NGC 7027

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.

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


HAWC+ talk

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. 

Orion Nebula field

An hourglass-shaped magnetic field in the Orion Nebula.

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.

galactic center B field

Magnetic fields trace dust rings around our galactic center.

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.

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

AER ebook cover

Cover of the recent AAS/IOP ebook edited by Drs. Chris Impey and Sanlyn Buxner, Astronomy Education, Volume 1.

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!

edu spaceship

Screenshot of the astronomy game used in Nicole Gugliucci’s classroom, showing the spaceship and accompanying physics.

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.

edu discord

An example of the “bedtime” reminder on the Cosmoquest Discord server.

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!

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. 

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

warped galaxy

This image of the Integral Sign galaxy (UGC 3697) shows a galaxy with one of the largest known warps. [DECaLS]

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

stellar stream

Artist’s impression of a stellar stream arcing high in the Milky Way’s halo. [NASA]

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.

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. 

AAS Values

Full list of AAS 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!

SOFIA Town Hall (by Abby Waggoner)


SOFIA, a modified Boeing 747SP carrying a 2.7-m telescope. [NASA]

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.


SOFIA flight paths for 2020.

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.

SOFIA time breakdown

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.

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

dark matter

The relative amounts of the different constituents of the universe. [ESA/Planck]

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). 

Abell 3827

This Hubble image shows part of the galaxy cluster Abell 3827. The blue structures surrounding the central galaxies are gravitationally lensed views of a much more distant galaxy behind the cluster. [ESO]

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!


This plot shows two subhalo mass functions, with mass of subhalo in solar masses on the horizontal axis and number of subhaloes of that mass on the vertical axis. A comparison of a subhalo mass function derived from a simulation (solid black with grey uncertainty) and a subhalo mass function derived from Hubble data (red with shaded uncertainty). Note that the two lines don’t differ significantly.

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

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

PSR B2224+65

Pulsar PSR B2224+65, as presented by Daniel Wang.

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

Butterfly Nebula

RGB image of the Butterfly Nebula, which shows extinction due to dust. [STScI, APOD/J. Schmidt; J. Kastner (RIT) et al.]

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

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.

strong optical lensing

Example of how strong gravitational lensing works, using a candle as a background source and a wine glass as the lens.

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. 

h0licow results

The latest results from H0LICOW.

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

Closing Remarks (by Briley Lewis)

AAS237 Closing

Astronomers gather over zoom to wrap up a great week of #AAS237!

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.

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


The spiral galaxy NGC 1559 is an example of a local star-forming galaxy. [NASA/ESA/Hubble]

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.

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

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!).

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

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


Magnetic fields in Messier 82, or the Cigar galaxy, are shown as lines over an optical/infrared composite image of the galaxy. [NASA, SOFIA, L. Proudfit; NASA, ESA, Hubble Heritage Team; NASA, JPL-Caltech, C. Engelbracht]

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

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. 


The team at NOIRLab.

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

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

AGN structure

The structural components of an AGN. Matter orbiting the black hole forms an accretion disk. There is also a torus, a donut-shaped cloud of neutral gas and dust, that could obscure the light emitted by the disk. [Aurore Simonnet, Sonoma State University]

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

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

Starlink Cerro Tololo

This November 2019 image is from the Dark Energy Camera on the Blanco 4-m telescope at Cerro Tololo Inter-American Observatory in Chile. It reveals the trails of 19 Starlink satellites that passed through the survey’s field of view during the six-minute exposure. [NSF’s National Optical-Infrared Astronomy Research Laboratory / CTIO / AURA / DELVE]

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.

satellites visible at night

Plot of number of satellites visible over the course of a night. Blue points show satellites at 1,000 km, orange at 500 km. [Patrick Seitzer]

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.

Starlink mitigation

Two of Starlink’s mitigation strategies described by Patricia Cooper. [SpaceX]

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.

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


Image of an astronomical log book from 1945. These observations are now part of the Digital Access to a Sky Century at Harvard, or DASCH, catalog. [DASCH/Harvard University]

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.

Hubble 5

Hubble 5 is a striking example of a “butterfly” or bipolar (two-lobed) nebula. [Bruce Balick (University of Washington), Vincent Icke (Leiden University, The Netherlands), Garrelt Mellema (Stockholm University), and NASA]

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.

supernova remnant 1E 0102.2-7219

Hubble view of supernova remnant 1E 0102.2-7219. [NASA, ESA, STScI, and J. Banovetz and D. Milisavljevic (Purdue University)]

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

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

ASAS-SNThe 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. 

heartbeat stars

This artist’s concept depicts “heartbeat stars”. [NASA/JPL-Caltech]

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

magnetar burst

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.

Henry Norris Russell Lectureship: Comets, Unseen Planets, and the Outer Fringes of the Solar System (by Haley Wahl)

The first plenary of the third day of AAS 237 was given by Scott Tremaine of the Institute for Advanced Study, who gave the Henry Norris Russell Lecture, an honor awarded to a scientist on the basis of lifetime eminence in astronomical research. His talk focused on one of his many interests: comets. Dr. Tremaine started off by giving a brief overview of comets, which are chunks of rock and ice with a radius of a few kilometers. They are thought of as “rubble piles” because of their low density and are believed to be leftover small bodies from the formation of our solar system. Atmospheres (coma) and tails appear when a comet approaches the Sun and once a comet becomes visible, it can survive for more than 100 orbits. 

Dr. Tremaine then dove into discussing the energy of comets and how we can predict where comets will be and where they come from by looking at how much energy they have when passing through our solar system. He then spoke about the Oort Cloud, a region far beyond the orbit of Pluto where a lot of comets are thought to originate. The Oort Cloud is far enough from the Sun that kicks from passing stars and torques from galactic tides can mess with the orbits of the comets in the Cloud, meaning that comets can be removed from it. There is a standard model of the formation of the Oort Cloud, which contains assumptions and initial conditions for how comets form. By using that theory and doing simulations, astronomers can pretty well determine the properties of the inner Oort Cloud. Like the standard model for particle physics, the standard model for the Oort Cloud isn’t perfect. 

Sedna orbit

Orbit of the comet Sedna.

The final part of Dr. Tremaine’s talk focused on the possibility of another major solar system body existing, an idea motivated by comets on very large orbits — for instance, Sedna!

Sedna and others like it do not follow the standard model … so how did they end up on their current orbits? The standard model is based on the planets and many test particles, so maybe it is oversimplified and we should factor in things like kicks from passing stars and the galactic tide to explain comet orbits. Simulations show that there is a possible undiscovered planet that is ~0.1–1 solar mass that is within 250 au of the Sun, nicknamed “Planet X” (this concept is also sometimes referred to as “Planet Nine”). There is a lot of speculation about whether or not Planet X exists and, if it does exist, where it came from.

Dr. Tremaine ended his talk by summarizing that the standard model of the formation of the Oort Cloud explains most but not all properties of comets and that there are possible hidden planets out there. In the next decade, we could improve constraints on Planet X or discover it, but we will not be able to rule it out. He finished by leaving up an XKCD comic:

XKCD planets

The realm of undiscovered planets. [XKCD]

Interview of Scott Tremaine and session live-tweeting by Haley Wahl

Press Conference: Bursting Magnetars (by Ellis Avallone)

NGC 253

NGC 253 is a bright spiral galaxy located about 11.4 million light-years away in the constellation Sculptor. [Dietmar Hager and Eric Benson]

The first press conference today was all about magnetars — neutron stars with astoundingly large magnetic fields. The talks today centered around a giant flare from one particular magnetar — not in our own galaxy, but instead in the nearby Sculptor galaxy (also known as NGC 253). Dr. Kevin Hurley from University of California, Berkeley started off by giving us some background on what makes this detection so exciting.

So-called giant magnetar flares occur when starquakes cause a magnetar’s strong magnetic field to rearrange. The Sculptor galaxy magnetar underwent such an event, producing a short burst of gamma rays that was detected by five of the satellites in the Interplanetary Network (IPN) — an array of telescopes essential for localizing gamma-ray bursts. It has long been suspected that some short gamma-ray bursts originate from magnetars, and the detection of one in a nearby galaxy confirmed this suspicion. Although giant magnetar flares represent the most extreme release of magnetic energy we observe in magnetars, we can only observe them out to about 50 million light-years. The triangulation of the signal with the IPN showed that the burst had to have come from the Sculptor galaxy. When triangulating a signal, there is always a chance of a false association, where a background signal is incorrectly associated with an object. However, the chance of this happening for this magnetar flare is about 1 in 230,000, which further confirmed the location of the flare. 

magnetar giant flare

The distinct light curve of a giant flare from a magnetar includes a sudden peak followed by a long, spiky decay tail. The spikes are caused by the gradually cooling hot spot on the magnetar’s surface rotating in and out of view. [NASA’s Goddard SFC]

Dr. Oliver Roberts from USRA then discussed some interesting aspects of the magnetar flare’s lightcurve. The flare’s duration is extremely short (about 100 milliseconds). Modulation from the rotation of the neutron star sets a magnetar flare light curve apart from a typical short gamma-ray burst’s light curve. Observing this modulation further confirmed the source of this signal. Roberts notes that this flare is the most energetic flare we’ve detected from a magnetar, which indicates expansion speeds of the ejected material near the speed of light. Dr. Nicola Omodei from Stanford University notes that the highest energy signals were detected after the initial burst, which is unique when compared to other magnetar flares. Omodei suggests that this is indicative of additional ejected material colliding with a bow shock from the initial burst.

What does this event mean in the context of other magnetar flares? Dr. Eric Burns from Louisiana State University wanted to find out if giant magnetar flares were being buried in short gamma-ray burst signals, which more frequently originate from neutron star mergers. Although the sample of giant magnetar flares only consists of a handful of events, it is large enough to provide insight into the occurrence rates of these events. With this information, Burns and his team determined that giant magnetar flares occur more frequently than supernovae, at least in the local universe.

Finally, Dr. Victoria Kaspi from McGill University commented on this result and what it means for other areas of astronomy. Most notably, giant magnetar flares are a potential source of fast radio bursts (FRBs), whose origin is still unknown. The occurrence rate for giant magnetar flares found by Burns is consistent with FRB occurrence rates. However, more work needs to be done to confirm that FRBs originate from magnetars.

Press release for the briefing

Live-tweeting of the briefing by Ellis Avallone

STScI Town Hall (by Mike Foley)

The Space Telescope Science Institute (STScI) manages many of the space telescopes, including the Hubble Space Telescope (which has been operational since the 1990s), James Webb Space Telescope (JWST), and Nancy Grace Roman Space Telescope (the latter two of which have yet to be launched). STScI also maintains the Barbara A. Mikulski Archive for Space Telescopes (MAST), which distributes data from over 20 astronomical missions. The Town Hall today focused on a Hubble program, planning for the Roman Telescope, and recent results from an advanced optics lab.


An artist’s illustration of the James Webb Space Telescope, a joint effort between NASA, the European Space Agency, and the Canadian Space Agency. [NASA/JWST]

First to speak was Ken Sembach, director of STScI, who gave a brief introduction to their mission and work. He started by giving a status update on the telescopes: Hubble is thankfully functioning as normal during the pandemic, JWST’s spectroscopic analysis tools are being integrated into MAST for online exploration, and the Kepler Mission has over 20+ new notebooks of documentation on its science applications. He also reported that the Data Science Mission Office has a new Head, Josh Peek, and a Data Scientist, Michelle Ntampaka. Additionally, MAST has also received a new prototype data sonification tool, Astronify (see Abby Waggoner’s summary about sonification and Astronify below!). JWST is scheduled to launch later this year, and STScI has received almost 1,200 proposals for Cycle 1 representing over 4,000 unique investigators. Roman is on track for launch in the mid 2020s.

He was followed up by Julia Roman-Duval, who presented updates about the ULLYSES Hubble program. ULLYSES (the Ultraviolet Legacy Library of Young Stars Essential Standards), a proposed mission that will last three years, represents the largest single Hubble program (observing run) ever, and its span will include nearly 1,000 Earth-orbits of Hubble, providing observations that can be used to study both high- and low-mass young stars. Around 500 of these orbits will be used to extend the spectroscopic library of O and B stars to low metallicity. These data will give important information about the properties of these massive stars, spectral templates for certain stellar populations, chemical information, and characterization of some galaxy-scale outflows in the circumgalactic medium. The other 500 orbits will be used to study T Tauri stars in eight nearby star-forming regions, allowing for an unprecedented look into the lives of young, low-mass stars.


Illustration of NASA’s Nancy Grace Roman Space Telescope (formerly WFIRST). [NASA]

Karoline Gilbert spoke next about the Roman telescope and how the community can begin to engage with it. Roman will launch in the mid-2020s and have a huge field of view, nearly 100 times larger than Hubble’s (which is currently about 1/10th the diameter of the full Moon)! All data from the Roman space telescope will be publicly available with no proprietary period, meaning anyone can access and use the data as soon as it is downloaded. Roman will be able to perform tasks much quicker than previous surveys; for example, it will image galaxy fields over 1,000 times faster than the CANDELS survey! Beth Willman, the Chair of the Roman Space Telescope Advisory Committee, and Megan Donahue, the Chair of the Roman Science Interest Group, are two points of contact for the community and anyone interested in getting involved with Roman.

Rémi Soummer finished up the Town Hall with updates from the Russel B. Makidon Optics Laboratory, a state-of-the-art optics lab at STScI created in 2013 to advance technologies for future generations of space telescopes. Recently, they worked on a project aimed at direct imaging of exoplanets, which is extremely difficult and requires sensitive technology. Some of their recent projects are aimed at enabling direct images of exoplanets. Using their equipment, PhD student Susan Redmond recently showed that they could maintain excellent contrast in coronagraph images, even when perturbations are introduced into the system over time. The lab has made a number of student-led improvements that will be relevant to future missions, and they are now operating remotely and have developed ways to maintain experiments throughout the pandemic.

Live-tweeting of the session by Mike Foley

Plenary: Distinguishing Black Hole Binary Formation Channels With Eccentricity Measurements and Other New Gravity Wave Probes (by Luna Zagorac)

The second plenary of the day, re-named “What (Else) Can We Learn About Binary Black Holes?,” was given by Professor Lisa Randall of Harvard University. She noted that the work she was presenting was done with Professor Zhong-Zhi Xianyu of Tsinghua University, as well as with students Alexandra Shelest and Nicholas Deporzio. Dr. Randall started off by introducing a particle physicist’s approach to a particular astronomical data set: LIGO’s observations of stellar-mass black hole mergers via gravitational waves! Data sets in particle physics are scarce, Randall argued, so we eke out the most physics possible from them — and we should do the same with LIGO’s data. With this in mind, what new information can we learn from LIGO data? Randall refers to this approach as BSA: Beyond Standard Astronomy.

black holes in a globular cluster

The dense and chaotic cores of globular clusters, as shown in this simulation still, may provide an ideal environment for black holes to interact dynamically and merge. [Carl Rodriguez/Northwestern Visualization]

The question that Randall has been exploring has to do with formation channels: how do all these binary black holes come to be? She is particularly interested in a dynamic formation channel, where a third black hole is present and aids in binary formation. But how do we probe the formation channel with the data we have? For a given black hole merger, we can obtain the spins of the black holes involved as well as the eccentricity of their orbit around each other. In the past, spin has not proven as useful an indicator of formation channels as initially thought. And till now, eccentricity has been mostly ignored because inspiralling black holes shed eccentricity very quickly — the system would need to start extremely eccentric to have any ellipticity left over right before the merger!

Thankfully, there is a mechanism that produces extremely eccentric orbits, called Kozai–Lidov. It is a feature only of the three-body system, making it extremely interesting for probing the dynamic formation channel when used with eccentric gravitational wave events such as GW190521. Furthermore, the launch of the gravitational wave observatory LISA will help the situation in two ways.


Artist’s impression of the Laser Interferometer Space Antenna (LISA). [NASA]

First, while we can measure eccentricity statistically with Advanced LIGO (in terms of sheer number of events), LISA will allow us to actually measure the orbital motion directly. Furthermore, because eccentricity can change really quickly while the black holes are inspiraling, we could be able to see the eccentricity variation in the LISA window over several years — a direct observation of the Kozai–Lidov effect!

Second, binaries that start with small eccentricities will be imaged with both LIGO and LISA, allowing us a multichannel view of the merger. In contrast, binaries with large eccentricities will only be seen in a single channel, thus allowing us to discriminate between dynamic and other formation channels. Ultimately, this may mean determining the origins of stellar-mass black hole binaries!

Live-tweeting of the session by Luna Zagorac

Press Conference: Dizzy with Data for DESI (by John Weaver)

The second press conference of the day was all about the Dark Energy Spectroscopic Instrument Survey, or DESI for short. The DESI Survey is conducted at the Mayall 4-meter telescope at Kitt Peak National Observatory and has been running since 2019. Its goal is to map the universe to better understand the nature and origin of, well, dark energy. But as we will see from the press conference today, whenever we peer into the night sky we find lots more than we bargained for. What more could we want? The Data Release 9 is out today.

Co-Project Scientist David Schlegel (Lawrence Berkeley National Laboratory) started us off with a brief overview of the survey. The DESI survey works by first collecting an incredible amount of images of the sky. A team of 150 astronomers help to condense 1,400 nights on 3 telescopes totalling a whopping 1 petabyte of data into vast maps of the night sky. They are aided by immense computing power with over 100 million supercomputer hours spent just on DESI. You can view the polished images here. Although the survey is not yet complete, there are already many exciting discoveries being made. Press release

Strong gravitational lenses help magnify distant background galaxies using the power of gravity. Xiaosheng Huang (University of San Francisco) explains that thanks to the DESI area, they are able to find many more of these incredibly rare lenses, affording new opportunities to explore the very distant universe. These “galaxy-sized telescopes” are bulked up by their massive dark matter halo which helps bend light from more distant background galaxies. Since there may be many images of the background galaxy caused by light traveling along different paths around the lensing galaxy, one unique application is to study supernovae by measuring the time delay between the supernovae seen in the duplicate images. This can ultimately help us to understand the nature of cosmic expansion. Press release

Cold brown dwarfs are some of the most bizarre and yet fascinating sub-stellar objects in the universe. Aaron Meisner (NSF’s NOIRLab) has collaborated with a huge team of citizen scientists through the Backyard Worlds: Planet 9 project, launched in 2017 at Zooniverse, and has since collected more than 7 million user ‘classifications’ from 150,000 contributors. The result? They have constructed the most complete 3D map of brown dwarfs in the solar neighborhood, selected from images from NASA’s WISE satellite together with the data from DESI. Predictions suggest that our solar neighborhood should host a variety of stellar types, brown dwarfs included. However, the results from Backyard Worlds suggest otherwise: they find the nearest brown dwarf seriously far away at 7 parsecs distance. That may mean that our solar neighborhood is tantalizingly devoid of brown dwarfs, or they’re possibly just too faint to be detected. The citizen scientists not only get to share in the limelight of the discovery, but they have the opportunity to work on projects connecting them to some of the premier facilities in all of astronomy. Press release

Black holes in galaxies also seem to be missing. The X-ray emission from all of the monster black holes found so far doesn’t add up to what we see from the cosmic X-ray background. Stephanie Juneau (NSF’s NOIRLab) has worked to correct this dire picture. By using the incredibly wide imaging from the DESI survey, she and her team have tracked down some of these missing black holes. The trick? Combining multiple imaging surveys with spectroscopic follow-up. This way they can identify candidate black holes from the images and then use DESI spectroscopy to confirm them. But the X-ray emission from black holes likes to ‘flicker’ on and off, making them even more difficult to find. If the survey can confirm all of their candidates, Juneau and her team can better understand how often black holes flicker, which has the potential to impact how we understand the growth of black holes and their connection to their host galaxies.

Live-tweeting of the briefing by John Weaver

Annie Jump Cannon Award in Astronomy: Hazy Views of Nearby Worlds: Standing Between Two Eras of Exoplanet Characterization (by Michael Hammer)


Artist’s illustration of NASA’s TESS mission observing a system of transiting exoplanets. [MIT]

The last plenary talk of the day was given by Professor Caroline Morley (Univ. of Texas at Austin), this year’s winner of the Annie Jump Cannon Award in Astronomy. An expert on characterizing exoplanet atmospheres, Morley “has advanced our understanding of clouds and photochemical hazes” and “paved the way for the robust detection of water and other molecules in exoplanet atmospheres.” Above all, she is also an Astrobites alum who helped us cover these very AAS meetings as recently as five years ago! Over the past decade, Morley has modelled a wide variety of atmospheres of (1) different-sized planets, and (2) different-temperature brown dwarfs. After years of relying mainly on the Kepler and Hubble space telescopes for her research, she is now looking forward to the new era of TESS and JWST! In the coming years, TESS will hunt down virtually all of the planets closest to Earth that are best-suited for having their atmospheres characterized, while JWST will enhance our capabilities for probing molecular features and other facets of these atmospheres like clouds and hazes with its much larger 6.5-meter aperture and a wider range of wavelengths into the mid-infrared.

The three-part overarching goal driving the field of exoplanet atmospheres is to find molecular biosignatures in the atmosphere of an Earth-like planet around a solar-type star. Before we can do that though, we had to start out by making concessions on all three parts. Most studies of exoplanet atmospheres are based on transmission spectra (see Morley’s own bite for an overview, and here and here for more recent updates) that are taken as a planet transits in front of its star. Similar to the limitations of detecting planets through transits, planets that produce deeper transits yield better-resolved spectra, making it easier to detect features in atmospheres of planets bigger than Earth or around stars smaller than the Sun. Meanwhile, planets that have thicker atmospheres (>1% by mass) than Earth (0.0001% by mass) are also easier to resolve. Beyond just biosignatures, we want to characterize what planetary atmospheres are made of in general.

cloudy exoplanet

Artist’s impression of a cloudy exoplanet. [NASA/ESA/G. Bacon, STScI/L. Kreidberg and J. Bean, University of Chicago/H. Knutson, Caltech]

Even those broader goals have not been straightforward to achieve. Morley and her collaborators have demonstrated that clouds in planetary atmospheres can (1) flatten molecular absorption and emission features, (2) re-radiate light at longer “redder” wavelengths, and (3) change the temperature in the atmosphere — effects that all make it harder to characterize the composition. In spite of those obstacles, Morley’s models illustrate that spectra with wide enough wavelength coverage can be sufficient to detect individual molecules, even if the spectrum appears to be flat! She and her collaborators have also shown that even if a single spectrum of a small sub-Neptune is not sufficient for characterization (due to degeneracies), gathering an ensemble of spectra of many sub-Neptunes can allow us to probe which atmospheres are hazy.

Beyond planets, another focus of Morley’s research has been brown dwarfs. The atmospheres of free-floating brown dwarfs are easier to resolve than those of planets around stars because their spectra are not contaminated by nearby starlight. And, more importantly, they may shed some insight on what planetary atmospheres are like because the coldest ones that we only started discovering this past decade (Y-type) have similar temperatures to planets — at least one is even colder than the Earth! Morley and her collaborators have shown that the atmospheres of Y dwarfs can have thick methane hazes and be out of equilibrium.

Sounds exciting? The AAS certainly thinks so, in that they decided to give next year’s Annie Jump Cannon Award to one of Morley’s collaborators: Laura Kreidberg. Stay tuned for more developments in the field of exoplanet atmospheres — TESS and JWST will certainly provide them!

Interview of Caroline Morley by Briley Lewis
Live-tweeting of the session by Michael Hammer

Hearing the Light: How Sonification Makes Astronomy More Accessible (by Abby Waggoner)

Clara Braseur (Space Telescope Science Institute) & Jenn Kotler (Space Telescope Science Institute) hosted this afternoon’s session on sonification.

As beautiful as the images, plots, and figures we use for astronomy are, visual based astronomy presents a barrier for individuals who have visual impairments or are blind. Sonification is a process that converts visual images into sounds, thus making astronomy more accessible. For a (really awesome) example, check out this NASA website for some examples that bring three astronomical objects to our ears. 

Not only does sonification make astronomy more accessible, but it also presents a new method of interpreting data. Our eyes are able to process roughly 100 frames per second, whereas our ears are able to process over one million frames per second, thus detecting information that our eyes may have missed. We are also able to filter out background sounds and noise more easily in audio rather than visual form a phenomenon known as the cocktail effect — which can make finding patterns in noisy data much easier. 

Sonification is a really cool method, but how does one go about doing it? Thanks to the program Astronify, sonification of your own data is super easy to do. Astronify is a python based code and can be installed on any computer for free using a simple installation command. You simply give it a table of data, such as flux and time, and let it run! Astronify is currently ideal for sonifying lightcurves, spectra, or any other 2D plot, but the Astronify team is working on introducing more dimensions and error bars on the sounds. Check out the two videos below for the sonification of lightcurve with no flare and a lightcurve with seven flares using Astronify. 

Sonification is an exciting tool we can use to make astronomy more accessible, and thanks to Astronify, it is becoming a process we can apply to our own data.



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.

Plenary: Prize Presentations (by Abby Waggoner)

Day two of AAS 237 began with a brief overview of outstanding astronomers and the awards they received for their contribution to the field. All of the awardees are listed in this twitter thread, along with a description of the awardees’ accomplishments. Awards ranged across all fields of astronomy, including instrumentation, theory, education, writing, and more. Congratulations to all of the awardees!

Live-tweeting of the session by Abby Waggoner

Plenary: A New Era for Galactic Dynamics in the Milky Way (by Briley Lewis)

This morning’s first plenary was from Adrian Price-Whelan (Flatiron Institute), astronomer and astropy developer. He opened with a message that likely resonated with many of us, acknowledging how difficult the past year has been and how hard it is to work and be productive. “It’s okay if you’re unproductive, it’s okay if you’re struggling for motivation, it’s okay if you need to prioritize yourself or your family.” 

The science part of this talk focused on galactic dynamics in the Milky Way. With all the surveys of Milky Way stars from the past few decades, we have lots of data to work with. Importantly, these surveys released their data publicly and spanned many modes of observation: photometry and time-domain imaging (2MASS, SDSS, GALEX), astrometry (Gaia), and spectroscopy (APOGEE, GALAH). Gaia is of particular importance, since it has added extremely precise parallaxes and proper motions for many stars in our galaxy. With all these data we can figure out stellar parameters, elemental abundances, kinematics, and more.

apw hipparcos to gaia

This plot from Price-Whelan’s talk shows the drastic increase in the number of stars with velocity measurements between the Hipparcos mission and the new Gaia mission.

For many years, studies of the Milky Way relied on “first order” models — smooth, simplified descriptions of the galaxy. Price-Whelan showed the classic “cartoon/textbook Milky Way” with a central bar, thin disk, thick disk, halo, and dark matter halo. We already know our galaxy also has sub-galaxies (like the Large and Small Magellanic Clouds, a.k.a. LMC/SMC) and dark matter subhalos

apw-mw cartoon

Cartoon of the Milky Way showing the different features mentioned.

The velocity of the Sun in the galaxy and our distance to the galactic center are well defined, and we have a good “big idea” picture of the galaxy’s overall density, rotation curve, and velocity dispersion in the halo. But with all these new data, like what we’re getting from Gaia, those first order models just can’t keep up with the precision. Price-Whelan is interested in looking at where we see deviations in the precise data from those first order models, to investigate the Milky Way’s structure in finer detail.

apw deviations

This plot from Price-Whelan’s talk shows observed data from SDSS and a corresponding smooth model. The third panel, the residuals, is what Price-Whelan is most interested in studying.

It turns out that satellite galaxies and mergers are a big factor in shaping the Milky Way as we see it and causing these deviations. For example, the Sagittarius Stream (created from the Sagittarius Dwarf Galaxy) perturbed the outer parts of the Milky Way, and the Gaia-Enceladus Merger led to the thick disk that we observe. In the dark matter distribution of the Milky Way, we also see our galaxy responding to the infall of the LMC/SMC.

apw sag passage

This comic shows the history of interactions between the Sagittarius Dwarf Galaxy and the Milky Way, tracing out the streams it left behind. [ESA; Ruiz-Lara et al. 2020]

apw streams

Image showing the observed stellar streams around the Milky Way, including Sagittarius.

We can also use the motion of these satellites to investigate the structure of dark matter in our galaxy. By measuring the orbits of these thin stellar streams (from disrupted star clusters), we can trace out the acceleration field and better understand where the dark matter is. Given that all this interesting galactic science arises from publicly available data, Price-Whelan concluded by emphasizing the importance of open-source software and open science, which encourages collaboration and community building. So, put your code on GitHub

Interview of Adrian Price-Whelan by Michael Foley
Live-tweeting of the session by Haley Wahl
Recording of this talk and hands-on access to some of Adrian’s visualizations available on his website

Press Conference: Galaxies & Quasars I (by Haley Wahl)

Old Faithful

Illustration of a monster black hole siphoning gas off of an orbiting giant star. [NASA’s Goddard SFC/Chris Smith (USRA/GESTAR)]

The first talk of the press conference was given by graduate student Anna Payne from the University of Hawaii, Manoa. Anna and her team discovered periodic flares coming from an active galactic nucleus in the galaxy ESO 253-3, and they examined them using ASAS-SN and the Swift Telescope. They can predict when these flares go off, and think that they may be caused by tidal disruption events. Press release

The next talk of the press conference was given by graduate student (and Astrobites author!) Gourav Khullar from the University of Chicago. He discussed COOL J1241+2219, the brightest galaxy observed from when the universe was < 1.2 billion years old. This galaxy is unique because it is near the epoch of reionization. The team found that this galaxy was consistent with a constantly star-forming galaxy and that it has formed a few times the number of stars of the Milky Way in just 1/10th the time, and at a much earlier time in the universe!

Cygnus A core

Most quasars are thought to be obscured by dust. [NASA/SOFIA/Lynette Cook]

Next was Bradford Snios from the Center for Astrophysics | Harvard & Smithsonian who discussed the discovery of a new quasar. The team focuses on quasar formation in the early universe; quasars are formed when black holes consume large quantities of matter for a long period of time. Because this process is so violent, most quasars are thought to be obscured by dust. It’s perhaps surprising, therefore, that we’ve found only a handful of obscured quasars at large distances! By using Chandra, the team uncovered the fourth obscured quasar ever discovered (which is at z = 4.56, or 10% the age of the universe), and it is 10–1000x brighter than other quasars discovered in the early universe!

The final talk of the press conference was given by Feige Wang from the University of Arizona, who talked about an exciting new discovery. The team announced the detection of the most distant quasar ever discovered, which is seen just 670 million years after the Big Bang and is powered by a black hole that is 1.6 billion times the mass of our Sun! Press release

Recording of the live press conference
Live-tweeting of this session by Haley Wahl

NASA Town Hall (by Mike Foley)

Today’s town hall featured a lot of exciting updates about planned missions and budgetary considerations. First up was Dr. Thomas Zurbuchen (Associate Administrator for the Science Mission Directorate at NASA), who stressed the importance of open communication between NASA and astronomers. “Science is important for all!” he said, emphasizing the necessity of connection with non-scientists as astronomers seek to publicize their work. 2021 will have many long-awaited launches and projects from NASA, and the public deserves to know about all of this cool science. 

Overall, the NASA Science Mission Directorate has a few key areas of focus for this year:

  1. Promoting open science through data sharing, open-source software, and other initiatives.
  2. Diversity and inclusion initiatives to “build the best teams we can.” Inclusion is now one of NASA’s criteria for evaluating mission success.
  3. Assessing and mitigating COVID-19 impacts on NASA research and missions.

In addition to these areas of focus, NASA also has a large number of projects planned for 2021. Below is a breakdown of 2021 milestones for the NASA science directorates. Some major highlights include the release of the Decadal Survey in the spring, which presents an overview of the state of astronomy and astrophysics in the United States. The telescope formerly known as WFIRST was renamed the Nancy Grace Roman Space Telescope in honor of NASA’s first chief astronomer and is well into development, with a completion date scheduled for the end of 2021. The James Webb Space Telescope (JWST) will also launch later this year, revolutionizing many areas of astronomy. Finally, the Mars Perseverance rover will land on February 18th, 2021!

NASA 2021 milestones

In terms of research, NASA has started to implement dual-anonymous peer review. Because of this, the proportion of accepted proposals with female-identifying PIs (principal investigators) is now consistent with the full application pool! There is overwhelming agreement that the dual-anonymous peer review process improved the overall quality of the peer review. Astronomy research will also benefit from a significant funding package from Congress, allocating over $500 million more than was requested and featuring significant funds for JWST, Roman, Hubble, and SOFIA

Live-tweeting of the session by Mia de los Reyes

HEAD Bruno Rossi Prize: Black Hole Imaging: First Results and Future Vision (by Mike Foley)

M87 EHT image

The first detailed image of a black hole, M87, taken with the Event Horizon Telescope. [Adapted from EHT collaboration et al 2019]

This year’s HEAD Bruno Rossi Prize went to Sheperd S. Doeleman (Center for Astrophysics | Harvard & Smithsonian) and the Event Horizon Telescope collaboration (EHT) for producing the first image of a supermassive black hole. This observation made headlines around the world and has already helped to place constraints on our understanding of supermassive black holes and their accretion disks. The talk began with a brief history of those pioneers who originally thought about accretion disks surrounding black holes. Jean-Pierre Luminet was the first one to create a simulation of the accretion disk around a black hole, setting the stage for the observations that the EHT can now make. 

Since then, simulations have improved significantly, and the EHT relied extensively on large samples of simulations of black hole accretion disks to understand their results. These accretion disks are enormous — the one observed around the black hole in M87 is large enough to fit our entire solar system, even beyond the distance traveled by Voyager 1! Nevertheless, M87’s accretion disk is extremely faint when observed from Earth, and it requires incredible resolving power to see. To observe it, the EHT needed to make use of a network of telescopes all across the globe. They combined them to make one “super telescope” with an effective diameter the size of the Earth. 

EHT 2017 campaign

Eight stations of the EHT 2017 campaign over six geographic locations. [EHT Collaboration et al 2019]

After obtaining the observations, teams of scientists within the EHT were created to independently analyze the results. This was done to ensure the least amount of bias possible in the results. The four independent teams used or developed their own data reduction algorithms, yet the results the teams achieved were strikingly similar. In every case, the accretion disk was clearly observed around the supermassive black hole. This allowed the EHT scientists to derive constraints on the black hole’s mass of roughly 6.5 x 109 solar masses. Their observation appears to pass every sanity check too, indicating that it is truly the shadow of a black hole.

Where to go from here? More resolution! The next generation EHT (ngEHT) will add new telescopes, improve hardware, and observe at two different wavelengths. Such improvements will yield a 3–10x increase in effective resolution, allowing for observations of up to 10 more sources and even potentially enabling scientists to create movies of a black hole! According to Dr. Doeleman, “ngEHT development is underway, with the promise of a black hole cinema by the end of this decade.” Such groundbreaking results will continue to revolutionize our understanding of supermassive black holes and help define the next era of astronomy. 

Interview of Sheperd Doeleman by Gloria Fonseca Alvarez
Live-tweeting of the session by Mike Foley

Special Session: Collaboration with Integrity: Partnerships with Indigenous Communities in the Americas and Polynesia (by Luna Zagorac)

This session was chaired by Prof. Aparna Venkatesan (University of San Francisco), who began it with a land acknowledgement for where the meeting would have been held: on the land of the Tohono O’odham Nation in Phoenix, Arizona. Prof Venkatesan further acknowledged the difficulty of the past year and the inequality that exists is society and astronomy, asking: “Can we choose a collaborative approach, rather than a transactional approach?… In gaining the stars, who are we losing?”

Afterwards, Prof. Venkatesan introduced Professor Nancy Maryboy and Professor David Begay of the Indigenous Education Institute and Northern Arizona University who spoke about Diné-Navajo astronomical knowledge. Prof. Maryboy noted that “the Diné-Navajo word for Star, Sitsoii Yoo, refers to my ancient relation from where I came…When we look at the Milky Way Galaxy at night we are actually looking at ourselves.” Prof. Begay underlined that the key words here are “ancient” and “relation,” reminding us that we are all made up of the elements of the cosmos. Prof. Begay went on to explain the connection of the hogan, the Navajo house, and the cosmos that is home to us all, noting that this is why there is no word meaning “homeless” in the Navajo language. Prof. Maryboy spoke more about heliophysics and relationships to the Sun called Johannaa’ éí, and depicted as a man on a horse carrying the solar disk. She also spoke of the Navajo hero twins that visit the Sun, comparing them to the NASA Solar Orbiter and Solar Probe. The Navajo have a long history of discussing travelling to the Sun, she noted. 

The next speaker was Dr. Kaʻiu Kimura, Executive Director of the ‘Imiloa Astronomy Center of Hawaiʻi at the University of Hawaiʻi – Hilo. Dr. Kimura has spoken at previous AAS meetings about A Hua He Inoa, an initiative to use ʻōlelo Hawaiʻi (the Hawaiian language) in naming conventions for naming astronomical objects. Celestial nomenclature and acknowledging connections with the sky has been a part of the Hawaiian universe since the very start (see A Catalogue of Hawaiian and Pacific Star Names), and Dr. Kimura noted that “through naming, we connect to events of historical experience…Names tell stories.” Some recent examples of of using ʻōlelo Hawaiʻi include: asteroid Kamoʻoalewa, alluding to a celestial object that is oscillating, like its path in the sky as viewed from the Earth; black hole Pōwehi, an “embellished source of unending creation,” referring to the recently-imaged black hole at the center of M87; and quasar Pōniuāʻena. Kimura also shared a video of one of the 30 kumu (teachers) from Hawaiian immersion schools, who spoke about the naming as the result of relaying modern technology with 1,621-year history of Indigenous Hawaiian intelligence. Dr. Kimura also emphasized the importance of building connection and developing meaningful relationships between communities, noting that true collaboration is authentic and embraces everyone.

Finally, for the panel part of the session Prof. Venkatesan introduced the remaining panelists: Dr. Douglas Simons of the Canada-France-Hawaii Telescope, Dr. Isabel Hawkins of Exploratorium, and Dr. Laura Peticolas of Sonoma State University. While we did not cover this part of the session in detail, we will end our write-up with a note from Dr. Hawkins that was echoed by Dr. Kimura: introducing Hawaiian naming conventions goes both ways, and Western-trained astronomers can benefit greatly from learning about the language and Indigenous astronomical knowledge more generally. 

Press Conference: Sloan: The Energizer Bunny of Sky Surveys (by Haley Wahl)

The Sloan Digital Sky Survey has been mapping out the universe for more than two decades now, and it’s still going strong! Today’s second press conference focused on some of the latest results to come out of the survey.

symbiotic binary

An artistic impression based on a computer simulation of the Draco C1 symbiotic binary star system showing material flowing off the red giant star onto the white dwarf. [John Blondin, North Carolina State University]

First up were Hannah Lewis from the University of Virginia and Jasmin Washington of the University of Arizona. They discussed their work on APOGEE (the Apache Point Observatory Galactic Evolution Experiment), a survey that provides a wealth of data for both galactic and extragalactic binary stars. The team studied an extragalactic binary composed of stars in a “symbiotic” relationship, where the white dwarf is consuming the outer atmosphere of its giant host. These stars are very rare, but both stars are very bright, so they can be observed even though they lie in a satellite galaxy outside of the Milky Way. Their work resulted in the first complete orbit derived for a symbiotic system outside of our galaxy! Press release

The second speaker was Dr. Allyson Sheffield from LaGuardia Community College, who discussed new discoveries in the Jhelum stellar stream. Her team examined this stream of stars and found the brightest known member. They also were able to deduce that the Jhelum stream stars may have originated in a satellite galaxy or a globular cluster, and found that stars from the Gaia-Enceladus-Sausage merger do not appear to be associated with the Jhelum stellar stream. Press release

Galaxy Zoo 3D

Left: optical image of a galaxy shown to citizen scientists. Right: the heat map of the galaxy’s internal structures collectively generated by the citizen scientists’ input. [Karen Masters (Haverford College), Coleman Krawczyk (University of Portsmouth), and the SDSS Collaboration]

Next, Dr. Karen Masters of Haverford College shared results from the Galaxy Zoo 3D project. This citizen science project crowdsourced the production of feature masks for all 10,000 galaxies in the SDSS-IV MaNGA survey (which does spectral mapping of nearby galaxies), revealing the internal structure of the galaxies and bringing us closer to being able to use all of the beautiful complexity in the MaNGA data. The team plans to do its final data release of MaNGA in December of 2021. Press release

The final talk of the press conference, “A Handoff from SDSS IV to SDSS V,” was given by Juna Kollmeier of Carnegie Observatories and Michael Blanton of New York University. SDSS IV is currently finishing its observations after its 6-year survey, and over the last 20 years, SDSS has made the largest 3D map of the universe, looked at over 10,000 nearby galaxies with MaNGA, and more! SDSS-V plates are currently being constructed using robots that place fibers, which will dramatically increase efficiency in the next phase of the survey. A few components of SDSS-V include: the Milky Way Mapper (which will measure stars in all stellar populations and across the galaxy), the Local Volume Mapper (which will study how stars form and exchange energy with interstellar gas), and the Black Hole Mapper (which will trace how black holes evolve on short and long timescales)!

Recording of the live press conference 

Plenary: Cosmology in the Era of Multi-Messenger Astronomy (by Tarini Konchady)

The last plenary talk of the day was given by Dr. Marcelle Soares-Santos (University of Michigan), who tackled how cosmology is changing as gravitational wave observatories come into their own. Soares-Santos is deeply involved in the Dark Energy Survey (DES), which aims to study dark energy and large scale structure to better understand the universe.

What’s the benefit to introducing gravitational wave science into cosmology? Over the past few decades, astronomers have been increasingly stymied by measurements of the Hubble constant — the rate at which the universe is expanding. Measurements of the Hubble constant from the cosmic microwave background differ significantly from those measurements made using redshifts and distances as determined by Type Ia supernovae. This is strange, because our models of the universe predict that the Hubble constant should have the same value no matter how you measure it!

Soares-Santos said gravitational wave events could provide a tiebreaker between these two measured values of the Hubble constant. The changing frequency of gravitational wave signals can give you the distance to the event, and the electromagnetic counterpart of the event would give you its redshift, allowing an independent measurement of the Hubble constant.

GW Hubble Posterior

The Hubble constant as estimated by the event GW170817 is shown by the blue curve. The dashed lines are confidence intervals on this estimate. The green region is the Hubble constant measurement made from the cosmic microwave background and the orange region is the measurement made from the distances and redshifts of Type Ia supernovae. [The LIGO Scientific Collaboration and The Virgo Collaboration, et al. 2017]

The first gravitational wave event with an observed electromagnetic counterpart was the binary neutron star merger GW170817. This was no small feat, since current gravitational wave observatories can’t pinpoint exactly where a signal came from, only the general area. Soares-Santos and her collaborators in the DES were among teams of astronomers trying to locate an optical counterpart to the merger. While they were narrowly beaten by the team at the Swope Telescope, they were able to use the wide reach of the DES’s Blanco Telescope to rule out any sources other than the merger.

With the electromagnetic signal of a neutron star merger in hand, Soares-Santos was able to demonstrate that combining DES data with less than ten neutron star mergers could significantly cut down on uncertainty in cosmological parameters. However, binary black hole mergers — the most common gravitational wave event so far — require a different approach.

There currently aren’t any known electromagnetic counterparts to black hole mergers. But if you know roughly where a merger took place and map out all the galaxies in that region, you can generate the probability that the merger took place in a particular galaxy. From there, you can determine the galaxy’s redshift and pair it with the distance as measured from the merger signal.

Soares-Santos closed by noting that this particular area of astronomy is changing at a breakneck pace (and would make a great entry point for new grad students!). More optical surveys are coming online in the next few years along with a larger gravitational wave observatory network. It’s feasible that by the late 2020s, we’ll have a high precision measurement of the Hubble constant just based on gravitational wave events!

Interview of Marcelle Soares-Santos by Gloria Fonseca Alvarez
Live-tweeting of the session by Abby Waggoner

pulsar timing array

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.

Welcome Address (by Abby Waggoner)

Welcome to AAS 237! This conference was initially going to be held in Arizona, but due to the COVID-19 pandemic, AAS 237 is being held virtually this week. Before we get into what’s going on this year, I thought it would be beneficial to take a moment to highlight some of the positive aspects of a virtual conference. Like AAS 236 (held in June 2020), attendance at AAS this year is at an all time high. So, even though we have to suffer through time zone differences and missing out on social aspects, the newest discoveries in astronomy are more accessible to astronomers (including students!) who otherwise might not have attended an in person conference because of a lack of time and/or funding. 

This year about 3,000 people have registered for AAS, contributing seven plenary talks, 623 oral talks, 521 iPosters, 268 iPosters+, 11 town halls, 59 exhibitor booths, and 71 exhibitor webinars. A lot is happening this week. Luckily, Astrobites is here to sum up as much as we can in this blog and in live tweets (search #AAS237 as well)! We’ll be covering everything from plenary talks to career sessions, so stay tuned in the coming week. 

While we’re hoping to “trash the pandemic in 2021,” as AAS President Paula Szkody stated, there are some big changes that are coming in the future. For example, how can we make a better virtual conference experience? If you have questions or recommendations, the AAS officers can be easily contacted, but it turns out there are many ways for students to become involved in AAS. First off, AAS officer elections are happening now, so if you’re a member, please go vote! Additionally, AAS members (including students!) can be involved in the Strategic Assembly, which meets every five years to determine the direction of AAS in the next five years, and members can also join a committee. While there are many committees, Paula highlighted three that have been important in the recent months: the Committee on Public Policy, the Ethics Committee, and the LPRS-LEOS 

Despite a global pandemic, we have found ways to connect and collaborate. Here’s to the beginning of an exciting week of science!

Live-tweeting of the session by Haley Wahl

Fred Kavli Plenary Lecture: The North American Nanohertz Observatory for Gravitational Waves (by Haley Wahl)

The conference was kicked off with a plenary by the National Radio Astronomy Observatory (NRAO) Dr. Paul Demorest. Dr. Demorest is part of the North American Nanohertz Observatory (NANOGrav) collaboration, a team of scientists spread throughout North America who are using pulsar timing to detect gravitational waves.

Dr. Demorest started off by introducing gravitational waves, which are ripples in the fabric of spacetime caused by the orbiting of large masses. Like sound waves, gravitational waves can have different frequencies, and that frequency is determined by what kind of object is emitting them (for example, the gravitational waves that LIGO detects are emitted by the mergers of neutron stars and stellar-mass black holes, whereas the gravitational waves that NANOGrav is sensitive to are emitted by objects like supermassive black hole binaries). NANOGrav uses pulsars, which are extremely dense, rapidly rotating neutron stars, to search for gravitational waves. Pulsars give off radio waves that cross our sightline like a lighthouse beacon. Millisecond pulsars (which are pulsars recycled in a binary system) have periods on the order of milliseconds, and they are extremely stable rotators, rivaling atomic clocks in terms of accuracy. Because they are so accurate, NANOGrav can model the exact time a pulse should arrive at our telescopes (called the “time of arrival”). As a gravitational wave comes toward us, it will push the spacetime in front of it and the pulsar will arrive slightly earlier than expected; if the gravitational wave is retreating, it will expand the spacetime between us and the pulsar, and the signal will arrive slightly later than expected.

gravitational-wave spectrum

The gravitational wave spectrum and detectors. Here, frequency of the gravitational waves is plotted against strain (the fractional change in the separation between objects caused by the passage of the gravitational wave). [NANOGrav]

The team uses data from two major radio telescopes: the Green Bank Telescope in West Virginia and the Arecibo Observatory in Puerto Rico. The Arecibo Observatory recently suffered a tragic collapse, but Dr. Demorest did highlight some of its many accomplishments, including discovering the first binary pulsar (which led to a Nobel Prize), pinpointing a periodicity in the pulsar at the center of the Crab Nebula, and detecting the first millisecond pulsar. The NANOGrav team “times,” or obtains the time of arrival, of pulses from pulsars spread all around the sky. If a gravitational wave passes between us and the pulsar, it will have a certain signature, called the Hellings-Downs correlation (to read more about it, check out this Astrobite explaining the original paper!), which relies on a wide angular separation between pulsars on the sky.

NANOGrav is currently observing 78 pulsars and adds ~4 pulsars to their array each year, and it observes each pulsar ~once a month. In NANOGrav’s latest data release (the 12.5-year release), the team finds significant evidence for low-frequency noise (a “common red process,” noise in the data set that is correlated in time; for more on the types of noise in the NANOGrav data sets, see Astrobites author Brent Sharpiro-Albert’s Twitter thread). Is this signal a detection of gravitational waves? The team isn’t sure. There is only very weak evidence for a Hellings-Downs (quadrupolar) angular correlation — it does not match up exactly with what they are expecting. How are they going to resolve this? With more data from recent, sensitive instruments like CHIME, MeerKAT, and FAST; upgrades to the Green Bank Telescope; and new pulsars. Beyond an initial detection, NANOGrav hopes to characterize the gravitational wave background, characterize properties of individual binaries and electromagnetic counterparts, and more! To learn more about NANOGrav’s latest data set, see Joe Simon’s talk at the press conference!

NANOGrav data

NANOGrav’s data plotted with the expected Hellings-Downs curve.

Live-tweeting of the session by Haley Wahl

CSMA Panel: A Discussion on Anti-Blackness in Astronomy (by Gourav Khullar)

This session, hosted by Dra. Nicole Cabrera Salazar and Prof. Lia Corrales (CSMA), was led and moderated by Ashley Walker (graduated from Chicago State University; applying to graduate schools), with a panel comprising junior Black astronomers and physicists Caprice Phillips (2nd year PhD student, Ohio State University, she/her), Erin Flowers (4th year PhD student, Princeton University, she/her), and David Zegeye (2nd year PhD student, The University of Chicago, he/him). 

A host of topics were discussed in this session, ranging from what it meant for the panelists to be Black in the US, to how anti-Blackness manifested itself in predominantly white spaces. All panelists shared suggestions of what action-oriented allyship looks like, and they discussed their individual and collective visions for the future of both astronomy as a whole, and Black astronomy in particular. An astrobite with details of this extremely insightful discussion will follow the AAS meeting, later this month. In the meantime, you can find the Astrobites Twitter coverage of today’s session by Michael Hammer here. Also, check out our piece from summer 2020 on #BlackInAstro: How Can We Support Black Astronomers? 

Press Conference: News from the Dark Side (by Susanna Kohler)

AAS 237’s press conference lineup kicked off with a discussion of a variety of things dark and hidden in our universe.

First up: a look at globular clusters, motivated by the past discoveries of mysterious dwarf galaxies that appear to be largely devoid of dark matter. Jessica Doppel, a graduate student at University of California, Riverside, discussed how adding globular clusters to the cosmological simulation Illustris allows us to better understand why some galaxies are missing dark matter. The simulations show that galaxies that host globular clusters with a low spread in velocities have often been stripped of a large fraction of their dark matter. This implies that ultradiffuse galaxies we’ve observed that have a very small spread in globular cluster velocities may have previously lost most of their dark matter.

What about dark matter closer to home? To understand the nature of dark matter in the Milky Way, we need precise measurements of the average acceleration of stars in our galaxy — tiny motions driven by the Milky Way’s dark matter and stellar mass. Sukanya Chakrabarti (Rochester Institute of Technology) presented work that uses the precise timing of pulsars as cosmic clocks to make the first direct measurements of our galactic acceleration. Determining these tiny changes in velocity provides valuable information that will help us to better understand the invisible forces that operate in our galaxy and beyond. Press release

Looking for more on NANOGrav’s latest news (see the summary of Paul Demorest’s plenary talk above)? The next presenter, Joseph Simon (University of Colorado, Boulder) provided us with a closer look at how NANOGrav works — namely, thanks to the incredible timing precision of the wide array of pulsars that “bob in an ocean of gravitational waves” — and then dug into the new, intriguing low-frequency signal that NANOGrav recently announced. This signal might correspond to a detection of the background ocean of gravitational waves, but it doesn’t quite match our expectations. So far, all we can say with certainty is that it’s a strong signal, a lot of sources of noise have already been ruled out, and we should have a better idea of what’s causing it with another couple years of data. It would be very exciting if we’ve actually found the gravitational-wave background after 12.5 years of searching with NANOGrav! Press release

Last up, Mattia di Mauro (National Institute for Nuclear Physics, Torino, Italy) rounded out the session on a different topic: the source of the unexpected excess of gamma-ray radiation spotted in the center of the Milky Way. Is this high-energy emission caused by dark matter particle interactions? Cosmic rays produced from the galactic center? Pulsars located in the galactic bulge? Di Mauro discussed the constraints that are imposed on the options by 11 years of Fermi-LAT data and state of the art models.

Live tweeting of the session by Haley Wahl

Historical Astronomy Division (HAD) Town Hall (by Luna Zagorac)

The Historical Astronomy Division (HAD) town hall started off with some regular division business. First up was a heartfelt congratulations to the winners of the September 2020 HAD elections, including Vice-Chair/Chair-Elect Terry Oswalt, as well as Amy Oliver and Samantha Thompson on the Executive committee. Next, the audience was reminded of HAD’s column in the AAS News Digest, “This Month in Astronomical History”, and that it is always recruiting new authors! If you have an idea or a pitch for the column, HAD would be delighted to hear from you, and you can contact them via the email listed for the column on their website. Furthermore, HAD dues are waived for junior, graduate, and emeritus members, making it easier for interested AAS members to join the Division without additional financial burden! One reason for becoming a member of HAD might be to turn in your nomination for the 2022 LeRoy E. Doggett Prize for Historical Astronomy, which any member of HAD can propose until March 1, 2021. Another might be to consider helping write obituaries for passed AAS members, which can be a thoughtful way to honor those that came before us, but also learn more about both their histories and science careers. 

Secchi Sicily

An image of the path of totality of the Total Solar Eclipse of 1870 over the island of Sicily, and a black and white photo of the Italian expedition to image the eclipse in Sicily, with Secchi circled. [Slide by Ileana Chinnici]

The majority of the session was led by special guest Ileana Chinnici, the winner of the 2021 Osterbrock Book Prize for her biography of Angelo Secchi titled “Decoding the Stars: A Biography of Angelo Secchi, Jesuit and Scientist.” Chinnici summarized her book for the audience, weaving the story of a man who was neither a hero, a heretic, nor a visionary. Rather than writing a hagiography, Chinnici strove to showcase Secchi for what he was: a Jesuit and a scientist. Despite Secchi’s tenure at the Georgetown Jesuit College near Washington, DC after he fled the 1848 revolutions in Italian states, there are few English-language sources on Secchi. Chinnici is looking to change this, both with Decoding the Stars and an upcoming work she co-edited, “Angelo Secchi and the 19th Century Sciences.” While we will not reveal all the details here interested readers will have to seek out Chinnici’s work for those one fascinating instance of Secchi’s legacy in science is his role in founding the Italian Spectroscopic Society (Società degli Spettroscopisti Italiani) in 1871, whose minutes and writings could be said to constitute the first astronomical journal. Furthermore, while Secchi’s legacy fell by the wayside in Italy, his legacy in the US lives on, most notably in NASA’s STEREO solar mission’s SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) telescopes.

Live-tweeting of the session by Luna Zagorac

Plenary Talk: From Galaxies to Faces: Recognizing the Implications of Artificial Intelligence in Astronomy and Society (by Briley Lewis)

The second plenary of the conference went beyond presenting interesting science results, as Brian Nord (FermiLab) led us to critically think about how we’re “living with the tools we create.” It focused on how algorithms permeate our lives, as do the choices we make in implementation and development of those algorithms. Nord asks us to consider the following question: “Who gets to decide what knowledge and tools we pursue, and who is in the room when those decisions are made?” (Just a disclaimer: this short summary can in no way fully do justice to this incredible talk, and I highly recommend you watch the recorded version if you are able!)

Nord started out with a timeline of development, explaining the starts and stops of artificial intelligence (AI) over the past hundred or so years. He defines artificial intelligence as “a class of algorithms to build models primarily driven by data.” These algorithms “learn” by training with historical data. The algorithms are also shaped by our choices: how we design them, what network architectures we choose, and the data we use to train them. We’re in another wave of AI development now, which is set apart from the past attempts by our extremely large data sets, improvements in computing, and more efficient algorithms. 

Nord classification

An example of classification in astronomical data from Nord’s talk.

Two critical challenges AI faces are bias and uncertainty. Because our training sets are historical, they cannot necessarily predict the future, and they are often limited in size and diversity, leading to bias. Uncertainty is also a main technological challenge in AI development, since there is currently a lack of reliable methods for error propagation. Despite these challenges, AI shows great promise as a powerful tool for astronomy. It has already been used for multiple scientific challenges: classification of strong lenses, image disentangling for CMB polarization and E modes, simulations that are sped up by GANs (generative adversarial networks), and self-driving telescopes. Classification is a particular strong suit for AI, which Nord describes as “almost a hands-down win because of how it accelerates looking through a large data set.” Astronomical experiments are getting too complex to design and develop in a timely manner using traditional methods, Nord claims, but they can be sped up with AI.

Nord art choice

An example of AI generated art in Nord’s talk. Panel A is the figure that was generated by AI.

Before diving headfirst into the pool of artificial intelligence, though, Nord reminds us to think about “what our role will be in this evolution” and to ask, “Maybe we can, but should we?” The allure of AI is strong: it can tell us what to watch, what to buy, how to distribute medicine more efficiently, possible solutions for climate change, how to make travel safer with self-driving cars, and it can even make art and play games now. But we mustn’t neglect the perils that come with this promise.

Using surveillance as a case study for the dark side of AI, Nord lists many examples of ethically questionable uses of these algorithms: Google collecting email data to sell ads, Amazon keeping microphones on in its smart devices, and Clearview AI selling a facial recognition neural net trained by social media data to law enforcement. These algorithms use biased training sets in order to predict emotions, gender, race, ethnicity, and more, all with implications for who gets healthcare, who gets into college, who goes to jail, and maybe even who dies in combat. 

Nord calls on us all to acknowledge our responsibility as scientists and citizens, saying that “we care about measurements and biases in our dark matter measurements, so why not biases in those who are incarcerated.” We need to consider whose dreams our communities value and who is in the room when knowledge is created and questions are asked. He explains how white supremacy permeates our spaces, including our research communities, and that fact is not divisive — division ensues from how we choose to respond to that fact. We should care about diversity in our communities, not because it supposedly increases our productivity, but because it is just. We bear responsibility for the things we create.

Given these heavy facts and the impending boom of AI, what can we do to ensure that these algorithms are used equitably and justly? Nord suggests reading about the ethical and social implications of our work, learning from scholars in critical race theory, ethics, social science, and beyond. We need to call out science that hurts people when we see it, and advocate for reform, such as banning biased facial recognition in law enforcement. We can also participate in and support organizations based on these principles, such as the Algorithmic Justice League, the AI Now Institute, FAT/ML, and the Alphabet Workers Union.

As scientists, we must remember that we are funded by the people that these algorithms impact, and we have the ability to change the way we collaborate, centering first and foremost the question of “is our community healthy?” like he and collaborators have in the Deep Skies Lab. We have an opportunity to reimagine our role in the future of science and AI, and it’s time we reconsider whose voices we are raising up.

Interview of Brian Nord by Mia de los Reyes
Live-tweeting of the session by Michael Hammer

Press Conference: Exoplanets & Brown Dwarfs (by Ellis Avallone)

The second press conference of the meeting was all about stellar companions, primarily exoplanets. First, Dr. David Ciardi (Caltech) talked about the decade-long confirmation of Kepler’s second planet candidate. KOI-5 was detected in the first 10 days of the Kepler mission, via a pristine transit lightcurve. With such a nice transit detection, why did KOI-5 take so long to confirm? The answer: it’s in a triple-star system. Initial follow-up observations with the Keck telescope on Maunakea revealed a secondary companion. When Dr. Ciardi and his group attempted to characterize KOI-5 with radial-velocity (RV) observations, they found that these signals were dominated by the stellar companions. With the sheer number of planet candidates Kepler was detecting, it isn’t surprising that KOI-5 got pushed to the back burner. A decade later, KOI-5 was observed with TESS, which brought Dr. Ciardi back to this elusive planet. The observation of a transit with TESS, along with new RV observations, gave Dr. Ciardi enough information to solve for the secondary star’s orbit. Subtracting this information from the RV signal revealed the RV signal of the planet — a 57 Earth mass object. We also learned from this second look at KOI-5 that the orbits of the planet and the multi-star system are misaligned. This once-forgotten planet may yet reveal more interesting information about how planets in multi-star systems form and evolve. Press release

gas giant exoplanet

Artist’s rendering of a 10-million-year-old star system with a gas-giant planet like Jupiter. [NASA/JPL-Caltech/T. Pyle]

Next, Dr. Paul Dalba, a postdoc at University of California, Riverside, told us all about studying giant exoplanets with the Giant Outer Transiting Exoplanet Mass (GOT ‘EM) survey. Most of the exoplanets we’ve detected orbit very close to their host star. As we move to orbits similar to the gas giants in our own solar system, the number of extrasolar cases we have decreases sharply. The GOT ‘EM survey seeks to fill the gap between the ultra-short period planets and the long period planets in our solar system. As its name implies, the GOT ‘EM survey seeks to measure masses of giant planets. Planet masses are a critical piece of information in understanding how planets form and evolve. The first results of this survey focus on the characterization of Kepler-1514b, a Jupiter-sized planet with a 218-day orbit. RV observations from Keck revealed a significant difference from Jupiter: KOI-1514b is nearly 6 times more massive. The high density of this planet leaves many open questions regarding how material is distributed within the planet. As GOT ‘EM observes and characterizes more of these giant planets, some of these questions may soon have answers. Press release

Moving on, Dr. Lauren Weiss, a postdoc at the University of Hawai`i at Mānoa, took a turn to talk about rocky planets, specifically TOI-561b. TOI-561b is a 3-Earth-mass planet originally detected with TESS and confirmed using RV observations from Keck. Follow-up observations revealed that this planet’s host star is located in the thick disk of our Milky Way, indicating that this star is around 10 billion years old! This finding suggests that TOI-561b is the oldest exoplanet we’ve found, which shows that rocky planets have been forming for far longer than originally thought. Additionally, thick disk stars are much more metal poor than the host stars of other rocky planets, which raises questions surrounding the stellar properties required for rocky planet hosts. In the context of astrobiology, Dr. Weiss speculates that these old rocky planets may serve as our best chance for finding intelligent life outside our solar system. Press release

Kepler starry night

Illustration of the planet-hunting telescope Kepler. [NASA/Ames Research Center/W. Stenzel/D. Rutter]

Finally, Travis Berger, a graduate student at the University of Hawai`i at Mānoa, discussed how Gaia has changed how we look at the Kepler sample. Prior to 2018, we lacked distances to the majority of Kepler stars. Thanks to Gaia, an observatory that aims to precisely map the Milky Way, we now have the measurements we need to tackle some of the biggest questions in exoplanet science. Precise stellar distances yield increased precision on stellar properties, including radii and ages. These constraints allow us to accurately analyze exoplanet demographics, which are key to understanding how solar systems form and evolve. Here, Berger specifically focuses on how planet properties vary with stellar age, particularly with respect to super-Earths and sub-Neptunes. Looking at the distribution of planets as a function of planet size and age, Berger found significantly fewer super-Earths in young planetary systems (those younger than 1 billion years) than in old planetary systems. This hints at a potential formation mechanism for super-Earths, where sub-Neptune sized planets become stripped of their thick atmospheres over time. Berger’s work is just one example of how valuable using survey data can be. Press release

Live-tweeting of the session by Ellis Avallone

Helen B. Warner Prize: Hidden Friends to Gravitational Wave Sources at the Hearts of Galaxies (by Michael Hammer)

This year, the AAS awarded the Helen B. Warner Prize to Professor Smadar Naoz (Univ. of California, Los Angeles) for “her many early career contributions to theoretical astrophysics.” Naoz, who was also the 2015 Annie Jump Cannon Prize recipient at AAS 227, has worked on a wide variety of topics including the “formation of the first stars” and the “unexpected orbital properties of hot Jupiters”, but she decided to focus today’s talk solely on black hole mergers and related sources of gravitational waves. Black hole mergers have been in the spotlight in astronomy ever since LIGO made the first ever detection of gravitational waves back in 2015! Since then, LIGO and Virgo combined have made 50+ detections of several different types of mergers. With this abundance of detections, it may be easy to forget that until a few years ago, we had no idea how many black hole mergers to expect. In fact, theoretical models had shown that under ordinary conditions, individual black hole pairs would take longer than the age of the universe to merge. If ordinary mergers are indeed that slow, then what are the sources of LIGO’s and Virgo’s gravitational wave detections?

That’s where Naoz came to the rescue. With her research group, she sought to calculate the rates of mergers in conditions that aren’t ordinary, focusing on black hole pairs “at the heart of galaxies.” This is an extreme location because of (1) the much higher number density of stars, and (2) the nearby supermassive black hole (SMBH) at each center. The heart of a galaxy is even more extreme if the SMBH has a >40° inclination between its plane and the orbital plane of a nearby black hole pair. In this case, the SMBH has the power to drastically alter the orbit of the black hole pair, turning it from near-circular to highly eccentric and back again! This repeating cycle is called the Kozai-Lidov mechanism. Naoz in particular developed the eccentric Kozai-Lidov (EKL) mechanism, which applies to more realistic cases where both black holes in the pair have mass and their orbit isn’t perfectly circular. Unlike the regular Kozai-Lidov mechanism, the eccentric Kozai-Lidov mechanism can excite the black hole pair to extremely high eccentricities of e > 0.99 so that one approaches the other, just like a comet approaches the Sun. With such a high eccentricity, these black holes are much more prone to collide on timescales even as low as a few hundred years, much faster than the age of the universe!

EKL causing mergers

Inclination (top) and eccentricity (bottom) evolution of a black hole pair near a SMBH inclined at >40 degrees. While the Kozai-Lidov mechanism (blue) only excites black hole pairs to e = 0.9, the eccentric Kozai-Lidov mechanism (red) can excites black hole pairs to e > 0.9999. Such extreme eccentricities lead the black holes to merge, creating gravitational waves!

Now that Naoz had a way for black holes to merge quickly, she wanted to know how many black hole pairs there were to begin with, to predict how many gravitational wave events LIGO can detect per year. Naoz and her group explored the rates at which binary star systems in the galactic center can form pairs of black hole pairs and other compact objects that produce gravitational waves. They found that most binary stars won’t produce black hole pairs or other gravitational wave sources because binaries are prone to becoming unbound and separating when other stars pass by. Even though outcomes that produce gravitational waves are less likely, Naoz and collaborators still find enough gravitational wave sources to predict that LIGO should be able to detect a few dozen events per year!

Throughout the talk, Naoz emphasized the contributions of her students to this work and highlighted current and recent grad students Sanaea Rose, Alexander Stephan, and Bao-Minh Haong in particular, as well as undergraduate Cheryl Wang.

Interview of Smadar Naoz by Briley Lewis
Live-tweeting of the session by Briley Lewis

Career Session: Public Speaking in a Virtual Environment (by Abby Waggoner)

Do you get the jitters just before giving a presentation? Do your hands clam up at the thought of talking in front of your colleagues? Does the idea of a virtual presentation make your hair stand on end? If you answered yes to any of these questions, you are like nearly every other human on this planet. This discussion-based session, led by Alaina G. Levine (Quantum Success Solutions), covered some important bullet points to consider when giving a presentation and how to calm your nerves. The main takeaways are listed below, but there was one common sentiment that Alaina emphasized again and again. 

“There is value in what you have to say.”

“You are the expert, and you have the capability to be a good speaker.”

“You have something of value to share, and your audience knows it. Your audience wants you to succeed.”

“There is a reason you have been given that platform.”

As the zoom chat filled with stories of presentation grief, Alaina repeated these phrases at every point during the discussion. The key takeaway from this session is this: fortify your confidence when giving a talk. Every time we speak, in our everyday conversations, in group meetings, and at conferences, our words hold value. Remember that what you have to say matters.

Other recommendations included:

  1. Fortify your confidence.
  2. Connect with your audience.
  3. Place sticky notes on your monitor, reminding you to look into the camera, not the screen. This allows the audience to feel more connected. 
  4. Remember to smile.
  5. Keep a clean and neat space behind you.
  6. Have lighting that frames your face.
  7. Present your information as a story. Your audience won’t remember a figure or table, but they’ll remember a story and how it made them feel.
  8. Tell your audience. Tell them again. Then summarize what you already told them.
  9. If someone is interrupting you (such as an unmuted listener), interrupt yourself to ask that person to stop being an interruption.
  10. Know the main points, but don’t write your speech word for word. 
  11. Ask yourself why your presentation is of interest to your audience.
  12. Own your mistakes. They will happen. You appear more confident when you recover and can continue after making a mistake. 
  13. Move your body! Alaina kept her hands in the camera shot to maintain non verbal communication typically lost over zoom. 
  14. Add dramatic pauses. 
  15. Increase and decrease your volume to emphasize points. 
  16. Pre-recorded talks: record them once, so you don’t record them again and again and again.
  17. Repeat questions out loud. 
  18. You aren’t expected to know everything. Your job is to communicate the knowledge that you have, so it’s okay to not know the answer to a question. 
  19. Remember: “You are the expert, and you have the capability to be a good speaker.”
  20. Remember: “There is value in what you have to say.”

Career Session: Combat Impostor Syndrome (by Abby Waggoner)

Whether you’ve realized it or not, you’ve likely felt impostor syndrome at some point in your life. Impostor syndrome is the internal doubt that many of us feel when surrounded by accomplished peers, the nervous feeling at applying for an internship or grant we don’t know if we can get, and the overall feeling of being a fraud. Almost everyone has experienced imposter syndrome, as the cartoon below shows. 

impostor syndrome

Everyone struggles with impostor syndrome sometimes. [errantscience.com]

In this session, Stephanie Deppe (Rubin Observatory & former Astrobites writer) highlighted the key manifestations of impostor syndrome and the key mindsets that lead to it. If you are interested in more information on impostor syndrome, check out this astrobite written by Stephanie. Stephanie’s astrobite and the points presented in today’s session are summarized from The Secret Thoughts of Successful Women by Valerie Young (a good read for all genders). In the second part of the session, Alaina G. Levine (Quantum Success Solutions) gave an overview of an article she wrote, How to banish impostor syndrome, where she listed some helpful goals and strategies to overcome impostor syndrome. 

If you find doubt clouding your accomplishments and self worth, I highly recommend utilizing the resources in this summary. We all feel this way at some point, like when we’re applying for grad school, switching fields of research, in group meetings, and at conferences. But make sure to remind yourself of everything you have accomplished to be where you are and where you are going. In the words of Alaina, the most important thing you can do is “honor yourself and everything that you do.”


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

AAS Nova Editor Susanna Kohler and AAS Media Fellow Tarini Konchady will join Astrobites Media Intern Haley Wahl and Astrobiters Ellis Avallone, Mike Foley, Michael Hammer, Gourav Khullar, Briley Lewis, Abygail Waggoner, John Weaver, and Luna Zagorac 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 as well as a number of additional sessions, so follow along here on aasnova.org or on astrobites.org!

Astrobites at AAS237

As with the summer meeting, we’re sad not to get to talk to you in person, but 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.

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 Haley at the press conferences all week.

Also, there’s a lot of Astrobiter science at AAS 237 — be sure to check out the talks and posters given by Astrobites authors in the schedule below.

Astrobiter science AAS237

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 AAS237 keynote speaker interviews here. Be sure to check back all week as the remainder are released!

AAS237 Speakers

AAS Publishing

Will you be joining us online for the 237th American Astronomical Society meeting? AAS Publishing looks forward to seeing you there! You can come find us at the AAS Publishing booth in the virtual exhibit hall, and you can check out AAS-Publishing-related endeavors in a number of events throughout the week (some already underway!). Below are just a few.

Publishing Data in the AAS Journals: A hands-on workshop (2-day workshop)

Thursday, 7 January, 11:00 – 13:00 (ET)
Friday, 8 January, 11:00 – 13:00 (ET)

How do you present data in your research articles? Do you include a few plots and tables? Or do you enhance your narrative through the use of animations and interactive figures? Make flip-books out of figure sets? Supply the underlying data behind your tables and figures so other authors can reproduce your work? The AAS Journals (ApJ, ApJL, ApJS, AJ, RNAAS, and PSJ) support all of these options and more – and 20% of our published content already contains at least one of these types of data products. If your research involves data and you want to learn how to better integrate it into your articles and present it in a way that will increase the readability, usefulness, and citations of your work, register now for the AAS journals’ newest workshop! On the first day of this workshop, the AAS data editors will discuss all of the ways ambitious authors can boost their future manuscripts. In addition to discussions of various available data products, this will also include tutorials on working with the latest versions of AASTeX and using the Overleaf collaborative environment, and there will be plenty of time for questions and answers. The second day is left open so that participants can drop in when they please with their own projects and receive one-on-one instruction and advice from the data editors.

Registration Fee: $15

Making the Most of AAS WorldWide Telescope workshop

Friday, 8 January, 11:00 – 12:30 (ET)

AAS WorldWide Telescope (WWT) is the American Astronomical Society’s official tool for visually exploring humanity’s scientific understanding of the Universe. This free and open-source software package can power everything from interactive “live” images in journal articles, to exploratory data visualizations in Jupyter notebooks, to immersive custom websites, to professional-grade planetariums. This interactive tutorial will introduce attendees to the WWT software ecosystem in the context of its applications to research, education, and public outreach.

Unified Astronomy Thesaurus Community Day

Wednesday, January 13, 16:10 (ET) in the AAS Publishing Booth

Come and meet with the UAT Curator and members of the UAT Steering Committee and learn how the UAT can be implemented at your organization or publication!

Want more info about the UAT? Check out this recent UAT webinar on youtube:

Chat with AAS Publishing and Astrobites

Want to chat with AAS Publishing? The following folks will be at the AAS Publishing booth all week:

Julie Steffen, AAS Chief Publishing Officer
Janice Sexton, AAS Editorial Operations Manager
Frank Timmes, AAS Lead Editor of the High-Energy Phenomena and Fundamental Physics corridor


You can also request to meet with AAS Journals Editor in Chief Ethan Vishniac, our data editors Greg Schwarz and Gus Muench, and the AAS’s Innovation Scientist and WorldWide Telescope Director Peter Williams.

You can find AAS Nova Editor Susanna Kohler and the Astrobites team at the Astrobites booth throughout the meeting.

Publishing Your AAS 237 Presentation in RNAAS

The Society’s venue for short works, Research Notes of the AAS (RNAAS), is accepting submissions for a focus issue covering work presented and discussed at our virtual meeting.

By publishing your AAS 237 presentation as a research note, you give it a permanent, citable home within the literature and make it available for all those unable to join us during the meeting. Research notes are short (up to 1350 words, plus a 150 word abstract, with a single figure or table), moderated by AAS editors, and searchable on ADS. Research notes cover a remarkable diversity of topics, and do not preclude later inclusion of results in more substantial, refereed work. 

GRB 181123B

Editor’s note: AAS Nova is on vacation until 2 November. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

As their name suggests, short gamma-ray bursts are very brief flashes of high-energy light that last less than a couple seconds — making them challenging to localize to their galaxy of origin. If you’re quick enough, however, you might be able to spot the faint but longer-lived afterglow in lower-energy wavelengths that follows the gamma-ray flash. And if you’ve got a powerful enough telescope, you might be able to spot this afterglow even when the explosion occurred ten billion light-years away!

Such is the case in a recent study led by Kerry Paterson (CIERA, Northwestern University), which announces the afterglow detection and localization of GRB 181123B using the Gemini North and Keck telescopes. GRB 181123B’s host galaxy lies at a redshift of z = 1.77, which corresponds to a time when the universe was just 3.8 billion years old! This is the second-most distant short gamma-ray burst we’ve pinpointed, and the most distant to also have an optical afterglow detected — providing a rare opportunity to study the mergers of neutron stars at “cosmic high noon”, when our young universe reached its peak period of star formation.

Check out the NOIRLab-produced video below for an artist’s illustration that shows how GRB 181123B compares to other gamma-ray bursts we’ve discovered so far.

Original article: “Discovery of the Optical Afterglow and Host Galaxy of Short GRB 181123B at z = 1.754: Implications for Delay Time Distributions,” K. Paterson et al 2020 ApJL 898 L32. doi:10.3847/2041-8213/aba4b0
CIERA press release and links to other resources: Short Gamma Ray Burst Leaves Most-distant Optical Afterglow Ever Detected

hot Neptune

Editor’s note: AAS Nova is on vacation until 2 November. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

Among the types of known exoplanets we’ve spotted in our galaxy, there lie some gaps. One of them is the hot Neptune desert — a dearth of Neptune-sized planets that orbit close to their host stars. We speculate that these planets may be in short supply because they’re too small to retain their atmospheres that close to the heat of their hosts, but this desert still raises a lot of questions.

We now have an excellent opportunity to learn more, with the Transiting Exoplanet Survey Satellite (TESS) discovery of one such “planet that shouldn’t exist”: LTT 9779b. This hot Neptune is blasted by the radiation of its host as it tears around its star in less than 24 hours. And yet, somehow, it still has an atmosphere!

In a pair of papers recently published in ApJL, scientists Diana Dragomir (University of New Mexico) and Ian Crossfield (University of Kansas) lead explorations of this unexpected planet using TESS and the Spitzer infrared space telescope. They examine the atmosphere of LTT 9779b in two ways: by using phase-curve analysis, which charts the change in the planet’s brightness as it orbits around its host, and by measuring the planet’s emission using its secondary transit, which is when it passes behind its star (see the video below).

To learn more about the authors’ discoveries, check out the following articles and press releases.

Original articles:
“Spitzer Reveals Evidence of Molecular Absorption in the Atmosphere of the Hot Neptune LTT 9779b,” Diana Dragomir et al 2020 ApJL 903 L6. doi:10.3847/2041-8213/abbc70
“Phase Curves of Hot Neptune LTT 9779b Suggest a High-metallicity Atmosphere,” Ian J. M. Crossfield et al 2020 ApJL 903 L7. doi:10.3847/2041-8213/abbc71
Press releases:
University of New Mexico: Data reveals evidence of molecular absorption in the atmosphere of a hot Neptune
University of Kansas: New study details atmosphere on ‘hot Neptune’ 260 light years away that ‘shouldn’t exist’

magnetar sGRB

Editor’s note: AAS Nova is on vacation until 2 November. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

The question of what happens after two neutron stars collide is still an open one — thrown into the spotlight in recent years with the detection of a gravitational-wave signal coincident with electromagnetic radiation from the neutron-star collision GW170817. Scientists are actively working to improve models of this process, and the latest comes from a team led by Philipp Mösta (University of Amsterdam). The authors’ 3D models show what might happen to a post-collision remnant — a hypermassive neutron star — as it evolves over time, gaining magnetic field strength and launching dramatic, relativistic jets and neutron-rich winds. The simulations show how a burst of gamma rays can be produced, as well as heavy elements like gold, all nicely matching observations of the 2017 merger.

Check out the video below to watch the authors’ simulated remnant (and its magnetic field lines) evolve for yourself.

Original article: “A Magnetar Engine for Short GRBs and Kilonovae,” Philipp Mösta et al 2020 ApJL 901 L37. doi:10.3847/2041-8213/abb6ef
NOVA press release: Improved model shows gamma rays and gold at merging neutron stars

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