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SOFIA Cycle 3 Approved Programs
Proposal ID: 03_0005
Principal Investigator: Christof Buchbender (I. Physikalisches Institut, Universitaet zu Koeln)
Title: Velocity resolved [CII] and [NII] observations in M33
Abstract: We propose to observe the emission of some of the major gas cooling lines of the interstellar medium (ISM), [CII] 158um and [NII] 205um in six giant HII region complexes of the nearby galaxy M33, using GREAT. These spectra will be combined with existing 12CO, 13CO, and HI spectral line cubes, and with maps of the far-infrared continuum. The aim is to use the intensity and velocity information of the FIR lines to study the origin of [CII] emission, i.e. to measure the fraction of [CII] emission from the different phases of the ISM, the diffuse ionized gas, the atomic cold neutral medium, CO-dark molecular gas, diffuse CO-bright clouds, and dense cloud cores. This will allow to establish the relations of [CII] with the FIR continuum as measure of the star formation rate (SFR) and of the star formation efficiency (SFE), which will help to interpret the unresolved emission of objects at much larger distances.
Proposal ID: 03_0007
Principal Investigator: William Reach (Universities Space Research Association)
Title: “Dark” Molecular Gas in the Diffuse Interstellar Medium
Abstract: Context: The physical conditions of diffuse interstellar gas in galaxies are a balance between radiation field and large-scale shocks. In particular the amount of molecular gas remains poorly known, despite being important for the initiation of cloud collapse and star formation. While a “CO-H2 conversion factor” is often used to infer H2, observations of far-infrared dust emission and gamma-ray nucleon interactions indicate there is no such factor in the diffuse medium. The distribution and amount of molecular gas in the diffuse interstellar medium is poorly known. We identified isolated clouds where high-resolution observations of the 21-cm H I line (from Arecibo) and submm emission from dust (Planck) indicate there is more total material than the measured atomic gas. By observing independent tracers of interstellar gas, we aim to calibrate the dust excess and determine how much, and what type of, material is responsible for the excess dust. Using FIFI-LS, we would measure the [C II] 157.7 micron line brightness toward locations in a single cloud where there is a significant “dark” column density that has a relatively sharp spatial signature. Detecting the [C II] line brightness from the filament will constrain the properties of the gas and test the hypothesis of whether the material is diffuse molecular hydrogen.
Proposal ID: 03_0012
Principal Investigator: Paul Goldsmith (Jet Propulsion Laboratory)
Title: SOFIA [CII] Observations of CNM Clouds
Abstract: We propose to carry out a study of the structure and evolution of clouds in the cold neutral component of the Galactic interstellar medium (ISM). Observation of the fine structure line of ionized carbon (C+) will enable us to determine conditions in these clouds and probe the transition from purely atomic to mixed atomic-molecular structures. The sample of clouds to be surveyed is drawn from the Millenium Arecibo 21-cm Absorption Line Study, which provides an unequaled data set of highly accurate atomic hydrogen column densities, line velocities and widths, and (very importantly) cloud temperatures, all relatively free of confusion from general HI background emission. The velocity-resolved [CII] spectra from SOFIA/GREAT will allow us to obtain cloud densities and thermal pressures of a sample of clouds of different column densities, and to study the correlation between ionized carbon and atomic hydrogen. We will use available Planck dust emisison data to obtain total hydrogen proton column denities, and by comparison with atomic hydrogen, the molecular hydrogen colum density, and we will thus be able to probe the atomic-to-molecular transition as function of HI column density. We anticipate obtaining CO absorption spectra for the same lines of sight using the ARGUS array on the GBT, which will delineate the ionized to molecular carbon transition, and accurate determine the”CO Dark Molecular Mass.” The evolution of clouds from purely atomic form to having molecular (CO) cores is likely an early step in the formation of molecular clouds, which may well be assembled from such transition objects. High-sensitivity observations of external galaxies increasingly show significant molecular material between spiral arms. It is thus likely that star formation in spiral arms does not begin with purely atomic clouds. Understanding the molecular component of the diffuse ISM is thus critical, and being able to measure the [CII] emission will enable us to accurately determine the mass of “CO dark molecular gas” and thus determine the total mass reservoir available for star formation
Proposal ID: 03_0014
Principal Investigator: Pierre Vernazza (CNRS, Laboratoire d’Astrophysique de Marseille)
Title: Uncovering the surface composition of the largest main-belt asteroids with FORCAST: 1 Ceres and 4 Vesta
Abstract: 1 Ceres is the largest body in the main asteroid belt representing about 25 percent of the belt’s total mass. While many of its physical properties such as size, mass, bulk density and albedo are quite well constrained, its surface composition remains elusive. Studies in the 0.4-4 micron range have not yet answered the question of its surface composition. We propose to carry out spectroscopic observations with high signal to noise ratio of this object with FORECAST over the 5-40 micron range in order to bring new constraints on its surface composition. Such high SNR is required in order to resolve the weak emissivity features in its spectrum, which in turn will allow us to properly identify the mineralogical and meteoritic analogs of this object. In addition, the obtained data will allow us to refine its albedo, its thermal inertia and its surface roughness, which is particularly helpful when comparing asteroids and meteorites. In order to avoid misinterpreting any spectral features due to the atmosphere, we need to properly estimate its contribution. To achieve this goal, the observation of Vesta will be helpful since its surface composition is well known from the VNIR range as well as its meteoritic analogs (HED meteorites). Note that this program was already accepted for cycle 1 observations but could never be scheduled. In summary, we propose high signal to noise observations of both Ceres and Vesta with FORECAST over the 5-40 micron range. These observations are of particular interest to the DAWN mission, which will arrive at Ceres in 2015.
Proposal ID: 03_0020
Principal Investigator: Robert Gehrz (University of Minnesota - Twin Cities)
Title: SOFIA Target of Opportunity (ToO) Observations of Bright Classical Novae in Outburst
Abstract: Galactic classical novae (CNe) contribute to Galactic chemical evolution by injecting dust grains and gases into the interstellar medium (ISM). We were awarded time for SOFIA Cycle 1 and 2 FORCAST and FLITECAM Target of Opportunity (ToO) grism observations of the temporal development of bright CNe. Here, we propose to extend our program into Cycle 3 to cover the continued development of CNe that became active during Cycle 2 and to initiate coverage of CNe that go into outburst during Cycle 3. The proposed observations can determine critical physical parameters that characterize the explosion and the effect of CNe on ISM abundances. In particular, our observations will yield the mass ejected, the mineralogy and abundance of the dust grains, and gas phase abundances of CNONeMgAl metals in the ejecta. The 5 to 37 micron spectral range of FORCAST grisms enables complete and simultaneous access to the many dust and gas emission features that must be examined to derive these parameters. Supplemental FLITECAM observations of a dusty ToO nova are requested to assess the hydrocarbon component of nova dust. Any new nova brighter than 8th magnitude at visual maximum can trigger our ToO program when supporting optical/IR ground-based observations indicate that the nova is in 1) a dust formation and growth phase, 2) a coronal emission development phase, or 3) the early free-free expansion phase. The timescales for SOFIA ToO follow-up observations for a nova that triggers our ToO program can range from weeks, months, and years for cases 1) and 2), to days and weeks for case 3).
Proposal ID: 03_0021
Principal Investigator: Robert Gehrz (Minnesota Institute for Astrophysics, University of Minnesota)
Title: SOFIA Target of Opportunity Observations of Supernovae in Nearby (D < 5 Mpc) Galaxies
Abstract: We propose to conduct repeated SOFIA FLITECAM and FORCAST grism Target of Opportunity (ToO) observations of supernovae in nearby (D < 5 Mpc) galaxies that may occur during the SOFIA Cycle 3 observing period. The objectives of the observations are to determine the temporal development of the ejecta and the nature of the interaction of the supernova radiation, ejecta, and blast wave with the surrounding material.
Proposal ID: 03_0022
Principal Investigator: Robert Gehrz (University of Minnesota - Twin Cities)
Title: Dust in the Winds of Proto-planetary Nebulae: RV Tauri Stars and SRd Variables
Abstract: We propose to obtain SOFIA FLITECAM and FORCAST grism spectra to examine the mineralogy of the circumstellar dust in a sample of post asymptotic giant branch yellow supergiants that are believed to be the precursors of proto-planetary nebulae. We are proposing here to finish observing the program remaining stars from our Cycle 2 program during cycle 3 and to extend the sample to contain the rest of the brightest RV Tauri and SRd stars, including those in the southern hemisphere. The proposed program will produce the first self-consistent sampling of the entire 2.8-37.1 micron spectral region for a broad cross-section of this class of objects. The wavelength coverage and spectral resolution of the grisms will allow us to produce accurate models of the composition and grain-size distribution of the silicate materials and to test for the presence of hydrocarbon components in the grain materials. Relationships between the chemical composition of the circumstellar dust and the elemental abundances of the central stars will be investigated. Models of the distribution of dust in the circumstellar environments of these stars can also be constrained by the data. Nine of our fourteen program stars are all accessible to SOFIA flights that occur from Palmdale, CA during Cycle 3 and a number of them are suitable for viewing during east-bound flight. The remaining five stars require a southern deployment.
Proposal ID: 03_0024
Principal Investigator: Aneurin Evans (University of Keele)
Title: Further observations of the BAG phenomenon
Abstract: We will continue our highly successful Cycle 2 observations, and use SOFIA FORCAST and FLITECAM grism observations to obtain the spectral energy distributions of stars that have recently undergone very late thermal pulses. These very rare, poorly observed, and little understood events can potentially give us a glimpse of the eventual fate of the Sun. With continued spectral and photometric coverage from 2.6 - 37.1 microns we will be able to determine the mass-loss rate from the central star and its variability, its physical state, and the nature and extent of its circumstellar dust shell. We will also be able to characterize carriers of the Unidentified Infrared (UIR) emission from those objects displaying such emission. Our observations will throw light on a phase of the evolution of low mass stars that is very poorly understood.
Proposal ID: 03_0028
Principal Investigator: Michael Person (Massachusetts Institute of Technology)
Title: Monitoring Pluto’s Atmosphere with Stellar Occultations During the New Horizons Flyby Epoch
Abstract: We propose to use SOFIA with HIPO and FLITECAM (FLIPO) to measure temperature, pressure, and possible particulate haze radial profiles of Pluto’s atmosphere by observing up to three stellar occultations by Pluto surrounding the time of the New Horizons encounter in mid-2015. Due to its highly elliptical orbit and seasonally variable obliquity, Pluto’s atmosphere is predicted to condense onto its surface within the next ~10 years (possibly within the next few years) and thus frequent observations are critical. Detection of the occultation central flash will allow measurement of the structure of Pluto’s lower atmosphere and atmospheric oblateness. We will use FLIPO to measure the refracted starlight simultaneously at visible and infrared wavelengths; this approach differentiates between two competing explanations for the deficiency in the observed light refracted from Pluto’s lower atmosphere (strong thermal gradients versus variable particulate extinction). Only an airborne platform such as SOFIA has the ability to place a large telescope in the center of the shadow path of these brief events while at the same time nearly eliminating the possibility of missing these time-critical observations due to unfortunate weather systems. Occultation predictions will be updated throughout the period preceding the observations with the goal of achieving sufficient prediction accuracy to place SOFIA directly in Pluto’s central flash. The timing of these events closely coincides with the New Horizons spacecraft’s closest approach to the Pluto system (July 2015), giving us a singular opportunity to tie encounter spacecraft measurements to the continuing Earth-based observing program whose goal is to measure the temporal variability of Pluto’s atmosphere in response to its changing seasonal obliquity (and resulting ice migration) and recession from the sun. Placing the instantaneous information obtained from the New Horizons encounter in the context of the long-term evolution of Pluto’s atmosphere is a key necessary step towards answering these questions.
Proposal ID: 03_0030
Principal Investigator: Glenn Orton (Jet Propulsion Laboratory)
Title: 17- to 37-micron Photometry and Spectroscopy of Uranus and Neptune
Abstract: We propose photometric and spectroscopic observations of Uranus and Neptune from 17 to 37 microns using the FORCAST instrument. This spectral region includes wavelengths for which there have been no spectroscopic observations, and the combined capabilities of SOFIA and FORCAST are ideally suited to make these observations. The anticipated observations will advance out knowledge of the radiative and convective processes shape the atmospheric dynamics of these two ice giants. They will also determine the extent of para vs. ortho H2 disequilibrium in the upper tropospheres of both planets and improve constraints on the He/H2 ratio. The latter is a crucial value required to eludicate differences in formation mechanisms that distinguish them from the gas giants, Jupiter and Saturn. The proposed observations are also vital for ongoing efforts to develop models for the spectra of both planets as key components of an absolute calibration system used by Herschel spacecraft instruments and other long-wavelength Earth-based observations.
Proposal ID: 03_0032
Principal Investigator: Els Peeters (SETI Institute)
Title: Aromatics versus aliphatics: revealing the structure of carbonaceous dust.
Abstract: The mid-IR spectra of almost all objects are dominated by strong emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 micron due to Polycyclic Aromatic Hydrocarbon molecules (PAHs). It is now well established that these mid-IR bands show clear variations in shape and peak position from one point source to another, as well as varying spatially within extended sources. The spectral diversity of the PAH band profiles reveals the nature of the carriers and hence allows one to study their formation and evolution throughout their life cycle. Although the origin of the profile variations is still under debate, the observations point towards a varying importance of aliphatics versus aromatics in the carrier molecules. We propose to obtain FLITECAM observations of sources showing extreme red B or C profiles and FORCAST observations of a source with an unusually strong 3.4 micron aliphatic band. Combined with previous results, the proposed observations are particularly suited to systematically investigate the connection between the PAH band profiles and the aliphatic emission bands at 3.4, 6.85 and 7.2 microns. These results will paint a necessary picture of the aromatic and aliphatic characteristics of the carbonaceous material and hence provide important clues on the origin of the PAH band profile variations.
Proposal ID: 03_0035
Principal Investigator: Thierry Fouchet (Observatoire de Paris)
Title: Searching for methyl in Jupiter
Abstract: Methane photochemistry in the atmosphere of Jupiter leads to the formation of heavier hydrocarbons and eventually stratospheric hazes. Hydrocarbon photochemistry is initiated by the photodissociation of methane at the homopause level, leading to the production of CH, CH2, and CH3 radicals. The methyl (CH3) radical plays a key role in the jovian photochemistry as its recombination leads to the production of the most abundant and stable heavy hydrocarbon, ethane (C2H6). Currently, the methyl radical has not been detected on Jupiter, leaving the ethane production rate unconstrained. Our aim is to detect for the first time the methyl radical with EXES, the Echelon- Cross-Echelle Spectrometer, on board SOFIA by searching for thermal emission within the Q-branch of CH3 ?2 band at 606 cm?1. The anticipated detection will yield the column abundance for this species. This quantity will directly constrain the production rates of ethane and will bring new, strong constraints to increase the reliability and accuracy of photochemical models.
Proposal ID: 03_0037
Principal Investigator: Mark Swain (Jet Propulsion Laboratory)
Title: The Origin of non-LTE Emission on Dayside of a hot-Jupiter Exoplanet
Abstract: Powerfully irradiated, short-period exoplanets can experience a combination of insolation and wind from the stellar primary that provides an environment unlike anything experienced by planets in our own solar system. These extreme environments provide a laboratory for testing our understanding of planetary atmospheres. The report from ground-based observations of strong 3.2 micron emission in the hot-Jupiter HD 189733b, attributed to methane undergoing a non-LTE (Local Thermodynamic Equilibrium) process, has generated considerable discussion. Although, non-LTE emission, including methane fluorescence is observed in our own solar system, the strength of the emission in HD 189733b was surprising. The original result has been both challenged and confirmed using ground-based observations that are all potentially subject to contamination by the absorption and variations arising in the troposphere and planetary boundary layer. Theoretical work consistent with the observations suggests that non-LTE emission may originate from high J number hot combination bands, however, improved measurements are needed to confirm this. Because the SOFIA observatory operates above the most significantly variable portion of the Earth’s atmosphere, SOFIA/FLITECAM offers a unique opportunity to decisively confirm and probe the physical origin of the strong emission around 3.2 micron. The calibrated observational stability offered by SOFIA (our team has considerable experience correcting for pointing errors and other instrument systematics), in combination with observations of the ingress and egress events, will allow the construction of a two-dimensional spectral images of the day side of HD 189733b and enable the comparison of the spatial distribution of the strong line emission to the continuum.
Proposal ID: 03_0038
Principal Investigator: Glenn Orton (Jet Propulsion Laboratory)
Title: Jupiter’s Stratospheric HCN, Hydrocarbon and Temperature Fields
Abstract: We propose to determine the stratospheric abundance of HCN in Jupiter that originated from shock-chemistry resulting from the 1994 Comet Shoemaker-Levy 9 fragment impacts, observing it as a function of latitude and using it as a tracer to understand the long-term effects of stratospheric circulation. We will also determine the latitudinal distribution of stratospheric CH3 and C2H2 abundances to test theories of photochemisty, as well as circulation. We will determine the vertical distribution of temperatures from 100 mbar to 0.01 mbar as a function of latitude. The observations will be made in two spectral settings, one centered near 712 cm-1 for HCN, CH3 and C2H2, and another at 1306 cm-1 that uses CH4 emission to determine temperatures. All lines except C2H2 are impossible or extremely difficult to access from ground-based observatories.
Proposal ID: 03_0039
Principal Investigator: Andrew Harris (University of Maryland)
Title: Understanding the excitation of NGC253’s starburst molecular gas
Abstract: We propose observations of the [C II] and CO J = 11-10 lines in NGC253’s nucleus to understand the excitation of molecular gas in regions of very active star formation. The [C II] spectroscopy will establish what fraction of the ionized gas is associated with CO in PDRs and will explore to what extent the striking and unusual difference in Hershel-HIFI CO and [C II] lineshapes is due to astrophysics or instrumental effects. The CO line yields a clean spectrum of the highest-excitation molecular gas. We will compare it with with mid- and some high-J data from the APEX telescope and Herschel-HEXGAL programs. Comparison with PDR and shock models will establish the importance of UV, cosmic rays, and shocks in heating molecular gas in starburst nuclei. These results are an expansion of the Herschel-HEXGAL program. Lineshape and velocity information are essential to identify and separate different physical structures, even at sub-beam scales; only GREAT on SOFIA can provide these data.
Proposal ID: 03_0041
Principal Investigator: Imke de Pater (University of California - Berkeley)
Title: Jupiter’s Tropospheric Dynamics from SOFIA Mapping of Temperature, Para-Hydrogen, and Aerosols
Abstract: We request time with FORCAST to observe Jupiter at mid-infrared wavelengths using 17-37 micron spectroscopy of the collisionally-induced H2-He continuum to derive the zonal mean tropospheric temperatures and para-H2 distribution. In addition, we request imaging in discrete filters between 5 and 37 micron to provide spatial context for the spectroscopy. This combination of imaging and spectroscopy will allow us to relate the distribution of aerosols to the rate of upwelling from the deeper troposphere, and will provide the first maps of para-H2 since the Voyager era.
Proposal ID: 03_0042
Principal Investigator: Klaus Huber (Hamburger Sternwarte, Universitat Hamburg)
Title: Do starspots inflate the exoplanet CoRoT-2b?
Abstract: We propose to use SOFIA’s combination of HIPO and FLITECAM to obtain simultaneous optical and infrared transit photometry of the CoRoT-2 system. This system consists of the highly active planet host-star CoRoT-2A and the unusually inflated hot Jupiter CoRoT-2b. CoRoT-2A’s surface is densely covered with starspots, which influence the transit lightcurves and, thus, complicate the determination of accurate planetary parameters. In particular, this can lead to an overestimation of the planetary radius, which could, at least partially, account for the unusually large radius inferred for CoRoT-2b. Using SOFIA, the weaker starspot contrast at longer wavelengths will allow us to derive an accurate planetary radius from infrared photometry and, thereby, pin down CoRoT-2b’s radius anomaly. Because of SOFIA’s unique capability to simultaneously obtain optical photometry, we will also be able to determine starspot temperatures and estimate the total spot-coverage of CoRoT-2A’s surface by comparing the deformation and depth of the infrared and visual-band transit lightcurves. Only SOFIA’s combination of HIPO and FLITECAM provides the quasi space-based high-precision multi-band photometry required to address these open questions on the young planetary system CoRoT-2.
Proposal ID: 03_0043
Principal Investigator: Leslie Looney (University of Illinois at Urbana - Champaign)
Title: Warm Gas and Shocks in the Filaments and Central Hub of Serpens South
Abstract: Serpens South, a young (~10^5 years) star forming region, has become an important cloud to study since its discovery 8 years ago. Serpens South has pronounced filamentary structure and a central hub with high protostellar content that allows the study of evolution within a star formation region before significant gas dispersal can occur. We propose to observe [CII] and [OI] (63 micron) toward the southern filaments and central hub of Serpens South (56 square arcminutes in total). These observations will trace the warm gas morphology (compared to the dense gas and the dust emission), estimate the bulk gas mass around the filament and hub region, test the formation mechanism for the hub, measure the feedback from the outflows in the region, and evaluate the UV radiation components.
Proposal ID: 03_0044
Principal Investigator: Leslie Looney (University of Illinois)
Title: Mapping the OMC1 Outflow in Mid-J CO Lines
Abstract: The Orion BN/KL region harbors the closest high-mass protostars, allowing a study of massive protostellar formation. However, there is growing evidence that these protostars have been through a violent interaction process, which may be a common occurrence in high-mass star-forming regions. This “explosion” is evident from 1) the 15 solar mass protostar BN and the 20 solar mass protobinary Source I moving in opposite directions and 2) the wide-angled outflow, OMC1. To better understand massive star formation, a deeper understanding of this environment is important. We propose to observe the OMC1 outflow using eight mid-J CO transition lines to characterize the morphology and the physical conditions of the outflow and its interaction with the photodissociation region (PDR). With the eight transition lines and radiative transfer models, we will correlate the CO lines with the PDR tracers and the “fingers” measured in H2 lines, which arise from the explosion that is thought to have powered the OMC1 outflow ~500 years ago.
Proposal ID: 03_0049
Principal Investigator: Terry Jones (University of Minnesota - Twin Cities)
Title: Massive Star Formation in the Large Magellanic Cloud
Abstract: We propose to take an infrared census of extremely young, luminous stars in two HII region complexes (N159 and N160) in the Large Magellanic Cloud (LMC). Imaging with FORCAST from 25 to 37 microns will allow us to distinguish cooler sources that shine brightly at Mid- to Far-IR wavelengths, but are less conspicuous (or absent) in the shorter wavelength Spitzer IRAC imaging. By imaging with FORCAST, we can take a census of luminous stars in all possible stages of early, massive star evolution for one region that has been forming stars for at most 2 million years (N159), and probably less. We can use the results of this census to draw comparisons between the two complexes and with regions of massive star formation in the Milky Way.
Proposal ID: 03_0051
Principal Investigator: Alexander Tielens (Universiteit Leiden)
Title: The characteristics and evolution of dense knots in the Supernova Remnant, Cas A
Abstract: Supernovae are key drivers of the evolution of the interstellar medium of galaxies as they are main sources of freshly synthesized elements, dust and kinetic energy. Dense Fast Moving Knots (FMKs) are an important component of supernova remnants as they may be prime sites for dust formation and their high densities protect this dust against the destructive action of the reverse shock. Herschel, Spitzer, Akari, and ground-based IR studies of dense clumps in the Cas A supernova remnant have revealed large column densities (4E19 per square cm) of warm (500-1000K) dense (1E5 to 1E6 particles per cc) CO gas. This dense environment is very conducive to dust formation and protection. However, the relationship of the molecular and ionic gas is unclear and the derived large column densities are much larger than shock models predict, indicating the importance of energy conduction by electrons from the surrounding hot plasma into the knot. Conduction is a key process in the evolution of knots and drives the overall morphology of supernova remnants and their interaction with the interstellar medium. We propose to observe three CO-rich knots in the [OIII] 52&88 and [OI] 63 fine-structure lines with FIFI-LS/SOFIA. We will compare the distribution of these atomic lines with that of CO and derive the physical conditions and column densities. A pilot program in Cycle 2 has demonstrated the feasibility of this project. The proposed observations will address the key questions: “Can FMKs protect dust ?”, “Are the observed variations in the mid-IR CO emission related to variations in the pre-shock density, column density, or the presence of additional heating sources for the gas?”, and “What is the importance of electron energy conduction for the heating of the gas and how do these knots dissolve and merge with the SNR/ISM?”
Proposal ID: 03_0052
Principal Investigator: Daniel Angerhausen (Rensselaer Polytechnic Institute)
Title: Observation of the primary transit of GJ 3470b: Warm Uranus transmission spectrophotometry with FLIPO
Abstract: GJ 3470b is one of the first known Uranus sized exoplanets. It occupies the transition regime between Super-earths and Jupiters. Previous observation of the handful of exo-Urani indicated cloudy/hazy atmospheres, making it difficult to probe their atmospheres in depth. Some of the species that we expect to find in their atmospheres (i.e. water, carbon dioxide, methane) are inaccessible from the ground because of the absorption by their counterparts in the Earth’s atmosphere. We propose here to address the state-of-the-art scientific question about the nature of exo-atmospheres, taking advantage of the unique capability of SOFIA to provide quasi space-based photometry, which the proposers were able to demonstrate with SOFIA cycle 1 and 2 observations: we will probe the atmosphere of GJ 3470b measuring the planet’s radii during one transit, in three optical and in one infrared channels with HIPO and FLITECAM (in the FLIPO configuration with one additional channel from the FPI+) on SOFIA. These observations will allow us to understand the overall structure and the chemical composition of GJ 3470b’s atmosphere.
Proposal ID: 03_0054
Principal Investigator: Rolf Guesten (Max-Planck-Institut fur Radioastronomie Bonn)
Title: Atomic Oxygen in protoplanetary disks
Abstract: We request observing time to study the [OI] and [CII] fine-structure line emission towards a selection of prominent proto-planetary disks with GREAT(L2,H). These high-resolution heterodyne receivers onboard of SOFIA provide the unique opportunity now to perform velocity-resolved spectroscopy of the [OI] 63 Î¼m line that has been shown by Herschel/PACS to be the by far strongest line in protoplanetary disks (and often the only one detected). Analysis of the velocity profiles will allow discriminating between contributions from the disk (and by comparison with the Keplerian velocity field, where in the disk the oxygen originates) and â€“ if present - from associated compact outflows (all unresolved in the PACS spectra). The demanding [OI] excitation conditions and comparison with the ionized carbon line [CII], to be observed in parallel, will allow constraining the physical conditions in the inner disks. At least for HD100546, the 5.6 arcsec resolution of GREAT will partially resolve the disk (8 arcsec), enabling a more detailed analysis of the velocity field and hence the excitation conditions across the disk.
Proposal ID: 03_0057
Principal Investigator: Christopher Tibbs (California Institute of Technology)
Title: Exploring the role of CII in current Spinning Dust Models
Abstract: We propose GREAT observations of the [CII] fine structure line at 158 micron (1.9THz) in 3 strips across the HII region RCW175. The currently favoured explanation for the observed anomalous microwave emission is that of electric dipole radiation from rapidly rotating small dust grains (PAHs and/or VSGs), commonly referred to as spinning dust. Although this hypothesis predicts that the source of the excess emission is due to dust, the small dust grains are sensitive to the ionization state of the gas, and hence the spinning dust models have a dependency on the abundance of the major gas ions. CII observations will enable us to investigate this dependency, and combining these observations with the available mid- to far-IR observations will permit a complete analysis of the role of both the dust and gas in regions of anomalous emission. We request a total of 2.3 hrs of GREAT observing time.
Proposal ID: 03_0058
Principal Investigator: Tracey Hill (Joint ALMA Observatory)
Title: Characterising young high-mass stars in Cygnus X using SOFIA.
Abstract: Cygnus X is a well known active star-forming region. Within this region, the DR21 and DR21(OH) regions are particularly enticing sites of high-mass star formation. The proximity of Cygnus X (1.4kpc) offers the unique opportunity to resolve intermediate/high mass protostars. We propose to image two regions within Cygnus X -- the DR21 & DR21(OH) region as well as the mlillimetre-identified Cyg-N3 region -- with the FORCAST continuum camera at four mid-infrared wavebands (19.7, 25.3, 31.5, and 34.8um). This SOFIA program is vitally needed to better understand the formation of massive OB-type stars. The 31.5 and 34.8 micron observations are particularly crucial as they complete our wavelength coverage of these sources, bridging the gap between Herschel at 70 micron and Spitzer at 24 micron, at better resolution than Spitzer, and comparable resolutions to Herschel. The 19.7um observations further provide the shortest wavelength data for SED fitting, whilst the 25.3 micron SOFIA observations provide the opportunity to image sources saturated in the Spitzer MIPS images. These SOFIA data will capitalise on our existing data fom 1/3mm (PdBI) and Herschel (500,350,250,160,70 micron), as well as Spitzer 24 micron for weaker sources in the field, and facilitate spectral energy distribution (SED) modelling. From tightly constrained SED models, we can obtain a far better constraint on key parameters such as the bolometric luminosity, temperature and envelope mass, from which we can estimate the evolutionary status of the cores.
Proposal ID: 03_0059
Principal Investigator: Matthew Hayes (Stockholm University)
Title: Far Infrared Spectroscopy of the Nearby Analogues of High-Redshift Galaxies
Abstract: We propose far infrared emission line spectroscopy of a sample of 23 local star-forming galaxies, drawn from the Lyman alpha Reference Sample (LARS), for which we have unrivalled high-resolution imaging and spectroscopy from HST, and 21cm HI observations from VLA+GMRT. Moreover the galaxies are selected as the close analogues of the high-redshift Lyman-break galaxies and Spitzer+Herschel selected galaxies found in extragalactic deep fields. The science goal of LARS is to determine what governs the escape of Lyman alpha (Lya) photons from galaxies, and thereby aid interpretation of high-z observations where Lya is the most used spectral probe. However given its clean selection and multiwavelength nature, LARS can equally well improve our understanding of FIR line observations of high-z galaxies. The target emission lines in this proposal are [CII], [OI], and [OIII] at 158, 63, and 88 micron, respectively. The motivations are that these lines: 1. are of increasing interest at high-z as new sensitive submm/radio interferometers come online 2. are proposed quantitative tracers of star formation rates, but their utility must be proven in appropriately analogous well-studied galaxies 3. when combined with models of photodissociation regions, enable estimates of the density and mass of PDR gas and provide vital constraints on our Lya radiative transfer models of galaxies. 4. provide uniquely robust estimates of nebular extinction and metallicity when combined with our optical IFU data. Astrophysical applications are many, especially when combined with the array of existing data. Specifically they will provide vital constraints on ISM structure, that are required for understanding the emission of the cosmologically vital Lya emission line. Moreover, SFR calibrations will be tested in star forming environments that resemble those of early galaxies and the legacy value of the sample is hard to overstate.
Proposal ID: 03_0062
Principal Investigator: Bruce McCollum (Catholic University of America)
Title: Exploring Emission Features of the First Known Stellar Merger
Abstract: There has been much theoretical work regarding the predicted effects of stellar mergers on clusters, galaxies, and binary star evolution, but until recently there has not been a single definite example of a merger to study. The 2008 nova of V1309 Sco was shown in 2011 to be an eclipsing binary that merged to produce the 2008 outburst. We obtained multichannel FORCAST imaging in 2014 revealing a strong mid-IR flux. Flux measurements from this imaging showed that the SED peaks somewhere in the FORCAST wavelength range. There is reason to expect a feature-rich IR emission spectrum, the lines of which will offer information of fundamental value to our understanding of recent merger remnants. We propose to obtain FORCAST spectra of V1309 Sco. These will be the first spectra of any merger remnant in the FORCAST bandpass range. The spectra will enable the first reliable dust modeling of the SED by pinpointing the SED peak and allowing accurate continuum measurements without strong emission-line contamination. Spectra across the FORCAST range may also help to identify future merger candidates from among other novae.
Proposal ID: 03_0064
Principal Investigator: Jean Chiar (SETI Institute)
Title: The Evolution of Preplanetary Matter: FORCAST Grism Spectroscopy of Ices from 5 to 8 microns
Abstract: The 5 - 8 micron spectral region, which is inaccessible to ground-based telescopes, is important to astrochemistry because it is rich in solid-state molecular absorption features arising in interstellar or circumstellar ices. These features provide a means of evaluating abundances for carriers that include organic species such as methane, formaldehyde and formic acid; moreover, some features are diagnostic of thermal or energetic processing of the ices, and hence provide insight into the evolution of preplanetary volatiles in regions of active star formation. However, data obtained on space platforms to date lack either the required sensitivity and spatial resolution (ISO SWS) or the required spectral resolution (Spitzer IRS) to fully isolate and characterize the absorption profiles over the range of relevant environments. We propose to use the FORCAST grism in cross-dispersion mode to yield spectra with resolving powers an order of magnitude higher than was possible with the Spitzer IRS at these wavelengths. Targets are selected to cover environments ranging from a prestellar core to the vicinities of low, intermediate and high-mass young stellar objects (YSOs). An important advantage of this gain in spectral resolution is the ability to ensure precise separation of solid-state and gas-phase features, crucial for YSOs with circumstellar gas-phase lines. The resulting spectra will allow us to reliably separate blended features and characterize structure in the underlying solid-state profiles with reference to data for laboratory analogs. The observations will provide new insight into the nature of the absorbers in this important spectral region and enhance our understanding of how the ices that form at low temperature in molecular clouds evolve in proximity to YSOs. This proposal was awarded 6.5 hours of time in Cycle 1 (panel evaluation 4.9/5.0) but partial observations of only 2 targets (out of 5) have been completed to date.
Proposal ID: 03_0065
Principal Investigator: Naseem Rangwala (University of Colorado at Boulder)
Title: Characterizing Warm Molecular Hydrogen in Active Star-Forming Systems
Abstract: Herschel observations of nearby star-forming galaxies have determined that the warm component of the molecular gas traced by the high-J CO lines dominates the luminosity (~90% of the total CO luminosity) and hence the energetics of the molecular ISM. At the temperatures (T = 300 - 2000 K) and densities (n_H < 1E6 per cubic cm) typically found in our survey, H2 emission is the dominant gas coolant, much more important than CO. A fundamental assumption of all analyses of CO emission has been that CO emission traces H2 over the entire range of physical conditions in the observed sources. However, a direct observational comparison of spatial distributions and kinematics of CO and H2 has never been made for the warm molecular gas. We propose to observe the warm H2, in S(1) and S(2) transitions, with the SOFIA-EXES instrument in a diverse sample of star-forming systems: NGC 253 (starburst nucleus), NGC 6240 (luminous infrared galaxy), NGC 1068 (Seyfert-2), and SgrB2(M)/(N) (Galactic hot cores). The primary goal is to compare these measurements with the warm CO (J = 6-5 transition) observed with the Atacama Large Millimeter Array (ALMA) to investigate differences in the kinematics and spatial distributions (for the extended targets) of the two molecules and thereby confirm whether CO is a reliable tracer of H2 in the warm gas.
Proposal ID: 03_0066
Principal Investigator: S. Megeath (University of Toledo)
Title: Characterizing the Energetics of the Youngest Protostars: FIFI-LS Spectroscopy of Herschel-Identified Extreme Class 0 objects in Orion
Abstract: We propose FIFI-LS spectroscopy observations toward 3 of the youngest known Herschel- detected Class 0 protostars in the Orion molecular clouds. Characterization of the far-IR spectrum toward these PACS Bright Red Sources (PBRS) is imperative: this is the only observational means to characterize the complete energetics of the outflow in the earliest stages of the star formation process. We have already obtained Herschel-PACS spectroscopy for 8/14 PBRS; for these, the CO rotation temperatures are systematically lower than the larger samples of ‘more typical’ protostars observed. Furthermore, all of the Herschel-detected PBRS also have CARMA CO (J=1-0) outflow maps, enabling us to identify tentative trends between the detection and morphology (compact or extended) of the CO outflow and the presence or lack of far-infrared emission lines. Moreover, we only convincingly detect [OI] emission toward the source with the brightest outflow emission; thus, [OI] may not be universally present in protostellar outflows. However, due to the small-numbers with PACS spectroscopy, it is unclear if these trends are real and the three proposed PBRS have outflow maps of varying morphologies, but no far-infrared spectra. The results from this program will provide a firm observational footing for the presence or lack of such trends and will strengthen the connection of the far-IR emission lines to the outflow.
Proposal ID: 03_0067
Principal Investigator: Miwa Goto (Universitats-Sternwarte Munchen)
Title: The Deuteration Ladder of H3+
Abstract: We propose to use SOFIA/EXES to search for the strongest absorption line of D3+ (triply deuterated H3+) at 5.296 um. Deuteration of H3+ begins with the reaction H3+ + HD -> H2D+ + H2 which is exothermic by 220 K (therefore, the backward reaction is slow in the cold ISM) and continues with similar exothermic reactions between deuterated product and HD until D3+ is produced. The efficiency of the initial reaction appears to be the key to making many deuterated molecules observed in the ISM detectable, despite the low abundance ratio D/H~1.5e-5, but has recently been brought into question by laboratory results suggesting much lower efficiency. If correct this would be a serious challenge to our understanding of the deuterium fractionation in the ISM. Experimental data from the ISM are critically missing, as (for technical and astronomical reasons) there are no sightlines on which H3+ and its isotopomers (H2D+, D2H+, and D3+) have been observed simultaneously. D3+, as the endpoint of the deuteration ladder, could be the most abundant isotopomer of H3+, including H3+ itself, when the physical conditions are met. We would measure D3+/H3+ ratio, or its upper limit, on several sightlines in order to quantitatively understand the deuteration process in the ISM. Our results from SOFIA/EXES will be combined with the ground-base observation of H2D+ on the same sightlines and already scheduled for later this year.
Proposal ID: 03_0072
Principal Investigator: Jean Chiar (SETI Institute)
Title: FLASH: FLITECAM Limits on the Abundance of Silicate Hydrates in the ISM
Abstract: The Science Vision for SOFIA identifies the Interstellar Medium (ISM) as a key area where SOFIA is well poised to make substantial contributions. As the SOFIA Vision points out, dust undergoes constant recycling in the ISM, from its creation in stellar outflows to its incorporation into protoplanetary disks. The observations we propose here will enable us to better understand the evolution of the silicate dust component, specifically the processing it undergoes in the ISM. The structure of the silicate, i.e., whether it is crystalline or amorphous, is a clue to its past evolution. In order to explain the extremely low abundance of crystalline silicates in the diffuse ISM, the process that amorphizes the stardust silicates must be efficient. Experiments show that one of the most efficient processes likely to occur in the diffuse ISM is irradiation by low-energy ions. This process will not only amorphize the grains, but also lead to formation of OH bonds within the grains. Just how much the grains are hydrated can be carefully measured by the SOFIA FLITECAM observations we propose here. To this end, we propose to use FLITECAM Grisms A and C to observe the OH stretching mode in hydrated silicates in the 2.216 to 3.467 micron region. Our targets are three bright highly reddened field stars that probe diffuse ISM dust. These observations are impossible from ground-based facilities due to telluric CO2 absorption, and existing spectra are only moderately reddened and/or of poor quality. The high S/N FLITECAM spectra will enable us to make a careful measurement of the actual hydration level of silicates, thus leading to a better understanding of the processes that affect silicates in the ISM.
Proposal ID: 03_0073
Principal Investigator: Jochen Eisloeffel (Thuringer Landessternwarte - Karl-Schwarzschild-Observatorium Ta)
Title: Probing the hidden atomic gas in Class I jets
Abstract: We propose to obtain FIFI-LS spectroscopic maps of three collimated bipolar outflows driven by Class I protostars in the 63mum and 145mum transitions of [OI]. These maps will enable us to to study the extent of warm low excitation atomic gas in these flows, to derive the mass flux rate in the atomic jet, measure the ionisation fraction of the gas to get more insight into its excitation mechanism, and measure the accretion/ejection ratio of matter in Class I sources. Surprisingly, with PACS on HERSCHEL such mapping observations were obtained only for the younger, deeply embedded Class 0 sources and for the older Class II sources that are already visible in the optical. The proposed observations will help to bridge the existing gap of knowledge between Class 0 and Class II sources after HERSCHEL, and will thus allow us evolutionary studies of the derived flow characteristics.
Proposal ID: 03_0078
Principal Investigator: Sarah Ragan (Max-Planck-Institut fur Astronomie, Heidelberg)
Title: Does oxygen outshine carbon in the CMZ?
Abstract: The Central Molecular Zone (CMZ) of the Milky Way contains a huge reservoir of molecular gas, and yet its star formation efficiency appears to be significantly lower than expected from standard star formation relations. This suggests that additional physics must be considered order to understand the regulation of star formation in the CMZ. We propose GREAT observations of the [OI] and [CII] transitions toward two compact clouds residing in the so-called 100 pc ring surrounding the Galactic Centre. These lines are predicted to be the primary coolants of molecular clouds in this harsh environment. Measuring the strength of the [CII] and [OI] line emission produced by the clouds will therefore allow us to constrain their total cooling rate, while the [OI]/[CII] line ratio and the ratio of both lines relative to the measured FIR emission will allow us to constrain the density and temperature of the clouds, and hence the intensity of the cosmic ray ionization rate in their vicinity. We can test models that predict that the CMZ is a unique environment in which oxygen dominates carbon as a coolant. The superb velocity resolution provided by GREAT will also allow us for the first time to study the kinematics of the warm gas in the clouds, which we expect to fill much of their volume. Finally, by comparing clouds at different locations within the 100 pc ring, we will be able to study whether the age of the clouds increases as we move away from Sgr A*, allowing us to test the idea that the formation of the clouds may have been triggered by the tidal influence of the Milky Way’s central black hole and nuclear star cluster. These ground-breaking observations are only possible with SOFIA and offer several different pathways to high-impact science.
Proposal ID: 03_0080
Principal Investigator: Karl Menten (MPIfR)
Title: Solving the Mystery of Class II CH3OH maser excitation
Abstract: Methanol (CH3OH) is the molecule with the largest number of known interstellar maser transitions. Soon after their discovery, it was realized that CH3OH masers come in two varieties, named Class I and Class II. Class I masers are found in outflows, significantly offset (>>1000 AU) from the driving source, and they are produced by collisions. On the contrary, Class II arise in the immediate vicinity (<1000 AU) of massive young stellar objects (YSOs) and are thought to be pumped by the intense far-IR radiation field of warm dust close to the protostars. Class II masers are a fundamental astrophysical tool in a broad range of applications, from accurate measurements of parallax distances throughout our Galaxy to detailed measurements of the 3D kinematics around massive YSOs. Most importantly, the masers pinpoint the exact locations of deeply embedded massive YSOs. However, the origin of the pumping mechanism behind their population inversion is still controversial and our current understanding is based only on radiative transfer models which rely on inaccurate molecular coefficients. Here we propose to directly observe the upward links (at 22.184 and 22.752 micron for the 12.2 GHz maser) that connect Class II maser levels (in the torsional ground state) with levels in the torsionally excited states, whose re-decay causes the inversion with the goal of confirming that the proposed pumping mechanism can work. This project has just now become feasible with the excellent spectral resolution that EXES will provide aboard SOFIA.
Proposal ID: 03_0082
Principal Investigator: Roberta Humphreys (University of Minnesota - Twin Cities)
Title: Cool Dust and the Mass Loss Histories of the Hypergiants
Abstract: A few highly unstable, very massive, evolved stars lie on or near the empirical upper luminosity boundary in the HR diagram. They represent a short-lived evolutionary stage, characterized by high mass loss and eruptive events. Many of them are strong infrared sources and powerful OH masers. Space and groundbased visual and near-IR imaging has revealed evidence for asymmetric ejections and multiple high mass loss events in the circumstellar ejecta of VY CMa and IRC+10420, for example. In this proposal, we turn our attention to the cool dust which may or may not be spatially coincide with the visual ejecta. It may have formed due to the recent mass loss episodes or be a fossil record of earlier mass loss. Measuring the cold dust will provide a more complete estimate of the total mass lost and the mass loss histories of these evolved stars. We propose long wavelength imaging from 11 to 37 microns with FORCAST of four cool hypergiants. For the peculiar warm hypergiant HR 5171A, the proposed imaging and spectroscopy will provide seriously missing information on the role of dust fornation and circumstellar extinction on its peculiar variability. The total telescope time requested is 6.4 hours.
Proposal ID: 03_0083
Principal Investigator: Stephan Schlemmer (I. Physikalisches Institut der Universitaet Koeln)
Title: Observing ortho-D2H+ absorption towards IRAS 16293-2422 A/B
Abstract: Following up on our successful observation of para-H2D+ with SOFIA/GREAT (Proposal 01_0184, Bruenken et al. 2014, submitted to Nature), we propose to observe for the first time the ground-state rotational line of ortho-D2H+ at 1.477 THz. The line is predicted to be detectable in absorption towards the bright Class 0 protostellar system IRAS 16293-2422 A/B embedded in the dark cloud L1689N in Ophiuchus. IRAS 16293-2422, consisting of a strong far-infrared source surrounded by a massive cool envelope, is an excellent target for this first detection attempt. We have recently detected the rotational ground-state transition of para-H2D+ in absorption at 1.37 THz in this source with SOFIA/GREAT, and the ortho-H2D+ line at 372 GHz with APEX/FLASH, allowing the ?rst determination of the ortho-to-para ratio of H2D+ in interstellar space. In combination with extensive chemistry and radiative transfer calculations we were able to derive the closely related ortho-to-para ratio of H2 in the cold envelope, which puts distinct limits on the age of the molecular cloud. Our radiative transfer calculations reproduce the observed para-H2D+ line and predict an absorption signal of around 300 mK for the ortho-line of D2H+, the next member in the deuterium exchange reaction network starting from H3+ and HD. Even with SOFIA/GREAT the proposed project is challenging and needs deep integration, but it also now renders possible the first detection of ortho-D2H+. This observation will give an estimate or put strong constraints to the abundance and ortho-to-para ratio of D2H+ in the envelope, allowing us to further re?ne our understanding of the deuterium chemistry and chemical evolution time scales.
Proposal ID: 03_0084
Principal Investigator: Andrew Rivkin (The Johns Hopkins University Applied Physics Laboratory)
Title: Characterization of OH and H2O in Asteroids
Abstract: Decades of observations have demonstrated that OH-bearing minerals exist on some asteroids, and recent work has begun to differentiate between and interpret differing band shapes in the 3-micron spectral region. However, this work is hampered by the inability to detect the OH band center and band depths near 2.7 microns from the ground, critical for determining the minerals present. Furthermore, observations of OH on the lunar surface, believed created by solar wind interactions with lunar regolith, add an additional twist to interpretations of the asteroidal spectra. We propose observations of several bright asteroids, some known to have OH-bearing minerals and some for which none are detected from the ground, in order to achieve the goals of better understanding the distribution of OH on the asteroids, and the origin of that OH.
Proposal ID: 03_0085
Principal Investigator: Sümeyye Suri (I. Physikalisches Institut der Universitat Koeln)
Title: [CII] and [OI] observations towards selected filaments in the Orion A Molecular Cloud
Abstract: We propose a pilot study to observe [CII] and [OI] towards 6 selected filaments in the Orion A molecular cloud. The goal of the proposed observations is to utilize these major cooling lines of the ISM in order to study the kinematics of the ambient diffuse gas surrounding the selected filaments, and the properties of the mass flow onto them. We will complement the diffuse gas observations with that of the dense gas (13CO, C18O, CS) obtained within the CARMA Orion Key Project, which is aimed at observing 1 square degree region of Orion A with an angular resolution of 6 arcsec (0.001 pc). With a spectral resolution of 0.5 km/s we will be able to disentangle the line profiles of the atomic lines obtained with SOFIA from that of the molecular gas and, hence, study the kinematic relation between the dense and the diffuse components of the gas. Furthermore, the [CII]/[OI] ratio will provide a measure of the density/UV field strength. Since it is the first time such objects will be studied in [CII] and [OI] in the region, the proposed SOFIA observations will reveal the importance of both [CII] and [OI] lines in studying such kind of filaments.
Proposal ID: 03_0086
Principal Investigator: Diane Cormier (Universitat Heidelberg)
Title: Disentangling the ISM phases of the nearby low-metallicity dwarf galaxy NGC4214 using velocity-resolved [CII]
Abstract: We propose to observe the far-infrared (FIR) fine structure line [CII] at 1.9 THz with the instrument GREAT onboard the SOFIA observatory in the nearby irregular dwarf galaxy NGC4214. The goal of this proposal is to unveil the dynamical structure of the [CII]-emitting ISM, and most importantly of the photo-dissociation regions (PDR), in three star-forming regions that exhibit different levels of activity. In combination with high-resolution CO and HI data, that our team has already acquired, this will allow us to characterize the physical properties of these regions, determine the origin of the [CII] emission, dissect the molecular cloud structures, and answer key questions of star formation at low metallicity.
Proposal ID: 03_0087
Principal Investigator: Diane Cormier (Institut fur Theoretische Astrophysik, Heidelberg)
Title: Deciphering Star Formation in Disk Galaxies: Relating ISM conditions to the Molecular Gas Fraction in NGC5055
Abstract: There is a regime in the interstellar medium (ISM) of disk galaxies where the gas, primarily atomic, becomes mostly molecular. This phase transition, which occurs at a typical radius in the disk, is at the basis of the formation of molecular clouds and growth of the disk. However, an important question remains: What are the actual ISM physical conditions where that phase transition occurs? To address this question, we propose to map the [CII] 157mu line with FIFI-LS around the phase transition in the prototypical spiral galaxy NGC5055. Combined with our rich ancillary dataset, the SOFIA observations will unveil, for the first time, the physical state of the gas (densities, temperatures) in the photodissociation regions, which are the key link between the HI and CO gas.
Proposal ID: 03_0088
Principal Investigator: Claudia Comito (I. Physikalisches Institut der Universitaet Koeln)
Title: Atomic oxygen across the Galaxy
Abstract: We propose to observe the ground-state fine-structure transition of [OI] at 4.7 THz towards the massive star-forming cores SgrB2(M) and (N). The spiral-arm clouds intervening between us and the target sources, plus the envelope around the sources, will produce absorption features at many different velocities. These observations, together with the vast database on light hydrides collected with HIFI, will allow us to estimate the contribution of [OI] to the overall oxygen budget across the Galaxy, to put stringent constraints on the modelling of oxygen chemistry in the ISM, and also to study small-scale chemical between (M) and (N).
Proposal ID: 03_0089
Principal Investigator: Francisca Kemper (Academia Sinica)
Title: Crystallization of silicates in massive young star cluster Westerlund 1: a nearby starburst analog
Abstract: We propose to observe dust forming stars in massive young cluster Westerlund 1 with the FORCASTgrism modes. The objective of this proposal is to determine the crystalline fraction of the silicates formed by the brightest mid-infrared point sources in this cluster, by disentangling the crystalline and amorphous silicate contributions to the infrared spectroscopy. This research is motivated by the discovery of large amounts of crystalline silicate dust in starburst galaxies (Spoon et al. 2006), while the silicates in the interstellar medium of our own galaxies are completely amorphous (Kemper et al. 2004). Spoon et al. explain the high crystallinity by the production by massive stars, although models show this may not be sufficient (Kemper et al. 2011). With these observations we hope to accurately pin down the crystalline silicate production by massive stars in a starburst environment.
Proposal ID: 03_0091
Principal Investigator: John Bally (University of Colorado at Boulder)
Title: FORCAST Imaging and Spectroscopy of the mini-starburst in W43
Abstract: The W43 ‘mini-starburst’ region is one of the most luminous giant HII region / massive star formation complexes in the Galaxy and the closest analog of a forming super star cluster. These observations will help constrain the properties of massive star formation in a densely clustered environment and set the context for our understanding of starbursts and the formation of super-star clusters. The goals of this program are:  Search for massive, embedded protostars and clusters in the Z-shaped star-burst region which contains about 50 massive sub-mm / mm wavelength clumps of dense gas and which are saturated in the mid-IR Spitzer images.  Determine the SEDs, luminosities, and relative evolutionary stages of these protostars and clusters.  Investigate the structure of the warm mid-IR dust emission associated with the HII region, the surrounding PDR, and the massive protostars.  Obtain 191” x 2.4” long-slit spectra at three position to sample the full range of physical conditions in W43 from highly embedded protostars, compact HII regions, PDRs, the evolved HII region, and post-main-sequence objects. Three FORCAST grisms will provide nearly-complete spectra from 8.4 to 37.1 microns using three slit positions containing W43-MM1, MM3, and the IR source in the WR+OB cluster. These observations will build a multi-wavelength, high resolution picture of a Galactic ‘mini-starburst’ covering its entire spectral energy distribution for comparison to extragalactic starbursts.
Proposal ID: 03_0092
Principal Investigator: Kate Su (University of Arizona)
Title: Nature of the Warm Excess in eps Eri: Asteroid belt or Dragged-in Grains
Abstract: Eps Eri and its debris disk provide a unique opportunity to probe the outer zones of a planetary system, due to its young age (~1 Gyr) and proximity (3.22 pc, the closest prominent debris disk by more than a factor of two). It is the Rosetta Stone for more distant exoplanetary debris systems and thus critical to understanding the mid-term evolution of our Solar System. From resolved images in the far-infrared and submillimeter along with spectra from 10-35 and 55-95 microns, Backman et al. (2009) found that the eps Eri disk has a complex structure, with multiple zones in both warm (asteroid-like) and cold (KBO-like) components. However, Reidemeister et al. (2011), on the contrary, suggested that the system has only one dominant cold belt and the warm excess originates from small grains in the cold disk, which are transported inward by the combination of P-R and stellar wind drags. Although both models fit the disk SED and marginally resolved far-infrared images relatively well, the resultant disk structures in the 15-50 AU range at mid-infrared wavelengths are expected to be very different. We, therefore, propose to obtain a 35 micron image of the eps Eri system using the FORCAST on SOFIA to test the validity of any models for this zone in eps Eri. No other available facilities can obtain such a 35 micron image, which will provide general constraints on the nature of the warm excess and any potential shepherding planets and their orbits in this iconic debris system. This is a re-submission of our approved cycle 2 program (02_0061), which was scheduled to be executed in Oct 2014. Due to the delay and the uncertain length of the SOFIA aircraft maintenance, it is not clear at the time of the cycle 3 deadline whether the approved observations will be executed in cycle 2. If the observations are carried out in cycle 2, we would withdraw the proposal in cycle 3.
Proposal ID: 03_0094
Principal Investigator: Helmut Wiesemeyer (Max-Planck-Institut fur Radioastronomie Bonn)
Title: Physico-Chemical Conditions in the Butterfly Nebula NGC6302
Abstract: The Butterfly nebula, NGC6302, is among the most complex planetary nebulae, owing to two major mass loss events leading to the formation of an equatorial torus and of the outflow lobes. The physical and chemical conditions across this generally oxygen-rich nebula, hosting one of the hottest known white dwarfs of the Galaxy, vary considerably. Their analysis therfore requires high spectral and spatial resolution. Abundance determinations with optical and UV lines suffer from spectral dilution and uncertainties concerning the ionization structure. Far-infrared (FIR) fine structure lines, collisionally excited, are thus extremely valuable for the determination of physico-chemical conditions, especially the [OI] and [CII] lines at 63 and 158 micron, respectively, which are among the brightest emission lines of the spectral energy distribution. Existing FIR observations (KAO, ISO/LWS, Herschel/PACS) suffer from spatial and/or spectral confusion. We propose to observe these two lines in NGC6302 with GREAT’s H/L2 band combination so as to obtain critically sampled, spectroscopic images and to provide a map of excitation conditions. For comparison, similar observations of the carbon-rich planetary nebula NGC7027, younger and on average hotter than NGC5302, were already obtained last May.
Proposal ID: 03_0095
Principal Investigator: Nicola Schneider (LAB, University of Bordeaux)
Title: Shocks or PDRs in S106 ? [OI] and high-J CO observations
Abstract: Ionizing radiation from massive stars creates HII and photon dominated regions (PDRs) at the HII region/molecular cloud interfaces seen in the FIR cooling lines of C+, O, and high-J CO. Stellar outflows, strong winds, and accretion shocks, however, can produce highly excited gas that possibly also emits in these ‘classical’ PDR tracer lines. We intend to disentangle spatially and spectrally the contributions of PDR and shock emission, using the [OI] 63 micron and CO J=16-15 lines as tracers complemented by our existing [CII] observations and many other spectral lines. Our target is the bipolar HII region S106, where previous C+ observations with GREAT/SOFIA revealed not only a very complex emission structure in space and velocity, but also a spatially extended line component at high velocities, not seen in any other atomic or molecular tracer and not associated with the bulk emission of the molecular cloud. PDR modelling will help to determine the relative contributions of PDR emission and shocks, and if we confirm a shock origin for part of the C+, the large number of so far not fully understood observations of spatially and kinematically extended C+ emission could be explained.
Proposal ID: 03_0097
Principal Investigator: Tom Megeath (University of Toledo)
Title: Broad [OI] in Outflows: The GREAT Observations of Orion Protostars
Abstract: The capability of GREAT to velocity resolve [OI] lines provides a new window on prototellar outflows. The [OI] line is a diagnostic of mass flows through J-shocks, and when the lineshape is resovled, places constraints on the flow of mass and momentum from jet/winds in an outflow. These constraints are independent of abundances and excitation. We propose a program to use [OI] to study the outflows of five protostars observed in the Herschel Orion Protostar Survey (HOPS), all of which have PACS 56-196 um spectra. These sources are the most luminous protostar in the HOPS sample, the protostar with the most luminous far-IR lines in the HOPS sample, and three moderate luminosity protostars with well studied outflows. By complementing the GREAT [OI] spectra with simultaneous GREAT CO J=16-15 spectra and the PACS spectra, we can constrain the flow of mass and momentum in both the jet/wind driven by the protostar and in the ambient material being entrained by the outflow. This will provide new informations on how outflows sweep and eject infalling material and thereby influence the final stellar masses of the protostars.
Proposal ID: 03_0098
Principal Investigator: Patrick Morris (California Institute of Technology)
Title: Locating and Measuring the High Mass Ejecta from the Unstable Massive Star System eta Carinae
Abstract: The luminous, massive binary system eta Carinae is both one of the nearest and most unstable objects in a class of evolved massive stars, near the end of its lifetime before expected destruction in a supernova. It experienced a major outburst in 1843, producing the well-known Homunculus nebula, containing some 15 to 40 Msun in warm (~170 K) and cool (90-110 K) dust and associated gas, according to mid-infrared ISO spectroscopy. The location of this material is very uncertain, due to large apertures of the spectroscopic observations, and lack of direct imaging beyond 25 microns. We propose to use the FORCAST imager with long wavelength filters to better locate and estimate the mass in thermal components of this material that may be resolved, constraining it to the interior regions or bipolar lobes of the Homunculus nebula, or in outer ejecta that would support the hypothesis of a major event prior to the 1843 eruption. This is crucial to understanding the mass-loss history of this object on the edge of a final supernova explosion, and provide constraints on the distribution and extinction properties of the dust in 3D hydrodynamical + radiative transfer numerical modeling of the Homunculus nebula.
Proposal ID: 03_0099
Principal Investigator: Inseok Song (University of Georgia Research Foundation, Inc.)
Title: FORCAST Spectroscopy of Extreme Debris Disks
Abstract: Debris disks provide a key clue in the formation and evolution of planets, however the exact connection between dusty debris and mature planetary systems remains unanswered. By investigating a sample of dustiest debris disks, we seek to analyze the origins of this extreme dusty debris. The four targets proposed contain more dust (fractional IR luminosity larget than 0.1%) than is typical for debris disk stars indicative of recent catastrophic events. Mid-infrared spectroscopy covers an important region of dust processing since silicate grains are known to emit strongly around 10 micron. Obtaining spectra of these targets will not only generate composition information but will allow for predictions of the size and location of the dust, thereby allowing for interpretations about the transient period of the dust. Special care was taken to exclude false debris disks. Using the FORCAST instrument on SOFIA, we will obtain mid-infrared spectra centered upon 11micron in order to detect broad silicate emission and/or gather information about the continuum emission of the dust. FORCAST spectra will provide information about the type of dust in the disk and enhance the spatial analysis of the debris since these stars lack any resolved imaging. In light of recent imaging of debris disks in scattered light (i.e. GPI, SPHERE), analysis of these dusty debris disks using mid-infrared spectroscopy will emphasize their position as excellent imaging targets leading to the discovery of new Solar System analogues. Understanding the composition of dust will points to what objects generated these large amounts of dust and thus provide insight into evolution theories such as giant planet migration or a period of late-heavy bombardment as happened in our Solar System.
Proposal ID: 03_0100
Principal Investigator: Hendrik Linz (MPIA Heidelberg)
Title: Catching H2 - a unique opportunity for EXES
Abstract: H2 is the most common molecule in the universe. However, because of no permanent dipole moment, it is not accessible by means of molecular line observations in the (sub-)millimeter. Furthermore, the vibrational ground-state quadrupole lines in the mid-infrared are observationally very challenging. The EXES instrument on SOFIA now opens a new window for direct H2 observations at high spectral resolution, that will not even be possible at the planned JWST. Here we propose an exploratory study of the H2 emission arising from the bulk of the warm gas within a hot molecular core. Beside the actual detection experiment, we want to exploit the high spectral resolution, equivalent to 6 km/s, to study the kinematics of this warm gas. Furthermore, due to the use of two transitions, a simple estimate for the temperature of different velocity components is possible. If successful, this will set the stage for future studies in this new exciting field.
Proposal ID: 03_0101
Principal Investigator: Jeonghee Rho (SETI Institute)
Title: Far-infrared Study of High Velocity Ejecta Associated with Cold Dust in Young Supernova Remnants
Abstract: Whether supernovae (SNe) are a significant source of dust has been a long-standing debate. Large quantities of dust observed in high-redshift galaxies raises a fundamental astrophysical question of the origin of dust in the Universe, since AGB stars, which are thought to produce most interstellar dust in the modern Milky Way, are too old to have evolved in high-redshift galaxies. In contrast, SNe, the end point of massive stars, can occur within millions of years after the onset of star formation. Our Spitzer observations of the young supernova remnant (YSNR) Cas A revealed that the ejecta maps show a remarkable similarity to the dust maps, confirming for the first time that significant quantities of dust forms in SN ejecta. The shape and composition of the dust continuum and type of dust is closely correlated with the nucleosynthetic layers of different heavy elements in the ejecta lines. Recent Herschel observations of YSNRs including Crab Nebula, Cas A, SN 1987A and G54.1+0.3 further confirmed that SNe are important dust factories. These results imply that SN dust could be responsible for the large dust masses detected in high redshift galaxies and in galaxies today, but only a handful of such observations exist, and it is not clear how much of this dust was formed in the previous stellar wind phase. Identifying SN ejecta and examining its physical conditions are the fundamental steps in developing an understanding of dust formation and dust evolution in ejecta. We searched for high velocity ejecta emission from ISO/LWS archival data, and identified four young SNRs which exhibit evidence for such emission in their spectra (G21.5-0.9, G54.1+0.3, MSH 11-54, and MSH15-52). These SNRs form a valuable sample for the study of cold dust emission from SNRs: in fact, we have studied such emission from these sources using Herschel archival imaging data, and so far two of these SNRs indeed feature a significant amount of dust in ejecta. The far-infrared ISO detected high velocity ejecta lines of [N II] at 57, 122 micron, [OIII] at 52, 88 micron, [O I] at 63 micron: some of these lines do not exhibit broadening within the ISO spectral resolution. We propose to observe [OIII], [OI], [CII], and [NII] lines towards the four SNRs in the sample with the SOFIA FIFI-LS: this instrument offers superior spectral resolution and higher sensitivity. Carbon and nitrogen lines are uniquely to be observed in far-infrared and critical in understanding CNO cycles of nucleosynthesis. Our observational goals are i) to identify high velocity ejecta emission and its physical conditions; ii) to examine dynamics of ejecta for comparison with SN explosion models; iii) to estimate ejecta mass of each element, and infer the progenitor mass of the SNR through comparisons with nucleosysnthesis models; iv) to correlate heavy elements in SNe and dust composition; v) to estimate efficiency of dust formation by comparing ejecta and dust masses and finally, vi) to test if SNe are the primary dust producer from ejecta in the early Universe.
Proposal ID: 03_0103
Principal Investigator: Friedrich Wyrowski (Max-Planck-Institut fur Radioastronomie)
Title: Probing high-J CO through the evolution of high-mass star forming clumps, Part II
Abstract: We propose to cointinue observing with SOFIA/GREAT a new representative sample of massive protostars taken from the ATLASGAL submm dust continuum survey that covers a large range of evolutionary stages. Adding to our available low- to mid-J data observations of high-J CO emission will reveal the warm CO components probing the inner heated envelopes (and their photon-dominated regions) and outflows (and their shocks). With additional modeling of the envelopes and the observed line profiles, we will be able to separate the contributions of the different components. The size of the sample will allow to search for evolution on a statistical basis. Our sample comprises sources which span the age and mass ranges adequate to represent the protostellar precursors of OB clusters, from infrared-quite objects to ultracompact HII regions.
Proposal ID: 03_0104
Principal Investigator: Gregory Sloan (Center for Radiophysics and Space Research, Cornell University)
Title: An infrared spectral survey of Galactic carbon stars
Abstract: We propose to observe a sample of bright carbon stars in the Milky Way with the FORCAST grisms. These new infrared spectra will correct the biases in the Galactic sample observed with the SWS on the Infrared Space Observatory. The SWS sample is the only existing sample of Galactic carbon stars with sufficient wavelength coverage to measure the quantity of warm circumstellar dust, and the FORCAST grism mode provides our only means of obtaining similar spectra. Two key populations of carbon stars are poorly represented in the SWS sample: variables with the longest pulsation periods, and overtone pulsators. Our SOFIA sample will double the number of overtone pulators and increase the longest-period pulsators from four to 27. These observations will enable more robust comparisons of Galactic carbon stars with the samples of metal-poor carbon stars in the Magellanic Clouds and other Local Group dwarf galaxies obtained by the IRS on Spitzer. This step is vital for a proper understanding of the role of metallicity in the mass-loss and dust-formation processes in evolved stars.
Proposal ID: 03_0108
Principal Investigator: Friedrich Wyrowski (Max-Planck-Institut fur Radioastronomie)
Title: Ammonia as a probe of infall in high-mass star forming clumps, Part III
Abstract: Infall is a fundamental process during star formation. While the number of studies towards high-mass star forming region of so-called ``blue-skewed’’ line profiles as infall evidence is increasing, their interpretation offers many pitfalls. Detecting infall via redshifted absorption in front of continuum sources is a much more direct method but so far mostly restricted towards absorption in the centimeter towards strong HII regions. A novel approach is to probe absorption of a rotational ammonia transitions in front of the strong dust emission of massive star forming regions. This method was used successfully by us during science demonstration time to determine infall rates towards three objects. Here we propose to continue this project to a larger range of stages to study infall through the complete evolution of massive star forming clumps.
Proposal ID: 03_0109
Principal Investigator: Jonathan Tan (University of Florida)
Title: Peering to the Heart of Massive Star Birth - IV. Surveying Across Evolution, Environment and the IMF
Abstract: We propose to continue our Cycle 2 survey of MIR/FIR (10-40 micron) emission from massive protostars, utilizing the unique capabilities of SOFIA-FORCAST. We have demonstrated theoretically and observationally that 10-40 micron observations are crucial for defining the spectral energy distribution of massive protostars and thus the bolometric flux directed towards us. The 40 micron peak brightness is typically very close to the actual protostar’s position, while at shorter wavelengths this is often not the case due to re-radiation via outflow cavities. SOFIA’s relatively high angular resolution at 30-40 microns, i.e. ~3” compared to ~6” of Herschel at 70 microns, is thus important for disentangling massive star formation activity, especially that occurring in crowded regions. With source G35.2 we have also demonstrated SOFIA’s ability to deliver high contrast imaging revealing fainter extended emission from the protostellar envelope that is impractical to observe from the ground at 10-20 microns. Combined with sophisticated radiative transfer modeling, analysis of this emission constrains the geometry of the outflow cavities, allowing more reliable measurement of the true bolometric luminosity and thus protostellar mass. Our goal is to continue to apply these techniques to a much larger sample of protostars, spanning a range of evolutionary and environmental states, from relatively isolated sources in Infrared Dark Clouds, to less extincted sources with compact (often jet-like) radio emission, to ultra-compact HII regions (where radio emission extends beyond MIR emission), to sources in crowded regions. We also include 10 intermediate-mass protostars to allow comparison with their more massive cousins. A typical observation will take ~60 minutes and the ~50 targeted fields of view will yield ~60 protostars: enough to begin to provide statistically significant samples in these different evolutionary and environmental states.
Proposal ID: 03_0110
Principal Investigator: L. Helton (Universities Space Research Association)
Title: A FORCAST Mid-IR Study of the Classical Nova V1369 Cen (Nova Centauri 2013)
Abstract: The Galactic cycle of chemical evolution depends on the redistribution into the ambient interstellar medium (ISM) of elements synthesized by thermonuclear processes. Classical novae (CNe) contribute to this cycle by deposition into the ISM of gas enriched through explosive nucleosynthesis and dust grains condensed in their ejecta providing the material from which the next generation of stars and planets grow. We propose to observe the nova V1369 Cen (Nova Centauri 2013) in the mid-IR with FORCAST to determine the ejecta mass, the degree of elemental enrichment in the ejecta, the dust grain mineralogy, and the processes of dust grain growth and destruction. FORCAST observations fulfill these goals by providing high S/N data in which we can 1.) measure H recombination, nebular, and coronal emission lines necessary to determine ejecta abundances and masses; 2.) measure prominent dust features from silicates and polycyclic aromatic hydrocarbons to track dust condensation, mass, grain size distribution, and processing; and 3.) estimate the energy budget of the eruption providing insight into the underlying white dwarf and the eruption’s contribution to the energy budget of the ISM. These observations will complement our extensive, on-going Chandra, Swift, and ground based optical and near-IR observing programs.
Proposal ID: 03_0113
Principal Investigator: Paul Hartogh (Max-Planck-Institut fur Sonnensystemforschung, Katlenburg-Lindau)
Title: Constraints for the hydrogen peroxide and water cycle on Mars
Abstract: Hydrogen Peroxide, H2O2, a key specie in catalytic cycles was detected in the Martian atmosphere for the first time in 2003 by Clancy et al. (2004) and Encrenaz et al. (2004). These early results varied between 20 and 40 ppb for the northern fall season (Solar longitude, Ls, = 206deg), more or less consistent with photochemical model calculations (e.g. Krasnopolsky 1993; Atreya & Gu 1994; Nair et al. 1994). Photodissociation of water vapor is the fundamental source of H2O2. It may also be produced by electrostatic discharge reactions during dust storms, in dust devils, or during normal saltation (Atreya et al. 2006). Near the surface, the concentration could exceed 200 times that produced by photochemistry alone. Such a large abundance is enough for condensation and precipitation of H2O2 to occur. In its solid phase on the surface, it may be responsible for scavenging organic material from Mars and/or present a sink of methane such that a larger source is required to maintain its steady-state abundance (e.g. Mumma et al. 2009, Hartogh et al, 2010a). Despite its importance for the atmospheric chemistry on Mars and the questions of organics on the surface/atmosphere, there are only a handful of observations and their results are inconsistent. Observations of Herschel/HIFI performed during Ls of 77deg and 10deg found either no (Ls=77deg, Hartogh et al, 2010a) or much less (Ls=10deg, Hartogh et al, in prep.) H2O2 than those reported from former observations and model predictions. Since the sensitivity or GREAT in band 2 is superior to that of HIFI, we proposed to observe H2O2 at Ls 100deg between 15-31 January 2016 in order to provide another crutial data point constraining the H2O2 cycle. They will be complemented by high SNR water vapor observations. This will set the photochemical context.
Proposal ID: 03_0114
Principal Investigator: Margaret McAdam (University of Maryland)
Title: Degree of Alteration on Asteroids: Mapping water in the Asteroid Belt
Abstract: We propose to measure the water content of primitive asteroid surfaces through emissivity features in the mid-infrared using FORCAST on SOFIA. Our targets are distributed throughout the middle and outer asteroid belt, allowing us to map the distribution of water in this population. Using newly found spectral trends in a suite of aqueously altered meteorites, it is possible to identify the degree of aqueous alteration on the surfaces of dark asteroids remotely. The key measurements required are FORCAST spectra of 30 primitive asteroids, 12 of which are observable during SOFIA Cycle 3, using the grisms G111 and G227 covering 8.4-13.5 and 17.6-27.7 microns respectively. These wavelength regions have strong spectral features from phyllosilicates, hydrated minerals that are produced during aqueous alteration. The presence and positions of these features indicate the mineralogy of the surfaces of asteroids and additionally, the degree to which the asteroids are altered. The anticipated results are quantitative constraints on the water content of primitive asteroids as a function of location in the asteroids belt, and thus a step towards understanding the distribution of water in the early solar system.
Proposal ID: 03_0116
Principal Investigator: Annie Hughes (MPIA)
Title: New insights for PDR modelling in low metallicity environments: the case of N44
Abstract: Photodissociation regions (PDRs) are ubiquitous in sites of massive star formation. Dominant PDR cooling lines, e.g. [CII], have become a popular means to assess star formation rates in high-z galaxies in the ALMA era. Yet such an application is still challenging with large uncertainties due to the wide range of physical conditions that can produce PDRs together with our crude knowledge on low-metallicity ISM. We propose GREAT [CII] and [NII] observations of the mini-starburst N44 in the low-metallicity Large Magellanic Cloud. Together with our recently obtained APEX CI and multi-J CO and 13CO maps at clump scales, we will determine realistic density and temperature of the molecular gas as input for low-metallicity PDR model to constrain the range of clumpiness of the ISM, volume density of H2, and influence of the FUV radiation field on such ISM. Adding known resolved massive stellar content from our previous studies, we can further calibrate using [CII] lines to trace star formation activity. These results will illuminate our understanding in ISM properties and star formation in the low metallicity environment like the early universe.
Proposal ID: 03_0120
Principal Investigator: Rodrigo Herrera-Camus (University of Maryland)
Title: The GREAT [CII] Account of the Low-Metallicity ISM in the SMC
Abstract: We propose to observe [CII] in 11 diverse star-forming regions of the Small Magellanic Cloud using GREAT and map [CII] and [OI] in 3 of the most extreme environments (N66, N76, and the Magellanic Bridge) using FIFI-LS. At a distance of 60 kpc and low-metallicity, the SMC is an ideal target to investigate the state of the ISM. Our proposal exploits the spectral resolution of GREAT (1 km/s) in order to determine conclusively whether the [CII] emission probes the cold neutral medium by comparing the resolved [CII] line profiles with those of HI and CO data. 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. Combining HI and CO data with measures of the [CII] emission provides a measurement of the column of molecular hydrogen (H2), potentially revealing “CO-faint” H2. We can then apply the information from the [CII] profiles in specific regions to larger regions mapped with Herschel PASCS in [CII] and [OI] and the proposed FIFI-LS maps of [CII] and [OI] to study the details of the low-metallicity ISM and how that relates to star formation. In combination with the ancillary datasets available on these sources and the ISM modeling expertise present in the team, these data will provide the best insights into the origin of [CII] emission and total amount of molecular gas (as compared to CO) at low metallicity, both of which are key to understanding high-z ALMA observations of those lines.
Proposal ID: 03_0121
Principal Investigator: Maria Kapala (Max-Planck-Institut fur Astronomie, Heidelberg)
Title: Investigation of the [CII] origins in the non-star-forming bulge of the M31
Abstract: The [CII] 158micron emission line is a good potential star-formation rate (SFR) tracer. [CII] is one of the brightest emission lines from a typical galaxy and can be measured at both low and high redshift - a great advantage in understanding galaxy evolution through cosmic time. However, [CII] is a complex line that arises from multiple ISM phases, which can be heated by various sources, and in particular sources unrelated to star-formation (SF). It is crucial to identify contamination from non-SF related [CII] emission, if one use it as tracer of SF. M31 is a testbed to extensively study the ISM of a typical L* galaxy at resolutions down to ~50pc scales. It allow us to further translate this knowledge to high-z surveys that are coming along with the new integral field spectroscopy instruments (e.g., MUSE in optical, KMOS in near-IR, MANGA, XSHOOTER UV to NIR) and interferometers (i.e. ALMA in radio). However, we encountered a puzzle in the bulge of M31, when trying to understand the origins of [CII], and particularly its relation to SF. The Andromeda’s bulge is dominated by old stellar populations, with no OB stars. Yet, the [CII] line was detected at 12sigma, peaking in the galaxy center, using low resolution (68’’) observations from Infrared Space Observatory (ISO). If there is no SF in the bulge, what is the heating source powering the [CII]? We propose to pursue this puzzle by mapping [CII] 158micron line at high resolution (12’’) using FIFI-LS instrument on-board SOFIA in the central part of the bulge of M31. FIFI-LS is the only instrument to date, that allow us to conduct such high spatial resolution investigation and to understand what is responsible for generating [CII], in the absence of SF. We also propose to fully exploit the capabilities of FIFI-LS to complement this study by simultaneously mapping the [OI] 63micron emission line in the blue channel. By associating spatial distribution of [CII] with already obtained maps of dust or Halpha emission, which have distinct spatial distributions, we can connect [CII] emission to neutral or ionized phases, respectively. In addition, within smaller, central regions [OI]/[CII] diagnostic tool will tell us whether the regions are photo-dissociation (PDRs) or X-ray dominated (XDRs).
Proposal ID: 03_0124
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 an unknown bright comet or comet outburst with this CY3 Target-of-Opportunity (ToO) proposal. A 5-27 micron spectrum coupled with 11, 19, and 31 micron dual-band photometry 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, and 23.5, 27.5, and 33 micron, the shapes of forsterite crystals can be constrained and their condensation temperatures inferred by comparison with theoretical and experimental data. 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 CY3 ToO bright comet as an unpredictable cometary outburst event or a comet discovered after the CY3 submission deadline that produces a comet with an integrated brightness of V<4 mag that is observable within CY3. A CY3 ToO comet will be at least as bright as CY3 target comet C/2013 US10 (Catalina). From 1995 through 2014, there are nine comet apparitions with V<6 mag, where six out of these nine were discovered within one year of perihelia and three were naked-eye within 2 months of discovery. FORCAST 5--31.5 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 model-constrained silicate crystalline fractions.
Proposal ID: 03_0126
Principal Investigator: Timothy Lee (NASA Ames Research Center)
Title: A Search for c-C3H3+: identifying the Cyclopropenylidene Precursor
Abstract: Cyclopropenylidene (c-C3H2) was the first interstellar organic ring molecule identified and is now known to be widespread in the interstellar medium. Gas phase chemistry models for the formation of c-C3H2 predict that the most important precursor is c-C3H3+ - which remains undetected. c-C3H3+ has no permanent dipole moment, so it produces no emission in rotational lines. Furthermore, our calculations indicate that expected optical depths are insufficient to detect this material in absorption in continuum sources. Using ab initio calculations for line wavelengths and intensities, we propose to search for c-C3H3+ emission in the giant star forming region SgrB2, which contains a large column of warm c-C3H2; and Orion KL which recently has been shown to possess detectable quantities of vibrationally excited CH2CHCN.
Proposal ID: 03_0127
Principal Investigator: Antoine Gusdorf (Observatoire de Paris, LERMA/LRA, ENS)
Title: GREAT observations of the W43-MM1 ridge
Abstract: We propose to map the W43-MM1 ridge, located in the W43 ‘mini-starbust’ region, one of the most massive and highly concentrated molecular complex of the Milky Way. W43-MM1 is the densest (5e4cm^-3 in ~8 pc^3) and coldest (~15 K) cloud structure of W43, and provides a huge mass reservoir (2e4 Msun) for the formation of a massive star cluster. Star formation has indeed been unambiguously detected in the southwestern part of the filament. On the other hand, very extended SiO emission has been detected throughout the whole filament, associated to low-velocity shocks. These could be tracing ‘colliding flows’, that are thought to facilitate the formation of massive stars. W43 hence offers two astrophysical challenges: the question of the origin of the extended SiO emission at low velocity, and that of the interplay between colliding flows and star formation. Answering these two questions necessitates to understand the propagation of two kinds of shocks in the region: low-velocity ones, associated to large-scale colliding flows, and higher velocity ones, associated to local star formation outflows. The goals of this program are:  to disentangle the kinematic components corresponding to these two kinds of shocks;  to tightly constrain the corresponding shock models, with view to evaluate both their chemical and energetic impact;  to probe the coherence of the low-velocity shocks throughout the filament, in relation with the differentiated star formation in its various regions. We propose to map the W43-MM1 filament in CO (11-10) at 1.267 THz and C+ at 1.900 THz with the GREAT receiver onboard the SOFIA telescope. Combined with the data obtained by our team in other molecular tracers, this program will allow for the emergence of a consistent picture on the chemical, physical, dynamical and kinematical conditions of the gas along the filament.
Proposal ID: 03_0130
Principal Investigator: Angela Cotera (SETI Institute)
Title: Star Formation in the Galactic Center: Massive stars and the ISM towards 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 star formation under extreme environmental conditions. The proposed observations enable us to complement large surveys of the region at multiwavelengths with a detailed invetigation of the stellar population; in particular the massive stars and their impact on the gas energetics. 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 density structure within a region known to contain both massive stars and massive YSOs. When combined with existing multi-wavelength observations, we will be able to address the crucial questions: Where are the massive stars? Do the massive stars regulate the energetics of the interstellar medium in the Galactic center?
Proposal ID: 03_0131
Principal Investigator: Nathan Smith (University of Arizona)
Title: Constraining the Mass in Cool Dust Shells Around Massive Stars
Abstract: We propose to observe a sample of circumstellar shells around hot, massive stars in order to estimate their ejected mass and to thereby help constrain the importance of eruptive mass loss in post-main sequence stellar evolution. Very few examples currently exist with accurate determinations of the mass lost in eruptive ejections, and access to mid-IR and far-IR wavelengths is critical because of the relatively cool dust temperatures in the extended fossil remnant shells. This proposal extends our successful Cycle 2 proposal to Southern Hemisphere targets, four of which are confirmed or candidate luminous blue variables (LBVs), which are hot stars in a post-main sequence stage exhibiting extreme mass loss events. In addition, we seek to observe during Cycle 3 our one LBV target (P Cygni) which was awarded time during Cycle 2 but was not observed. We also include two of the recently discovered “MIPS Nebulae”, whose ejected shells bear strong resemblance to our LBV target Hen 3-519.
Proposal ID: 03_0135
Principal Investigator: Kevin Croxall (Ohio State University)
Title: Exploring Far-IR Abundance Diagnostics in Nearby Galaxies
Abstract: Gas phase metallicity strongly influences the physical conditions within the ISM, and is thus instrumental in understanding the evolution of galaxies and the ISM. However, this fundamental parameter of galaxy evolution can be difficult to measure in a manner that is free from large systematic uncertainties. We propose to better understand both the calibration of gas phase abundances through a careful study of far-IR diagnostics. Using FIFI-LS on SOFIA, we will obtain line maps of [O III] and [N III] lines in extragalactic HII regions. FIFI-LS provides unique access to these diagnostic lines that were previously only available at higher redshift where spatial resolution confuses their interpretation. Pairing Herschel observations of fine-structure lines with observations of the [O III] 52 micron and [N III] 57 micron lines, which lay just beyond the limits of Herschel, will dramatically increase our understanding of the ISM by (1) providing access to an unobserved, yet dominant, ionization species of nitrogen, (2) directly probing the density of the O++ gas, and (3) significantly strengthening the ability to determine a gas phase abundance that is temperature independent.
Proposal ID: 03_0138
Principal Investigator: Silvia Vicente (Kapteyn Astronomical Institute)
Title: [OI] and OH line profiles from proplyds in Orion and the Carina nebulae
Abstract: Proplyds are a special class of low-mass young stellar objects (YSOs) modulated by the external environment. They are found embedded within or near a HII region and are identified by their typical cometary photoionized envelopes. The photoevaporation of these disks determines their lifetime and hence their potential as planetary nurseries. We have conducted a Herschel survey of a sample of 3 proplyds in the Orion and Carina nebulae with the PACS and HIFI instruments with the goal of understanding the photoevaporation process in these objects. The [OI]63 line was detected with PACS in the Carina proplyd but failed in Orion due to the high nebular emission. With HIFI we could spectrally resolve the emission from the proplyd and the nebula for all sources in the [CII]157 line. Here we propose to observe a sample of 4 proplyds in the [OI]63 line with the GREAT instrument on SOFIA. A spectral resolution better than 0.2 km/s and a SNR of 10 will resolve the line profile and separate it from the stronger nebula emission. The line profile will allow to establish the origin of the [OI]63 emission, if from the disk, a jet, or both, and to set strong constraints on the physical conditions and excitation processes of the gas (shocks vs. UV). In addition, we also want to confirm the detection of OH in the proplyd 244-440 and conduct a pilot survey of OH in the other proplyds. We will use the OH163 line covered by GREAT in Cycle3.
Proposal ID: 03_0139
Principal Investigator: David Principe (Rochester Institute of Technology)
Title: Mid-infrared Imaging of X-ray Sources in L1630 and NGC 2264: Investigating the Onset of Magnetic Activity in Protostars
Abstract: Magnetic fields play a fundamental role in both very early and late stages of star formation, but the evolution from primordial (cloud core) to young star magnetic field is very poorly understood. Combined IR and X-ray observations of the youngest, most deeply embedded (Class 0 and I) young stellar objects (YSOs) provide an essential means to trace the earliest epochs of YSO magnetic activity. We propose SOFIA/FORCAST observations of three fields in the L1630 (Orion) and NGC 2264 star formation regions that encompass clusters of deeply embedded YSOs, many of which were detected in X-rays by Chandra. These fields include potential rare examples of X-ray-emitting Class 0 YSOs. FORCAST imaging will establish the 10-40 micron SEDs (hence YSO classes) -- and therefore constrain the YSO evolutionary states and disk and envelope masses -- of the X-ray-detected (magnetically active) vs. X-ray-undetected objects in these star formation regions.
Proposal ID: 03_0140
Principal Investigator: Lars Kristensen (Smithsonian Institution Astrophysical Observatory)
Title: Where is the oxygen in protostellar outflows?
Abstract: Oxygen (O) is the third-most abundant element in the Universe after hydrogen and helium. Despite its high elemental abundance, a good picture of where oxygen is located in low-mass protostellar outflows and jets is missing: we cannot account for > 60% of the oxygen budget in these objects. This hole in our picture means that we currently do not have a good understanding of the dominant cooling processes in outflows jets, despite the fact that [O I] emission at 63 micron is one of the dominant cooling lines, nor how cooling processes evolve with protostellar evolution. To shed light on these processes, we propose to observe the [O I] 63 micron line with SOFIA-GREAT toward five low-mass protostars. As a first step, the velocity-resolved line profile will be decomposed into its constituent components to isolate the relative contributions from the jet and the irradiated outflow. Second, the [O I] line profile will be compared to those of H2O, OH and CO to obtain the relative atomic O abundance with respect to CO, H2O, and OH. Third, the effects of evolution will be examined by observing protostars at different evolutionary stages. These three approaches will allow us to quantify: the oxygen chemistry in warm and hot gas, the relative amounts of material in the outflow and the jet, and finally to start tracing the evolutionary sequence of how feedback evolves with time.
Proposal ID: 03_0141
Principal Investigator: Norbert Werner (Stanford University)
Title: The role of cold gas in the evolution of nearby giant elliptical galaxies
Abstract: It is now well established that most if not all giant elliptical galaxies host central supermassive black holes that play a role vital to the formation and evolution of the host galaxy. Most of these black holes, also known as active galactic nuclei (AGN), are in the so called 'radio-mode', driving powerful relativistic jets which can extend to large distances and have a profound impact on their surroundings. So far radio-mode AGN feedback has been systematically investigated in the X-ray and radio bands. The use of multi-wavelength data probing the cold and warm gas phases is, however, also crucial to understand heating and cooling throughout the putative 'AGN feedback loop'. Recently, using far-infrared spectral imaging in the [CII] line with Herschel PACS, together with extensive optical and X-ray data, we have studied the physics and origin of the multi-phase material in the cores of eight nearby, X-ray and optically bright giant elliptical galaxies. In 6/8 systems, we detect filamentary nebulae containing multi-phase material spanning a temperature range of at least five orders of magnitude, from ~100 K to ~10^7 K. Whereas previous attempts to detect the HI atomic line in these galaxies failed, our Herschel observing program established that the far-infrared [CII] line emission is particularly strong in these systems. Indeed, [CII] is the best tracer of cold gas in giant elliptical galaxies, being ~3800 times stronger than the CO(1-0) molecular emission (Werner et al. 2014). Relatively short snapshot observations in the [CII] line with the FIFI-LS on SOFIA provide the most efficient way of detecting the presence of cold gas in these galaxies. Here, we propose far-infrared observations of the [CII] cooling line in additional 12 giant ellipticals with the FIFI-LS on SOFIA. With this study, we will obtain high-quality [CII] data for the complete sample of nearby X-ray luminous and optically bright giant ellipticals within a distance of 100 Mpc (Dunn et al. 2010) with DEC>0. This sample will allow us to 1) to establish the fraction of X-ray bright giant ellipticals that host reservoirs of cold gas; 2) correlate the presence of cold gas with the thermal stability of their hot atmospheres to test whether the cold gas in giant ellipticals cools directly from the hot phase; 3) correlate the presence of cold gas with the dynamical state of the galaxies, and the radio properties and powers of relativistic jets; 4) build a sample for a follow up with ALMA to probe the role of cold gas in feeding radio mode AGN.
Proposal ID: 03_0146
Principal Investigator: Jose Fonfria (Universidad Nacional Autonoma de Mexico (UNAM))
Title: Vibrationally excited water in the envelope of the C-rich AGB star IRC+10216
Abstract: The recent detection of warm water in the circumstellar envelope of the C-rich AGB star IRC+10216 forces us to check the models which explain the chemical richness in this kind of environments. Water, a molecular species commonly observed in O-rich circumstellar envelopes, is present in C-rich ones with an abundance significantly larger than that predicted by those models. In order to find an explanation to the water formation phenomenon in C-rich envelopes it is necessary to know where water is formed and which the physical conditions prevailing in these regions are. A number of detected lines involve excitation temperatures up to 1000 K suggesting that water is formed in the innermost envelope. In this sense, observing vibrationally excited water around 6 um is one of the best ways to derive the required information.
Proposal ID: 03_0151
Principal Investigator: Geoffrey Blake (California Institute of Technology)
Title: THz Observations of Interstellar and Planetary CO2 Ice: Unlocking the Power of FIFI to Explore Solid-State Astrophysics
Abstract: Using state-of-the-art THz spectroscopy, we have recently shown that many key astrophysical species present spectroscopic signatures in the THz region of the spectrum. As these features are structure-, composition-, and temperature-sensitive, they provide insight into the physical conditions within the target sources. While within the planned range of FIFI, the most distinctive feature of the most abundant ice, water, is outside of FIFI’s current reach. Instead, we target the second most abundant species - CO2. We propose proof-of-concept observations to explore FIFI’s ability to target the broad, solid-state features characteristic of ices. We will target two transitions of CO2: a previously-known feature at 85 um, and a new signature at 145 um. We propose to observe a massive protostar (NGC 7538 IRS 9), and the Martian polar ice caps.