Editor’s Note: This week we’re at the virtual 238th AAS Meeting. Along with a team of authors from Astrobites, we will be writing updates on selected events at the meeting and posting each day. Follow along here or at astrobites.com. The usual posting schedule for AAS Nova will resume on June 14th.

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LAD Plenary Lecture: Origins of Astrochemical Complexity (by Luna Zagorac)

Astrochemical complexity and its origins is a topic that is just too — well, complex! — to cover in a single plenary. For this reason, Karin Öberg (Harvard University) began with a small amendment to the talk title: she focused on “(Icy) Origins of Astrochemical Complexity (During Planet Formation).” Specifically, she tracked the origins of volatile organic compounds through the process of planet and star formation. In chemistry speak, “volatile” means that these molecules prefer to be in the gas stage, while “organic” means that they necessarily have a carbon (C) atom, often linked to oxygen (O) and nitrogen (N). Understanding where these molecules come from is crucial, because they are the building blocks of life on Earth!

But before we can have life, we have to have a planet. The story of planet formation, roughly, is as follows: first, there is a cloud of dust; as this cloud collapses it forms a protostar in the center, and subsequently a protoplanetary disk around it. This system evolves until it begins to look something like our solar system: a central star with (some terrestrial) planets orbiting it, one of which might contain a life-form. But where along this celestial journey did we pick up enough organic volatile molecules to make up said life-form?

The answer: at every stage! First, consider the cloud stage: this is the only stage of the process cold enough (~10 K!) to form ices of volatiles such as methanol, CH3OH. Because these ices are also detected in the later protoplanetary disk, this must mean the ices survive into the next stage of the process! Furthermore, though it’s too cold to spontaneously turn these methane ices into more complicated compounds, lab experiments show that there are a few channels for getting these reactions started. One channel is an influx of energy from a stray cosmic ray, which would break up an icy molecule and send it over its activation potential for reacting with its neighbors; another has to do with oxygen insertion (see Jenny Bergner’s LAD Dissertation Talk Prize for more on this!). Once the protostar forms, it warms up its surroundings to about ~30 K, where not only is it easier to form complex molecules, but different mixtures become possible. All of these compounds are inherited by the protoplanetary disk, which in turn hosts its own in situ chemical reactions further contributing to molecular diversity and complexity.

The takeaway: not only are organic chemical environments of planet-forming regions shaped by cloud, protostellar, and in situ disk chemistry, they are also shaped by ice organic chemistry. For the latter, lab experiments have been and continue to be crucial in identifying new formation pathways and their efficiencies.

Interview of Karin Öberg by Ellis Avallone
Live-tweeting of the session by Luna Zagorac

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Press Conference: Molecules in Strange Places (by Tarini Konchady)

The first presentation at this briefing was given by Kate Gold (Bryn Mawr College) and Deborah Schmidt (Franklin & Marshall College). They discussed the preliminary results of a search for molecules around planetary nebulae (PNe). PNe play a key role in determining the chemical content of the interstellar medium, so it’s important to ascertain what molecules can survive the violent irradiation that occurs in the PNe stage. Models suggest that scarcely any molecules make it out intact, but observations point to the opposite being true! Using the 12 Meter Telescope and the Submillimeter Telescope in Arizona, the team searched for signatures of the molecules HCN and HCO+ in 13 PNe of varying ages. Not only did they find significant fractions of these molecules around most of the observed PNe, they also found that the presence of those molecules did not change significantly with PNe age.

The next presentation was given by Lucy Ziurys (University of Arizona) on using ALMA (Atacama Large Millimeter/submillimeter Array) to search for the previously mentioned molecules in other galaxies. Given that PNe are an end stage for some stars, they have a lot to tell us about stellar evolution. One open problem in astrophysics is how we get very non-spherical PNe from roughly spherical stars. With the relatively new discovery that PNe can be molecule-rich, researchers decided to try using ALMA to make “molecular images” of PNe by observing the molecular gas associated with these objects. These images offer a new window into PNe because the cold molecular gas produces features that don’t usually show up in optical images. These results could point us to how PNe are shaped.

The third presentation was given by Lilia Koelemay (University of Arizona) on the detection of organic molecules on the outer edges of the Milky Way. While our galaxy has some assumed habitable zone (the “galactic habitable zone”), organic molecules have been found much further out than the extent of that habitable zone. This motivated another search for organic molecules in molecular clouds at distances between ~42,000 light-years and ~77,000 light-years from the center of our galaxy. The search found that the abundances of the relevant organic molecules didn’t change much with distance — extending the “OZ” or organic zone of the Milky Way. This finding informs our ideas of where life could arise. Press release

The last presentation was given by Annie Hughes (Institut de Recherche en Astrophysique et Planétologie) on the PHANGS-ALMA (PHANGS: Physics at High Angular resolution in Nearby GalaxieS) survey of molecular gas across a large sample of galaxies. Molecular gas is critical to star formation and star formation influences galactic structure, so it follows that we could learn a lot by studying the distribution and properties of molecular gas in a large variety of galaxies. With this in mind, the PHANGS-ALMA survey mapped CO emission across 90 galaxies. With these observations, the team found that molecular clouds in the central regions of galaxies tended to be denser, more massive, and more turbulent than their counterparts on the outskirts. Press release

Live-tweeting of the session by Tarini Konchady
YouTube recording of the session on the AAS Press Office channel

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STScl Town Hall (by Sabina Sagynbayeva)

Dr. Nancy Levenson, the deputy director of STScI, reported on the status of the existing and upcoming missions and described new opportunities designed to advance astrophysics through the 2020s.

She started off reporting the most recent status of the institute: Most Institute staff are working from home now. More people will return on-site in the coming months, but STScI will not host visitors or conferences in person through the calendar year due to focus on current missions.

What missions? Here’s a status update on a few:

• JWST is going to launch later this year!
• Hubble’s doing great. Cycle 28 is underway, and the review for Cycle 29 will happen this month. STScI encourages you to share your results if you used Hubble or another telescope supported by STScI, and STScI can help disseminate newsworthy findings. Hubble’s program ULLYSES, a large Director’s Discretionary program for the community to obtain a spectroscopic reference sample of young low- and high-mass stars, put out its second data release in March 2021.
• The Nancy Grace Roman Telescope will provide a Hubble quality with 100 times the field of view. Roman is working toward launch in the mid-2020s. Also, the primary mirror is complete and all WFI science detectors are available. Levenson also reports that ALL data from Roman will be available with zero exclusive access period. Also, Mikulski Archive for Space Telescopes (MAST) can provide data from Hubble, Webb, Roman, Pan-STARRS, and others.

STScI user committees welcome your input! Their reports and contact information are available on the STScI.edu website:

• Space Telescope Users Committee (STUC)
• JWST Users Committee (JSTUC)
• MAST Users Group (MUG)
• Roman Space Telescope Advisory Committee (RSTAC)

Next, Christine Chen discussed the JWST Cycle 1 General Observer (GO) Program. Approximately 33.5% of successful proposals are led by PIs from ESA countries, and 4% by PIs from Canada, but overall there were proposals from all over the world. She also reminded us of the Dual Anonymous Review: proposal reviews were conducted with the identities of the proposal teams removed from the proposals, and each panel has a Leveler who helps to keep the panel discussion focused on the selection criteria.

Chen outlined some of the approved proposals:

• Protoplanetary disks observations will study the chemistry of water and organics in the terrestrial planet forming regions (<5 AU) and use coronagraphic imaging to search for protoplanets in at least 12 disks
• Transiting exoplanet observations include the study of sub-Neptunes and super-Earths with time-series spectroscopy and planets transiting active M dwarf stars.
• Nearby Galaxy Observations will contribute to understanding of the stellar populations and ISM within nearby galaxies
• AGN outflows and feedback observations will leverage 5–28 µm spectroscopy to determine the heating mechanisms for and estimate the energetics of outflows; characterize the molecular gas, dust, AGN, star formation and metallicity within the central regions; and map the AGN’s influence on the distribution of metals and star formation in different environments
• Galaxy imaging surveys will image the sky using NIRCam (and MIRI), providing the gold-standard imaging data set for galaxy assembly studies, studying the sources responsible for the reionization of hydrogen, and probing the era of the first galaxies, pushing beyond z = 10
• Galaxy spectroscopic surveys will observe thousands of galaxies using NIRCam and NIRISS WFSS to provide line diagnostics reaching redshifts up to z = 7 and beyond, enabling characterization of the physical properties of galaxies all the way to cosmic dawn

A final point mentioned is that STScI is hosting JWebbinars! These are entirely virtual classes with ~40 participants with hands-on instructions on common data analysis methods for JWST observations. All materials are made available after the classes.

Live-tweeting of the session by Sabina Sagynbayeva

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Meeting-in-a-Meeting: Transient Discovery with Machine Learning (by Sabina Sagynbayeva)

Gautham Narayan (University of Illinois at Urbana-Champaign) opened the session with “Deep Learning for Multimessenger Astrophysics.” How can we classify sources in the huge volume of photometric data expected in the future? Narayan presents on the Photometric LSST Astronomical Time-series Classification Challenge (PLAsTiCC), a means of using deep learning to classify the time-domain sky. The primary goal? To set up a massive time-domain simulation infrastructure and jumpstart machine learning photometric classification efforts.

Andrew Vanderburg (University of Wisconsin-Madison) next talked about “Exoplanet Detection using Machine Learning”. The problem in exoplanet detection is that planets are not the only things that cause stars to dim periodically! We have a lot of data from Kepler and TESS, but we need to identify the dimmings that are specifically caused by planets. Machine learning does two things better than humans: it can perform similar tasks much faster, and it can perform pattern recognition, identifying predictive relationships between different observations that are too complex for traditional methods to solve. Vanderburg presented on how these advantages have been leveraged for exoplanet detection with great success, resulting in multiple potential new planets and the first mass measurement of a known planet around an active star.

Michelle Lochner (University of the Western Cape/ South African Radio Astronomy Observatory) next discussed “Transient Classification and Anomaly Detection in the LSST Era.” The Vera Rubin Observatory will produce an incredible dataset, but it is also going to be an incredible challenge. There are rare events that we know exist, e.g. kilonovae, which Lochner calls “known unknowns.” But unknown unknowns are exciting, too! How do we discover new phenomena among 10 million possibilities? An interesting anomaly to one scientist isn’t interesting to another scientist — so here comes active learning. Lochner built Astronomaly, a package for active anomaly detection for astronomical data. By running machine learning algorithms, this pipeline picks up things that are strange and gives an image a score of how “interesting” it is. Lochner concluded by mentioning their mentoring program for women and gender minorities in physics (and they need more mentors!).

Ashish Mahabal (Caltech) talked about “Machine Learning Aided Classification of Transients and Variables in ZTF.” The Zwicky Transient Facility (ZTF) has a catalog of billions of astronomical objects and specialized filters depending on science use cases. It registers hundreds of thousands of events every night. Mahabal provided an overview of parts of the machine learning workflow in place to discover and classify transients by combining ZTF photometry and spectra from the SED Machine (SEDM).

Guillermo Cabrera-Vives (Department of Computer Science, University of Concepción) wrapped up with “Machine Learning within the ALeRCE System: Past, Present and Future”. ALeRCE is an astronomical alert broker — a system that ingests, processes, and redistributes alerts that come from programs like ZTF — or, in the future, LSST. ALeRCE receives an alert stream about possible transient detections, and then applies machine learning to classify the transient, crossmatch it with archival catalogs, and more.

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NSF Town Hall (by Macy Huston)

The NSF Town Hall began with updates on Division of Astronomical Sciences (AST) staffing from interim director Chris Smith, followed by updates on observatories and instruments. In recent NOIRLab news, the Dark Energy Survey’s first three years of observations have produced 30 new papers. Meanwhile, the Dark Energy Spectroscopic Instrument (DESI) has completed its trial and begun the five year survey. Exciting news at the Green Bank Observatory is the development of radar capabilities by the NRAO on the Green Bank Telescope.

Finally, the Covid-19 pandemic has caused delays and additional expenses in telescope construction. The Daniel K. Inouye Solar Telescope is now estimated to begin operations at the end of 2021. Its Cycle 1 call for proposals will be May 1, 2022, and the start of steady-state observations is anticipated for November 2022. The Vera C. Rubin Observatory is now estimated to begin operation in the first half of 2024.

James Neff reviewed the AST division’s programs and budgets. Two new programs for postdoctoral fellows (MPS-Ascend, NSF 21-573) and pre-tenure faculty (MPS-LEAPS, NSF 21-570) have deadlines approaching in mid-June. Funding opportunity deadlines and program leads were reviewed, and are available on their website.

Ashley Vanderley presented the status of the recently collapsed Arecibo Observatory. Cleanup, an environmental assessment, and an investigation of what went wrong are underway. The observatory team also prioritizes historical preservation, salvaging objects such as a receiver and some reflector panels for display at the site or a museum. The Arecibo Observatory Options Workshop is currently underway. Those who did not register in time are able to watch informational talk recordings on the website and submit ideas to Arecibo-feedback@nsf.gov.

The Electromagnetic Spectrum Management (ESM) exists to ensure the scientific community access to portions of the EM spectrum needed for research. This has been expanded from a focus on radio to include infrared and optical concerns, increasing the management team from 1–2 members to 3–4. Their astronomical concerns are keeping clean, wide bandwidths for radio astronomy, keeping dark skies in the optical/IR, and broadening participation.

Lastly, Chris Smith returned to present the NSF’s fiscal year 2022 budget request. The request increased from $8.5B in FY2021 to $10.17B. Their goals prioritize fundamental research, emerging technology, equity, climate science and sustainability, and research infrastructure. They are looking forward to the Astro2020 community recommendations to help guide upcoming year budgets. They will examine science priorities, the required facilities, and how to support a diverse pool of science-engaged people.

Live-tweeting of the session by Macy Huston

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Annie Jump Cannon Prize Lecture: Turbulent Beginnings: A Predictive Theory of Star Formation in the Interstellar Medium (by Ellis Avallone)

The first afternoon plenary of AAS 238 Day 2 is by Blakesley Burkhart (Rutgers University), winner of the 2019 Annie Jump Cannon Prize! Dr. Burkhart is an expert in turbulence, a complex phenomenon that affects space at a vast range of scales.

Her talk begins by first highlighting Annie Jump Cannon herself, whose work in the early 20th century set the stage for the now well-established subfield of stellar evolution. Star formation, however, is an astrophysical process that remains largely unsolved. According to Dr. Burkhart, “We really don’t have a good predictive model [for star formation].” Uncertainties in star formation processes, incidentally, reverberate through all aspects of astrophysics, from galaxy dynamics to planet formation.

Next, Dr. Burkhart describes a key question that threads through star formation research: the star formation efficiency problem. If we assume gravity is the only factor that causes gas in the interstellar medium to collapse into stars, we should observe a star formation rate around 250 solar masses per year. However, if we look at our own galaxy, we observe a star formation rate around 3 solar masses per year. This makes one thing abundantly clear: star formation is incredibly inefficient! Our key problem is now focused on not forming stars, i.e., preventing star formation from being too efficient in our models.

Dr. Burkhard notes that when we look at star formation observationally, we find that star formation efficiency rate is around 1% for both close-by and high redshift galaxies. These similarities from such a diverse galaxy sample indicate that there’s something universal about the physics in star-forming clouds. With that, Dr. Burkhart describes the analytical models and simulations that are critical for understanding this problem.

Most analytical models use a lognormal distribution to describe the density of gas in star-forming clouds. This distribution offers a straightforward way to compute properties of a star-forming cloud — like the star formation rate. However, when we look at observations, we find that parameters that we expect to be correlated with one another are not correlated at all. Therefore, the model has to be adjusted! Dr. Burkhart and her group looked to simulations to determine how to adjust the model and found that at high densities, the gas density distribution behaves much more like a power law. They additionally found that the power law distribution agreed much more strongly with observations.

Simulations are also incredibly useful for looking at which physical processes suppress star formation. Dr. Burkhart’s group found that turbulence does not provide support against gravitational collapse in a star-forming cloud, which was quite the surprise! Instead, magnetic fields and feedback from young stars are the processes that prevent the cloud from collapsing efficiently, and therefore do all the heavy lifting against gravity. When they incorporate these factors into their analytical model, they are able to reproduce the star formation efficiency rate and gas depletion time expected in simulations, which bodes well for future comparisons with observations.

Interview of Blakesley Burkhart by Pratik Gandhi
Live-tweeting of the session by Ellis Avallone

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Meeting-in-a-Meeting: Measuring the Properties of Stars with Machine Learning (by Mia de los Reyes)

In this session of the “Machine Learning in Astronomy” splinter meeting, we learned about some of the ways data-driven techniques can be used to study stars!

Stella Offner (The University of Texas at Austin) started us off by speaking about “Harnessing Machine Learning to Identify Stellar Feedback.” Stars are messy! They inject energy and momentum into their environments, and this feedback can produce all kinds of features in the interstellar medium. Such features, like bubbles and outflows, are often identified visually — but this is time-consuming, subjective, and hard! Offner described an algorithm that instead uses convolutional neural networks to identify these features. After being trained on simulated maps of molecular emission, this algorithm does a great job of finding structures produced by feedback — it’s even been able to show that the feedback in these features scales almost one-to-one with the number of individual young stars in a molecular cloud!

Next, Anna-Christina Eilers (MIT) discussed “Mapping the Milky Way with data-driven models.” We live in an era of abundant information about the positions, motions, and spectra of stars in the Milky Way, which can be used to answer open questions about our galaxy’s formation and evolution. But these data have uncertainties! Eilers is using machine learning techniques to derive precise distances and to calibrate stellar abundances. For example, by assuming that red giant branch stars have “standardizable” luminosities, Eilers can use photometric and spectroscopic data to predict their distances with high precision. Similarly, stellar abundances can be predicted using a function of stellar properties. These can be used to make precise maps of stellar velocities and abundances in the Milky Way.

Melissa Ness (Columbia University) went more in-depth on stellar abundances with a talk on “Measuring the properties of stars with data-driven computational approaches.” Surveys like APOGEE and LAMOST are providing us with millions of stellar spectra. What information is contained in these spectra, and how can we use them for science? Ness describes how pipelines like The Cannon are able to reproduce stellar spectra with a simple model that includes only a few stellar properties, like effective temperature, surface gravity, and iron abundance. Interestingly, although spectra contain information about many elements, just a few elements (like iron and magnesium) are needed to predict the abundances of other elements. Finally, data-driven techniques can be used to identify stars with outlier spectra, which can help probe the physics of stellar evolution.

Lily Zhao (Yale University) also discussed stellar spectra, but focused more on measuring radial velocities rather than abundances. In the talk “Machine Learning for Extreme Precision Radial Velocity,” Zhao explained that in order to discover an Earth-like planet using radial velocities, we’d need a spectrograph with around 10 cm/s precision. Next-generation spectrographs can reach sub-m/s precision, but spectroscopic effects from stellar activity become a significant source of error. This is where machine learning comes in! Data-driven techniques can effectively reduce the impact of stellar activity on radial velocity measurements.

Last but not least, J. Ted Mackereth (CITA / Dunlap Institute / University of Toronto) spoke about “The Stellar Age Revolution, feat. Asteroseismology, Spectroscopy, and Machine Learning.” One of the most precise ways to measure stellar ages is by using asteroseismology, which is classically done by measuring the global properties of stellar oscillations. We can do even better if we use more detailed information about individual frequencies, or if we use additional information from spectroscopy! Again, data-driven techniques can help with this. For example, using combined data from APOGEE abundances and Kepler asteroseismic data, a neural network can significantly improve upon uncertainties in stellar ages. With these more precise measurements, we can start to pick out patterns of ages, dynamics, and abundances in the Milky Way.

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LAD Laboratory Astrophysics Prize: Tales from a Life in Laboratory and Observational Molecular Astrophysics (by Luna Zagorac)

The winner of the AAS LAD Laboratory Astrophysics Prize, Geoffrey Blake (Caltech), looked back on a long career of astrochemical achievements in his talk. The Blake group at Caltech focuses on spectroscopy, spanning the range from microwave to infrared and near-optical frequencies. This is equivalent to a range in temperatures from a few to a few thousand Kelvin, allowing them to probe a wide variety of molecular motions in the sky. Blake emphasized the exquisite quality of ALMA data for astrochemistry, noting that his group worked on laboratory instrumentation to bring it in step with the quality and quantity of observational data. On the other hand, the opposite is true when studying chiral molecules with three dipole moments: they are very-well understood in the lab, but they would require circularly polarized light sources in the sky imaged with an instrument at least the size of the Square Kilometre Array to study observationally. Finally, he highlighted how Spitzer data allows us to study ices and gases (including water!) in planetary formation contexts. He closed out his talk with acknowledgements of both his mentors and past and current students and postdocs, noting particularly how lucky he was to become a Duke Microwaver during his time at Duke University, which ultimately led him to discovering his own astrochemical path.

Live-tweeting of the session by Luna Zagorac

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LAD Dissertation Prize: Oxygen Insertion Chemistry: A Low-temperature Channel to Organic Molecule Production (by Luna Zagorac)

The graduate thesis written by Jenny Bergner (University of Chicago) was instrumental in the discovery of a new pathway for complex molecules to form in the icy interstellar medium (ISM): it’s no wonder that she won the LAD Dissertation Prize! Recreating the conditions of the ISM in the lab (a temperature of about 10 K and pressure many orders of magnitude below atmospheric), Bergner was able to use infrared spectroscopy to monitor what happened to icy molecules under these conditions. Turns out, an oxygen singlet state (a form of oxygen atom denoted as O(1D)) is able to insert itself directly into the bond between a carbon and hydrogen atom, forming new organic compounds in a process called O-insertion. The kicker? It’s able to do this without any energy input — meaning, it could even happen in the harsh conditions of the ISM!

This process leads to fragmentation, meaning that new but less complex molecules are produced. However, this is true of so-called saturated hydrocarbons, with a single bond between the C and H atom. In unsaturated hydrocarbons, which might have double or triple bonds between two carbon atoms, an analogous process called O-addition can take place, again with no energy input. Thus, O-insertion and O-addition are able to account for much of the astrochemical complexity seen in ISM ice. Furthermore, no other mechanism can explain the production of ethylene oxide (which has been detected in the ISM). Finally, Berger talked briefly about the role of comets in transferring ISM ices into protoplanetary systems. Small grains could not survive this journey, but larger ones were found to experience virtually no loss on this journey.

Interview of Jenny Bergner by Luna Zagorac
Live-tweeting of the session by Luna Zagorac

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SPD Harvey Prize Lecture: A Journey from Quiet Sun Magnetic Fields to Flares (by Sabina Sagynbayeva)

The SPD/AAS early career Karen Harvey Prize is awarded in recognition of a significant contribution to the study of the Sun early in a person’s professional career. This year’s winner, Lucia Kleint (University of Geneva), got into research on solar flares accidentally, but she continues to investigate their inner workings today while also trying to understand how to improve solar observations! 

Solar flares are powered by strong magnetic fields; an incredibly useful tool for studying these magnetic fields is polarimetry, a method where polarization of spectral lines are used to reconstruct solar magnetic fields. Dr. Kleint’s PhD focused on the variation of the turbulent magnetic field over the course of a solar cycle. However, they found that polarization gets canceled out due to the sum between positive polarity and negative polarity. But at the Sun’s limb, the polarization is not zero. That’s why they position the spectrograph very close to the limb (5’’ from the limb). In simulations, they can see that the polarization is decreasing. The Hanle effect (depolarization depending on the magnetic field) can help to detect even small magnetic fields. They measured the magnetic field every month and found no variation, a surprising constant from 2007–2010!

Why does the turbulent magnetic field depend so much on the spectral line it’s observed with? Maybe these spectral lines show different things! We need separate images of the Hanle effect, but so far it’s not possible. They are still unable to properly resolve small-scale magnetic fields due to a lack of photons. Here is where DKIST comes in: this behemoth of a solar telescope is able to look at fine scales on the solar surface using multiple spectral lines.

Dr. Kleint continues to look at solar flares today. People have a general idea how solar flares work, but we still have a hard time predicting them. Dr. Kleint is particularly interested in how to predict solar flares, understanding how their energy is dissipated and the evolution of their magnetic structure, and why other sun-like stars produce much stronger flares than what we observe on the Sun.

When solar flares were first observed, interpreting these observations was extremely difficult.  Today, dedicated flare campaigns at numerous observatories around the world have yielded an overabundance of data. One such flare campaign at the Dunn Solar Telescope has observed what NASA has called the best-observed flare, which sparked the authorship of dozens of papers analyzing this single event!

Even with this abundance of flare observations, puzzling things kept showing up in the observations. Observations from the Solar Dynamics Observatory HMI instrument prompted the adoption of a new flare mode. However, the difference in activity between the solar surface and atmosphere at the flare site leaves more questions unanswered. So the question is: Are our models valid for all flares, or only for particular flares? Machine learning has been critical for digging through the mountains of flare observations, however Dr. Kleint wants to know how we can improve instrumentation to address these unanswered questions. 

Her wish list:

• So far, we have no regular high-resolution chromospheric magnetic field measurements. Do we need DKIST, or a spacecraft?
• Advances in flare modeling and analysis (Radyn, RH, STIC, machine learning)
• Automatic analysis of millions of spectra/images, which may enable flare prediction

The observations wouldn’t be possible without telescopes! Dr. Kleint discussed the recent redesign of the GREGOR solar telescope, located in Spain. The improvements included a new mirror, producing higher contrast; a new optics design, which solved image aberrations; and reduction of vibrations and temperature variations.

There are still many open questions from quiet Sun magnetic fields to flares that are waiting to be explored.

Live-tweeting of the session by Sabina Sagynbayeva

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Seminar for Science Writers: Get Ready for Webb! (by Tarini Konchady)

Christine Pulliam and Hannah Braun (Space Telescope Science Institute) introduced this seminar, which is intended to give an overview of the James Webb Space Telescope (JWST) and the science it will do. First, Eric Smith (NASA Headquarters) provided a description of the final months before JWST’s expected launch and the commissioning that will follow. The telescope continues to be tested to ensure it will work after launch, and the Cycle 1 observing programs have been announced (see the summary of the STScI town hall). Following launch, JWST will see a roughly 180-day commissioning, during which it will ready itself to observe. This process includes the deployment of the telescope mirrors and the calibration of the scientific instruments on board. Cooling is also a critical part of this process, since JWST will be observing in the infrared.

The following speakers focused on the science that will be done by JWST. Dan Coe (Space Telescope Science Institute) discussed how the telescope will allow us to view the oldest galaxies yet — in fact, it will put us in reach of the first galaxies to have formed in the universe. This part of JWST’s mission will include observing the Hubble Ultra Deep Field. One interesting note is that the faintest galaxies JWST will be able to see can be observed in two ways: by staring into seemingly empty patches of sky for a very long time, or by identifying lensing systems. Spectra of these distant galaxies will also be extremely valuable, as they can tell us about the composition of those galaxies.

Next, Ilse Cleeves (University of Virginia) discussed JWST’s potential impact on the study of planet and star formation. Specifically, astronomers are very interested in how formation happens and the chemical composition of the resulting stars and planets. Right now, ALMA has been our best probe of star and planet formation, and its high quality observations have opened many avenues for JWST to explore. These avenues include observing the earliest stages of star formation, characterizing the composition of cold interstellar medium, and constraining the sort of material that forms terrestrial planets.

Knicole Colón (NASA Goddard Space Flight Center) followed with an overview of the exoplanet science that can be done with JWST. Aside from the previously mentioned formation questions, JWST will also be able to study the compositions of exoplanets and their atmospheres. The telescope’s strength here lies in its infrared capabilities; direct imaging of exoplanets will be more viable than it has been before, and a wider range of chemical signatures will be detectable in transiting exoplanets’ atmospheres. JWST will also afford us detailed study into the disks that form planetary systems.

Finally, Heidi Hammel (Associated Universities for Research in Astronomy) covered the solar system science planned with JWST. Given JWST’s observing position, it will not be able to observe much interior to the Earth’s orbit. However, that still leaves a lot to explore! JWST will be able to create surface maps of Mars, tracing dust, water, and other material. It will also be able to explore the diversity in asteroids and comets. The gas giant planets also have a lot to reveal, from why Jupiter’s Red Spot is red to the weather on Uranus. Planetary moons that appear to have water, like Europa and Enceladus, will also be studied. The even more distant Kuiper belt objects will be within JWST’s reach, and the telescope is also ready for unexpected events like the 1994 Jupiter impact.

More information can be found at https://webbtelescope.org/ and https://webbtelescope.org/news/webb-science-writers-guide.

Live-tweeting of the session by Macy Huston
YouTube recording of the session on the AAS Press Office channel

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Plenary Lecture: Our Galaxy in Context: Satellite Galaxies around the Milky Way and Its Siblings (by Mia de los Reyes)

Marla Geha (Yale University) wrapped up Day 2 of #AAS238 by discussing the “nieces, nephews, and niblings” of the Milky Way: the low-mass satellite galaxies around Milky Way-like galaxies! Why focus on these small galaxies? The ~60 known satellite galaxies around the Milky Way are useful laboratories for testing theories about cosmology and galaxy formation.

From a cosmological standpoint, these galaxies can help us probe the nature of dark matter! One extreme example: “cold” (i.e., non-relativistic) dark matter simulations predict lots of low-mass galaxies (galaxies with stellar masses < 106 solar masses), while “warm” dark matter models predict far fewer of them. Satellite galaxies can also answer questions about galaxy formation and evolution — in particular, what processes turn off (“quench”) star formation in galaxies? Nearly all of the satellites close to the Milky Way have been quenched, while low-mass galaxies further away still have gas and are still able to form stars. Is this “quenching fraction” characteristic of all galaxies that are satellites of more massive galaxies, or is the environment around our Milky Way somehow unique?

In order to make quantitative comparisons between satellite galaxy populations, we need to observe approximately 100 Milky Way-like galaxies. This is where the Satellites Around Galactic Analogs (SAGA) survey comes in! The SAGA survey has so far identified around 40 Milky Way-like galaxies, and many of their satellites look very similar to the Milky Way’s satellites. Overall, the numbers and luminosities of satellite galaxies around Milky Way-like hosts are consistent with what we see in the Milky Way, and with predictions from simulations. But the quenched fractions of satellite galaxies seem much lower than we expect from our galaxy and from simulations! Hopefully more data will help us figure out what’s going on — and maybe soon we’ll be able to study more low-mass galaxies in general, not just ones around Milky Way-like galaxies!

Interview of Marla Geha by Mia de los Reyes
Live-tweeting of the session by Mia de los Reyes

Editor’s Note: This week we’re at the virtual 238th AAS Meeting. Along with a team of authors from Astrobites, we will be writing updates on selected events at the meeting and posting each day. Follow along here or at astrobites.com. The usual posting schedule for AAS Nova will resume on June 14th.

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Welcome Address (by Luna Zagorac)

The 238th Meeting of the American Astronomical Society was opened by President Paula Szkody, who acknowledged that the meeting was originally scheduled to take place in Anchorage, Alaska. While Dr. Szkody acknowledged many people are missing the in-person interactions of AAS meetings, meeting online has allowed more folks to join the summer meetings that would be possible in-person. Dr. Szkody led us through AAS officer and staff changes, progress of AAS publications, changes to prize nomination processes, and more. Finally, Dr. Szkody gave us a quick overview of the schedule of the meeting, and highlighted that another pro of meeting online is the ability to go back and watch overlapping talks. Read on for summaries of the plenaries and press conferences of Day 1 of #AAS238!

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Fred Kavli Plenary Lecture: A New Era of Measuring Magnetic Fields in Galaxies (by Mia de los Reyes)

Astronomers like to joke that a classic question to ask after any colloquium is: “What about magnetic fields?” For a very long time, magnetic fields have been easy to “hand-wave” away because we honestly haven’t known much about them. But that’s starting to change, even in complex systems like galaxies. As Enrique López Rodríguez (Stanford Kavli Institute for Particle Astrophysics and Cosmology) points out, we’re finally starting to put together a “complete picture of galaxy evolution from a hydromagnetic framework.”

This is in part due to the impressive efforts of facilities like the Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA can observe magnetic fields by measuring the polarization of light in far-infrared wavelengths. This polarization is caused when dust grains align along magnetic field lines; light scattered by the aligned dust grains then gets polarized. Using this technique, Dr. López Rodríguez and his collaborators have been able to produce beautiful maps showing magnetic field strength and structure around nearby galaxies. From these maps, we’ve been able to determine that in spiral galaxies, large-scale magnetic fields tend to be ordered and follow the spiral arms. However, small-scale dynamo processes (like turbulence from star formation or galaxy interactions) can make the magnetic field more chaotic on local scales. Other phenomena might also affect galactic magnetic fields — for example, strong outflows caused by extreme starbursts can drag a galaxy’s magnetic field away from the galactic plane!

These are exciting first steps towards a deeper understanding of how magnetic fields contribute to galaxy evolution. Hopefully new observations (from facilities like SOFIA, and potentially even future telescopes like the proposed Origins Space Telescope) will help us continue to understand how magnetic fields work on all scales.

Interview of Enrique López Rodríguez by Luna Zagorac
Live-tweeting of the session by Mia de los Reyes

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Press Conference: Stars & Clusters (by Macy Huston)

The first press conference presentation of AAS 238 was given by James Schroeder (Wheaton College, Illinois) & Gregory Howes (University of Iowa), who explored the connection between aurorae and Alfvén waves. Aurorae are caused by disturbances in Earth’s magnetic field which accelerates charged particles. These, in turn, perturb atmospheric particles, emitting the beautiful design we often call the northern lights. Alfvén waves are a type of disturbance in magnetic fields where ions oscillate on magnetic field lines, and they have been detected during auroral events. The team used the Large Plasma Device to produce Alfvén waves in a lab, and found that electrons moving at nearly the speed of the waves would “surf” them and be accelerated. So, Alfvén waves can cause the acceleration of electrons which causes aurorae! Press release

Next, Emily Mason (USRA & NASA Goddard SFC) discussed the jet/coronal mass ejection continuum. Solar eruptions seem to exist on a spectrum, but we are most familiar with jets (small-scale ejections of plasma from a star) and coronal mass ejections (significant expulsions of plasma and magnetic fields from a star). The 2016/03/13 solar event appears to be the missing link between these two categories. In the observations, we see a “failed eruption” that collapses before material exits the Sun. The mechanism behind this event is not yet fully understood, and magnetohydrodynamic simulations are underway. Press release

Peter Garnavich (University of Notre Dame) presented the second known propeller cataclysmic variable, J0240. A cataclysmic variable star (CV) is a white dwarf (WD) star that varies in brightness over time as it accretes mass from a red “donor” star. A unique category of these is the “propeller” CV, in which the WD’s rapid rotation and magnetic field cause a significant amount of the gas pouring off the donor to be ejected from the system. The first of these found was AE Aquarii, and J0240 is the second. It is the first that has been visibly eclipsing. The measurements show a spiral pattern in the gas ejection, recurring fast flares, and absorption lines directly showing the gas. The system likely formed when a period of unstable mass transfer increased the WD’s rotational speed. As this rotational energy is used to eject gas, the WD will slow again, returning to a normal CV state. So, the propeller CV is likely a short-lived evolutionary phase that can happen in CV systems. Press release

Kris Davidson (University of Minnesota) presented Eta Carinae’s evolution over time as a “supernova imposter.” Supernova (SN) imposters, or giant eruptions, look like SN explosions, but their stars somehow survive. While several of these have been seen, Eta Carinae is the only one near enough to study in detail. It was one of the brightest stars in the sky in the mid-1800s and ejected 10–20% of its mass. Stars undergoing this process are expected to return to their normal states in ~40 years, but Eta Carinae has been weird for almost 200 years. It was discovered that the star has a hot but smaller companion star, and the pair’s colliding winds make the recovery process unsteady. The star has become brighter than its nebula and is expected to eventually ionize its nebula, dramatically altering its appearance and properties. 

Lastly, Luke Bouma (Princeton University) presented the discovery that NGC 2516, an open cluster thought to extend about 30 light-years, has a surrounding halo which extends to 1,500 light-years. Stars form in clusters, where many get ejected, while the densest regions hold together longer as open clusters. NGC 2516 was thought to be a typical 30 light-year open cluster, but recent Gaia observations suggested that a halo of stars around it are spatially nearby and possibly evolutionarily connected, though different teams reached different conclusions about this. In a new study, scientists followed up with observations from TESS, measuring rotation periods from the stars’ light curves. Using these periods to estimate age (gyrochronology), the team found that the cluster’s core and surrounding halo are the same age, confirming that they formed together. This discovery about NGC 2516 leads to the question of how many other open clusters may actually be larger than we thought. Press release

YouTube recording of the session on the AAS Press Office channel
Live-tweeting of the session by Macy Huston

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NASA Town Hall (by Sabina Sagynbayeva)

Paul Hertz, the Director of the Astrophysics Division in the Science Mission Directorate (SMD) at NASA, told us about the present and the future of NASA’s missions. He started off by reminding us of one of the most exciting accomplishments of 2021: the landing of Perseverance! He also reminded us of other major accomplishments: Parker Solar Probe’s images are the first to show the planet’s dust ring for nearly its entire 360-degree span around the Sun; Fermi’s Gamma-ray Burst Monitor detected a short outburst of gamma rays; Fermi’s Large Area Telescope detected GeV photons within minutes of the outburst. 

One of the important missions of the future is the launch of the James Webb Space Telescope. The launch is scheduled for October 2021, and so far all observatory deployments were successfully completed and Cycle 1 observing programs were selected. There’ll be a special session on Webb Space Telescope on Wednesday: Session 305. We also should expect a complete Nancy Grace Roman Space Telescope by the end of 2021!

There are a lot of exciting scientific projects that are coming in the near future, but today Hertz also emphasized DEI, and what NASA does to achieve inclusive and diverse teams. He also spent some time talking about how COVID-19 affected NASA’s missions and also what they have accomplished during the pandemic. So let’s dig into these two topics. 

NASA is creating a multi-pronged approach to achieve diversity and inclusion. One example is their web page with NASA-provided wellness resources for its researchers to better maintain a work-life balance. NASA also encourages all interested members of the public to collaborate on citizen science projects. Moreover, Dual-Anonymous Peer Review (DAPR) has been successful in removing some implicit bias towards women scientists, and according to a questionnaire DAPR improved the overall quality of the peer review. NASA is also developing a policy to ensure that the results of its federally funded scientific research are shared openly.   

NASA has been in a mandatory telework configuration due to COVID-19 for over one year now. NASA Centers are planning for ramping up onsite activities when the 25% occupancy limit is lifted. SMD is working toward multiple launches scheduled for the fall and winter of this year, including Webb, Lucy, Landsat-9, DART, IXPE, and GOES-T. Hertz also mentioned that government-wide rules allowed the flexibility to continue to pay salaries on a case-by-case basis for researchers, even if they couldn’t work during COVID-19. 

The NASA budget for fiscal year 2022 will help NASA accomplish its main goals, such as building the Earth Systems Observatory to enhance and integrate Earth system science and applications to increase the nation’s preparation, mitigation, and resilience in the face of climate change. It also keeps NASA on the path to land the first woman and the first person of color on the Moon and supports NASA efforts to strengthen inclusion, diversity, equity, and accessibility both within NASA and among the space community.

Finally, Hertz is stepping down from his position in 6 months but he emphasizes that he has accomplished all his goals. But the message he wants us to hear is: “[Looking at all these future missions], it’s a great time to be an astrophysicist!”

Live-tweeting of the session by Sabina Sagynbayeva.

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Plenary Lecture: The Time Is Now: Findings from TEAM-UP Report to Increase the Number of African Americans with Bachelor’s Degree in Physics and Astronomy (by Ellis Avallone)

The first afternoon plenary on day 1 of AAS 238 is all about the findings and lessons learned from the American Institute of Physics (AIP) TEAM-UP report! We covered the release of the report back at AAS 235 in January 2020, where we learned about the factors that lead to African American undergraduate student success in physics and astronomy departments. Tabbetha A. Dobbins (Rowan University), one of the founding members of the TEAM-UP task force, described the formation of the task force and what lessons were learned from it. 

The majority of the talk was focused on the 5 factors that TEAM-UP found were essential to African American student success: a sense of belonging, physics identity, academic support, personal support, and supportive leadership and structures. Dr. Dobbins also emphasized the importance of viewing students holistically, not just as students but as whole people with intersecting social identities and experiences. With these 5 factors in mind, Dr. Dobbins moved on to discussing recommendations for departments outlined in the report. 

She prefaced the discussion on departmental recommendations by introducing a case study. In the case study, a junior professor is looking to help a Black student who is struggling and isolated. However, the junior professor is unsure of how to help. Dr. Dobbins then described the recommendations made by the report. A key point: these suggestions purposefully do not include recommendations for students, but rather focus entirely on fixing the environments so that minoritized students can thrive. 

In the context of the case study, the first recommendation involves creating a culture where everyone is welcomed (i.e. having common spaces within the department, inviting speakers who can discuss the development of a student’s physics identity, and developing informal mentoring relationships). The department should also provide incentives for faculty to support minoritized students, both financially and as mentors; the report found that students who work as teaching or learning assistants are more likely to develop a sense of belonging and physics identity. 

To learn more about what you can implement in your department, check out the full report and follow the TEAM-UP task force for updates on the important work they continue to do!

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Press Conference: Black Holes & Active Galactic Nuclei (by Susanna Kohler)

For the second press conference of AAS 238, we turned to the ever-mysterious topic of black holes and their host galaxies. 

Alexia Lopez (Jeremiah Horrocks Institute, U. of Central Lancashire) opened the briefing with a recent unexpected find: an enormous arc of galaxies spanning a stunning 3.3 billion light-years across the sky. Such large-scale structures in the universe aren’t expected under the cosmological principle, an underlying tenet in the standard model of our universe that states that matter should be distributed homogeneously and isotropically on large scales. Press release

What happens to the active nuclei of galaxies (AGN) — accreting supermassive black holes — as they age? We may now have front-row seats to find out, according to Kohei Ichikawa (Tohoku University)! New multiwavelength observations of the heart of Arp 187 show some expected AGN features, like the presence of large-scale jets, but others are missing, like a central radio core. Ichikawa and collaborators have concluded that Arp 187 represents a “dying AGN” — the nucleus has already shut off, and we’re now seeing only the large-scale relics of its past activity.

Next up, W. Niel Brandt & Qingling Ni (Pennsylvania State University) introduced us to a new survey, XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS). XMM-SERVS is providing a unique X-ray look at the sky that fills the gap between deep surveys that cover small fields (<1 deg2) and shallow, wide-field surveys (tens or hundreds of deg2). In particular, XMM-SERVS provides X-ray coverage of three so-called Deep-Drilling Fields of the upcoming Rubin Observatory’s Legacy Survey of Space and Time (LSST) — fields of 10 deg2 that Rubin will observe much more often than the rest of the sky. XMM-SERVS has cataloged 12,000 X-ray sources in these fields, providing valuable context for LSST and a powerful view of growing supermassive black holes in a wide range of cosmic environments. Press release

Few events are more dramatic than the merger of two galaxies containing supermassive black holes at their centers — but Jonathan Williams (National Science Foundation & University of Maryland) is ready to top that with new observations of a triple merger of galaxies. In the source 2MASX J1631, two galaxies hosting AGN appear to be in the process of merging, and a third galaxy — possibly a dwarf galaxy that has already passed through the other two — lies nearby, tied to the pair via a tidal stream. Scientists are using this system to tackle fundamental questions about why galaxy cores turn on and off, and how merging galaxies evolve over time. Press release

In May 2019, LIGO detected the collision of two monster black holes of ~66 and ~85 solar masses in an event called GW190521. This raised eyebrows, as it’s believed that black holes of ~50–120 solar masses shouldn’t be able to form; stars the right size to form these black holes are thought to explode in something called a pair instability supernova. In our final briefing today, Jorick Vink (Armagh Observatory and Planetarium) introduced a possible explanation for this paradox: if a supergiant star evolves in a very low-metallicity environment, its disk winds would be very weak, preventing it from losing a lot of mass and entering the unstable size range. Such a star could successfully collapse into a black hole like the ones witnessed in GW190521 without first blowing itself apart.

YouTube recording of the session on the AAS Press Office channel
Live-tweeting of the session by Luna Zagorac

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Newton Lacy Pierce Prize Lecture: Stargazing and Supergiants: Betelgeuse, Dying Stars, and the Observational Future of Stellar Astrophysics (by Mia de los Reyes)

About a year ago, Betelgeuse became the subject of national attention when it dimmed dramatically, sparking questions about whether it was about to explode. Betelgeuse seems to be back to its normal brightness now (although you can check here for daily updates if you’re worried), and Emily Levesque (University of Washington) assures us that it’s (probably) not going to explode anytime soon. Levesque, the winner of this year’s Newton Lacy Pierce Prize for outstanding research in observational astronomy, finished off the first day of #AAS238 with a brief review of some of the science we’ve learned just from this one fascinating object.

High-resolution images of Betelgeuse show that its Great Dimming in late 2019 only affected its lower hemisphere. If Betelgeuse isn’t about to explode, what could have caused this dimming? First, convection may have produced a “cold spot” on Betelgeuse’s southern hemisphere, making it look dimmer… but there’s some disagreement about how much Betelgeuse’s temperature actually changed in 2019, and whether it was enough to cause the observed change in brightness. Alternatively, the Great Dimming could just be a “normal” variation in brightness, caused by pulsations or binary interactions that aren’t unusual for red supergiants like Betelgeuse. The final — and perhaps the most convincing — explanation is dust. Red supergiants eject lots of mass, which produces large dust grains that can block some of the light from a star.

Even if this particular star doesn’t explode in our lifetimes, we still want to know what happens to red supergiants right before they die. To fully understand what happens when the most massive stars in the universe go boom, we’ll need more observations of red supergiants near and far — including Betelgeuse. Fortunately, as Levesque emphasized, complementary observations from upcoming space telescopes and ground-based observatories will help us learn more!

Interview of Emily Levesque by Huei Sears
Live-tweeting of the session by Mia de los Reyes

This week, AAS Nova and Astrobites are attending the virtual American Astronomical Society (AAS) summer meeting.

AAS Nova Editor Susanna Kohler and AAS Media Fellow Tarini Konchady will join Astrobites Media Intern Luna Zagorac and Astrobiters Mia de los Reyes, Ellis Avallone, Sabina Sagynbayeva, and Macy Huston to live-blog the meeting for all those who aren’t attending or can’t make all the sessions they’d like. We plan to cover all of the plenaries and press conferences, so follow along here on aasnova.org or on astrobites.org!

Where can you find us? We’ll be at the Astrobites booth in the Grad Student Fair all week — stop by and join us in the chat room! In addition, you can catch Susanna, Tarini, and Luna at the press conferences all week.

We’ll also be hosting a short webinar on Wednesday at 5pm ET at the Astrobites booth, discussing how you can use Astrobites and/or get involved.

While we wish we could talk with you all in person, we’re glad to have this virtual alternative! We look forward to seeing you in sessions and visiting your posters throughout the next three days.

Lastly, if you’re interested in reading up on some of the keynote speakers before their talks at the meeting, be sure to check out the interviews conducted by Astrobites authors! They’ll be published throughout this week, and they provide a great opportunity to discover more about these prominent astrophysicists and learn about the paths they took to where they are today.

You can read the currently published AAS 238 keynote speaker interviews here. Be sure to check back all week as the remainder are released!

Editor’s Note: This week we’re at the virtual 237th AAS Meeting. Along with a team of authors from Astrobites, we will be writing updates on selected events at the meeting and posting each day. Follow along here or at astrobites.com. The usual posting schedule for AAS Nova will resume on January 19th.

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Plenary: The Role of Magnetic Fields: Galactic Science from HAWC+/SOFIA (by Ellis Avallone)

 

The first plenary of the last day of AAS was all about galactic magnetic fields. Dr. David Chuss from Villanova University is an expert in submillimeter polarimetry, a technique that utilizes the polarization of light in submillimeter wavelengths to obtain information about low-magnitude magnetic fields. Today’s talk focused on results from the HAWC+ instrument, a polarimeter on the plane-turned-telescope SOFIA. HAWC+ is especially adept at detecting galactic magnetic fields, which are notoriously difficult to measure and are often neglected. By measuring the polarization of light from magnetically aligned dust grains, we can accurately trace magnetic fields throughout our galaxy. 

A central question that drove the development of HAWC+ surrounds the role of magnetic fields in star formation. Star formation is surprisingly inefficient (both within and outside our Milky Way), and dynamic support from magnetic fields in molecular clouds can prevent the collapse of gas into stars. Magnetic fields in turn are “frozen” into matter, where they trace the motions of matter while also influencing system dynamics through magnetic pressure. It was theorized that in a gas cloud with magnetically regulated star formation, the gas would be free to collapse along magnetic field lines. However, in regions where gas motions were perpendicular to the magnetic field, magnetic pressure would prevent the gas from fully collapsing. This interaction between the magnetic pressure and gas dynamics would cause the magnetic field to follow an hourglass shape. When HAWC+ observed the Orion nebula, the closest massive star-forming region to Earth, it found the hourglass magnetic-field orientation indicative of magnetically regulated star formation. Chuss then notes that polarimetry can also be used to estimate magnetic field strengths, which can provide further insight into the balance between gas and magnetic field dynamics. With both magnetic field strength and orientation measurements, we can map the distribution of magnetic flux, which then gives us the relative importance of gravitational and magnetic motions throughout a star forming region.

For the final portion of the talk, Chuss turned to our galactic center. Magnetic fields can also affect the dynamics of material near the centers of galaxies, and our own Milky Way provides us with an up-close example. HAWC+ looked at the region directly surrounding our central black hole, Sagittarius A*, and found magnetic field lines tracing a ring of warm dust that surrounds the region. Additionally, HAWC+ found that the magnetic fields of the cool and warm dust near the galactic center are quite different in orientation from one another. Finally, Chuss discussed the magnetic fields of radio filaments in the galactic center. These bands of electrons radiate via synchrotron emission and are bound by magnetic fields that are perpendicular to the galactic plane. HAWC+ observations suggest that reconnecting magnetic fields at the surface of cloud structures are causing electrons to be accelerated to relativistic speeds.

There are still many open questions surrounding magnetic fields in our galaxy. With HAWC+, we can begin to unravel how deeply magnetic fields permeate processes in our universe.

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Special Session: Astronomy Education in a Rapidly Changing World: Best Practices from Research and Instruction (by Briley Lewis)

As all current students and teachers know, the past year has been an off-road adventure in online teaching for many of us. Today’s special session addressed this unique challenge in education, focusing on how to support astronomy education during the pandemic. To start, Sanlyn Buxner (University of Arizona & Planetary Science Institute) introduced a great general resource: two volumes of astronomy education content recently published by AAS-IOP Astronomy. The first focused on learner-centered teaching in astronomy, and the second, more recent volume dealt with online learning specifically. 

Next, Molly Simon (Adler Planetarium) discussed using citizen science, an interactive activity well-suited for online learning. Zooniverse, which started with Galaxy Zoo, is now the largest citizen science platform with over 2 million registered volunteers worldwide and many different subjects (even beyond astronomy!). In her research, Simon realized that manipulating spreadsheets, a traditional lab activity, is not necessarily the best approach to build data literacy; instead, she has developed new materials using Zooniverse that have students draw conclusions from graphs and other data representations. These materials are accessible fully online, consisting of a lecture tutorial, citizen science activity, and guided inquiry experience. They’re doing pilot testing now, so if you want to implement it in your classroom, reach out to Molly!

Nicole Gugliucci (Saint Anselm College) brought in yet another engaging online learning activity: video games! The game “At Play in the Cosmos” by Norton ties in with their eBook and includes autograding options, and it takes students on a spaceship adventure that even guides them through relevant physics equations. Students responded positively to this, saying they liked fun ways to apply concepts like this!

In a presentation called “Interrupting the d00mscroll with Astronomy”, Pamela Gay (Planetary Science Institute) describes a different approach to education in the pandemic, saying that “sometimes you just have to help people get through the moment so tomorrow they can learn.” With the Cosmoquest collaboration, they have been creating content for live internet audiences. In the pandemic, she says they realized delivering content isn’t enough right now, people need a place to come together. They’ve started doing “Community Coffee” sessions on Twitch, bringing together art and science on a Monday morning to get the week started. Using Discord, they’ve built a community chat server for people to hang out. It’s moderated by a team across the world to keep a safe and inclusive space, and they’ve created open-source bots to interact with people — they even have one that will give you a reminder to stop scrolling and go to bed! They’re doing all sorts of cool things to help people get through this together and enjoy astronomy, even building a scale model of the solar system in Minecraft.

Lastly, Matthew Wenger (University of Arizona) shared about his experiences building self-paced massive open online courses (MOOCs) on Coursera. A different approach to learning than the traditional college classroom, these types of free online courses target adults seeking education out of interest. Along with collaborators, Wenger has built two different astronomy courses, and he emphasized that peer reviewed writing assignments have been key for building student engagement in this online format. Students get to interact with one another, and bonus: writing is a great way to deepen understanding and reach higher levels of Bloom’s Taxonomy of Learning like “evaluating” and “analyzing”! 

This special session gave so many great ideas for not only dealing with online learning, but helping students thrive. As one commenter said, online learning has lots of possibilities, it’s not just a lesser stand-in for face-to-face instruction!

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Special Session: Supporting Marginalized Students in Astronomy: A Discussion Among Program Leaders on Best Practices and Ongoing Challenges (by Ellis Avallone)

This session, moderated by Prof. Kelle Cruz from Hunter College, invited leaders of diversity, equity, and inclusion initiatives to discuss the successes and challenges associated with these programs. Leaders of notable bridge programs and research internships were in attendance, including those from the Fisk-Vanderbilt Bridge Program, the Columbia University Bridge Program, Cal-Bridge, and AstroCom NYC. The panel discussed several topics, ranging from securing funding to implementing change in a department’s culture. The discussion started off with an introduction to bridge programs. These programs are designed to bridge the transition between undergrad and graduate school, and they typically focus on supporting and retaining marginalised students. The panelists noted that one of the challenges to running a bridge program is that, due to the length of most graduate programs, it takes a long time (on the order of 10 years) to see the results of a given bridge program and understand how it has impacted their students. A positive aspect of this is that the most successful programs provide long-term mentorship and support for their students, even after they’ve moved on to graduate school or industry. 

The session also included a discussion on how to best enact change within departments that want to tackle DEI projects but do not currently have support systems in place. A few panelists mentioned the importance of outside societies, whose primary focus is to evaluate a department and recommend concrete actions the department can take to improve their diversity (e.g. the AAS Site Visit Oversight Committee). Additionally, the AIP TEAM-UP report (covered by astrobites at AAS236) includes several recommendations on how departments can best support marginalized students. Finally, the panelists emphasized that cultural change within a department has to come from department leadership working with marginalized folks, and the panel advised students to identify allies within their departments who are focused on implementing substantial change. 

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Press Conference: The Modern Milky Way (by Haley Wahl)

The first press conference of the final day of AAS 237 was all about new discoveries in our home galaxy. The first speaker was Sailee Sawant from the Florida Institute of Technology, who talked about charge-injection devices. These devices employ simple, cost-effective, yet powerful techniques that allow astronomers to image a very dim companion to a very bright star (they allow extreme contrast imaging). The team has been successful in detecting and resolving previously uncatalogued sources, along with Sirius B (the very faint companion to the star Sirius A). Press release

Next up was Xinlun Cheng and Borja Anguiano from the University of Virginia talking about the galactic warp, which is the bending of the disk of our galaxy. Using stellar motions from Gaia, they were able to characterize the Milky Way’s warp and show that it could have originated from a galactic perturbation from a satellite galaxy less than 3 billion years ago. Press release

The next talk was given by Jeffrey Andrews of Northwestern University, who discussed Theia 456, a possible new stellar association in the galactic disk. He and his team found that Theia 456 is a new stellar structure in the Milky Way and spans 200 pc, or 25 degrees across the sky (that’s ~50 times the diameter of the full Moon). The stars in the structure most likely have a common origin because of their consistent age and metallicity. The team concludes by saying that this is just the beginning, and that there are possibly more of these stellar structures out there! Press release

The final talk of the session was given by Kat Barger from Texas Christian University, who talked about the Milky Way’s defense against an incoming gas cloud. She discussed Complex A, a giant gas cloud that is currently bumping elbows with our galaxy. The halo of our galaxy, however, is fighting against it and slowly dissolving the gas cloud. Complex A is currently the best-mapped gas cloud that did not originate from the Milky Way, and it helps us decipher how galaxies obtain the gas they need to form stars.

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AAS Strategic Assembly Town Hall (by Haley Wahl)

This town hall, which was rescheduled from Wednesday, focused on the strategic plans of the AAS. President Paula Szkody (University of Washington) started off by introducing the AAS vision statement, which says, “We seek a world where all people value and benefit from a scientific understanding of astronomy that enhances their connection to and enjoyment of the universe around us.” She then went on to the AAS values, which state principles such as, “We act with scientific integrity and transparency as we responsibly and impartially acquire, share, manage, and use scientific data and understanding.” See image below for full set of values. 

After some discussion, she shared the five strategic priorities of the AAS:

1.  Build equitable and inclusive practices within the astronomy research community
2. Address significant global issues that affect astronomy
3. Improve astronomical science dissemination, scientific publication and literacy, STEM education, and professional learning across all career paths chosen by astronomers
4. Cultivate our network of partnerships to strengthen new initiatives, advance our mission, and strive toward our vision
5. Improve transparency and interconnections among the AAS Board, Divisions, Committees, and Members to accomplish our goals

The rest of the meeting was devoted to answering questions from the Slack channel (#aas-strategic-assembly-town-hall). Visit the AAS strategic planning website for more information about their strategic plans!

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SOFIA Town Hall (by Abby Waggoner)

In this town hall, Margaret Meixner, the Science Mission and Operations Director, welcomed us to discuss SOFIA, an infrared observatory that flies in an airplane in the Earth’s stratosphere. She began by listing SOFIA’s science highlights from the past year: 

• The first detection of molecular water on the Moon’s surface
• Results suggesting that gravitational collapse of molecular clouds and star formation can occur even in the presence of strong magnetic fields
• The detection of a “cold” quasar, a galaxy in which the central supermassive black hole is actively accreting matter, yet the star formation in the galaxy is still going strong (a surprising result, since black holes are thought to halt star formation)
• Evidence of the building blocks of complex organic molecules, found in disks around massive stars via high-resolution spectroscopy
• The first detection of the molecule ¹³CH in the interstellar medium.

Meixner highlighted that SOFIA observations were suspended March–August 2020 due to the pandemic, and the observatory is currently suspended in Hamburg, Germany for scheduled maintenance. The image below shows every flight path SOFIA took in the past year.

Next up, James Jackson, the Associate Director for Research, gave us an overview of the Cycle 8 observations and Cycle 9 proposing cycle. Because of the pandemic-related shutdown, Cycle 8 is now scheduled to continue until July 2, 2021, but unfortunately the 2020 Southern Hemisphere deployment is no longer feasible. Instead, a number of flights will be conducted from Germany to accomplish high priority programs. Cycle 9 proposals vastly exceeded the available 820 hours of observing time, with 3,243.5 hours requested worldwide. The Cycle 9 breakdown is shown below. Jackson also highlighted a virtual workshop titled “Rock, Dust, and Ice: Interpreting Planetary Data” happening in March 2021.

The final section of the town hall was an overview of the current and future SOFIA instrumentation, from William Reach, the Associate Director for Science Operations. The future of SOFIA aims to address questions concerning star and planet formation, the path to life, and calibrating the distant universe. These science cases will be addressed by developing new instrument capability that will improve sensitivity, map polarization, increase mapping speed, and more. 

The presenting group concluded by highlighting that SOFIA continues to make new discoveries, and with the upcoming instrumentation upgrades, SOFIA will be able to target more and more areas of the sky and astronomy.

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Plenary: Stress-testing the Cold Dark Matter Paradigm: Trouble on Small-scales? (by Luna Zagorac)

The plenary by Professor Priyamvada Natarajan (Yale Univ.), which described projects undertaken with many collaborators, had as its central theme the interplay of high-resolution simulations and exquisite data sets, and how this interplay can be used to learn more about our universe. Comprising only a small fraction of the total energy density of the universe, baryons (i.e., “ordinary matter”) make up the astrophysical objects and systems we can image directly with instruments like the Hubble Space Telescope. On the other hand, substantially more of the energy density is in so-called dark matter (DM), which cannot be probed in the same way. However, if we accept that dark matter is cold (meaning it moves slowly with respect to the speed of light), and given cosmological parameter values from the cosmic microwave background, we can now use very sophisticated simulations to make mock “observations” of dark matter on computers. Comparing results from real and “mock” observations, Natarajan stress-tests our understanding of cold dark matter (CDM). 

In particular, she uses clusters of galaxies for such comparisons, focusing on gravitational lensing. This is useful for several reasons, including the fact that galaxy clusters originally provided evidence for DM, and they offer constraints on DM and dark energy at once. In gravitational lensing, how much the light bends is proportional to the mass of the lensing object, and it’s also dependent on the ratio of angular distances to the object being lensed and the object doing the lensing. Therefore, if the lensing data are good, we can use them to both constrain cosmological parameters (probing dark energy) and map distribution of matter (probing dark matter). 

If the object doing the lensing is massive enough, we can even see multiple images of a lensed object. By mapping the objects we see multiply lensed, we can reconstruct the so-called caustics of the lensing object, which relate to its shape and concentration in its very inner parts (see Figure SL3 here for an illustration). This allows us to build a subhalo mass function: in other words, we can predict how many smaller dark matter clumps of a given mass live within a smooth dark matter distribution called a halo. This is predicted by the CDM paradigm, and the simulations agree with the data here: CDM isn’t feeling too stressed about it!

What does stress CDM out is galaxy–galaxy lensing: a regime in which both the lensed and lensing objects are restricted to being galaxies. With galaxy–galaxy lensing we can probe the mass within the inner 5–10 kpc of the galaxy, gaining detailed information about mass distribution (and therefore dark matter distribution) within that range. Turns out, there is an order of magnitude discrepancy between simulations and data here: lenses are ten times less efficient in CDM simulations than in the data! After ruling out issues with the simulation or data resolution, this leaves us with two possibilities: 1) We have a poor understanding of the interplay between DM and regular matter in the cluster cores, or 2) there are deeper problems with the CDM paradigm! This is exciting, Natarajan explained, since gaps like these (see: Mercury’s orbit and General Relativity) sometimes lead to discoveries of new physics. With even better simulations being developed and many space-based missions on the horizon (such as JWST, Roman, and Euclid), Natarajan concluded this is an exciting time to be stress-testing CDM.

Live-tweeting by Luna Zagorac

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Press Conference: Evolving Stars & Nebulae II (by Abby Waggoner)

The final press conference of AAS 237 was the second set of briefings on evolving stars and nebulae. The session began with Dr. Daniel Wang, from the University of Massachusetts, Amherst. In this talk, Dr. Wang discussed the pulsar PSR B2224+65 (image to the right), which had a strange jet (in the green box) pointing in the “wrong” direction. Using X-ray light, hot energetic particles were detected in the jet, suggesting that the jet’s unanticipated direction could be caused by magnetic fields. Press release

Next up, Dr. Joel Kastner, from the Rochester Institute of Technology, discussed recent observations of the NGC 6302 planetary nebula, more commonly known as the Butterfly Nebula. Typically, we expect nebulae to be spherical, since gas should expand equally in all directions after a supernova. But the Butterfly Nebula, as demonstrated in the picture to the right, is clearly not spherical. Dr. Kastner tells us the strange shape is likely caused by a combination of shocks and winds, which can be identified by tracing excitation and extinction in the nebula. 

The final presentation of the press conference was given by Dr. Paula Moraga Baez, from the Rochester Institute of Technology, and Dr. Jesse Bublitz, from the Green Bank Observatory. Dr. Moraga Baez and Dr. Bublitz told us about recent observations and measurements of the NGC 7027 nebula (shown in the cover image). Perhaps most notably, they discussed the observations of CO⁺ — which represents the first mapping of CO⁺ in a planetary nebula and only the second CO⁺ map of any object. CO⁺ is significant because it can tell us about the physics and chemistry in NGC 7027 when observed together with molecules such as H₂ and HCO⁺. Press release

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Lancelot M. Berkeley Prize: H0LiCOW! Cosmology with Gravitational Lens Time Delays (by Gourav Khullar)

The last plenary talk for the meeting was by Prof. Sherry Suyu (Max Planck Institute for Astrophysics), winner of this year’s Lancelot M. Berkeley − New York Community Trust Prize for Meritorious Work in Astronomy (Berkeley Prize). 

Prof. Suyu started the plenary session by thanking her H0LiCOW collaborators and family for this prize, and she then jumped into an introduction to the concept of the Hubble constant, the expansion of the universe, and how measurements of this cosmological parameter have spanned decades, with different levels of precision. She also discussed the H₀ tension — the tension that exists between a direct local measurement of H₀ via the cosmic distance ladder (with Cepheid stars), and another measurement via the early-universe cosmic microwave background. Following this, the introduction to gravitational lensing via accessible examples (see the example in the image below) was a great precursor to the science of galaxy- and cluster-scale lenses.

Prof. Suyu then shared her work as part of the H0LiCOW (H₀ Lenses in COSMOGRAIL’s Wellspring) collaboration, where the objective has been to use six lensed quasars (and measurements of quasar variability from different images) to measure gravitational lensing time delays. Mathematically, time delay measurements involve the Hubble constant, which makes this methodology an independent means of measuring H₀ (with ~2.4% precision) that could potentially solve the H₀ tension. Prof. Suyu shared the work that her team has done to track a single quasar (and all its lensed images) across two decades, and the associated results from high-cadence (daily) and high signal-to-noise-ratio measurements of flux from this object, with huge success. 

Prof. Suyu also talked about the HOLISMOKES (Highly Optimised Lensing Investigations of Supernovae, Microlensing Objects, and Kinematics of Ellipticals and Spirals) collaboration, which is specifically interested in studying the progenitors of Type Ia supernovae (like SN Refsdal) as well as measurements of H₀. Finally, Prof. Suyu gave a nod to future facilities like JWST and Rubin Observatory — which will generate a sample of quasars on the order of ~100 — that can allow us to study the above phenomena from a statistical perspective.

Interview with Sherry Suyu by Gourav Khullar
Live-tweeting of the session by Tarini Konchady

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Closing Remarks (by Briley Lewis)

To wrap up the week, AAS President Paula Szkody (University of Washington) and AAS Executive Officer Kevin Marvel said a quick few words. (Unfortunately, there can’t be a big closing reception with free food per usual! Hopefully in 2022!) They announced that the format for the AAS 238 meeting this summer is still to be determined, depending on the COVID-19 situation. They also thanked the large number of people that it takes to make this conference happen: the attendees, the volunteers, the session chairs, the Chambliss judges, the coordinators, the exhibitors, the sponsors, everyone involved! Kevin Marvel emphasized that “there’s no way we can have a conference without attendees” and this virtual conference brought together a lot of people, some of whom wouldn’t have been able to join in person. That brings us to the end of this whirlwind week of science — thanks for following along with Astrobites!

Editor’s Note: This week we’re at the virtual 237th AAS Meeting. Along with a team of authors from Astrobites, we will be writing updates on selected events at the meeting and posting each day. Follow along here or at astrobites.com. The usual posting schedule for AAS Nova will resume on January 19th.

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Royal Astronomical Society (RAS) Gold Medal in Astronomy: A Schematic Model for Black Hole Growth and Galaxy Quenching (by Haley Wahl)

The first plenary of the fourth day of AAS 237 was given by Dr. Sandra Moore Faber (UC Santa Cruz), winner of the Royal Astronomical Society’s incredibly prestigious Gold Medal in Astronomy (previous winners of this medal include Albert Einstein and Stephen Hawking!), with her talk on black hole growth and galaxy quenching. Galaxy quenching is the process by which galaxies stop forming stars. Dr. Faber started off by showing the Hubble sequence and posing the major question of the talk: “How do galaxies stop forming stars?” Astronomers can predict the distribution of the mass of dark matter halos, inside which galaxies form and grow. But why do the dark matter halos keep growing but the galaxies inside them do not?

Dr. Faber focused her question on a specific kind of galaxy: middle-sized galaxies like our own Milky Way. In the current paradigm for these galaxies, their quenching is thought to be caused by feedback from accreting central supermassive black holes, and that feedback is ejective (e.g., by blowing out the gas), preventative (e.g., by heating up the gas), or both. Black holes grow at the centers of galaxies during their formation; the black hole has little effect when a galaxy is young and the black hole is small, but eventually the black hole becomes massive enough to affect the galaxy itself and cause its star formation to quench. It is possible that the growing black hole at the center of the galaxy affects the gas in the halo surrounding the galaxy and alters its ability to cool and fall in. There are a few unanswered questions in this process, such as what the rules are for black holes growing in mass, the nature of black hole feedback, how that feedback interacts with gas in the galaxy, the origin of black hole scaling laws, and what exactly happens when galaxies start to quench. There is a lot left to understand.

Scaling laws are extremely important for answering these questions. Dr. Faber related galactic scaling laws to the zero-age main sequence for stars, which, when understood, unlocked the sequence of nucleosynthesis and how stars shine. By understanding the equivalent scaling laws for galaxies, we can understand how they evolve and how their star formation quenches. She then presented five relations: stellar mass vs. halo mass, mass vs. star formation rate, galactic radius vs. stellar mass, central stellar density vs. stellar mass, and black hole mass vs. central stellar surface density. By examining all of these relations — and how they relate to each other — we can learn a lot about how galaxies are quenched. One very important aspect of this process is the boundary between star-forming and quenched galaxies, and what happens when a galaxy crosses it in a given relation, suggesting the conditions are right for quenching.

What causes this quenching boundary and why does it move? pic.twitter.com/TudLbeLwDF

— astrobites (@astrobites) January 14, 2021

These scaling relations are starting to reveal the nature of galaxy evolution, and how the different variables come into play. One interesting point we have learned from all this is that the connection between dark matter halos and black holes is incredibly tight. There are still many unsolved questions about galaxy quenching, but more advanced modeling is getting us closer to answering the question of how and why galaxies stop forming stars!

Live-tweeting of the session by Haley Wahl

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Special Session: What to Expect Under a Biden-Harris Administration (by Briley Lewis)

This special session, composed of panelists with experience in a variety of science policy roles, was held to discuss “the upcoming presidential transition and what we can expect during the first months of the new administration.” Panelists included Joel Bregman (University of Michigan), Jack Burns (University of Colorado, Boulder), Dahlia Sokolov (no affiliation), and Mike Holland (University of Pittsburgh), and the panel was moderated by Joel Parriott (AAS Director of Public Policy) and Kelsie Krafton (AAS Bahcall Fellow).

Although President Elect Biden has assembled a transition team, the transition process has been slow to start due to resistance from the current administration. There are also many other committees and groups that deal with NASA, NSF, NIST, and the DOE: the House Committee on Science, Space, and Technology, the Senate Committee on Commerce, Science, and Transportation, the House and Senate Appropriation Committees, the House Committee on Energy and Commerce, and the Senate Committee on Energy and Natural Resources. The American Institute of Physics (AIP) also has tools for tracking the federal science budget and new appointments & nominations.

Since the transition team relies on advice from a number of parties, the AAS has already sent letters to the NASA transition team and the NSF transition team. Burns reported that he also made two recommendations to the transition team: don’t completely change the scientific agenda, and work on increasing the NASA budget to $25 billion (or at least avoiding cuts to NASA/NSF). Although changes in policy and priorities are to be expected for any change in administration, Burns emphasized that stark changes in scientific agenda creates uncertainty, both within NASA and with international partners, and impedes progress, saying, “Let’s build on infrastructure we already have in place.”

A participant brought up the question of how we can reduce this uncertainty, possibly creating mechanisms for longer-term commitments to projects and making it easier for international partners to commit and fund partnerships. Although multi-year appropriations are often suggested as a solution to this problem, the panelists emphasized that there is also a lot that scientists involved in major projects can do to increase stability, such as setting clear, stable science priorities, improving project management, and controlling budget overrun.

With another stimulus package likely coming soon, the panelists were asked how this spending would affect science. A certain amount of money should be allocated for “research recovery funds” (including a stimulus for NASA) and Sokolov commented that currently the biggest risk is not to the science goals, but to the pipeline of researchers. With postdocs in limbo, students unable to graduate, and hiring freezes, she expressed worry over a possible loss of talent. (The AIP has also put out information on how COVID-19 is affecting the sciences.) Science education is also likely to be an area of interest for the incoming administration, which has placed emphasis on diversity, equity, and inclusion, as well as affordability issues both at the undergraduate and the graduate levels.

The Endless Frontiers Act is a recently introduced piece of legislation from Sen. Chuck Schumer that proposes changes to the NSF. Someone in the Q&A session raised concern that if funding is split between basic and applied sciences without a significant increase in the overall budget, it would lead to a major decrease in basic science support. Although there is a “legislative firewall” built into the legislation, Sokolov warned that those measures can be essentially ignored by an appropriations committee, so this proposal needs careful consideration of how it would change normal NSF operations. Burns added that the NSF is governed by the National Science Board, which generally helps to moderate and implement changes to the agency.

Participants also questioned when the announcement of a new NASA administrator is expected. Although no timeline was given, the panelists expressed the hope for a choice sooner rather than later, and Burns stated that the administration is looking to hire the first woman administrator to NASA, with some very qualified names already put forward for the position. Additionally, panelists discussed the Artemis mission, tasked with landing “the first woman and next man on the Moon by 2024.” Burns expressed doubt that the 2024 goal would be met, calling it “very unlikely” since the budget doesn’t accommodate for developing human landing systems. However, he was hopeful that private companies would work on this goal, too, mentioning that Jeff Bezos and his company Blue Origin have stated that they will go to the Moon whether or not NASA does. In response, participants expressed concerns about private interests setting priorities for space exploration, mentioning the small satellite problems (which will be discussed further in a later session today!).

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Press Conference: Galaxies & Quasars II (by John Weaver)

The first press conference of Day 4 of AAS 237 continued the theme from earlier — galaxies and quasars. Four scientists were featured in the hour-long conference, each presenting a different aspect of galaxy evolution.

First up was Adi Foord from Stanford University, who discussed her work on supermassive black holes. When galaxies collide, we can see what happens on large scales using optical and X-ray imaging. But what happens to the supermassive black holes that reside at their centers? In what’s known as the “final parsec problem”, theory predicts that pairs of inspiralling supermassive black holes may stall out, never getting close enough to merge. However, Dr. Foord points out, this problem is mitigated when there is a third black hole involved in the merger, due to the faster circularization of their orbits. Finding collisions of three galaxies, whose supermassive black holes may actually merge quickly, is therefore of interest. Dr. Foord and collaborators used SDSS imaging to pick a handful of promising galaxy triple mergers, and then used Chandra to locate the X-ray-bright black holes. They confirmed four probable double black hole mergers and one triple merger. They also found that the dust and gas in these merging galaxies is enormous, and it’s significantly higher in the group of galaxies with the triple black hole merger. Press release

Incredibly, they can see the same shells seen by Hubble, but using amateur telescopes with longer observation times! #AAS237 pic.twitter.com/eCwtB0apvl

— astrobites (@astrobites) January 14, 2021

Next in the line up was Duilia de Mello (Catholic University of America) to talk about the Deep Images of Mergers or DIM Project. She has teamed up with a group of amateur astronomers in Brazil who use their own telescopes to image galaxy mergers. The crazy part is that they have been able to combine their efforts to match images taken in space by Hubble! By spending longer (41 hours!) observing with common amateur telescopes using extremely broad filters, they are able to cheaply image extremely faint features of galaxies — in particular, the tidal and shell features surrounding spheroidal galaxies, which are typically associated with galaxies that have recently undergone a major merger. These images can help us to understand the chaotic lives of these galaxies. De Mello is now gearing up to conduct a massively larger campaign to image the faint features of many other galaxies using the awesome power of amateaur astronomers! Press release

The next talk was from Jordan Guerra Aguilera (Villanova University), who started us on the theme of magnetic fields in galaxies. Specifically, Jordan and his team studied the well-known Cigar Galaxy (M82) which is known for its amazing outflowing material. By using a combination of complex measurements, grounded in the science of polarimetry, they were able to not only estimate the magnetic field strength of M82 to be a whopping 1 milligauss, but also map out the entire extended magnetic field way beyond the edge of the galaxy. With this magnetic field map in hand, they were able to determine that material ejected from M82 will escape the magnetic field lines altogether. Press release

Continuing on the theme of magnetism was Alejandro Borlaff (NASA Ames Research Center) who discussed groundbreaking insight into the magnetic fields in the disk of the Whirlpool Galaxy (M51; see the cover image at the top of today’s post) using the HAWC+ instrument aboard NASA’s SOFIA observatory (the one that’s an airplane!). Previous studies of magnetic fields in galaxies explored how the magnetic field structure interacts with the filaments of gas, and in turn how that can affect or regulate star formation. However, these studies were done at bluer wavelengths that we can measure from the ground, and they mapped the magnetic fields of the diffuse gas and then assumed a similar behaviour from the cold molecular gas, from which stars can form. SOFIA is special because it flies at the edge of space, which means it can observe far-infrared light that is absorbed by our atmosphere. By directly measuring the magnetic field associated with the cold molecular gas, Dr. Borlaff and his team were able to identify differences between the magnetic fields of the diffuse and molecular gas, meaning that much of what we thought we knew about magnetic fields and star-formation will have to be re-written. Press release

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NOIRLab Town Hall (by Gourav Khullar)

In this town hall, NOIRLab (the National Optical-Infrared Astronomy Research Laboratory) leadership discussed its missions, updates and future plans, with the session titled “Enabling Breakthrough Discoveries for a Diverse and Inclusive Community.” The mission statement of NOIRLab — which is the umbrella organization unifying all NSF night-time optical/IR facilities into one — is to enable discoveries with observatories, and to develop data products and services for an inclusive astronomy community. The organization wishes to be an agent of change in the community via their projects, facilities, and modes of engagement. 

In this session, we heard updates from:

1. Gemini Observatory (and their new networks to coordinate observations of target-of-opportunity events, and adaptive optics and radial velocity measurement instruments)
2. Vera C. Rubin Observatory (and their operations, plans for first light in October 2022, and community engagement plans)
3. Community Science and Data Center (CSDC; which will manage their new dual-anonymous proposal system, open-access time with Keck Observatory consisting of 40 nights over 4 years, and the Astro Datalab data query and analysis service)
4. Mid-scale observatories (like CTIO in Chile and operations with its 4-m Blanco telescope, and Kitt Peak National Observatory and its new DESI survey). 

For the fiscal year 2021, NOIRLab will prioritise bringing the DESI survey online, expanding imaging capabilities, strengthening relationships with local communities, and building a program to protect dark skies from light pollution and satellite constellations. 

Live-tweeting of the session by Gourav Khullar
Twitter thread by NOIRLab

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Plenary: Thermal-IR Astronomy: Progress & Future Prospects (by Abby Waggoner)

The second plenary talk today was given by Chris Packham from the University of Texas, San Antonio. In the 1940s, Carl Seyfert identified bright, stellar-like objects at the centers of distant galaxies. We now know these bright sources of light are active galactic nuclei, or AGN. AGN are bright across the entire electromagnetic spectrum, and many astronomers believe this bright emission is caused by accretion from the disk and torus surrounding the AGN, as shown in the figure to the right. However, the exact relationship between the accretion disk and the black hole were not well understood. This plenary talk walked us through infrared imaging and modeling done by Dr. Packham and his collaborators to better understand the relationship between the central black hole and the surrounding accretion disk and torus.

Unfortunately, it is difficult to obtain a high enough resolution when observing AGN to fully understand the relationship between the torus and the black hole. It turns out, protoplanetary disks can be used as an initial guide to AGN physics. This comparison provides a new way of interpreting AGN physics, but there are many different types of AGN. For example, some have jets and some have scattered or transmitted light,  while others do not. The one common component between all AGN is the presence of a dust molecular torus. This theory, known as the Uniform Theory, suggests that the torus plays a key role in the bright AGN emission. But,  what exactly is that role? And what exactly does the torus look like? 

To answer these questions, we turn to infrared astronomy. Light emission from the torus peaks in mid-infrared light (MIR), meaning the torus is easiest to observe in MIR wavelengths. Initial models, shown in the left figure above, from Pier & Krolik (1992) and Pier & Krolik (1993) suggested that the torus was a smooth and homogeneous distribution of gas and dust, but this model was unable to accurately match observations. Thankfully, Sptizer and Gemini provided the data needed! The data combined from these telescopes led to the Clumpy Torus model (shown in the right figure above), which suggests that the torus is full of lots of individual clouds, rather than a single continuous disk. 

Now with high resolution images and an accurate model of the torus, Dr. Packham and his team moved on to longer wavelengths to get a better picture of the entire torus. Combining observations across many wavelengths gives us a better sense of everything going on. Imagine only being able to see things that are blue, but having to figure out everything in a room. If you could also see red, yellow, and purple, you would get a much better idea what all is in the room. As promised, observations with SOFIA and ALMA further confirmed the clumpy model while better defining the structure of the torus. 

Now, what does the future hold for AGN and the torus? Dr. Packham tells us there is still much to learn. The science team is currently working on a new MIR camera called MICHI, and when MICHI and JWST (launching October 2021!) observations are combined in the future, we will gain higher resolution images and spectra, be able to trace thermal disk emission to potentially probe forming planets, probe snow lines, and even detect complex organic molecules. 

Live-tweeting of the session by Briley Lewis

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Special Session: Astronomy and Satellite Constellations (by Briley Lewis)

Conversations in astronomy about protecting the night sky from light pollution have been going on for decades, but satellite constellations and the rapid industrialization of space have brought about new challenges. There are cultural, environmental, health, and scientific impacts to be considered, but as panelist Jeff Hall (Lowell Observatory) said today, space is currently a bit of a “Wild West environment.”

To address these challenges and inform policy decisions, astronomers and satellite operators have collaborated to mitigate the effects of these satellite constellations. In the past few years, the NSF and AAS hosted the SATCON1 workshop, culminating in a report on impacts and mitigation strategies, and the IAU and partners hosted the Dark and Quiet Skies workshop, creating a report to be presented to the UN Committee on the Peaceful Use of Outer Space. The AAS also maintains a Committee on Light Pollution, Radio Interference, and Space Debris. In today’s session, astronomers and satellite operators met once again to discuss these issues and increase awareness of these issues with AAS members.

When SpaceX’s Starlink satellites first went up, many people panicked upon seeing images of the night sky filled with bright streaks. Panelist Patrick Seitzer (University of Michigan, Ann Arbor) reported that the AAS has set a goal for these satellites to stay at magnitude 7 or fainter; that is, they shouldn’t be visible to the naked eye in excellent dark sky conditions. There’s a caveat to this though: objects further away may look fainter to our human eyes, but an object in a higher orbit is actually in better focus for a telescope and has a longer travel time (thus, exposure time) across a detector, causing more problems for astronomy. As a result, the AAS additionally recommends that these satellites stay below 600 km.

Panelist Harvey Liszt (NRAO—Charlottesville) then went on to describe the effects of these satellite constellations on radio astronomy. Certain bands are designated as protected for radio astronomy, but satellites often infringe on the edges of these bands or exploit complexities in FCC rules to engage in behavior that is harmful to radio astronomy. One participant pointed out that radio astronomy is also done outside of these protected bands, so avoiding those regions alone doesn’t mean a project has zero impact. Aparna Venkatesan (University of San Francisco) brought yet another dimension to this discussion, reminding us that the night sky and other resources “have value outside of their utility and what we do with them.” She asked participants in this discussion to consider who is missing from our decision-making, and to consider that there are other value systems and cultural perspectives to bring to these issues, reminding us that BIPOC are already dealing with a crisis from the disproportionate effects on them from climate change, the COVID-19 pandemic, systemic racism, and more. (You can read more from Venkatesan on space as an ancestral global commons here.) She also pointed out that pace is an issue, since everyone is trying to get this done first; the industry of satellite constellations is very fast paced, which means it’s also capable of responding quickly — but it often does not mesh well with the slow, ponderous, Ent-like pace of academic science.

Next, each satellite operator gave an overview/update on their mitigation efforts. Patricia Cooper, representing SpaceX’s Starlink, stated a goal of having their satellites be invisible to the naked eye within a week of launch. They are minimizing their impact by adding sunshades to block antenna reflection and maneuvering satellites to reduce their reflective surface area. Julie Zoller, representing Amazon Kuiper, states that although they have not yet launched any satellites, they are using astronomers’ recommendations in their designs. They are using the minimum number of satellites needed to provide service, staying below the recommended altitude, and using steering that allows them to roll and minimize reflection similar to Starlink. Zoller also expressed the importance of their service, stating the need for reliable internet in underserved communities, which is a problem that has only been worsened by the pandemic. Lastly, M. Vanotti, representing OneWeb, started off by saying their company is recovering after filing Chapter 11 bankruptcy. They have also recently reduced the number of satellites in their constellation and say they are committed to responsible space operations, but their orbiting altitude is still set as 1,200 km, far above the recommended orbits. All three companies present also confirmed that they have plans for de-orbiting their satellites at the end of their operational lifetimes. Amazon Kuiper, due to their low orbits, will be able to de-orbit within one year with propulsion systems, or within ten years if propulsion fails.

Responding to questions about international coordination of mitigation efforts, panelists suggested that the orbital debris tracking community could be a good example to look to. As Jeff Hale aptly said, “Lots of people are trying to get into the game, and bad things will happen if they just don’t care.” Hopefully, the satellite operators will continue to consider astronomy and other impacts in their plans, and these conversations between stakeholders will continue as well.

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Press Conference: Evolving Stars & Nebulae I (by Ellis Avallone)

The second press conference of the day was all about evolving stars and nebulae, and the talks centered primarily on eclipsing binaries and supernova remnants. James Davenport from the University of Washington started off by discussing the exciting eclipsing binary HS Hydrae. Although HS Hydrae was first discovered in the 1960s, recent observations have allowed us to understand some of the strange behavior it exhibits. The amplitude of the eclipse signals in this system’s light curve has been gradually decreasing since its discovery, and this is due to a third non-eclipsing star that causes the two inner stars to “tumble” through space. It was predicted by astronomers in 2012 that sometime in 2022, the eclipses of HS Hydrae would vanish entirely. Last year, TESS observed this star just before this critical point. Davenport and his team were then interested in whether this variability persisted prior to HS Hydrae’s initial discovery. They consulted the DASCH project, which catalogues photographic plate data from as far back as the 1880s. This archival data showed that this change in HS Hydrae’s eclipse amplitude had been seen before, and confirmed that we should expect to observe eclipses again in about 200 years. Press release

Next, Ethan Kruse from NASA Goddard SFC told us about how we can use machine learning to discover eclipsing binaries in survey data. We have the best chance of detecting lots of eclipsing binaries when we look at the sky for a long time, i.e., with survey telescopes. While Kepler helped us out a ton with getting binary light curves with long baselines, it only looked at a small patch of the sky. The TESS mission, Kepler’s younger sibling, is an all-sky survey that can give us an orders-of-magnitude larger sample than Kepler. The machine learning pipeline developed by Kruse and his team has already detected 20,000 eclipsing binaries in TESS data within their small test sample. As the TESS mission continues, we expect to add tens of thousands of these interesting systems to our current sample.

Moving on, Sagiv Shiber from Louisiana State University discussed an interesting aspect of binary star evolution. The phenomenon, called grazing envelope evolution, occurs when the envelope from an evolved primary star grazes the orbit of a less-evolved companion. Grazing envelope evolution sets on when jets erupt from an accretion disk around the companion. Shiber determined that these jets prevent the companion star from being engulfed by the evolved primary and that jets can cause fast outflows from the poles of the system, which leads to the presence of lobes in the stellar remnant. Press release

The last two talks were all about supernova remnants. First, Dan Patnaude (Center for Astrophysics | Harvard & Smithsonian) talked about the connection between supernova remnants and the supernovae that formed them. Although we have very few examples where we’ve observed both supernova and remnant, a recent detection caught the eye of Patnaude and his team. SN1996cr is located in the nearby Circinus galaxy, and although the initial supernova wasn’t observed in detail, archival data has assisted tremendously in characterizing this object. Patnaude has been able to effectively look back in time with this object, even without perfect observations.

Finally, John Banovetz from Purdue University discussed the characterization of another supernova remnant, 1E 0102.2-7219 (also known as E0102). Using archival images from Hubble, Banovetz determined the location of the expansion center by considering the trajectory of the expanding material. The difference between the expansion center and the location of a possible surviving neutron star indicate a high velocity of the remnant. Banovetz was also able to determine that the system is about 1,700 years old. Press release

Live-tweeting of the briefing by Ellis Avallone

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Dannie Heineman Prize for Astrophysics: The All-Sky Automated Survey for Supernovae (by Mike Foley)

The final plenary talk of the day was given by Chrisopher Kochanek (The Ohio State Univ.), this year’s recipient of the Dannie Heineman Prize, an award that recognizes outstanding mid-career work in the field of astrophysics. Dr. Kochanek is one of the architects of ASAS-SN, the All-Sky Automated Survey for Supernovae. ASAS-SN is fully automated and can observe and identify transient objects without human intervention. A transient object is anything that changes substantially in the sky over time; asteroids, cataclysmic variables, novae, and supernovae are the most common. By taking a large number of images across the sky and comparing images of the same region over time, ASAS-SN can identify what changes between images. 

To do this, ASAS-SN doesn’t need large telescopes. In fact, their network of telescopes features individual mounts that have four lenses, each only 14 cm in diameter. By distributing these mounts around the world and continually monitoring the sky, ASAS-SN aims to serve as the “first responder” when a transient event occurs. Once ASAS-SN reports on a transient event, it can be followed up by larger telescopes for further study. Dr. Kochanek noted that amateur astronomers also play a large role in detecting and following up on transient events! ASAS-SN has historically done better at detecting supernovae closer to the centers of their host galaxies (the galaxy in which the supernova went off) than both amateur and professional surveys. 

ASAS-SN has been incredible for detecting huge quantities of variable events that other surveys often miss. For example, ASAS-SN has identified over 400,000 variable stars, with over 200,000 of those representing new discoveries. Thanks to its continuous monitoring of the sky, it also has observed a number of particularly interesting objects. These include repeated partial tidal disruption event ASASSN-14ko and an extreme version of a heartbeat star, where the emitted light goes through quick periods of dimming and brightening that resemble a human heartbeat.

Finally, ASAS-SN also provides a remarkable amount of data for static sources, such as normal stars. Later this year, Dr. Kochanek and collaborators will release Sky Patrol 2.0, which will feature continuously updated light curves for 106 million stars! ASAS-SN has been one of the leaders in promoting open data, creating a full database for users to query light curves observed by ASAS-SN. Thanks to Dr. Kochanek and the ASAS-SN team, the night sky is being well-monitored. 

Live-tweeting of the session by Abby Waggoner
Interview of Chrisopher Kochanek by Ellis Avallone