Editor’s Note: This week we’re at the 245th AAS meeting in National Harbor, MD, and online. 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 for daily summaries, or follow @astrobites.bsky.social on Bluesky for more coverage. The usual posting schedule for AAS Nova will resume on January 21st.
Table of Contents:
- Workshop: Strategies for Mentoring Undergraduate Researchers (From Sunday, 12 January)
- Welcome Address by AAS President, Dara Norman (NSF NOIRLab)
- Fred Kavli Prize Plenary Lecture: The Terrestrial Worlds of Low-Mass Stars, Dave Charbonneau (Harvard University)
- Congressman Glenn Ivey Visit
- Press Conference: A Feast of Feasting Black Holes
- Plenary Lecture: Galaxy Evolution Eras Tour: The Formative Years of Star Formation and Supermassive Black Hole Growth, Alexandra Pope (University of Massachusetts Amherst)
- Press Conference: Supernovae and Massive Stars
- Plenary Lecture: Punching Back Asteroids: The Deflection of Dimorphos by the DART Mission, Jason Kalirai (Johns Hopkins Applied Physics Laboratory)
- Plenary Lecture: Direct Observational Constraints on Planet Formation and Accretion, Kate Follette (Amherst College)
Workshop: Strategies for Mentoring Undergraduate Researchers (by Lindsey Gordon)
This workshop came out of the Council for Undergraduate Research and Dr. Carol Hood’s work at Cal State Bernardino on programs like CalBridge. It’ll be offered again at future conferences including the American Physical Society conference. The workshop was split into two parts. In the first, small groups discussed mentoring strategies based on experiences. What makes a good mentor? What makes a bad mentor? The important takeaway was student-centered / student-driven mentoring. In the second half, the development of individual development plans was discussed, using real student examples. These plans work backwards from a goal to create a roadmap for the student’s research, and they are broadly applicable to mentorship beyond research.
Welcome Address by AAS President, Dara Norman (NSF NOIRLab) (by Lindsey Gordon)
This year marks the 125th anniversary of AAS, and 50th AAS President Dara Norman gave opening remarks on Monday morning. She honored our colleagues who have lost their homes in the LA fires and couldn’t attend this year. (This article from the LA Times lists ways to help those affected by the fires, and the Federal Trade Commission provides guidance on how to donate safely and avoid scams.) Dr. Norman emphasized the importance of the AAS working groups, who are dealing with the rise in AI, the overwhelming numbers of applicants to astronomy graduate programs, and our carbon footprint. The 2027 summer meeting will be held fully virtually in response to members’ concerns about climate change, equity and access, and the health of our members. “This will not be your grandma’s virtual meeting,” Dr. Norman quipped. The meeting overlaps with the International Astronomical Union general assembly, which the virtual format allows flexibility for. She concluded by emphasizing the diversity of our community and the need to retain that diversity and to maintain our community.
Fred Kavli Prize Plenary Lecture: The Terrestrial Worlds of Low-Mass Stars, Dave Charbonneau (Harvard University) (by Lindsey Gordon)
David Charbonneau is a pioneer in observations of transiting exoplanets, and in the new plenary format of taking the Q&A session two-thirds of the way through your talk when the slides fail. He and Prof. Sara Seager (MIT) won the 2024 Kavli Prize for their work on exoplanets and their atmospheres.
His work focuses on terrestrial planets: how they form their atmospheres, how those atmospheres depend on the planet and the host star, how they might lose their atmospheres, and how we might be able to detect the atmosphere and its chemical contents.
So how do we study planetary atmospheres? It turns out we can only study systems within 15 parsecs of us with stars that are ~30% the radius of the Sun. JWST and the Extremely Large Telescope are expected to be able to detect molecules in the atmospheres of planets in that range. Dr. Charbonneau described his work on the M spectral class, which covers a huge range of stellar sizes. The M-dwarf stars he cares about for this work are the ones that fall into that 30% solar radius category. However, stars at these masses are fully convective with no radiative zone. This has huge implications for the star’s magnetic and emission activity and long-term angular momentum evolution.
There are 413 stars that fit into their observing parameters. For these stars his group studied:
1. The rate of occurrence of terrestrial worlds using the transit method, of which they find 7 in that group. They then studied the sensitivity rate — did we find all the planets that are there? — by injecting fake observations for different planetary sizes and periods. From this they were able to infer the intrinsic rate of occurrence of terrestrial planets. They didn’t see large terrestrial planets or small planets that we would’ve expected to find if they were there. This led them to conclude that there is a high occurrence rate — at least one rocky planet per two low-mass M dwarfs — and the distribution of those planets’ radii peaks at 1 Earth radius.
2. The rate of occurrence of gas giant (Jupiter-like) planets using the radial velocity method. One-third of the stars in the population had no spectra, so they set out to complete the sample. The presence of Jupiter in our solar system was highly influential to the properties of our terrestrial planets; systems without such a planet may have evolved very differently. They found that essentially none (<1.5%) of the low-mass stars had a Jupiter analog, and therefore the terrestrial planets in those systems may be very different than in ours.
At this point, the presentation equipment failed. He took questions at this time, during which he told us about his favorite planet, which is a cold, rocky planet in the habitable zone around a calm star that is a great opportunity for determining if rocky planets can retain their atmospheres.
3. Characterizing the stellar magnetic activity and other properties. They found two populations of very fast and very slowly rotating stars, suggesting a rapid transition between those states. They found the flare rate of the rapid rotators is much higher than slow rotators, which could have serious implications for the survival of an atmosphere. The stellar spindown is also very mass-dependent, with larger stars spinning down faster.
Congressman Glenn Ivey Visit (by Lindsey Gordon)
“Goddard in the house!” Congressman Glenn Ivey has represented Maryland’s 4th congressional district — which includes Goddard Space Flight Center — since 2023. He paid a visit to the exhibit hall floor on Monday morning, where he emphasized the importance of work in the sciences, particularly in the role of climate change in the recent wildfires in CA. He’s working to keep science, NASA, and Goddard moving in the right direction in what is a very exciting time in our industry.
Press Conference: A Feast of Feasting Black Holes (by Lindsey Gordon) (Briefing video)
Witnessing the Birth of a New Plasma Jet from a Supermassive Black Hole
Eileen Meyer (University of Maryland, Baltimore County)
Dr. Meyer discussed 1ES 1927+654, a nearby “changing look” active galactic nucleus (AGN) that brightened by 100x in 2018 over the course of a few months. This is a rare event, and the system has been monitored closely across a range of wavelengths ever since. In 2022 the X-ray emission picked up, and then the radio peaked as well, 60x brighter at the peak. The radio peak suggests that AGN jets were turned on, which had never been observed before, and challenged beliefs about the on/off timescales for jets. Very Long Baseline Array observations saw the emergence of jets going 33% the speed of light. This might be the birth of a compact symmetric object, due to the initial brightness peaking resembling a tidal disruption event. | Press release
Rapidly Evolving X-Ray Oscillations in the Active Galaxy 1ES 1927+654
Megan Masterson (Massachusetts Institute of Technology)
Masterson (an Astrobiter!) discussed the same source as Dr. Meyer and highlighted its X-ray variability. The Neutron star Interior Composition Explorer (NICER) and XMM-Newton observations show a short-term periodicity around the supermassive black hole, which is rare to observe. The period has declined from 18 to 7 minutes over the past ~2 years and is stabilizing around 7 minutes. This could be due to either oscillations of the new jets, or due to an orbiting white dwarf very close to the black hole. The system is observable by the Laser Interferometer Space Antenna (LISA), which could confirm the white dwarf if it is one. | Press release
Uncovering the Dining Habits of Supermassive Black Holes in Our Cosmic Backyard with NuLANDS
Peter Boorman (California Institute of Technology)
Dr. Boorman discussed the work of the NuLANDS project, which used infrared observations to find a population of both obscured and unobscured AGN. The obscuration comes from the donut-shaped accretion disk of material being “eaten” by the black hole. Different levels of obscuration occur depending on the orientation of the donut relative to the observer. AGN are infrared bright regardless of orientation, allowing a complete sample to be found and then categorized. They found a very balanced population of ~35% heavily obscured, ~37% obscured, and ~28% unobscured AGN, which makes a great sample for future studies. | Press release
The Discovery of a Newborn Quasar Jet Triggered by a Cosmic Dance
Olivia Achenbach (United States Naval Academy)
We’ve been navigating by the stars for millennia now, but modern methods also use radio signals for calibration. Radio systems that switch from an “off” state to an “on” state could affect these methods. Achenbach studied a system of a recently turned-on radio-bright AGN to study trigger mechanisms for new jet formation. She found a system with evidence of previous jet activity that had been recently reignited by galaxy–galaxy interactions with a tidal tail connecting the two. | Press release
Plenary Lecture: Galaxy Evolution Eras Tour: The Formative Years of Star Formation and Supermassive Black Hole Growth, Alexandra Pope (University of Massachusetts Amherst) (by Archana Aravindan)
The AAS 245 is just another stop in Dr. Pope’s Galaxy Evolution Eras Tour! Galaxies, just like Taylor Swift, go through different eras. In this plenary talk, Dr. Pope, Professor of Astronomy at the University of Massachusetts Amherst and the chair of the Five College Astronomy Department, focuses on the formative years of galaxy growth. This period is commonly known as cosmic noon, occurring between 10 and 11 billion years ago. During this time, galaxies formed stars at a rapid rate and black holes in galaxies grew quickly.
There appears to be some correlation between the rapidly growing supermassive black holes (active galactic nuclei (AGN)) and the star formation in galaxies. This manifests itself in several scaling relations that are observed between the mass of the black hole and the mass of stars in the galaxy in which it resides. However, we still do not know how exactly the two processes correlate with each other. Dust plays an important role in our (limited) understanding of the correlations between black holes and star formation in galaxies at cosmic noon. The majority of cosmic star formation is hidden behind the dust, with observations indicating that 50–75% of AGN are in obscured dust-filled galaxies. Luckily, with JWST, we can finally pierce through the dust and look at dusty galaxies to understand the correlations!
It’s me, hi, I’m the problem!
The biggest problem (other than dust!) in understanding the correlation between star formation and black hole growth is that measurements of the black hole accretion rates and star formation rates are often not taken from the same sample of galaxies. Using the MIRI instrument on JWST, Dr. Pope and her collaborators simultaneously study the black hole accretion rate and star formation rate in the same sample of dusty galaxies at cosmic noon. AGN and star formation activity have unique spectral signatures that can be disentangled from one another, allowing measurements of both the black hole accretion rate and star formation rate in the same galaxy. Their ultimate goal is to track the galaxies as they land on the scaling relations between the mass of the black hole and the mass of the stars.
End Game?
JWST covers the mid-infrared part of the electromagnetic spectrum, and the Atacama Large Millimeter/submillimeter Array helps us understand the submillimeter wavelengths in these cosmic noon galaxies. However, the far-infrared wavelengths are not well observed and are likely holding a wealth of information about the interplay of AGN and star formation activity. Enter the Probe far-Infrared Mission for Astrophysics (PRIMA), which is one of the two missions selected for a concept study by NASA. This far-infrared observatory will be able to measure scaling relations, redshifts, black hole accretion rates and star formation rates for nearly 60,000 galaxies. After a detailed evaluation, NASA will select one concept in 2026 to proceed with construction, for a launch in 2032. With PRIMA, Dr. Pope is hopeful that we might finally understand how black holes and stars in a galaxy co-evolve!
Press Conference: Supernovae and Massive Stars (by Jessie Thwaites) (Briefing video)
JWST Discovery of a Distant Supernova Linked to a Massive Progenitor in the Early Universe
Dave Coulter (Space Telescope Science Institute)
Supernovae are responsible for a huge variety of astrophysical phenomena, including star formation and heavy element production. At the beginning of our universe (right after the Big Bang), the first stars began to form. These stars were “considerably different than stars today,” and their supernovae featured “gargantuan explosions,” says Dr. Coulter. Using the JADES transient survey with JWST, some of the earliest supernovae can be studied, including the case of AT 2023adsv which is at redshift 3.61when the universe was less than 2 billion years old. This study marks a major first step towards finding the earliest supernovae and studying the evolution of some of the earliest stars. | Press release (PDF)
Core-Collapse Supernovae as Key Dust Producers: New Insights from JWST
Melissa Shahbandeh (Space Telescope Science Institute)
Dust is incredibly important in astronomy; it provides the building blocks for stars and planets that eventually create our universe as we know it today. Massive dust reservoirs have recently been detected in high-redshift galaxies, leading astronomers to re-think how dust is formed in these systems. Dr. Shahbandeh describes how core-collapse supernovae, specifically Type IIN supernovae, could be the answer. By studying supernova 2005ip with Spitzer and JWST, they can study the life cycle of dust, from the supernova that spreads material throughout the system, to the new star that forms, to the formation of solar systems and planets (and maybe life!), to the cycle’s repeat when the new star goes supernova. Dr. Shahbandeh finds that supernovae are rapid dust factories, and continue to create dust, even years after explosion! | Press release (PDF)
JWST Tracks the Expanding Dusty Fingerprints of a Massive Binary
Emma Lieb (University of Denver)
Lieb discusses an interesting binary system, known as WR140, which is enriching its local environment with dust. It consists of a massive, evolved star with strong stellar winds (called a Wolf-Rayet star) and an O-star companion. They are in a highly eccentric orbit around each other, and when they pass at their nearest point (called periastron), their stellar winds collide and produce dust, “kind of like a big belch.” By taking two images of this system nearly a year apart with JWST, Lieb can study the expanding shells of dust produced by these near passes. They find that the shells are moving at nearly 1% of the speed of light, and are non-uniform, which provides clues to the dust’s formation. | Press release
Stellar Pyrotechnics on Display in Super Star Cluster
Kristina Monsch (Center for Astrophysics | Harvard & Smithsonian)
The super star clusters (SSC) are being studied by EWOCS! Not the cute fluffy characters from Star Wars, but by the EWOCS Project, which is an international team studying the star formation processes in the Westerlund 1 and 2 clusters. These clusters consist of young, massive stars (more than 100 times the mass of our Sun), and are able to ionize their surroundings. Westerlund 1 (Wd1) is nearby (4.2 kpc away), and includes massive stars at many different phases of stellar evolution. By observing this cluster in the near- and mid-infrared with JWST’s NIRCam and MIRI instruments, Dr. Monsch can pierce through the dust in these clusters to observe the stars near the center of the cluster. They can study the powerful winds from these massive stars to gain insight into how these stars form, impact their environment, and die. | Press release
A Blue Lurker Emerges from a Triple-System Merger
Emily Leiner (Illinois Institute of Technology)
While studying the cluster Messier 67, Dr. Leiner noticed something strange. Most stars in this cluster are the same age and have similar rotations, but there are a few peculiar “blue lurker” stars that rotate suspiciously fast for their age. Hubble observations of one of these stars revealed a white dwarf with a larger mass than expected for the cluster’s population orbiting the blue lurker star.
Dr. Leiner discovered that this was the remnant of a triple system, where two closely orbiting stars merged and blew their outer envelope away, leaving behind the white dwarf. This caused accretion onto the third star — the blue lurker — which sped up its rotation. Triple star systems are fairly common (around 10% of Sun-like stars are in a triple system), they are only beginning to be understood. | Press release
Plenary Lecture: Punching Back Asteroids: The Deflection of Dimorphos by the DART Mission, Jason Kalirai (Johns Hopkins Applied Physics Laboratory) (by Bill Smith)
Everyone who takes an introductory astronomy class learns about calculating orbits of celestial bodies, but Dr. Kalirai’s talk focused on humanity’s first successful attempt to change one. He gave an overview of the DART (Double Asteroid Redirection Test) mission, a mission designed to test our capabilities to defend Earth from an asteroid that might be heading towards impact by sending a spacecraft to smash into the asteroid to see if the impact could alter an asteroid’s trajectory to miss impact.
He began with a charge for humanity: “Let’s not be like the dinosaurs!” He followed this up with an overview of the potential threat, noting that we still haven’t found many of the asteroids that could hit Earth that are big enough to result in planetary-scale catastrophic consequences, noting examples like the Chelyabinsk impact in Russia.
He began his explanation of the mission by explaining why the “D” in DART stands for “Double.” Because asteroids orbit the Sun, it would be impossible with current technology to measure the change in an orbit of one due to the impact of a spacecraft. To get around this, the DART team identified two asteroids in a binary orbit around each other. By crashing the craft into one of them, they are able to measure the impact’s effect by studying the change to the binary orbit of the asteroids, so they ultimately decided on the Didymos–Dimorphos asteroid binary system as their target.
Next, Dr. Kalirai discussed some of the unique technical challenges of the mission, including installing a CubeSat called LICIA that would deploy before impact to collect data about the impact, and the automated guiding system that was necessary for the spacecraft to the smaller of the two asteroids in the system, because it was not identifiable until the spacecraft was essentially almost there.
Dr. Kalirai then reviewed what the DART mission team learned from the impact itself. First, it slowed the orbital period of the asteroid by about a half hour, when the original goal of the mission was about 7 minutes. They measured the momentum enhancement (called a beta), which was a factor of 3.6. A beta factor of 1 indicates the amount of momentum transfer if the craft simply hit the asteroid with no ejected material, and a beta factor higher than this indicates that the ejected material from the impact further affected the asteroid’s orbit. A measurement of 3.6 was higher than anticipated, and provided an optimistic result for this technique’s ability to potentially defend Earth in the future.
A slide from Dr. Kalirai’s talk. On the left is a simulation snapshot of a DART-like spacecraft impacting a dense rocky object of similar size to the target asteroid, and on the right is an image soon after the impact of the spacecraft and asteroid.
Dr. Kalirai concluded with two main points. First, although the DART mission itself was successful, he stressed the need to find the asteroids we still don’t know about and highlighted the future Near-Earth Object Surveyor Mission. Second, he described a “table top exercise” between multiple national, state, and local agencies to simulate a potential asteroid impact on Earth. He noted that the outcome of the exercise was that, even if the technology might exist, it must still be deployed by collaboration of governments and agencies working together to do it for it to be effective.
Plenary Lecture: Direct Observational Constraints on Planet Formation and Accretion, Kate Follette (Amherst College) (by Jessie Thwaites)
Dr. Follette’s talk focused on two of her favorite topics: direct imaging techniques for detecting exoplanets, and effectively teaching students both inside and beyond the field of astronomy. She brought those techniques to life in her talk, requiring audience participation throughout and highlighting the importance of understanding other worlds through high-contrast detections.
Dr. Follette outlined four main methods of exoplanet detection (three of which are described in this Astrobite): transit photometry, where a planet eclipses its star and causes a dip in brightness; radial velocity, where the wobble of the star indicates the presence of a planet; microlensing, where a planet passing in front of a star causes a brief increase in brightness; and direct imaging — Dr. Follette’s speciality.
As she describes, there are many reasons to love direct imaging, from the visceral satisfaction of being able to identify planets by eye in the data to the amount of information one can obtain from the technique. Direct imaging can help characterize orbits of these planets and enable detailed modeling of an exoplanet’s atmosphere through analysis of its spectrum. The planets imaged with this technique tend to be young, as young planets tend to be brighter than older planets.
This field is also rapidly developing both technology and methodology to hopefully detect exo-Earths (smaller, Earth-sized exoplanets) in the future, and to identify biosignatures in their atmospheres. Direct imaging is built on sophisticated and rapidly evolving hardware and software techniques, including adaptive optics, coronagraphy, differential imaging techniques, and post-processing algorithms. Dr. Follette has also written a tutorial for anyone interested in learning more about the field.
A slide from Dr. Follette’s talk, highlighting their method for identifying protoplanets in a disk.
To search for exoplanets, the team considered circumstellar disks, which can have a variety of substructure — some of which is likely due to the presence of exoplanets! The challenge is identifying the planet itself in the data. They optimize their selection methods on injected signals; that way, they avoid confirmation bias. They search for the planets in the wavelength range where the planets are brightest, specifically in the H-alpha line, and subtract these measurements from the main emission of the disk (shown in the above figure). With this method they are able to identify several planets in their sample! From there, they aim to translate the detected light into a physical parameter by inferring the properties of planet populations.
In the final part of the talk, Dr. Follette focused on physics education and mentorship. There are several courses in the undergraduate curriculum at Amherst College aimed at developing students’ soft skills for research, including setting goals, time management, presentation skills, and becoming more comfortable asking questions. These are important skills to help close the opportunity gaps that some students may face. Dr. Follette also emphasized the importance of normalizing struggling (which happens to everyone!) and celebrating non-linear career paths, as well as non-astronomy or non-academic paths for students.