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SOFIA Cycle 2 Programs in Do If Time Category
Proposal ID: 02_0001
Principal Investigator: Charles Woodward (University of Minnesota - Twin Cities)
Title: FORCAST Observations of Comet C/2012 K1 (Panstarrs)
Abstract: Comet dust provides a window to the early evolution of our Solar System, and its composition can constrain dust formation and mixing processess extant in our proto-planetary disk. Comet C/2012 K1 (PanStarrs), a dynamically new (1/a < 1e-4) Oort Cloud comet, is predicted to reach a [V] of 7 mag or less in 2014 Apr-May passing within 1.7 AU of the Earth (pre-perihelion). As a “new" comet (first inner solar system passage), the coma grain population is expected to be extremely pristine, unencumbered by a rime and insufficiently irradiated by the Sun to carbonize its surface organics. We propose SOFIA (+FORCAST) grism observations to obtain 8 to 27.7 micron spectra to enable derivation of the coma grain properties. The region from 9 to 12 micron contains features from amorphous and crystalline silicates (e.g., 11.2 micron) while 17.6 to 27.7 micron covers discrete resonances from crystalline silicates key to ascertaining the shape of the crystals and their condensation T(K) within our protoplanetary disk by comparison to model and lab data and contains potential spectra signatures providing new clues as to whether organics, including carbonates and phyilosilicates, are extant in comets. “Snap-shot" images of the comet two wavelengths will detect coma structures like jets, linking these morphologies to grain properties (derived from color temperature maps).
Proposal ID: 02_0002
Principal Investigator: Charles Woodward (University of Minnesota - Twin Cities)
Title: Comet Grain Albedo and Coma Structure
Abstract: Spectrophotometric analysis of materials released from comet nuclei during perihelion passage through sublimation, outgassing, and nucleus fragmentation provides insight into the physical conditions in both the environment beyond the “frost line’’ (>5 AU) where icy planetesimals aggregated and the hotter dust formation zones closer to the proto-sun where refractory materials condensed. We are initiating a concerted effort to measure comet dust albedos, a basic parameter characterizing the size distribution and physical properties of comet dust, with SOFIA (+FORCAST), targeting in CY2 comet C/2012 K1 (Panstarrs). Only ~12 comets have measured IR grain albedos at various phase angles, and multi-epoch observations of individual comets show considerable scatter about the expected phase function. Scattering in albedo is very important as it reflects: (1) heliocentric variations of dust properties; and (2) difference in dust produced by comet outbursts and other activities. Thus, scattering in albedo is diagnostic about inhomogeneity of comets. Our science goals are to: (1) develop an empirical study that combines compositional information from the mid-IR with albedo and dust color to determine the mineral and physical properties of comets; and (2) increase the number of comets with well-determined albedos.
Proposal ID: 02_0003
Principal Investigator: Thomas Harrison (New Mexico State University)
Title: Ascertaining the Origin of the Mid-Infrared Emission from HR Del
Abstract: Classical novae (CNe) are almost certainly the progenitors of Type Ia supernovae. CNe are interacting binaries where a cool, late-type secondary star is transferring matter to a white dwarf. Eventually, sufficient mass is accreted onto the white dwarf to trigger a thermonuclear runaway. This explosion is the CNe outburst. Early theories for the outbursts of CNe proposed that after the explosion, the central source would enter a phase of stable burning at high luminosity. As mass is lost from this object, its psuedo-photosphere contracts, and the effective temperature would rise to the point that it would primarily emit in the EUV and X-ray. Recent X-ray surveys of CNe no longer support this scenario. However, mid-IR observations of several old novae showed strong line emission many years after outburst. In a recent WISE survey of old CNe, we discovered that HR Del (Nova Delphini 1967) is a very strong mid-IR source. We believe that this flux is from line emission photoionized by a hot central source. If this is true, then HR Del must have continued nuclear burning on the white dwarf to maintain this level of irradiation. This complicates our idea about how CNe return to quiescence. We propose to use FORCAST to obtain mid-IR spectra of HR Del to confirm the line emission hypothesis.
Proposal ID: 02_0013
Principal Investigator: Joel Green (University of Texas at Austin)
Title: Dust and gas in FU Orionis objects: FORCAST spectroscopy of outbursting young stars
Abstract: Mid-IR dust features occasionally vary dramatically in T Tauri stars, but are typically consistent over multiple epochs. Most T Tauri silicate features indicate both grain growth and high crystallinity fractions. In contrast, outbursting sources (FUors) exhibit some grain growth but pristine silicate emission features. We propose to observe four classical FU Orionis objects (FU Ori, V1057 Cyg, V1515 Cyg, V1735 Cyg) in order to determine whether the outburst influences the dust feature or instead highlights a larger dust radius where processing has not yet occurred. These sources were all observed with Spitzer-IRS in 2005-6, and have declined in overall brightness at different rates, providing several different case studies. Their bright continuum (1-6 Jy) over the 5-40 um range provides the perfect opportunity to observe them with FORCAST spectroscopy, with a 7 year baseline to probe changes in their mid-IR properties. This will be the first mid-IR variability study of FUors.
Proposal ID: 02_0014
Principal Investigator: Joel Green (University of Texas at Austin)
Title: What is the evolutionary state of HBC 722?
Abstract: We propose to observe the pre-main sequence, currently outbursting young star HBC 722, with eight photometric bands on SOFIA-FORCAST spanning 5-25 um. HBC 722 flared beginning in 2009, after the end of the Spitzer cryogenic mission, and is not well- characterized post-outburst in the mid-IR. With FORCAST, will be able to characterize its mid-IR properties and classify the developmental stage of the source relative to other classical outbursting stars. HBC 722 is the most recent addition to a small class of young stars that have flared over 5 magnitudes in a 1 yr timescale, likely tracing a sudden accretion event from the circumstellar disk to the star. Their evolutionary state has variously been connected to both the Stage I and II phases of star formation, and is often associated with protoplanetary formation. FORCAST imaging will provide strong constraints on the infrared excess of the source, disk shape/settling, dust properties, and mid-IR variability, as it appears to be approaching peak luminosity during Cycle 2. We propose to observe HBC 722 to provide mid-IR characterization of an FU Orionis-type flare during peak outburst, a rare window into disk accretion processes.
Proposal ID: 02_0017
Principal Investigator: Harriet Dinerstein (University of Texas at Austin)
Title: The Energetics of H2 near very hot stars: Illuminating Radiative Feedback in analogs of the high-mass First Stars
Abstract: We propose to use FORCAST to observe rotationally excited H2 emision lines in planetary nebulae with very hot (T > 100,000 K) central stars. Conditions in these regions are analogous to those in the gas surrounding the first stars (Pop III) in the universe, which are thought to have had very hot photospheres. Since H2 is the primary coolant, its behavior in such environments determines whether radiative feedback from Pop III stars will be positive or negative: whether it will facilitate or suppress further mass accretion and star formation. Observations with ISO and Spitzer of the Helix Nebula, ionized by a very hot star, show a high H2 rotational temperature (~1000 K) not easily accounted for by shocks or conventional photodissociation regions. This has been attributed to the presence of a substantial amount of H2 in the ionized zone, due to gas-phase reactions that dominated H2 production in the (dust-free) early universe. To test the generality of this phenomenon we observed several similar targets with Spitzer. The H2 lines observed at high spectral resolution were well-measured, but the S(5), S(6), and S(7) lines were subject to blending with ionic lines and dust features at the low spectral resolution of IRS-SL. The higher spectral resolution of FORCAST will yield definitive line fluxes and more accurate temperatures. These observations will give us insight into the behavior of H2 near very hot stars, which is relevant to the state of gas near Population III stars and the operation of radiative feedback in the early universe.
Proposal ID: 02_0020
Principal Investigator: Bhaswati Mookerjea (Tata Institute of Fundamental Research)
Title: Probing cold gas in the outer galaxy: [CII] absorption with GREAT
Abstract: Very little is known about the physical and chemical composition of interstellar matter in the outer Galaxy. Since the outer galaxy is expected to be metal-poor and have larger UV-penetration, singly ionized carbon (and not CO) is likely to be the dominant gas-phase carbon-bearing species in the cold molecular clouds in the outer Galaxy. Furthermore recent Herschel detection of [CII] emission (Langer et al. 2010) from a large number of molecular clouds not detected in CO suggests that we need to re-assert the role of [CII] as a tracer of cold ‘molecular’ clouds. We have detected deep self-absorption features in [CII] towards the two outer galaxy sources IRAS 20406+4555 and 05345+3556, located in the direction of the anti-center using HIFI/Herschel. Here we propose [CII] observations to probe the nature and spatial extent of the cold foreground gas, which gives rise to these absorption dips.
Proposal ID: 02_0023
Principal Investigator: Diane Wooden (NASA Ames Research Center)
Title: FORCAST Observations of a Bright ToO Comet
Abstract: We propose to measure the dust and organics of a bright unknown comet or comet outburst with this CY2 Target-of-Opportunity (ToO) proposal. A 5-39 micron spectrum of a ToO bright 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. The crystalline fraction of comet dust has become a benchmark for models of heating and radial transport in our protoplanetary disk. In addition, by measuring the wavelengths, relative intensities, and feature asymmetries of crystalline peaks at 11.2, 19, 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. 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 bright ToO comet determine the dust properties and the comet’s dust properties links to the physical and chemical conditions in the solar nebula, and help to fulfill the SOFIA Science Case for Evolution of Our Solar System. We define a CY2 ToO bright comet as an unpredictable cometary outburst event or a comet discovered after the CY2 submission deadline that produces a naked-eye comet that is observable within CY2. From 1995 through 2013, there are eight bright comet apparitions where five out of eight are ToO comets. For CY1, the likelihood was low for a ToO bright comet but comet ISON was discovered and activated. FORCAST 5-39 micron observations of a bright 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 17 comets with known silicate crystalline fractions.
Proposal ID: 02_0025
Principal Investigator: Pierre Vernazza (CNRS, Laboratoire d’Astrophysique de Marseille)
Title: Uncovering the surface composition of the largest main-belt asteroids with FORCAST
Abstract: This is a long-term project whose goal is to study the mid-infrared spectral properties over the 5-40 micron range of large main belt asteroids for which the 0.4-4 micron range has been unable to constrain their surface composition. During Cycle 1, we have been awarded observing time with FORCAST to observe both 1 Ceres and 2 Pallas. Here, we propose to carry out spectroscopic observations with high signal to noise ratio of 4 Vesta, 10 Hygiea and 12 Victoria with FORCAST over the 5-40 micron range in order to bring new constraints on their surface composition. Such high SNR is required in order to resolve the weak emissivity features in the asteroid spectra, which in turn will allow us to properly identify the mineralogical and meteoritic analogs of those objects. In addition, the obtained data will allow us to refine the albedo, the thermal inertia and the surface roughness of these objects, which is particularly helpful when comparing asteroids and meteorites. In order to avoid misinterpreting any spectral features due to the atmosphere - which also applies for interpreting cycle 1 data - we need to properly estimate its contribution. To achieve this goal, the observations of both Hygiea and Vesta will be helpful since Hygiea has already been observed in this wavelength range by ISO and since Vesta’s surface composition is well known from the VNIR range as well as its meteoritic analogs (HED meteorites).
Proposal ID: 02_0032
Principal Investigator: Christer Watson (Manchester University)
Title: Testing models of a MIR-identified wind-blown bubble
Abstract: 1 Ceres, 2 Pallas, 4 Vesta, 10 Hygiea and 13 Egeria are among the largest bodies in the main asteroid belt representing about 40 percent of the belts total mass. While many of their physical properties such as size, mass, bulk density and albedo are quite well constrained, their surface composition remains elusive (apart for Vesta). Studies in the 0.4-4 micron range have not yet answered the question of their surface composition. We propose to carry out spectroscopic observations with high signal to noise ratio of these objects with FORCAST over the 5-40 micron range in order to bring new constraints on their surface composition. Such high SNR is required in order to resolve the weak emissivity features in the asteroid spectra, which in turn will allow us to properly identify the mineralogical and meteoritic analogs of those objects. In addition, the obtained data will allow us to refine the albedo, the thermal inertia and the surface roughness of these objects, which is particularly helpful when comparing asteroids and meteorites; also, SOFIA offers us a great opportunity for collecting the first complete mid-infrared spectra ever assembled for both Ceres and Vesta, which is of particular interest with respect to the Dawn mission. In order to avoid misinterpreting any spectral features due to the atmosphere, we need to properly estimate its contribution. To achieve this goal, the observations of both Hygiea and Vesta will be helpful since Hygiea has already been observed in this wavelength range by ISO and since Vestas surface composition is well known from the VNIR range as well as its meteoritic analogs (HED meteorites). This is a long-term project whose goal is to study the mid-infrared spectral properties of large main belt asteroids for which the 0.4-4 micron range has been unable to constrain their surface composition.
Proposal ID: 02_0033
Principal Investigator: Volker Ossenkopf (Universitaet zu Koeln)
Title: Spectrally resolved OH line emission in Orion
Abstract: OH plays a crucial role in the chemistry of the interstellar oxygen network. It is produced through three different formation routes sensitive to the gas density, cosmic rays, the X-ray ionization rate, the local UV field, and the energetic impact of shocks. By comparing the line profiles of OH with those of different, chemically related species that have been observed already, we will be able to uniquely identify the different chemical routes creating and destroying OH in Orion. We propose to perform spectrally resolved observations of the ground-state OH transitions near 2.51 THz in the Orion Bar and Orion S. For Orion S, the variation of the profile along the main outflow is to be mapped. In total we ask for an observing time of 2.6h.
Proposal ID: 02_0040
Principal Investigator: Eric Murphy (California Institute of Technology)
Title: Estimating the Strength of Anomalous Microwave Emission in NGC6946
Abstract: We propose to use FLITECAM grism spectroscopy on SOFIA to help determine the origin of anomalous microwave emission originating in an extranuclear star-forming region within the nearby spiral NGC6946. Although detected as a prominent CMB foreground component between 0.3--3cm over 15 years ago, our understanding of the physical process producing this emission remains highly incomplete. The leading theory suggests that it arises from ultrasmall (<10^-7 cm) grains having a non-zero electric dipole moment that are rapidly rotating. Currently, the strength of the anomalous component in NGC6946 relies solely on a crude radio thermal/non-thermal decomposition using extremely coarse (25") resolution radio data. We propose to use FLITECAM grism spectroscopy to measure Br-alpha at 4.05um, which should not suffer significantly from extinction, to accurately estimate and subtract the contribution of free-free emission from the 1cm data, providing an accurate characterization of the anomalous microwave emission for modeling purposes. By combining the proposed FLITECAM data with new Jansky VLA imaging at similar spatial resolution (i.e., 2", which is similar to the size of the anomalous emission component), we will be able to determine the strength of the anomalous dust emission at a level that is ~>2 times better than has been possible to date. Our observations will also detect any 3.3um PAH emission if present. If the origin of the anomalous microwave component is indeed spinning ultrasmall dust grains, we may expect a strong signal of 3.3um PAH emission related to the anomalous emission component.
Proposal ID: 02_0049
Principal Investigator: Markus Roellig (Universitat zu Koeln)
Title: Mapping hot CO in DR21-C
Abstract: We plan to spatially resolve the physical and dynamical structure of the massive star forming region DR21-C which has a prominent bipolar outflow visible in 2 micron emission of vibrationally excited H2, tracing hot, shocked gas. Particularly, we want to measure the local variation of the shock contribution to the CO excitation. While the shock is hardly affecting most of the molecular line emission of the region, only CII shows an additional broad wing indicating that the CII emission is not only originating from the warm gas, but also from the ionized wind in the blister outflow. Recent Herschel/HIFI observations of hot CO emission lines along and across the outflow direction reveal a more complex dynamical structure of the highly excited gas. The gas dynamics and energetics change significantly toward energetically higher lying states and hint at multiple, differently excited gas components. We propose to map the area around the central cluster in the 12CO J=11-10, J=13-12, and J=16-15 lines to spatially resolve the highly excited molecular material in DR21. Since the three different lines are subject to different excitation conditions the proposed maps will allow us to spatially resolve the local gas energetics at different beam sizes (16, 20, and 23 arcsec). These will be the first spatially and spectrally resolved maps of very high-J CO emission of a Galactic PDR and will greatly help to increase ouor understanding of the interplay between PDR and shock excitation in massive star forming regions.
Proposal ID: 02_0051
Principal Investigator: Antoine Gusdorf (Observatoire de Paris)
Title: High-J CO observations of the Cepheus E protostellar outflow with GREAT
Abstract: With this proposal we want to observe high-J CO lines with the GREAT spectrometer onboard the SOFIA telescope in the Cep E outflow associated to an intermediate-mass protostar. Our aim is to clarify the spatial origin (jet, outflow ?) of the spectral bullets detected in CO lines during our previous, Cycle 0 campaign. The requested observations will also allow us to directly investigate the physical conditions (abundances, column density, and excitation temperatures) of the different kinematical component seen in the CO line profiles. In a second step, more detailed shock modelling will be done, that will allow us to understand the energetics and mass-loss rate of the considered outflow, and that will also open the door for future chemical studies.
Proposal ID: 02_0052
Principal Investigator: Mark Rushton (Jeremiah Horrocks Institute)
Title: SOFIA observations of recurrent novae
Abstract: Recurrent novae are interacting binary systems containing a massive white dwarf and a low mass secondary star. They are of interest for a number of reasons, not least because they may be progenitors of type-Ia supernovae. In some recurrent novae, infrared excesses are observed due to dust in the secondary wind, which is shocked by the nova ejecta. We propose to use SOFIA/FORCAST to follow-up our Basic Science observations and observe three of these recurrent novae: RS Oph, T CrB, and V407 Cyg. Our aims are to measure the spectral energy distribution of the dust emission, to determine the nature of the dust, to measure the mass-loss rates, and to monitor their long term behaviour in the infrared region.
Proposal ID: 02_0055
Principal Investigator: Lars Kristensen (Smithsonian Institution Astrophysical Observatory)
Title: COPS-GREAT: CO in ProtoStars with GREAT
Abstract: Low-mass embedded protostars drive strong bipolar jets, which shock the surrounding gas on 100-1000 AU scales and entrain colder gas in outflows on 10,000 AU and larger scales. The aim of this proposal is to analyze the transition between shocks and entrainment and to quantify the mass in each component. We plan to do this by observing the CO 13-12 line with GREAT in five sources. Outflows from young protostars are a major source of feedback on both protostellar and cloud scales. However, our understanding of how they entrain or impact the protostellar envelope is still in its infancy. High-J CO observations are required to analyze in detail the transition where the outflowing gas goes from being colder (T ~ 100 K) entrained outflowing gas to being directly excited by the shocks causing the entrainment. These observations will allow us to quantify the amount of currently shocked gas with respect to the entrained gas, as well as examine shock properties as a function of velocity, and thereby quantify the feedback from a protostar on its natal material.
Proposal ID: 02_0059
Principal Investigator: Brian Williams (NASA Goddard Space Flight Center)
Title: The Composition of Dust in a Type IIn Supernova
Abstract: Type IIn supernovae (SNe) are a relatively rare and poorly-understood subclass of core-collapse (CC) SNe that have been linked to progenitors, such as luminous blue variables, with extremely high mass loss rates. Spitzer observations have revealed that many Type IIn SNe exhibit late-time (>100 days) infrared (IR) emission from hot dust, much more so than other types of CC SNe. Unlike in other CC SNe, where dust observed is generally attributed to newly formed dust in the ejecta, dust in Type IIn SNe arises from a pre-existing shell of material from the progenitor system. Thus, late-time IR observations of Type IIn SNe serve as a probe of the mass loss history of the progenitor. Simply knowing the composition of the dust, whether silicate or carbonaceous in nature, is a strong constraint on the type of progenitor system that leads to these SNe. Although Fox et al. (2011) identified ten Type IIn SNe with late-time IR emission from warm Spitzer data, only one of these (2005ip) was observed at wavelengths beyond 4.5 microns. Recently, two more Type IIn SNe (1995N and 2006jd) have been detected in the mid-IR (12 microns) with WISE, bringing the grand total of all Type IIn SNe observed at wavelengths beyond 4.5 microns to a whopping three. We propose here for 11.1 micron SOFIA observations of the young, nearby, bright SN 2010jl, a SN being closely monitored by Hubble, Keck, Spitzer, and Chandra. This SN occurred after the WISE mission ended, making SOFIA the only instrument capable of observing in the important mid-IR, necessary to remove degeneracies from dust models, and characterize the type and amount of dust present in the pre-SN circumstellar medium. This will help constrain the overall amount of dust that can be formed by these SNe, which may be a significant contributor to the overall dust budget of the ISM.
Proposal ID: 02_0065
Principal Investigator: Inseok Song (University of Georgia Research Foundation, Inc.)
Abstract: Title: Characterising a young, isolated, dusty star HD166191
Among hundreds of debris disks known to date, there are only a handful of extremely dusty warm debris disk stars. This subset of stars are believed to be undergoing recent dust enriched events caused by planetary collisions. These stars all show prominent mineralogical features in the whole Spitzer/IRS spectral range. However, they show a variety of different mineralogical compositions when studies in detail. This diversity in mineralogy may imply the underlying diversity in the formation and evolution of terrestrial planets. Recently, we identified another extreme warm debris disk using WISE data. In this proposal, we propose to obtain 5-37 micron mid-IR spectra which can only be obtained currently with SOFIA/FORCAST. With the FORCAST spectra, we can fully analyze the dusty disk of HD166191, which will be added to the very small group of important stars.
Proposal ID: 02_0073
Principal Investigator: Michael Mumma (NASA Goddard Space Flight Center)
Title: A GREAT search for Deuterium in Comets
Abstract: Comets are understood to be the most pristine bodies in the Solar System. Their compositions reflect the chemical state of materials at the very earliest evolutionary stages of the protosolar nebula and, as such, they provide detailed insight into the physical and chemical processes operating in planet-forming disks. Isotopic fractionation ratios of the molecular ices in the nucleus are regarded as signatures of formation processes. These ratios provide unique information on the natal heritage of those ices, and can also test the proposal that Earth’s water and other volatiles were delivered by cometary bombardment. Measurement of deuterium fractionation ratios is thus a major goal in contemporary cometary science and the D/H ratio of water - the dominant volatile in comets - holds great promise for testing the formation history of cometary matter. The D/H ratio in cometary water has been measured in only eight comets. Seven were from the Oort Cloud reservoir and the D/H ratio was about twice that of the Earth’s oceans. However, the recent Herschel measurement of HDO/H2O in 103P/Hartley-2 (the first from the Kuiper Belt) was consistent with exogenous delivery of Earth’s water by comets. Outstanding questions remain: are cometary HDO/H2O ratios consistent with current theories of nebular chemical evolution or with an interstellar origin? Does the HDO/H2O ratio vary substantially among comet populations? Hartley-2 is the only Kuiper Belt comet with measured HDO/H2O, are there comets with similar ratios in the Oort cloud? These questions can only be addressed by measuring HDO/H2O ratios in many more suitable bright comets. We therefore propose to measure the D/H ratio in water in a suitable target-of-opportunity comet by performing observations of HDO and OH with the GREAT spectrometer on SOFIA. A multi-wavelength, ground-based observing campaign will also be conducted in support of the airborne observations.
Proposal ID: 02_0075
Principal Investigator: Alessio Caratti o Garatti (Max-Planck-Institut fur Radioastronomie)
Title: Probing H2 jets from high-mass YSOs
Abstract: Protostellar jets from massive stars provide a unique opportunity to study the mechanisms of massive star formation as well as turbulence in molecular clouds. Unfortunately, little is known about their physical properties. Our recent study showed the fundamental role played by the H2 pure rotational lines in the cooling and momentum transport of the IRAS20126+4104 massive jet. These lines, visible in the mid-IR, appear to trace the coldest and most massive regions of the massive jets. We thus propose to use FORCAST grisms to investigate the physical properties of the cold H2 component of massive jets, so far investigated in just one object. A similar SOFIA/FORCAST proposal was previously accepted with a substantial reduction on the requested time. Thus our pending SOFIA/FORCAST Cycle 1 observations will be able to investigate only one or two HMYSO jets only from 4.7 to 13.7 um. Here, we aim at enlarging our small sample, covering a wider wavelength range (up to 28 um), which includes several bright atomic and molecular lines. This study will provide us with a sample large enough to understand the structure and physics of massive jets, so far unknown, clarifying the role of the cold H2 component. Moreover, we wish to combine these data with recent NIR spectroscopy, which traces the warm H2 component, providing us with direct estimates of momentum, mass flux and energy flux of these jets. In this way we can understand which is the main component responsible for carrying out the momentum.
Proposal ID: 02_0081
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 also propose to obtain 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: 02_0098
Principal Investigator: Rodrigo Herrera-Camus (University of Maryland)
Title: Disentangling the Sources of [CII] 158 micron Emission in Nearby Galaxies
Abstract: We propose to use the GREAT instrument on board SOFIA to spectrally resolve [CII] and [NII] 205 micron emission in two nearby, star-forming galaxies: NGC 6946 and M 101. The goal is to disentangle the sources of the multi-phase interstellar medium that contribute to the [CII] emission. Our proposal exploits the high spectral resolution of GREAT to obtain line profiles in 14 regions, chosen to represent a diversity of environments in terms of star formation activity, radiation field strength, metallicity and gas content. The line profiles of [CII] will be compared to those of [NII] 205 micron, CO, and HI. The comparison to [NII] and CO reveals the fraction of the [CII] emission arising from diffuse ionized gas and HII regions. The comparison to CO and HI will allow us to measure the contribution to the [CII] emission from the cold neutral medium and photodissociation regions. In combination with the ancillary datasets available on these sources and the ISM modeling expertise present in the team, these data will provide the best insights into the origin of [CII] emission in galaxies.
Proposal ID: 02_0099
Principal Investigator: Colette Salyk (National Optical Astronomy Observatories, AURA)
Title: A search for warm methane in protoplanetary disks
Abstract: We propose a search for gas phase methane in a protoplanetary disk known to harbor a variety of other chemical emission features, including those of carbon monoxide, water, carbon dioxide, hydrogen cyanide, and acetylene. Methane is one of the only gas-phase C,N or O-bearing species that has not yet been searched for in the planet-forming inner regions of disks, due to the fact that the peak wavelengths are difficult to observe from the ground, but were also not covered by the Spitzer Infrared Spectrograph. Yet knowledge of the methane abundance throughout protoplanetary disks can have important implications for disk chemistry and planetary diversity. The detection and characterization of methane in a protoplanetary disk therefore represents a unique and exciting opportunity for SOFIA.
Proposal ID: 02_0103
Principal Investigator: Athol Kemball (University of Illinois at Urbana - Champaign)
Title: Cosmological nucleosynthesis: the lithium problem II
Abstract: A measure of the primordial lithium abundance provides significant observational constraints on current models of big-bang nucleosynthesis (BBN), including the confrontation between BBN models and the observed cosmic microwave background anisotropy measurements, and dark matter particle physics in the early universe. Current optical measurements of halo star lithium abundances are subject to significant systematic uncertainties. SOFIA, however, uniquely allows observations of new sub-millimeter LiH rotational transitions, providing an important alternative approach to the lithium problem. Although, the lowest LiH rotational transition, (v=0, J=1 - 0) at 443 GHz is heavily absorbed in the atmosphere, and has only been searched for in red-shifted extragalactic absorption, SOFIA uniquely allows a search for the (v=0, J=3 - 2) transition near 1.3 THz in the local ISM directly. We propose here to search for this LiH transition in both its isotopomers toward high-density molecular clouds in Orion. If detected, this will provide an important estimate of galactic LiH abundance, and help to answer one of the important cosmological questions regarding primordial nucleosynthesis.
Proposal ID: 02_0109
Principal Investigator: Nicolas FLAGEY (Jet Propulsion Laboratory)
Title: Mid-IR characterization of the dusty circumstellar envelope around Be/B[e]/LBV candidates
Abstract: Massive stars play a key role in the dynamics and the enrichment of the Galaxy. However, their evolutionary timescales are short, which makes them difficult to identify and characterize. In the mid-IR survey of the Galactic plane, we found more than 400 dusty shells associated with evolved stars. A significant fraction of those also exhibit an IR excess around the central source. Most of these are now identified or suggested as massive Be/B[e]/LBV stars. We propose to obtain the mid-IR spectrum for 8 such sources to identify the nature of the excess, characterize its properties, and relate it to the mass loss history of the star.
Proposal ID: 02_0111
Principal Investigator: Harshal Gupta (California Institute of Technolo)
Title: A Deep Search for HD+ and Complementary Observations of H2D+ toward Sgr B2(N)
Abstract: We propose sensitive observations of the ion HD+ and the related ion H2D+ toward the Galactic Center source Sgr B2(N). The HD+ ion is a polar surrogate for H2+, whose formation by cosmic-ray ionization is thought to be the rate-limiting step in the ion-molecule chemistry of interstellar clouds. In addition to providing insights into this fundamental first step of interstellar chemistry, the proposed observations would allow us to study key parameters, such as the molecular fraction and the cosmic-ray ionization rate of interstellar clouds. Because HD+ was one of the first polar molecules thought to be formed in the primordial gas, and may have played a role in the radiative cooling and structure formation in the early universe, constraints on the production of HD+ obtained from the proposed observations may help refine models of primordial chemistry.
Proposal ID: 02_0116
Principal Investigator: Benjamin Sargent (Rochester Institute of Technolog)
Title: An EXES Search for Formaldehyde Gas in the Class I/II Young Stellar Object IRAS 04278+2253
Abstract: We propose to obtain high-resolution mid-infrared spectroscopy at 5.65915 microns wavelength of the Class I/II Young Stellar Object (YSO) IRAS 04278+2253 using EXES on SOFIA to search for absorption from formaldehyde (H2CO) gas. Low spectral resolution (R~90) Spitzer-IRS spectra of this YSO and a number of T Tauri stars (TTSs) show an unresolved band of absorption of full width half maximum (FWHM) of ~0.6 microns centered around 5.7 microns wavelength. Modeling of the Spitzer-IRS spectrum of IRAS 04278+2253 and the other TTSs indicates this band may be due to formaldehyde. Detection of individual absorption lines in high spectral resolution mid-infrared spectra of YSOs would be a significant finding, as the relatively recent mid-infrared spectral studies of TTSs that have found evidence for circumstellar gas in protoplanetary disks have found emission lines from gases such as H2O, OH, CO, CO2, HCN, and C2H2 (e.g., Carr & Najita 2008; Salyk et al 2008; Salyk et al 2009; Carr & Najita 2011; Pontoppidan et al 2011), but they do not find absorption lines, and they do not find H2CO.