AAS 248: Day 1 – AAS Nova

Editor’s Note: This week we’re on the 248th AAS assembly in Pasadena, CA. Along with a crew of authors from Astrobites, we can be writing updates on chosen occasions on the assembly and posting every day. Follow alongside right here or at astrobites.com for day by day summaries, or observe @astrobites.bsky.social on Bluesky for extra protection. The ordinary posting schedule for AAS Nova will resume on 22 June.

Table of Contents:

Fred Kavli Plenary Lecture: Richard Teague, Revealing the Dynamics of Planet Formation (by Lexi Gault)

Richard Teague (Massachusetts Institute of Technology) gave the Fred Kavli Plenary Lecture on his groundbreaking work within the dynamics of planet formation. The examine of planet formation, as Teague launched, has superior considerably within the final twenty years with the invention of 1000’s of exoplanets and the launch of cutting-edge devices. While planets are discovered all over the place orbiting all kinds of stars, not all planetary techniques look the identical. Our photo voltaic system seems very totally different from different exoplanetary techniques, difficult our understanding of planet formation and requiring us to construct an image that works throughout the board.

Where do we glance to construct a greater understanding of planet formation? Planets are inherently the byproduct of star formation, forming in protoplanetary disks round new stars. These disks are full of fuel and dirt, concentrating mass into rings that then ultimately kind planets. Exactly how this course of proceeds is variable, and the ensuing planetary system depends upon how the fabric within the protoplanetary disk mixes and combines into planets. Teague in contrast planets to bread: we all know the easy checklist of components that it takes to make them, however what you find yourself with depends upon the way you convey those self same components collectively. We want to review what is going on within the planetary mixing bowls to know how planets kind.

The full exoALMA pattern. All 15 disks present proof of substructure of their fuel emission. [Teague et al. 2025]

Leveraging the excessive spatial and spectral decision of the Atacama Large Millimeter/submillimeter Array (ALMA), Teague and collaborators have developed exoALMA, a planet-hunting marketing campaign specializing in the still-forming planets of protoplanetary disks. This venture has centered on 15 sources, acquiring and analyzing high-resolution observations to discover the kinematics, 3D velocity buildings, and mass distributions inside these protoplanetary disks.

The first science outcomes from exoALMA have began to disclose that the planet formation course of is extremely dynamical — exact kinematic measurements uncover dynamical perturbations inside protoplanetary disks throughout their pattern. These perturbations level to the impacts protoplanets have on disk kinematics and mass distributions as they proceed to kind, and the excessive decision of ALMA observations unlocks the inside workings of protoplanetary disk.

Looking ahead, Teague emphasised that the long run is broad for planet formation science. The upcoming Wideband Sensitivity Upgrade on ALMA will allow much more detailed maps of protoplanetary disks, unlocking the mysteries of planet formation whereas it occurs.

Return to Table of Contents.

Press Conference: The Science of Stellar Remnants (Briefing video) (by Lucas Brown)

In AAS 248’s very first press convention session, we heard from a wide range of scientists and analysis groups on all kinds of stellar remnants: white dwarfs, supernovae, pulsars, and past. Basically, if it got here from a dying star, it was truthful recreation for this session.

Boron and Beryllium as Unlikely Probes of Extrasolar Planets

First up was Ben Zuckerman (University of California, Los Angeles), who up to date us on ongoing analysis into the presence of boron and beryllium in sure white dwarf techniques. For some context, there exist many white dwarf techniques during which a companion object — typically a planet — can have its materials accreted onto the floor of the white dwarf on account of tidal disruption throughout shut approaches in its orbit. This deposition of fabric can then be detected by way of spectral signatures in observations of the white dwarf.

In 2021, proof was first offered for 2 white dwarfs being “polluted” with hint quantities of beryllium, which is a very uncommon component, cosmically talking. This raises the query of how a lot beryllium ended up in these techniques. In the hunt for solutions, nevertheless, one other thriller has emerged: lacking boron. As Zuckerman went on to explain, boron was additionally lately found in a few of these white dwarf techniques, however at an abundance roughly equal to that of the beryllium. This is regardless of boron being a couple of hundred instances extra frequent within the universe, additional muddying the waters of what precisely is inflicting such a wierd sample of heavy metals in these techniques. Work stays ongoing to discover a bodily mannequin that may reconcile these observations.

White Dwarf Kicks by way of Episodic Mass Ejection from Red Giant Stars

In the mannequin explored by Jim Fuller and collaborators, repeated mass-ejection occasions could cause purple large stars to be “kicked” as much as a comparatively excessive velocity earlier than they collapse to kind white dwarfs, explaining the excessive velocities many white dwarfs are noticed to have. [Jim Fuller]

Next we heard from Jim Fuller (Caltech). Fuller stuffed us in on some current research aiming to elucidate why white dwarfs usually receive such excessive velocities when shaped. Just like our personal Sun sometimes ejects plumes of plasma from its floor, the purple large stars that ultimately kind white dwarfs are anticipated to periodically bear mass-ejection occasions. But in contrast to with our personal Sun, these ejections can shear off a big quantity of the star’s complete mass — as much as ~0.01% per ejection. Each time such an ejection happens, Newton’s third legislation ensures that the star itself will even obtain a random velocity enhance in the other way. Over many 1000’s of ejections, assuming they happen randomly in all instructions, this could considerably “kick” a meandering purple large as much as speeds exceeding half a kilometer per second. Once such a star collapses to kind a remnant white dwarf, the white dwarf may have this extra velocity too.

Additionally, this random ejection course of predicts that purple giants in binary techniques will expertise a form of “random walk” of their orbital parameters, not simply their total velocity. This can result in the entire dissociation of binaries, or to the direct collision of a purple large with its companion — resulting in predictions about what number of broadly spaced white dwarf binary techniques ought to exist. | Press release

Probing Intrabinary Material in a New Spider Millisecond Pulsar

Rebecca Kyer (Michigan State University) gave an replace on analysis into so-called “spider” millisecond pulsars. These quickly rotating neutron stars are a sub-class of pulsar characterised by their very excessive spin price and the presence of a companion from which the pulsar is accreting materials. Such techniques are additional sub-classified as both “Black Widows,” which have very low-mass companions (~3% photo voltaic mass), “Redbacks,” which have bigger companions at ~10-80% photo voltaic mass, and “Huntsmans,” which have extra large red-giant companions. These Huntsman pulsars are the latest class, with solely two recognized circumstances — till now!

Kyer offered proof collected by their crew that will point out the invention of a 3rd Huntsman pulsar. The proof entails radial velocity measurements of the companion star, which reveals an orbital interval of three.64 days and variable H-alpha emission. In these techniques, the radio emission sometimes related to the pulsar might be blocked from our view for unpredictable quantities of time on account of clouds of scorching fuel and dirt that emerges from the advanced interplay between the pulsar and purple large winds. Despite this, Kyer hopes that with sufficient focused observations with the Green Bank Telescope, a radio sign will ultimately be detected, confirming the pulsar’s presence.

Image of Messier 83 in each X-ray and optical mild. Prominent X-ray sources might be seen as small colourful blobs strewn all through the galaxy. Some of those X-ray sources are supernova remnants, a subset of which have lately been discovered to point out variability of their brightness. [X-ray: NASA/CXC/SAO; Optical: NASA/ESA/AURA/STScI, Hubble Heritage Team, W. Blair (STScI/Johns Hopkins University) and R. O’Connell (University of Virginia); Image Processing: NASA/CXC/SAO/A. Jubett, L. Frattare and P. Edmonds]

NASA’s Chandra Finds Unexpected Fireworks in Aftermath of Stellar Explosions

Finally, we heard from a crew of three researchers — Andrea Prestwich (Catholic University of America / NASA Goddard SFC), Roy Kilgard (Wesleyan University), and Zoe Hoiland (Vassar College) — on an sudden supernova discovery. Traditionally, supernovae are modeled as having a comparatively fixed or barely lowering luminosity, a minimum of after their preliminary explosion. As the stellar materials is blasted away from the progenitor’s core, it interacts with the encircling interstellar medium and a blob of scorching, shocked fuel is left over. This blob will ultimately cool and dim, however usually over a very long time interval, resulting in the aforementioned prediction of fixed or barely lowering brightness.

However, in 14-year Chandra observations of a supernova remnant in Messier 83, Prestwich and her collaborators really discovered vital X-ray variability, with the remnant sometimes even rising in brightness. In a follow-up examine, it was discovered that supernova remnants in Messier 51 likewise present this up-and-down variability. In distinction, an evaluation of remnants in Messier 101 confirmed zero variable remnants. Notably, the previous two galaxies are very actively star-forming, whereas the latter shouldn’t be. Some doable theoretical fashions to elucidate this variability embody the opportunity of stellar materials falling again on the compact object leftover by the supernova, creating an accretion disk that may generate variable emission. Alternatively, it has been proposed that there may very well be a neighboring star to the remnant object, forming an accreting X-ray binary system that would additionally induce variability. | Press release

Return to Table of Contents.

Plenary Lecture: Sanmi (Oluwasanmi) Koyejo, The Measurement Gap: What AI Can Get Wrong and Why Astronomers Are the Fix (by Lexi Gault)

Sanmi (Oluwasanmi) Koyejo, a professor of pc science at Stanford University, centered this plenary discuss on the restrictions of AI because it turns into extra built-in with science and the way astronomers will help clear up these issues. Koyejo started by addressing the query of why an AI researcher is speaking to astronomers. His analysis explores easy methods to set AI requirements and easy methods to finest assess the efficiency of an AI mannequin, which turns into notably essential when these fashions are used to do science.

Evaluating the efficiency of an AI mannequin depends on benchmarks, a hard and fast set of questions with recognized solutions which can be used to attain the AI. These benchmarks are easy, reproducible, and comparable, however passing a benchmark doesn’t equate to getting a significant scientific consequence. Benchmarks assume low-cost checks, quick suggestions, and glued questions, however science is none of these issues; answering astronomy questions depends on telescope time, and floor fact can’t be discovered rapidly.

Much like telescopes, AI benchmarks are measuring devices with noise that may compound. If you run an AI mannequin many instances, the purpose is usually convergence on an agreed-upon reply, however attending to an agreed-upon reply doesn’t imply that the reply is appropriate. Koyejo’s current analysis discovered that AI fashions extra usually agreed with one another than they did with the precise fact. This is made worse when AI is used to guage itself. For instance, Koyejo notes the rising variety of educational paper submissions on account of AI-written papers vastly exceeds the capability of human reviewers. If AI instruments are used to guage AI-generated paper submissions, the AI will are inclined to favor AI-written supplies, ignoring the precise scientific benefit. Making analysis of AI an AI drawback compounds its failures, straying farther from an accurate reply.

This is the place astronomers are available. Having the knowledgeable information of what “correct” seems like, having the ability to decide which errors matter, entry to costly floor fact (telescope time), and a tradition of blind evaluation (not realizing precisely what the reply ought to be), astronomers are effectively geared up to construct requirements for AI analysis. We can outline what good AI is for astronomy and use our experience to assist construct the requirements. Koyejo left the viewers with the cost to have interaction with AI (engagement doesn’t imply endorsement), in order that astronomers will help set the requirements for acceptable AI use in science.

Read Astrobites’s interview with Sanmi Koyejo.

Return to Table of Contents.

Press Conference: Variable, Windy, and Disruptive: The Behavior of Supermassive Black Holes (Briefing video) (by Niloofar Sharei)

This press convention centered on what supermassive black holes do to the world round them, from relativistic jets of essentially the most well-known black gap, to the multi-phase winds launched from lively galactic nuclei, to temperature-shifting coronae, and even the radio burps which can be produced years after a black gap tears aside stars.

Chandra Tracks the Evolving Jet from Messier 87’s Black Hole: 

Camille Poitras (Laval University) offered the most important Chandra X-ray film of jet evolution within the well-known supermassive black gap Messier 87 (M87). M87 has been studied throughout the electromagnetic spectrum, however X-ray observations of its jet have all the time suffered from blur as a result of high-energy photons are arduous to focus. Using improved Chandra calibrations and deconvolution strategies, the crew produced a 13-year X-ray film of M87’s jet from 2012 to 2025. Tracking a vivid knot throughout the jet, Poitras’s crew noticed it break up into two parts in 2023, with one element transferring at an obvious 5 instances the velocity of sunshine (which is a recognized phantasm referred to as superluminal movement). That allowed the crew to look into the place and the way the particles are being accelerated to excessive energies alongside the jet. | Press release

Watching a Black Hole Wind Grow: Chandra and Hubble Reveal the Early Stages of Galaxy

Multiwavelength photographs of two close by quasars present that the recent X-ray (purple) and heat ionized (inexperienced) fuel are much more prolonged within the backside system. Click to enlarge. [Anna Trindade Falcao]

Anna Trindade Falcao (NASA Goddard SFC) offered mixed Chandra and Hubble observations that will seize a supermassive black gap wind in its earliest levels of development. Active galactic nucleus (AGN) suggestions is believed to occur, however the way it begins stays poorly understood. Studying two close by quasars during which Chandra (tracing scorching X-ray wind) and Hubble (tracing heat ionized fuel) knowledge are aligned, the crew discovered that the recent and heat phases prolong collectively and never independently. This would recommend a single multi-phase outflow. Their crew proposed a four-stage sequence for AGN suggestions and in addition argued that their two techniques seize the earliest levels of that course of.

The three sorts of wind launched from an accreting supermassive black gap. Click to enlarge. [Xin Xiang]

XRISM Reveals Changing Accretion-Driven Winds in a Nearby Active Galaxy:

Xin Xiang (University of Michigan) offered essentially the most detailed X-ray portrait of the winds flowing out of NGC 4151, an lively galaxy roughly 16 million light-years away with a 30-million-solar-mass black gap. Every main X-ray observatory has noticed this galaxy earlier than, however earlier devices couldn’t separate its a number of wind parts. With the high-resolution X-Ray Imaging and Spectroscopy Mission (XRISM) spectrometer, Xiang resolved three wind populations by velocity: heat absorbers (100–1,000 km/s), very quick outflows (1,000–10,000 km/s), and ultra-fast outflows (over 10,000 km/s). Across 14 XRISM observations over a 12 months, they discovered that the quick winds activate three hours after every vivid X-ray flare, matching the anticipated timescale for magnetically pushed wind. | Press release

NuSTAR Reveals a Significantly Variable Active Galactic Nucleus Corona

Xiurui Zhao (Caltech) offered the primary observational proof of great temperature variation within the corona of an AGN. The corona produces about 90% of all X-ray photons from an AGN, however its temperature can solely be measured with X-ray missions delicate to high-energy spectral curvature like NASA’s NuSTAR. They in contrast NuSTAR’s observations throughout a number of years and located that regardless of having the identical luminosity in 2015 and 2024, the 2024 corona was considerably cooler than the 2015 corona. In follow-up observations in 2025, it was again at its earlier temperature. This is the primary clear commentary of coronal temperature variability in an AGN. | Press release

New Surprises from Radio Observations of Tidal Disruption Event Outflows

Kate Alexander (University of Arizona) offered new radio observations of tidal disruption occasions (TDEs). TDEs happen roughly as soon as each 100,000 years in a given galaxy. It occurs when a star drifts too near the black gap, is stretched and squeezed into an extended stream of particles (a course of astronomers name spaghettification) and a few of that particles falls onto the black gap whereas the remaining is thrown outward and lights up in radio. Alexander and her crew used six years of Very Large Array monitoring of a number of dozen close by TDEs. They discovered that many TDEs unexpectedly activate within the radio years after the unique occasion, even lengthy after their optical mild has light. Their crew mixed radio knowledge with X-ray and optical accretion-rate measurements and located that these late-time radio flares seem when the black gap is consuming both in a short time or very slowly, however not at average charges! This sample matched what’s seen in stellar-mass black holes and this implies that accretion physics might function equally throughout many orders of magnitude in black gap mass. | Press release

Return to Table of Contents.

Plenary Lecture: Mario Jurić, Early Results from the Rubin Observatory: Mapping the Solar System and Beyond (by Kerry Hensley)

Mario Jurić (University of Washington; PI of the University of Washington Rubin operations component) started by remarking on how our collective idea of what an astronomer is has been remodeled over the previous 25 years. While a Google picture seek for “astronomer” yields an array of individuals pointing small telescopes on the night time sky, as we speak’s model {of professional} astronomy seems fairly totally different: enormous telescopes with huge cameras overlaying huge swaths of the sky, with evaluation aided by software program and knowledge deposited in large databases.

This speedy transition was first spurred by enterprises just like the Sloan Digital Sky Survey, which collected 20 terabytes of uncooked knowledge from 1.2 billion observations. Now, digital sky surveys are frequent, and so they’re turning into ever bigger. The subsequent large digital sky survey would be the Legacy Survey of Space and Time from the NSF–DOE Vera C. Rubin Observatory — an observatory that may “download the universe” and is poised to rework our understanding of every little thing from asteroids to darkish vitality.

Rubin launched its first photographs on 23 June 2025, and amongst these gorgeous photographs is a broad view that incorporates 1000’s of galaxies within the Virgo cluster, a golden tangle of 4 colliding galaxies, a close-by galaxy cluster, a distant galaxy cluster, and a handful of close by spiral galaxies bursting with star formation. As unbelievable as this picture is, Jurić emphasised that it’s only one nonetheless picture in a film: as Rubin returns to the identical fields of view time and time once more, it’ll spot issues that change brightness (like variable stars and transients) and issues that transfer (like asteroids).

Jurić highlighted 4 areas during which Rubin has already contributed vastly, specializing in discoveries inside our photo voltaic system:

1. 1. Asteroid variability: Rubin has already collected a whole bunch of 1000’s of observations of asteroids, ensuing within the discovery of extraordinarily quick rotators like 2025 MN45, which will need to have a particularly excessive tensile power to not fly aside.
   2. Observations of interstellar object 3I/ATLAS: During the observatory’s commissioning survey, the Rubin crew realized that that they had noticed 3I/ATLAS earlier than it was found — however in observations that had been technically below embargo. Recognizing the excessive impression of the info, the crew discovered a technique to share their findings, main the 150-person collaboration to jot down a paper on their findings in a mere three days.
   3. High-precision asteroid photometry: While analyzing the commissioning knowledge, the Rubin crew found systematic offsets within the positions of asteroids — however no different sorts of objects. They discovered that this impact various throughout the sky and was worse within the south. They ultimately found that as a result of most asteroids are noticed from the north, that catalogs of asteroid orbits are systematically biased at a stage of 20-40 milliarcseconds. Luckily, Rubin will present the much-needed southerly knowledge obligatory to wash up these catalogs inside a couple of 12 months.
   4. Outer photo voltaic system research: Researchers found 380 new trans-Neptunian objects in Rubin’s commissioning knowledge. (Compare that to simply 5,000 recognized trans-Neptunian objects in complete!) In the time for the reason that commissioning knowledge had been collected, a whole bunch extra candidate objects had been found.

With such huge knowledge yields from Rubin, how can we effectively flip knowledge into science? Jurić outlined methods for dealing with large datasets utilizing well-crafted knowledge codecs, computing instruments, and AI. In specific, Jurić highlighted the Astronomical Catalog Inference Driver, or ACID, which he inbuilt 4 weeks on his cellphone utilizing Claude. The device is akin to “a product developed in >3 years by extremely capable human professionals” and might quickly deal with immense knowledge tables, exhibiting how AI can speed up the event of instruments to deal with tomorrow’s datasets.

Read Astrobites’s interview with Mario Jurić.

Return to Table of Contents.

Plenary Lecture: Esra Bulbul, Cosmology and Baryons Across Scales: Probing Halo Mass Function to Cosmic Filaments with eROSITA (by Lexi Gault)

Esra Bulbul (Max Planck Institute for Extraterrestrial Physics) started her plenary discuss initially of time — the Big Bang marked the beginning of the universe, and from there we try and constrain cosmological parameters to be able to perceive how the universe was born and the way it has developed. Bulbul notes that loads of work has been finished to constrain cosmology from the cosmic microwave background (CMB), and we should examine these early time measurements to these from later instances to construct a full image. In cosmology, tensions have arisen between early-time and late-time probes. CMB measurements of the Hubble fixed and S8, the “clumpiness” parameter of the universe, don’t agree with late time probes that discover that the universe is accelerating sooner with smaller fluctuations than the CMB predictions. How can we work towards resolving this pressure?

The prolonged ROentgen Survey with an Imaging Telescope Array (eROSITA) is an area telescope that has carried out the primary imaging all-sky survey within the medium X-ray vary, searching for to map the large-scale buildings of the universe to higher constrain cosmological constants. eROSITA focuses on discovering galaxy teams and clusters by way of the recent X-ray fuel inside and between them throughout the final 5-7 billion years of the universe. Since its launch in 2019, eROSITA has accomplished greater than 4 full-sky surveys. Of the million X-ray sources detected by eROSITA, solely 12,247 (1%) are galaxy clusters and teams.

From the noticed X-ray emission from the galaxy clusters and teams, the eROSITA crew has been in a position to measure the temperature of the intercluster medium throughout the pattern. Working with weak gravitational lensing surveys, they’ve been in a position to measure the lots of the newly found clusters and teams. These measurements present that eROSITA has detected sources throughout three orders of magnitude in mass, reaching from the galaxy stage to large-scale clusters.

The galaxy cluster and group observations permit them to constrain just a few cosmological parameters together with S8 (density fluctuations), Ωm (matter density), and w0 (darkish vitality). From the spectacular eROSITA knowledge, Bulbul confirmed that they may constrain S8 and Ωm to 5 instances higher precision than ever earlier than! These late-time outcomes are absolutely in line with what has been measured from the early-time CMB measurements. Additionally, the darkish vitality measurements agree with what has been measured thus removed from the Dark Energy Spectroscopic Instrument survey.

Bulbul then switched us from the thrilling cosmological outcomes to these relating to baryon detection. A putting consequence from eROSITA was the detection of scorching fuel effectively past what is usually thought-about the gravitational extent of a galaxy cluster — reaching out to 16 million light-years, usually bigger than the galaxy cluster itself. This underscores the significance of X-ray surveys in detecting the very prolonged fuel encapsulating the largest-scale buildings of the universe.

Looking ahead, Bulbul mentioned the long run work deliberate for eROSITA. Transitioning now to working with the deepest knowledge of the survey, the crew expects to seek out about 40,000 galaxy clusters with about half of these getting used for cosmology. They anticipate acquiring even greater precision on cosmological parameter measurements, akin to that obtained from CMB observations. The work of eROSITA is revolutionizing cosmology at later instances within the universe, and the long run is thrilling.

Read Astrobites’s interview with Esra Bulbul.

Return to Table of Contents.