Editor’s Note: This week we’re at the 244th AAS meeting in Madison, WI, 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 June 17th.
Table of Contents:
- Fred Kavli Prize Plenary Lecture: UNCOVERing Astronomical Gems from Our Backyard to the Edges of the Observable Universe (Rachel Bezanson, University of Pittsburgh)
- Press Conference: Disks, Atmospheres, and Astronomy from the Moon
- Plenary Lecture: Ices in Our Backyard: Searching Ices in the Solar System with JWST (Noemi Pinilla-Alonso, Florida Space Institute)
- Press Conference: Stars and Their Antics
- Plenary Lecture: The Broad Legacy of George Ellery Hale: Observatories, Institutions, and Civic Development (Sam Hale, Alliance of Historic Observatories)
- Solar Physics Division George Ellery Hale Prize Lecture: Solar Irradiance: Earth’s Energy Source (Judith Lean, University of Colorado)
Fred Kavli Prize Plenary Lecture: UNCOVERing Astronomical Gems from Our Backyard to the Edges of the Observable Universe, Rachel Bezanson (University of Pittsburgh) (by Nathalie Korhonen Cuestas)
JWST has pushed our cosmic horizons well beyond what we could previously observe. Its incredible sensitivity, instrument suite, and wavelength coverage makes it excellent at observing previously invisible distant galaxies. These early galaxies can help us understand how galaxies form stars, when they stop growing so rapidly, and how a central supermassive black hole might affect galaxy growth. During this year’s Fred Kavli Plenary Lecture, Prof. Rachel Bezanson discussed how her JWST program UNCOVER is helping us answer these questions.

This diagram shows how a massive galaxy cluster can bend the light rays coming from a more distant galaxy, resulting in magnified images. Click to enlarge. [NASA, ESA & L. Calçada; CC BY 4.0]
By observing galaxies which have been lensed by a massive galaxy cluster Abell 2744 (also known as Pandora’s cluster), Prof. Bezanson is challenging our previous assumptions about galaxy evolution. Many of the galaxies she’s observed are very massive — they can be as massive as the Milky Way, yet their age is just 3% of the age of the universe — and have signatures of evolved stellar populations in their spectra. Some also have supermassive black holes that are much more massive than we’d expect. Our models for galaxy evolution have to be able to explain how these galaxies and their black holes have grown so large, so quickly. Further JWST observations and development of our theoretical models will begin to answer long-held questions and bring up new ones.
You can read Astrobites’s interview with Rachel Bezanson here.
Press Conference: Disks, Atmospheres, and Astronomy from the Moon (by Kerry Hensley)
The first presentation of the AAS 244 press conference series, given by Lisa Prato (Lowell Observatory), tackled the topic of circumstellar disks. Circumstellar disks occur naturally during star formation, forming when a swirling cloud of gas collapses and creates one or more stars. These disks are the sites of planet formation and dissipate after roughly 10 million years, although the time frame can be far shorter. It’s not yet known what sets the lifetime of a circumstellar disk. To learn more, Prato’s team studied planet-forming disks around binary stars. Stars in a binary system have the same age, composition, and radiation environment. Differences in the disks around these stars can then be traced to differences in the stellar properties, such as mass and rotation rate. Prato’s team used the Keck Observatory and the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the circumstellar disks of the FO Tau and DF Tau binary systems. The two stars of FO Tau each had a tidy circumstellar disk and appeared similar in the data from both observatories. Keck data suggested that one star in the DF Tau system lacked a disk, but ALMA showed something different: the secondary star in the system has a disk with a large gap in the middle! Prato proposed that a possible misalignment of the secondary star’s disk could be related to the formation of the cavity. [Press release]

Demonstration of how Beta Pictoris’s spectrum has changed between the Spitzer observations 20 years ago and the recent JWST observations. Click to enlarge. [Roberto Molar Candanosa/Johns Hopkins University, with Beta Pictoris concept art by Lynette Cook/NASA]
Moving from planet formation to fully formed planets, Thomas Beatty (University of Wisconsin-Madison) presented new JWST observations of a sub-Neptune exoplanet named GJ 3470 b. Astronomers can compare the composition of exoplanet atmospheres to the composition of protoplanetary disks to understand the planet-formation process, much like a baker might try to discern the steps needed to make a finished cake from a list of ingredients. Astronomers have mostly looked for carbon and oxygen in exoplanet atmospheres over the last two decades, but there are many other ingredients to look for. Using JWST to observe GJ 3470 b, Beatty’s team found water, methane, carbon monoxide, carbon dioxide, and a surprising compound: sulfur dioxide. Sulfur dioxide has been seen in the atmosphere of another exoplanet, WASP-39b, which is twice as hot and a hundred times more massive than GJ 3470 b. The researchers didn’t expect to find so much of this molecule in the atmosphere of a small and cool exoplanet — in fact, the planet’s atmosphere contains more than a million times more sulfur dioxide than expected. Sulfur dioxide is a major new ingredient that can be used to trace the formation of small sub-Neptune exoplanets, which are one of the most common types of planets. [Press release]

“Selfie” by ROLSES showing the prematurely deployed antenna, circled. [Intuitive Machines]
Plenary Lecture: Ices in Our Backyard: Searching Ices in the Solar System with JWST, Noemi Pinilla-Alonso (Florida Space Institute) (by Will Golay)
Noemí Pinilla-Alonso, a planetary science professor at the Florida Space Institute and the University of Central Florida, gave the final talk of the inaugural morning of AAS 244. In her talk, she described the different kinds of ice in our solar system and discussed what they can tell us about the formation of planetary systems and their relationship to the interstellar medium and molecular clouds.
Ices in our solar system encode information about various stages of its formation history. The most distant objects, broadly categorized as “trans-Neptunian objects” (TNOs), span a spectrum of ice histories. Some of these dirty, icy bodies never melted and thus trace the conditions of the solar nebula. Others have undergone some melting and differentiation; observations of these objects can probe the process of planetary growth and the diffusion of molecules throughout the solar system.
Although TNOs can provide many insights into the solar system’s formation (and the formation of planetary systems in general), they have remained largely unexplored because they are often small and distant, making detailed photometric and spectroscopic studies challenging. Pinilla-Alonso highlighted how JWST, the premier space telescope for infrared observations, will uncover the secrets of our most distant solar system members with its unprecedented spectroscopic capabilities.

A slide from Noemí Pinilla-Alonso’s plenary lecture showing examples of the three spectral groups of trans-Neptunian objects: bowl, double-dip, and cliff-type. Click to enlarge. [Slide by Noemí Pinilla-Alonso]

A slide from Noemí Pinilla-Alonso’s plenary lecture showing how the three spectral classes of trans-Neptunian objects may represent a transition in the distance at which these objects formed from the central star in the protoplanetary disk. Click to enlarge. [Slide by Noemí Pinilla-Alonso]
You can read Astrobites’s interview with Noemí Pinilla-Alonso here.
Press Conference: Stars and Their Antics (by Ben Cassese)
In the afternoon, attendees once again filed into the press briefing room ready to consume another round of news-worthy astronomy research. This session, titled “Stars and Their Antics,” contained talks on individual weird stars, the motions of enormous clusters, and some of the earliest explosions in the universe.
Up first was Adam Burgasser, University of California San Diego, who set the tone with a presentation on a newly discovered speedy star. This object, initially flagged through the citizen science program “Backyard Worlds: Planet 9” doesn’t provide observers the strongest first impression. It’s dim, red, and at only 8% the mass of the Sun with a surface temperature of about 2000K, it easily fits into the “L subdwarf” category of diminutive stars. But, what it lacks in presentation it more than makes up for with pep. Burgasser and colleagues clocked in moving at more than 100 km/s along the line of sight and more than 450 km/s in total. That’s more than a million miles an hour, or so fast that this star has a good chance of escaping the Milky Way altogether. So far the team is not sure how this star got so fast: it may have been kicked around by a supernova, or scattered off a black hole, or it could have fallen in from a satellite galaxy. However it got started, though, it won’t be around for long (cosmically speaking), and the researchers hope that additional measurements can help reveal both where it came from and where it’s going. [Press release]
Up next was Janus Kozdon, a graduate student at Clemson University, who told the assembled audience about his work on a protoplanetary disk with a mysterious line profile. After models of the disk failed to provide a good fit, Kozdon and collaborators realized they could reproduce what they were seeing by considering not just one disk of emitting material, but a pair of two concentric ones. They landed on a best-fitting solution with two nested, eccentric disks, aligned so that their long axes face perfectly away from one another. This eccentricity was likely induced by a baby planet still in the process of growing and forming, a rare and exciting find. [Press release]

Illustration of the symbiotic nova system HM Sagittae. [NASA, ESA, Leah Hustak (STScI)]
Sankrit was followed by Cameren Swiggum (whose hometown is Madison, WI!) from the University of Vienna. Swiggum and collaborators used data from the Gaia spacecraft to trace the trajectories of the nearest, youngest star clusters backwards in time. The team found that, intriguingly, the clusters seem to converge on three distinct but nearby locations about 30 million years ago. These locations must have been huge, dense, chaotic regions that spawned numerous stars quickly. These conditions are ideal for forming large stars that live fast and die young, and the team estimates that there could have been more than 200 supernovae caused by stars born in these progenitor clusters. [Press release]

Three examples of transients discovered through the JADES program. [NASA, ESA, CSA, STScI, Christa DeCoursey (University of Arizona), JADES Collaboration]
Plenary Lecture: Plenary Lecture: The Broad Legacy of George Ellery Hale: Observatories, Institutions, and Civic Development, Sam Hale (Alliance of Historic Observatories) (by Catherine Slaughter)
Each year, the American Astronomical Society’s Solar Physics Division (SPD) awards the George Ellery Hale Prize to “a scientist for outstanding contributions to the field of solar astronomy.” On Monday, to preface the AAS 244 Hale prize talk, Sam Hale, grandson of George Ellery Hale, gave a lecture highlighting his grandfather’s work and multifaceted legacy of astronomical research and the advancement of the sciences in the United States. Sam himself is not an astronomer, but he presently serves as the CEO and Board Chairman for the Mount Wilson Observatory. He is also a founding member of the Alliance of Historic Observatories, an international consortium of famed astrophysics research sites.
As astronomers, whether or not we know his name, we are familiar with George Ellery Hale’s (GEH, as Sam Hale refers to him) legacy. In the talk, Hale laid out his grandfather’s many achievements. GEH is known for spearheading the construction of the Yerkes, Palomar, and Mount Wilson observatories, his work in heliophysics and the invention of the spectroheliograph, and his efforts to elevate American science on the world stage and establish international partnership between European and American astronomers. In addition, GEH was an original member of the AAS and founder of the Astrophysical Journal.Interwoven with stories of his grandfather’s achievements, Hale featured many of the significant scientific discoveries made by other astronomers using the resources GEH worked to build. Of particular note is Edwin Hubble’s work on Mount Wilson, where he took the observations of distant galaxies that became our foundational evidence that the universe is expanding.
At the end of the session, Hale left the audience with the reminder that it was his grandfather’s “insatiable curiosity” that drove him through life — a curiosity that continues to benefit the field to this day.
Be sure to take a look at our interview with speaker Sam Hale for more!
Solar Physics Division George Ellery Hale Prize Lecture: Solar Irradiance: Earth’s Energy Source, Judith Lean (University of Colorado) (by Jessie Thwaites)

Slide showing the total solar irradiance, along with the presence of faculae and sunspots. Click to enlarge. [Slide by Judith Lean]
The solar irradiance is the radiative output of the Sun, which is inherently interconnected with Earth’s atmosphere and climate. The Sun undergoes an 11-year cycle, which determines how much power is emitted. It can have any number of sunspots, which decrease the Sun’s irradiance, or bright faculae, which do the opposite. The irradiance is driven by the magnetic structure of the Sun, and Dr. Lean has developed a model of the Sun’s dynamo to understand these fluctuations. That model, based on 40 years of observations of the Sun, helps us to understand the cycles of the Sun (in addition to the 11-year cycle, it also undergoes a 27-day cycle due to its rotation, a 100-year cycle, and a 2,400-year cycle that are able to change the amplitude of the minima and maxima for the cycle), and predict the Sun’s activity for the future.

Slide showing the contributions to global surface temperature changes. Click to enlarge. [Slide by Judith Lean]