SOFIA science was all over the 237th AAS Virtual Meeting January 11-15, 2021! This webpage lists all SOFIA-related events during the meeting. All times are Eastern Time.
Download a printable PDF of SOFIA sessions here .
AAS 237th meeting registrants may view any of the events on the AAS virtual meeting website .
Special Session: Assessing the Impact of Stellar Feedback
Tuesday January 12, 4:10-5:40 pm ET - session 223
This oral session will feature talks by the following invited speakers:
- Xander Tielens (U. Leiden) - PI of SOFIA Legacy program FEEDBACK
- Laura Lopez (OSU)
- Mélanie Chevance (U. Heidelberg)
- Hector Arce (Yale)
- Susanna Widicus Weaver (U. Wisconsin-Madison)
- Crystal Martin (UCSB)
Session description:
Observational evidence shows that feedback - stellar winds, heating, and radiation - from protostars, low-mass and high-mass stars is a major contributor to the dynamics, morphology and chemistry of the interstellar medium. Stellar feedback leads to the creation and expansion of HII regions and drives shock chemistry throughout the ISM. At a larger scale, galactic-scale winds, fountains and chimneys can also have a profound impact on galactic structure and evolution. Understanding why and how stellar feedback affects its environment is one of the key questions in modern astrophysics. In particular, one standing problem is the relative importance of radiative as opposed to mechanical feedback. Another outstanding problem is how feedback varies with different ISM conditions (e.g., metallicity and density). This session will include recent theoretical and observational results which contribute to the understanding of the role of stellar feedback across different scales, from protostellar clouds to galaxies. We will place a particular focus on the exploration of the link between feedback and star formation, the shaping of ISM structures, and the chemistry in shocks regions and ionization fronts. Recent observations (IR surveys and high-resolution mm-wave images) of the kinematics and temperature gradients in stellar environments, displaying in detail the interaction of various types of stars and their surrounding ISM, will be presented.
X. Tielens: The C+ Universe
The interaction of massive stars with their environments regulates the evolution of galaxies. Mechanical and radiative energy input by massive stars stir up and heat the gas and control cloud and intercloud phases of the interstellar medium. Stellar feedback also governs the star formation efficiency of molecular clouds. On the one hand, stellar feedback can lead to ashredding of the nascent molecular cloud within a few cloud free-fall times thereby halting star formation. On the other hand, massive stars can also provide positive feedback to star formation as gravity can more easily overwhelm cloud-supporting forces in swept-up compressed shells. Moreover, stellar feedback is an important source of turbulence in the interstellar medium. The combination of sensitive THz heterodyne receiver arrays with a nimble telescope on SOFIA enables large scale, [CII] 158µm surveys of regions of massive star formation. This line is the main cooling line of neutral gas in the interstellar medium and therefore a key diagnostic of interstellar gas energy balance. In addition, the high spectral resolution inherent to heterodyne techniques allows a detailed study of the kinematics of photodissociation regions, which separate ionized from molecular gas. I will present results of the [CII] 158µmsquare degree Orion Survey and the SOFIA/upGREAT FEEDBACK Legacy Program, their analysis and implications for the interaction of massive stars with their environment and their role in the evolution of galaxies.
L. Lopez: Assessing the Dynamical Role of Stellar Feedback using Multiwavelength Observations
Stellar feedback is dynamically important on the small scales of star clusters up to the large scales of whole galaxies. Despite its profound influence, a major challenge in feedback studies is setting observational constraints on the relative role of the many stellar feedback modes (such as direct radiation, dust-processed radiation, photoionization heating, protostellar outflows, stellar winds, and supernovae). Fortunately, high quality mutltiwavelength survey data are now available for the Milky Way and other Local Group galaxies, facilitating observational assessment of stellar feedback mechanisms in a variety of sources. I will present results from these multiwavelength programs, including new results showing how the pressures associated with different feedback modes vary between young, compact HII regions and more evolved HII regions. In particular, the dust-processed radiation pressure dominates in 95% of the younger sources, whereas the photoionized gas pressure is the dominant term in evolved sources. I will discuss the implications regarding the dynamical evolution of the HII regions and the lessons for feedback prescriptions in star and galaxy formation simulations. Finally, I will highlight the complementary constraints that can be obtained from integral field spectroscopy.
M. Chevance: The lifecycle of molecular clouds in nearby galaxies
The cycling of matter in galaxies between molecular clouds, stars and feedback is a major driver of galaxy evolution. However, it remains a major challenge to derive a theory of how galaxies turn their gas into stars and how stellar feedback affects the subsequent star formation on the cloud scale, as a function of the galactic environment. Star formation in galaxies is expected to be highly dependent on the galactic structure and dynamics, because it results from a competition between mechanisms such as gravitational collapse, shear, spiral arm passages, cloud-cloud collisions, and feedback processes such as supernovae, stellar winds, photoionization and radiation pressure. A statistically representative sample of galaxies is therefore needed to probe the wide range of conditions under which stars form. I will present the first systematic characterisation of the evolutionary timeline of the giant molecular cloud (GMC) lifecycle, star-formation and feedback in the PHANGS sample of star-forming disc galaxies. I will show that GMC are short-lived (10-30 Myr) and are dispersed after about one dynamical timescale by stellar feedback, between 1 and 5 Myr after massive stars emerge. Although the coupling efficiency of early feedback mechanisms such as radiation and stellar winds is limited to a few tens of percent, it is sufficient to disperse the parent molecular cloud prior to supernova explosions. This limits the integrated star formation efficiencies of GMCs to 2 to 10 per cent. These findings reveal that star formation in galaxies is fast and inefficient, and is governed by cloud-scale, environmentally-dependent, dynamical processes. These measurements constitute a fundamental test for numerical sub-grid recipes of star-formation and feedback in simulations of galaxy formation and evolution.
H. Arce: Outflow feedback from low-mass protostars
Jets and winds from young stars are among the most prominent signposts of star formation. Protostellar winds originate within a few au (or less) of the forming star and may reach linear sizes of a few parsecs. As they travel through the circumstellar envelope, the surrounding core and host cloud, they push and accelerate the ambient gas, thereby injecting energy and momentum into their surroundings at various size and density scales. This has considerable impact on the dynamics, distribution, and chemical composition of the gas in the star-forming environment, and also helps decrease the star formation efficiency of the region. I will show recent millimeter interferometer (ALMA and SMA) observations of low- and intermediate-mass protostars at different evolutionary stages that reveal how outflows interact with their circumstellar environment (within a few 100 to a few 1000 au of the forming star), and discuss how outflows influence the star formation process.
S. Widicus Weaver: UV Photodissociation and Thermal Processing in Interstellar Ice
It has been shown through both laboratory and observational studies that direct and cosmic-ray induced UV photodissociation drives a complex network of chemistry in interstellar ices. Astrochemical models have demonstrated that gradual heating of these UV-processed ices during star formation can lead to a wide variety of complex organic molecules. Additional modeling and observational studies have shown that these molecules are likely incorporated into protoplanetary disks and participate in the chemical processes leading to planet formation. Stellar feedback mechanisms are therefore directly involved in the chemical evolution of chemistry in the interstellar medium and could potentially serve as molecular starting points for prebiotic chemistry in the universe. Our observations of the chemistry of star-forming regions have shown that there is wide variation in the chemical compositions of hot cores, and that methanol photodissociation on icy grains may be the key process feeding the formation of larger prebiotic molecules. To test possible chemical routes in interstellar ices, we have built a novel laboratory experiment that couples the traditional tools of ice studies -- FTIR spectroscopy and mass spectrometry -- with the structure specificity of rotational spectroscopy. Such measurements can provide the "ground truth" to guide observations of star- and planet-forming zones. In this talk we will present both the observational and laboratory studies and discuss these results in the context of stellar feedback mechanisms.
C. Martin: galactic winds and supernovae
Gaseous outflows appear to be a ubiquitous property of star-forming galaxies across cosmic time. Cosmological hydrodynamical simulations require higher outflow efficiencies in lower mass galaxies in order to explain the observed distribution of galaxy stellar masses and gas-phase metallicities. Yet typical dwarf galaxies have very low specific star formation rates today, raising the question "Can we observe strong feedback in low mass galaxies?" Studying feedback in dwarf galaxies with extreme emission-line spectra provides some answers and offers insight into the interplay between radiative and mechanical feedback in young galaxies. These galaxies have an extremely dense star cluster, and I will present new integral field spectroscopy that reveals how the young, low-metallicity stars change the gas kinematics and excitation of the surrounding interstellar medium. The results suggest that the EUV spectrum is harder than that produced by typical star clusters, the escape of Lyman continuum radiation is anisotropic, and fast outflows may be impacting the densest interstellar gas.
AAS 237th meeting registrants may view the session on the AAS virtual meeting website .
SOFIA Town Hall
Friday, January 15, 1:40-2:40pm ET - session 519
The US-German Stratospheric Observatory for Infrared Astronomy (SOFIA) continues to provide to the international community a unique access to mid- and far-infrared observations with a broad range of instruments. SOFIA is in its 8th observing cycle and will start its 9th cycle in July 2021.
During this Town Hall, the SOFIA Director, Margaret Meixner, and the SOFIA team will report on the Instrument Roadmap, a document which will be delivered to NASA in the Fall of 2020 describing the priorities, timelines and modalities for SOFIA instruments' upgrades and new instrument development . This report will be based on the feedback from the community on the most compelling science cases and technical feasibility considerations, which will have been collected during a series of workshops in the Summer of 2020.
Further topics will include the status of the observatory, the ongoing Cycle 8 observations including Legacy Programs, a summary of the proposal selection process and outcome for Cycle 8 and the implementation of the recent reviews’ recommendations.
In addition to communicating the current status and plans by the SOFIA program, this Town Hall will allow direct feedback by the SOFIA user community regarding current operations and future plans.
AAS 237th meeting registrants may view the Town Hall on the AAS virtual meeting website .
Press Conference: Galaxies and Quasars II
Thursday, January 14, 12:15-1:15pm ET
Magnetic Highway: Channeling the M82 Super Wind, Jordan Guerra Aguilera (Villanova University)
Magnetic Chaos Hidden in the Whirlpool Galaxy, Alejandro Borlaff (NASA Ames Research Center)
Astrobites summary
Vew the press conference here
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Plenaries
Thursday 3:10–4:00 pm ET, Plenary Session 421. Thermal-IR Astronomy: Progress & Future Prospects, C. Packham
Astrobites summary
AAS 237th meeting registrants may view the plenary on the
AAS virtual meeting website
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Friday 11:00–11:50 am ET, Plenary Session 500. The Role of Magnetic Fields: Galactic Science from HAWC+/SOFIA, D. Chuss
Astrobites summary
Astrobites interview
AAS 237th meeting registrants may view the plenary on the
AAS virtual meeting website
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Webinars
SOFIA hosted two webinars during the meeting.
Tuesday, January 12, 12:30-1:00 pm ET
"Exploring the Mid-IR Galactic Center with SOFIA Legacy Maps" led by James Radomski and Nicole Karnath. The Galactic Center legacy maps obtained with FORCAST at 25- and 37-μm provide a large-scale view of bright infrared emission in the region, with an unprecedented spatial resolution. The detected emission allows one to constrain the dust spatial distribution and temperature, and to identify compact sources, including candidate young stellar objects, hence providing unique contextual information for the study of the closest galactic nucleus. We will present this publicly available dataset and different techniques to derive information and exploit its scientific value.
View the webinar video here
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View the webinar slides here
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Wednesday, January 13, 1-1:30 pm ET
"SOFIA Archive Opportunities: Science-Ready Data and Funding" led by Ed Chambers, Luisa Rebull and B-G Andersson. The SOFIA Archival Research Program (SARP) is now open for proposals to fund research projects primarily using SOFIA data. The purpose of this program is to encourage the use of available SOFIA archival data and to realize the full potential of the SOFIA archive. In this webinar we will present the search and visualization functionalities for SOFIA data in the IRSA archive , highlight and describe select high-potential public datasets, and discuss the mechanics of the open funding call.
View the webinar here
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View the webinar slides here
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NASA hosted a webinar highlighting SOFIA science.
Tuesday, January 12, 2:30-3:00 pm ET
"SOFIA: Science from the Stratosphere" by James De Buizer. SOFIA’s mid- and far-infrared observations are uncovering new clues about the birth of stars and planets, our interstellar origins and the path to life, magnetic fields and the distant universe. View the webinar here .
Zoom Chat with SOFIA Mission Operations Director Margaret Meixner
Wednesday, January 13, 2:40-3:10 pm ET
Join SOFIA Mission Operations Director Margaret Meixner at the SOFIA booth to ask any of your questions about SOFIA.
Zoom Chats with SOFIA Project Scientist Naseem Rangwala
Monday, January 11, 2:40-3:10 pm ET, NASA booth
Wednesday, January 13, 4:10-4:40pm ET, SOFIA booth
Join SOFIA Project Scientist Nassem Rangwala at the NASA and SOFIA booths to ask any of your questions about SOFIA.
Contributed Presentations
Monday, January 11
12:30–12:40 pm ET, Oral Session 114.04. [O I] Self-Absorption and Absorption toward a Bubble-shaped PDR in the Nessie Nebula, J. Jackson et al.
12:40–12:50 pm ET, Oral Session 109.04. Dying of the Light: Cold Quasars & The Shutdown of Galaxy Growth, K. C. Cooke et al.
1:20–1:30 pm ET, Oral Session 114.09. Tracing Cloud-Cloud Collision: Orion A, W. Lim et al.
4:10–5:40 pm ET, iPoster 137.01. CO-dark Molecular Gas and Star Formation across the Nearby Spiral Galaxy NGC 6946, R. Klein et al.
We present SOFIA/FIFI-LS observations of the [CII] 158 μm cooling line across the nearby spiral galaxy NGC 6946. We combine these with UV, IR, CO and HI data to compare [CII] emission to dust properties, SFR, H2 and HI at 560 pc scales via stacking by environment (spiral arms, interarm and center), radial profiles, and individual, beam-sized measurements. We attribute 73% of the [CII] luminosity to arms, 19% and 8% to center and interarm region, respectively. [CII]/TIR, [CII]/CO and [CII]/PAH radial profiles are largely constant, but rise at large radii (> 8kpc) and drop in the center ("[CII]-deficit”). This increase at large radii and the observed decline with the 70/100 μm dust color are likely driven by radiation field hardness. We find a near proportional [CII]-SFR scaling relation for beam-sized regions, though the exact scaling depends on methodology. [CII] also becomes increasingly luminous relative to CO at low SFR (interarm or large radii), likely indicating more efficient photodissociation of CO and emphasizing the importance of [CII] as an H2 and SFR tracer in such regimes.Based on the observed [CII] and CO radial profiles and different models, we find αCOto increase with radius, in line with the observed metallicity gradient. The low αCO and low [CII]/CO ratios imply little CO-dark gas across NGC 6946, in contrast to estimates in the Milky Way.
4:10–5:40 pm ET, iPoster 137.02. Expansion of an H II Region Bubble in the Nessie Nebula Triggers Star Formation in the IRDC Filament, J. Jackson et al.
Using the GREAT instrument aboard the airborne SOFIA observatory, we have imaged [C II] 157.74 micron and [O I] 63.18 micron line emission from a bright photodissociation region (PDR) associated with an ionized ``bubble'' located in the Nessie Nebula, a filamentary infrared dark cloud. A comparison of SOFIA data with ATCA radio data shows that the bubble has a classic PDR structure, with a uniform progression from ionized gas (traced by radio continuum), to photodissociated gas (traced by {C II] and [O I]), and on to molecular gas (traced by NH$_3$) from the interior to the exterior of the bubble. The bubble is expanding into the Nessie Infrared Dark Cloud filament. At the location of the interaction, a luminous YSO has formed, indicating that feedback from the expanding bubble has triggered the formation of the YSO. Successive triggering of star-formation along the filament as the bubble expands may explain the large cluster of stars toward the western edge of the bubble and its unusual tear-drop shape.
4:10–5:40 pm ET, iPoster 137.03. SOFIA FEEDBACK Survey: Exploring the Kinetics of the Stellar Wind Driven Shell of RCW 49, M. Tiwari
One of the most important problems in modern astrophysics is to understand the role of massive stars in driving various physical and chemical processes in the Interstellar Medium (ISM). Massive stars inject an immense amount of mechanical and radiative energy into their immediate vicinity. Stellar winds are responsible for the mechanical energy input, which can push the gas into shell-like structures (as in the Rosette Nebula, Waering et al. 2018 and in the Orion Nebula, Pabst et al. 2019). The radiative energy input comes from the heating of gas through stellar extreme-ultraviolet (EUV, hv > 13.6 eV) and far-UV (FUV, 6 < hv < 13.6 eV) photons that can ionize atoms, dissociate molecules and heat the gas giving rise to H II regions and photodissociation regions (PDRs). These stellar feedback mechanisms power the expansion of H II regions and shock fronts causing morphological features that appear as shells or bubbles in the ISM. We unveil the stellar wind driven shell of the luminous massive star-forming region of RCW 49 using SOFIA FEEDBACK observations of the [C II] 158 μm line. The complementary dataset of the 12CO and 13CO J = 3 -2 transitions is observed by the APEX telescope and probes the dense gas toward RCW 49. Using the high spatial and spectral resolution provided by the SOFIA and APEX telescopes, we disentangle the shell from a complex set of individual components of gas centered around RCW 49. We find that the shell of radius ~ 6 pc is expanding at a velocity of 13 km s-1 toward the observer. Comparing our observed data with the ancillary data in X-Ray, infrared, sub-millimeter and radio wavelengths, we investigate the morphology of the region. The shell has a well defined eastern arc, while the western side is blown open and is venting plasma further into the west. Though the stellar cluster, which is ~ 2 Myr old gave rise to the shell, it only gained momentum relatively recently as we calculate the shell's expansion lifetime ~ 0.27 Myr, making the Wolf-Rayet star WR20a a likely candidate responsible for the shell's re-acceleration.
4:10–5:40 pm ET, iPoster 137.04. Stellar feedback and triggered star formation in the prototypical bubble RCW 120, M. Luisi
Radiative and mechanical feedback of massive stars regulates star formation and galaxy evolution. Positive feedback triggers the creation of new stars by collecting dense shells of gas, while negative feedback disrupts star formation by shredding molecular clouds. Although key to understanding star formation, their relative importance is unknown. Here we report velocity-resolved observations from the SOFIA legacy program FEEDBACK of the massive star-forming region RCW 120 in the [CII] 1.9 THz fine-structure line, revealing a gas shell expanding at 15 km/s. Complementary APEX CO J=3-2 345 GHz observations exhibit a ring-structure of molecular gas, fragmented into clumps that are actively forming stars. Our observations demonstrate that triggered star formation can occur on much shorter timescales than hitherto thought (<0.15 Myr), suggesting that positive feedback operates on short time periods.
4:10–5:40 pm ET iPoster Session 153.01. Tracing a cloud-cloud collision towards the DR21 ridge with [CII], L. Bonne et al.
4:10–5:40 pm ET iPoster Session 153.02. The SOFIA Mid-Infrared Imaging Survey toward Giant HII Regions: W49A, J. De Buizer et al.
4:10–5:40 pm ET iPoster Session 153.15. How Massive Star FEEDBACK Carves Pillars out of Dense Gas, R. L. Karim et al.
4:10–5:40 pm ET iPoster Session 153.16. SOFIA Elucidates the Structure of the Galactic Center H II Region/PDR Sgr B1, J. P. Simpson et al.
Tuesday, January 12
12:40–1:00 pm ET, Oral Session 219.04. Bayesian Analysis for Characterization of Analogs to High-z Galaxies, S. M. Motino Flores et al.
4:10–4:20 pm ET, Oral Session 229.01.Accretion in the Inner Regions of Disks Around Massive Young Stellar Objects, A. Barr et al.
5:00–5:10 pm ET, Oral Session 228.05. Magnetic Field of the Galaxy M82, J. Guerra Aguilera, et al.
5:20–5:30 pm ET, Oral Session 232.06. Mapping the Magnetic Field in Fillamentary Cloud L1495/B211 with SOFIA HAWC+, P. Li et al.
Wednesday, January 13
12:50–1:00 pm ET, Oral Session 306.05. Dust Alignment and Magnetic Fields in the 30 Doradus Star-Forming Region, S. Coude et al.
1:20–1:30 pm ET, Oral Session 308.07. Magnetic Field in the Central Region of the Circinus Galaxy with SOFIA/HAWC+, L. Grosset et al.
4:10–5:40 pm ET, iPoster 342.07. New Insights into the ISM Conditions in Infrared-Luminous Galaxies, M. Jimenez et al.
4:10–5:40 pm ET, iPoster 343.03. Towards Understanding the Galactic H II Region Sgr B1: Dust properties and Massive Stars, A. Cotera et al.
4:10–5:40 pm ET iPoster Session 348.05. Polycyclic Aromatic Hydrocarbons (PAH) and Paschen-Alpha Imaging Survey of NGC 2024 with FLITECAM, J. Klusmeyer et al.
Thursday, January 14
12:30–12:40 pm ET, Oral Session 406.04. The First Mid-Infrared Detections of HNC and H13CN in the Interstellar Medium, S. Nickerson et al.
12:40–12:50 pm ET, Oral Session 408.04. Deconstructing IR emission in AGN Deconstructing IR Emission in AGN using SOFIA/HAWC, L. Fuller
4:10–4:20 pm ET, Oral Session 430.01. The Multi-Phase Spiral Magnetic Field of M51, A. S. Borlaff et al.
4:30–4:40 pm ET, Oral Session 430.03. The Magnetic Feld across the Warped Molecular Disk of Centaurus A, E. Lopez Rodriguez
4:30–4:40 pm ET, Oral Session 441.03. Molecular Gas along the Bar of NGC 7479, D. Fadda et al.
Friday, January 15
12:50–1:00 pm ET, Oral Session 511.06. Building a High-Resolution Mid-Infrared Spectral Line Database for Hot Molecular Cores, N. Rangwala
4:40–4:50 pm ET, iPoster-Plus Session 526.04. SOFIA/FLITECAM 3-5.4 micron Spectroscopy of PAHs in Planetary Nebulae, E. C. Smith et al.
SOFIA Exhibit Hall Booth
SOFIA staff will be available at a virtual exhibit booth for discussion and Q&A. Be sure to visit and pick up some virtual swag!