investigator: David Trilling (Northern Arizona University)

Title: FORCAST spectra of primitive asteroids: Unraveling compositional mysteries in the Main Asteroid Belt

Abstract: Primitive asteroids dominate the mass in the Main Asteroid Belt. This fact makes a thorough understanding of their compositions important to our knowledge of the materials present in the asteroid population. Unfortunately, the visible and near-infrared (0.4-2.5 micron) spectra of these objects present only subtle spectral features and neutral to moderate slopes, which makes definitive compositional analysis difficult. Observations of the largest primitive, low-albedo objects in the Main Belt in the 3 micron region have shown the presence of large diagnostic features indicative of materials such as phyllosilicates, water-ice frost, organics, and carbonates. However, observing in this wavelength region from the ground is always difficult. The addition of SOFIA FORCAST spectra will provide powerful new constraints on the compositions of these objects. We propose to observe the 10 micron silicate emission spectral feature of 17 asteroids with known 3 micron features using SOFIA FORCAST. The combination of compositional information from the visible, near-infrared, and mid-infrared spectral regions will enable us to further constrain the compositions of these objects and help reveal what our growing knowledge of the 3 micron region may imply for an object's physical properties and origin. SOFIA's unique capabilities as a stratospheric observatory will be essential to capturing valuable data in these wavelengths. The proposed observations will further the critical work that has been done in the 3 micron region using the IRTF. The resulting science could result in a targeted JWST program to further the scientific questions posed in this proposal.

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Program ID: 75_0105

Principal Investigator: Yao-Lun Yang (RIKEN)

Title: Measuring the Luminosity of A Recently Discovered Outbursting Protostar

Abstract: Episodic accretion is widely suspected to play an important role in protostellar evolution. Actually confirming this suspicion observationally has been a challenging task due to the sparse time-sampling of far-infrared observations, which contain the bulk of the luminosity. Using archival NEOWISE data, we recently discovered a luminosity burst in a "well-known" young, Class 0, protostar, B335, which is often used as the test-bed for dynamical and chemical models of star formation. Its luminosity peaked at 2018 and has been declining. We also find emission of complex organic molecules (COMs) brightened during the luminosity burst. B335 is scheduled to be observed with JWST later this year to probe the composition of the ice that leads to the rich complex chemistry. However, the luminosity of B335 at the current epoch is unknown and we have to rely on extrapolation because there are no far-IR observations after 2018, when its brightness peaked. We aim to use HAWC+ to obtain far-IR photometry of B335 to measure its current luminosity. We propose to measure the photometry of B335 in all HAWC+ bands to construct the SED of B335 at the current epoch and derive its current luminosity. The current luminosity derived from the proposed SOFIA observations would be an essential parameter for the interpretations of the scheduled JWST observations along with archival and proposed ALMA observations. The luminosity variation would have a direct impact on the chemical evolution of COMs as well as the outflows of B335. We would derive the current luminosity of B335 by modeling its SED constructed from the proposed HAWC+ observations. The luminosity variation would be the corner stone of future analysis of ALMA and JWST observations.

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Program ID: 75_0106

Principal Investigator: Edward Montiel (USRA)

Title: The SOFIA/EXES Mid-IR High Spectral Resolution Library

Abstract: We are proposing to create a high spectral resolution (R = 50,000) legacy library of classical, MIR-bright sources covering from 5.23 to 28.3 micron with SOFIA/EXES. Ro-vibrational transitions and non-polar molecules can only be studied within this wavelength regime. This sample includes objects within the Solar System, high mass protostars, and evolved stars. For our sample, we expect to generate and provide line lists identifying all the features in their spectra as well as versions of the spectra deconvolved to JWST/MIRI resolution. This library is likely to be the most definitive collection of MIR spectra until a space-based mission includes a high spectral resolution instrument.

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Program ID: 75_0107

Principal Investigator: Yvonne Pendleton (NASA Ames Research Center)

Title: Hydrocarbons in Diffuse ISM Dust: Probing the Cyg OB2-12 sightline with EXES

Abstract: Interstellar dust is a key component of the interstellar medium as it regulates the radiative transfer of radiation in the disk of galaxies, dominates the infrared appearance of dust enshrouded objects and the interstellar medium as a whole, provides surfaces for catalytic reactions forming icy mantles, serves as a repository of much of the heavier elements, and are the building blocks of pebbles, cometesimals, and planetesimals in protoplanetary disk. Despite its importance, the composition of interstellar dust is still heavily debated. This is particularly true for the carbonaceous components as its spectral features are weak and are typically blends of absorption by different compounds. Disentangling these components in low resolution spectra with limited S/N has proven to be challenging. We propose to use EXES on SOFIA to observe the star, Cyg OB2-12, from 5.69–8μm at a resolution of 1400–1900, depending on wavelength, and to obtain a high signal-to-noise (~300) spectrum. We propose to combine this with a 2-5.3μm spectrum using SpeX on the IRTF. Because of its high extinction (10 magnitudes of visual extinction) and high intrinsic brightness, this star is the “standard bearer” of infrared extinction studies in the interstellar medium. The EXES wavelength range contains the CC stretching modes of olefinic and aromatic carbon compounds as well as the bending modes of aliphatic carbon compounds. The 3μm SPEX spectrum contains the CH stretching modes of these compounds. Existing spectra of these wavelength ranges show that these modes are present but have insufficient S/N and resolution to separate out the individual features of these carbon compounds. The proposed observations will provide a unique view of the composition of carbonaceous interstellar dust. EXES on SOFIA is the only instrument that can measure this wavelength range in this star as it is too bright for MIRI/JWST.

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Program ID: 75_0108

Principal Investigator: Jose Fonfria (IFF-CSIC)

Title: Simultaneous determination of mass-loss rates and CO abundances of evolved stars from H2 rotational lines with SOFIA/EXES

Abstract: The recent first detection of the H2 S(1) line toward the carbon-rich AGB star IRC+10216 and the further simultaneous estimate of the mass-loss rate and the CO abundance with respect to H2 opens the door to apply the same method to other evolved stars. Until now, the impossibility of detecting H2 lines forced astronomers to estimate the mass-loss rates of asymptotic giant branch (AGB) and red supergiant (RSG) stars from observations of the CO rotational lines. In this process, standard CO abundances were assumed since there was not possible to accurately determine this quantity from observations. Consequently, mass-loss rates are affected by indeterminated uncertainties that hamper the comprehension of the physical and chemical evolution of the circumstellar envelopes and their central stars. We aim to apply the method developed after the detection of the H2 S(1) to determine the mass-loss rates and CO abundances of the envelopes of a sample of AGBs, RSGs, and one hypergiant star. This work will rely on very sensitive high spectral resolution observations at 6.9 and 17um carried out with the EXES spectrograph. These observations will provide us with spectra of H2 S(1) with S/N typically of 5. The H2 S(5) line, which is expected to form much closer to the star than the S(1) line, will be also observed to give information about the dust opacity in the envelope. The modeling of the H2 S(1) line will result in a mass-loss rate, which is independent of the CO abundance. The comparison of this mass-loss rate and previous estimates calculated from CO observations will allow us to determine the CO abundance. This project will show if it is possible to use this method to systematically characterize circumstellar envelopes of evolved stars or it can be applied only to a reduced number of objects.

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Program ID: 76_0001

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: Community Science: HAWC+ Polarimetry of 30Dor

Abstract: This program will acquire Band C and D polarimetry of the bright FIR regions in 30 Dor, as a community data set. A four pointing Band C map will match the area of a single pointing band D map, yielding estimates p/sig_p>3 for most of the area.

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Program ID: 76_0002

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: FORCAST S-DDT Program Cycle 6

Abstract: These are the S-DDT (Strategic DDT) Programs for Cycle 6.

This program includes 75_0022 among other observations.

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Program ID: 76_0003

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: Strategic DDT Observations of Galaxian Magnetic Fields

Abstract: To provide archival images of nearby galaxies in far-infrared polarization with HAWC+, utilizing surge capacity flights.

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Program ID: 76_0004

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: High resolution spectral survey of the massive protostar NGC 7538 IRS 1

Abstract: We will observe the high-mass protostar NGC 7538 IRS 1 with EXES at high-resolution (R=55000) from 5.5 - 8.0 microns.

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Program ID: 76_0005

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: Resolving pure rotational water vapor transitions in massive protostars

Abstract: We will use EXES to take resolved spectra of the 19 micron region of massive protostars that have been detected with deep 5-7.5 micron ro-vibrational water vapor bands. The 19um water vapor transitions will be sensitive to different but related absorbing structures in the protostellar envelope.

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Program ID: 76_0006

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: [OI] Observations of the Horsehead Nebula

Abstract: We will map the Horsehead Nebula and the L1630/IC434 interface using upGREAT’s High Frequency Array. These [OI] data will allow us to study the atomic gas in the transition region between the HII region IC434 and the dense molecular cloud L1630, including its dynamics. This project is an important complement the upGREAT [CII] map (DDT project 75_0015) of this iconic region.

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Program ID: 76_0007

Principal Investigator: Harold Yorke (SOFIA/USRA)

Title: S-DDT Program: The Far-Infrared Properties in the EDGE-CALIFA Galaxy Sample

Abstract: We propose to obtain [CII], [OI], and dust continuum information in up to 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 that uniquely leverages the [CII] and continuum science. Moreover, the galaxies are selected to fall in a poorly studied area of the SFR-[CII] relation, intermediate between "normal disks" and "starbursts", allowing us to study the onset of the "[CII] deficit". We will use these observations to study the relation between [CII] emission, cooling, and SFR, the "[CII] deficit", and the relation between dust, extinction, and molecular gas. Two of these galaxies were observed by FIFI-LS in cycle 5, confirming our estimates for the [CII] emission. All analysis expertise and ancillary data are in place to quickly publish the survey results, assuming we obtain about 15 objects.

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