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Editor’s Note: This week we’ll be writing updates on selected events at the 56th Division for Planetary Sciences (DPS) meeting happening in Boise, Idaho, and online. The usual posting schedule for AAS Nova will resume on October 14th.

Table of Contents:


Press Conference: Quanzhi Ye, Elizabeth Silber, and Victor Oyiboka (Briefing video)

The first of two press conference sessions at this year’s DPS meeting featured research regarding small bodies and planets of the inner solar system. First up was Quanzhi Ye (University of Maryland/Boston University), who described a search for potentially hazardous asteroids in the Taurid complex. The Taurid complex is a collection of debris from comet 2P/Encke, which descended from a parent body some 10,000–20,000 years ago. The size of the parent body is unknown but may have been as large as 100 kilometers across. When Earth passes through the debris left behind by this comet, observers on the ground see a meteor shower. Unlike better-known meteor showers like the Perseids, the Taurids aren’t particularly active, but they are unusually rich in large particles that create dramatic fireballs when they burn up in Earth’s atmosphere.

The Taurids have been known for a century, and a significant year-to-year variation in the activity level has become apparent. This variability happens because some of the Taurid complex is trapped in a resonance with Jupiter (these trapped particles are called the Taurid resonant swarm); when Earth passes close to the center of these trapped particles, the activity level is particularly high. While most of the trapped Taurid particles are tiny, the resonant swarm may also contain asteroids 100 meters wide or larger that have been trapped by Jupiter’s gravity. This means that when Earth passes close to the center of this particle swarm, it could be passing close to potentially hazardous asteroids — but how many hazardous asteroids are actually there?

To answer this question, Ye and collaborators analyzed data from the Zwicky Transient Facility during two recent encounters with the Taurid swarm. They found no trace of potentially hazardous 100-meter-plus asteroids — phew! The non-detection suggests that there are only 9–14 asteroids this large in the Taurid swarm. This is tiny compared to the 3,000 or more known potentially hazardous asteroids. These observations also allowed the team to estimate the size of the comet 2P/Encke parent body at just 10 kilometers, which is smaller than previously thought.

Next, Elizabeth Silber (Sandia National Laboratories) discussed a topic of importance to planetary defense. Earth is constantly being bombarded with debris, and while most of this debris is extremely fine and poses no threat to us, larger objects can be destructive. Large meteoroids (objects up to 1 meter in diameter) and asteroids (objects larger than 1 meter in diameter) can generate shock waves that can be felt on the ground and can damage property and cause injuries. For example, in 2013, the house-sized (18-meter-wide) Chelyabinsk meteor exploded with an energy equivalent to 440 kilotons of TNT and shattered thousands of windows.

cartoon showing different types of meteors and their light curves and infrasound measurements

Demonstration of how the properties of a meteor are reflected in light curves and infrasound measurements. Click to enlarge. [From slide by Elizabeth Silber]

In order to predict destructive events like these, it’s important to be able to characterize asteroids. This can be done using a variety of ground- and space-based techniques. Silber focused on the measurement of asteroidal impact energy with infrasound: low-frequency sound below the threshold of human hearing. Infrasound detectors provide a powerful way to study asteroids because they can be deployed in remote areas and can work night and day and in essentially any weather conditions.

Silber’s goal was to develop a practical way to estimate an asteroid’s impact energy — and eventually size and velocity — which will help to assess future threats. The team combined a sample of infrasound measurements with other measured asteroid properties and light curves to assess the reliability of the infrasound technique. Ultimately, this work will aid in determining the rate at which asteroids of various sizes impact Earth’s atmosphere and the level of risk associated with asteroids of different sizes.

Finally, Victor Oyiboka (University of Texas at Dallas) introduced new work on the role of radioisotopes on the evolution of Earth-like planets. Radioisotopes are radioactive forms of elements. Essentially, these are unstable atoms that split into more stable forms and release energy. As radioactive isotopes in a planet’s interior decay into more stable forms, the energy released heats the planet, helping to shape its evolution.

plot of heat production as a function of planet age

Model results for the heat production of Earth-like exoplanets as a function of planet age. [From slide by Victor Oyiboka]

Oyiboka and collaborators used the properties and half-lives — the time it takes for half of a radioactive sample to decay — of several critical radioisotopes to model the amount of radioactive heat produced by an Earth-like planet as a function of time after the formation of the galaxy and the planet’s age. For Earth, the most important radioisotopes were initially aluminum-26, which provided the bulk of the internal heat to the young Earth, and iron-60. These short-lived isotopes have long since decayed, leaving behind long-lived isotopes like potassium-40, thorium-232, uranium-235, and uranium-238 that still exist today. The team’s calculations gave them an estimate of the heat produced internally, which they then converted to a flux of heat through the planet’s surface. These estimates will be useful for studies of planetary evolution and habitability.

Slides from these three presentations are available in the press kit.

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Plenary Lecture: Laboratory Investigations Toward Understanding Ocean World Surfaces (Tuan Vu)

The first of four plenary sessions at this year’s conference introduced laboratory experiments relevant to planetary science. First was Tuan Vu of NASA’s Jet Propulsion Laboratory, who described laboratory work that explores the salts and ices that might be found on some of the ocean worlds in our solar system. Ocean worlds — planetary bodies with surface or subsurface oceans — are potential habitats for life beyond Earth and are therefore of great interest to planetary scientists. Among our solar system’s ocean worlds are Jupiter’s moon Europa, which likely contains twice as much water as Earth, and Saturn’s tiny moon Enceladus, which despite its small size may contain 14–20% as much water as Earth. These moons’ subsurface oceans are thought to be salty and chemically complex, and knowing the composition of these worlds’ oceans is critical to understanding their geochemistry and habitability.

Vu focused on Europa, which is soon to be visited by the Europa Clipper mission. Unlike Enceladus, which frequently broadcasts the contents of its ocean via plumes that erupt from fissures in its surface, Europa only rarely emits plumes. This means that researchers will likely need to glean the composition of Europa’s oceans by studying its surface, which may be spotted with frozen brine from infrequent plumes or ocean material welling up through cracks in the ice shell. The first challenge for this tactic is measuring the composition of the surface. Then, researchers must translate the composition of ices on the surface to the composition of liquids in the moon’s ocean by determining how ocean materials will be altered by deposition on the surface and exposure to the intense radiation environment.

Observations from ground-based telescopes, the Hubble Space Telescope, and the Galileo spacecraft have found evidence for sodium chloride (NaCl), sodium- and magnesium-containing minerals, and sulfates on Europa’s surface. Vu’s team created laboratory brines from sodium, chloride, magnesium, and sulfate ions and observed the minerals that formed under different ion concentrations, ion ratios, and freezing rates. These experiments showed that mirabilite (NaSO4) preferentially forms over epsomite (MgSO4) even when magnesium ions are abundant. However, epsomite has been observed on Europa, with sodium instead latching on to chlorine to form NaCl. This combination cannot be achieved by the simple freezing of ocean materials. Instead, it requires an ocean rich in NaCl and a surface that is bombarded by ionizing radiation, further processing the ocean materials after they reach the surface and freeze.

plot of surviving colony forming units under different experimental conditions

Colony forming units (CFU) of Pseudoalteromonas haloplanktis bacteria after exposure to ambient conditions, vitreous salt hydrate, and crystalline salt hydrate. [From slide by Tuan Vu]

Considering the effect of freezing rate, Vu’s team found that flash freezing creates glassy, amorphous blobs of frozen brine rather than sharply defined crystals. These glassy structures appear to be highly stable — in other words, they’re unlikely to crystallize over time. This has a couple of interesting implications: first, amorphous (otherwise known as vitreous) salt tends to have fewer spectral features than crystalline salt. (Here, salt is used in the chemical sense to mean a compound made from positive and negative ions; table salt — sodium chloride — is just one example of a salt.) This means that if future missions to Europa find unexpectedly bland surface spectra, amorphous salt may be to blame. Second, amorphous salt is less likely to damage cellular structures when freezing than crystalline salt. This has important consequences for the search for life on Europa. To investigate this finding further, Vu’s team acquired a bacterium that is found in antarctic seawater — which is both cold and extremely salty — and brought samples of bacteria down to 100K (roughly the temperature of Europa’s surface) in the presence of amorphous or crystalline salt. Remarkably, many of the bacteria survived the journey to freezing and back, with the amorphous sample faring better than the crystalline sample.

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Plenary Lecture: The Next-Generation Laboratory Experiments on Planetary Materials (Xinting Yu)

Certain worlds in the solar system can appear deceptively Earth-like while being completely alien. Such is the case for Saturn’s largest moon, Titan, which sports familiar-looking seas, clouds, and dunes. Xinting Yu (University of Texas at San Antonio) was introduced to materials science via Titan’s curiously Earth-like dunes. Earth’s dunes are primarily made of quartz, while Titan’s dunes are made of organic material.

Yu and collaborators initially attempted to study Titan-like dunes in a wind tunnel using ground walnut shells and coffee grounds as a stand-in for the dune material. However, these materials were a poor analog, leading the team to explore tholins as an option. Tholins are a class of molecule thought to exist in Titan’s ever-present haze layer. They can be created by adding energy to a mixture of nitrogen and methane. While tholins excel at imitating organic compounds on Titan, they’re also toxic and time-consuming to make. (In three days, the team generated just one gram of the 2–3 kilograms they needed for the wind tunnel.) Instead of going this route, Yu’s team studied the material properties of Titan’s dunes and used these properties to scale the wind tunnel data.

This experience led Yu to bring materials science techniques to planetary science questions. With the Dragonfly mission expected to touch down on Titan (on the dunes, in fact!) in 2034, materials-science-inspired studies of Titan are timely. Recently, Yu’s planetary materials lab has sought to answer two pressing questions: 1) does the fact that lab-made Titan materials are prepared in air that contains oxygen and water vapor — two things absent from Titan’s atmosphere — affect their properties, and 2) are the tholins made in labs really like the tholins on Titan?

plot of total surface energy of lab-generated tholins

Demonstration of how the total surface energy of lab-generated tholins changes with the chemical mixture used to make them (represented by the color of the bar) and the experimental setup (labeled on the horizontal axis). Click to enlarge. [From slide by Xinting Yu]

To answer the first question, Yu’s team devised a method to create tholins without ever letting them touch Earth air. As it turns out, exposure to Earth’s atmosphere completely changes the material. To answer the second question, Yu’s team first collaborated with other Titan-materials labs to compare the properties of tholins created in different labs. While the lab setups used to create the samples were all different, they were transported, stored, and analyzed the same way. This study showed that the largest determining factor in the surface energy (a measure of the “stickiness” of the molecules, which impacts their behavior) of tholin samples is the experimental setup. This study also allowed the team to show that tholin samples energized with cold plasma rather than ultraviolet light provided the best match to existing Titan cloud observations.

Yu’s team has put together a database of these materials for anyone wanting to study Titan. Yu closed the talk with a video tour of the Planetary Material CHaractErization Facility (PMCHEF) and a reminder than tholins aren’t just relevant to Titan — hazes are thought to be common in exoplanets, and laboratory studies can help researchers peer into those planets’ atmospheres as well.

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Plenary Lecture: Spectroscopy of Fine-particulate Minerals in the Laboratory and the Field: A TREX Perspective (Melissa Lane)

Melissa Lane (Fibernetics) closed out the session with a two-part talk that covered spectral characterization of mineral dust and investigation of rover techniques. In order to interpret spectra of distant planets, researchers need to be able to refer to laboratory spectra of common planetary materials. Lane’s team’s goal was to collect far-ultraviolet to mid-infrared laboratory spectra of 27 types of mineral dust. Why study dust? Dust is ubiquitous in the solar system, coating geological features of interest and interfering with human and robotic exploration.

Example Frankenspectrum of olivine

Example Frankenspectrum of olivine. [Slide by Melissa Lane]

The team created samples of finely ground minerals and distributed them to several labs for analysis. Using a variety of setups, the labs returned spectra of the materials over different wavelength ranges, which Lane and collaborators scaled, adjusted, and stitched together to create a single “Frankenspectrum” for each mineral. All 27 Frankenspectra are available on the Planetary Data System along with the original, unadjusted spectra. While the Frankenspectra have limitations — Lane notes that they weren’t collected under vacuum conditions, which means that the mid-infrared portions of the spectra aren’t appropriate for comparing to spectra of airless bodies — this study goes a long way toward providing an extensive library of reference spectra for planetary studies.

Lab spectra are also important for guiding autonomous robotic exploration of planetary worlds. In the second portion of the talk, Lane’s team used the Zoë rover to explore the outcomes of different rover mission architectures: 1) autonomous rover, 2) traditional remote-team-guided rover, and 3) astronaut and semi-autonomous rover. The team traveled to Yellow Cat, Utah, and to the Hopi Buttes volcanic field in northern Arizona, both of which have a variety of geologic features. They found that while the autonomous rover was the fastest, it missed things that the human-guided scenarios caught.

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logo of the American Astronomical Society

AAS Director of Scholarly Publishing Kerry Kroffe

AAS Director of Scholarly Publishing Kerry Kroffe [Nick Leoni]

Last month, Kerry Kroffe joined the AAS staff as Director of Scholarly Publishing. While Kerry may be new to the AAS staff and to many members of the AAS community, he and the AAS journals go way back — read on to learn about Kerry’s journey to his present role and his goals for the AAS journals publishing experience.

The Path to the AAS

After his first publishing role with a for-profit book publisher, Kerry joined the staff at the University of Chicago Press working as the Assistant Publication Manager for the AAS journals in 2000. Working with former AAS CEO Bob Milkey and current CEO Kevin Marvel, he found that the AAS journals embodied a publishing ethos that spoke to him — rather than a for-profit model that endlessly seeks to maximize profit at the expense of the contributors or the audience, the AAS staff sought to be good stewards of the literature, and to serve the authors and the readers.

“I’ve worked with medical professionals, biopharm, all sorts of groups out there, and I’ve honestly just not found a community that I resonate with as much as the astronomers,” Kerry says.

Kerry Kroffe photographed at Grand Canyon National Park

In addition to thru-hiking, Kerry’s also a fan of national parks — he’s hiked in 27 of them, including Grand Canyon National Park, seen in the background here. [Kerry Kroffe]

When the AAS journals portfolio transitioned publishers from the University of Chicago Press to the Institute of Physics (IOP) Publishing in 2008, Kerry followed. He shepherded AAS journals articles through the publishing process at IOP until 2014, when he planned to undertake a thru-hike of the 2,200-mile Appalachian Trail. But the trail would have to wait — having already told IOP his plans to depart several months in the future, Kerry got an offer he couldn’t refuse: to work at the Public Library of Science (PLOS), a nonprofit open-access science publisher.

“It had always been a dream of mine to work at PLOS,” Kerry says. “I loved what they stood for.” At PLOS, he was responsible for all of the editorial operations — everything on the peer-review side, as well as production for all of the journals. Eventually, the IT and business analytics teams came under his wing as well. Kerry remained at PLOS, eventually overseeing nearly 80 staff, for five years.

In 2019, life had other plans once again, and Kerry stepped away from his successful role at PLOS for personal reasons. While evaluating future moves, fate intervened when Julie Steffen — AAS Chief Publishing Officer at the time and Kerry’s former coworker at University of Chicago Press — emailed to announce her retirement.

Now, as AAS’s Director of Scholarly Publishing, Kerry will lead and support the AAS publishing team and interface with IOP Publishing and eJournal Press, which provides the peer-review software. He’ll also maintain the various AAS publishing imprints as well as monograph publishing.

How Can We Make Your Experience More Delightful?

When you think about the process of publishing research in an academic journal, does the word delightful come to mind? Kerry hopes so, and one of his aims as Director of Scholarly Publishing is to make the publishing process delightfully effortless.

“One of the things that I’m really interested in is how we can change our interaction with our contributors to make it as frictionless as possible,” Kerry says. Part of this goal is ensuring that authors are only asked for materials that are absolutely necessary, rather than making them jump through hoops that take their time away from what really matters: research! (Kerry recalled a time when authors were asked to make print-ready CMYK versions of all their images — a task important for the publication of a physical article, but one that’s well outside a researcher’s purview.)

To succeed in this goal, Kerry welcomes feedback and constructive criticism from the tight-knit AAS community. “These journals are for the community in which we exist,” Kerry says. “I want to hear from our researchers how we can better perform for you. It’s not just about what we offer now, but what you would like to see in the future. I would love to hear if things go swimmingly, but I also do want to hear when things don’t go great. Constructive criticism is some of the most valuable feedback someone can ever give.”

Want to chat with Kerry about the AAS journals and share your feedback? You can find him at the AAS publishing booth throughout the upcoming 245th AAS meeting in National Harbor, Maryland.

logo of the American Astronomical Society

In 2017 we announced a new AAS-sponsored program for graduate students: the AAS Media Fellowship. This quarter-time opportunity is intended for current graduate students in the astronomical sciences who wish to cultivate their science-communication skills.

photograph of Lexi Gault

Lexi Gault (Indiana University) has been selected as the 2024–2025 AAS Media Fellow.

We are pleased to announce that Lexi Gault, an astronomy PhD candidate at Indiana University, has been selected as our AAS Media Fellow for 2024–2025.

Lexi majored in astronomy and mathematics at Valparaiso University, with minors in French and studio art. Now a fourth-year graduate student at Indiana University, Lexi works with Betsey Adams (ASTRON) and John Salzer to study the impacts of stellar feedback-driven outflows on the interstellar medium in nearby low-mass galaxies.

Outside of research, Lexi participates in a number of community outreach activities and serves as a research mentor. She’s also been to the top of the Green Bank Telescope a few times, most recently as a participant in the Green Bank Observatory Single Dish Summer School in 2023!

photograph of the 2023 Single Dish Summer School participants

Lexi (front row, just right of center) with the participants of the 2023 Single Dish Summer School. [Green Bank Observatory; CC BY-NC-ND 2.0]

As the AAS Media Fellow, Lexi will regularly write and publish summaries of the latest astronomy research on AAS Nova, assist in managing the distribution of press releases as part of the the AAS Press Office, and gain a broad understanding of the worlds of scientific publishing, communications, and policy. Lexi will also be assisting with the press conferences at the upcoming 245th meeting of the AAS, so please say hello if you’re attending the meeting in National Harbor, MD, next January!

As we welcome Lexi to the team, we’ll also soon bid farewell to Ben Cassese, our 2022–2024 AAS Media Fellow. Ben will be continuing his PhD studies at Columbia in the Cool Worlds Lab under David Kipping, where he is searching for moons around extrasolar planets. Following his enjoyable and enriching time as the Media Fellow, he hopes to pursue some freelance science writing and will be sure to say hi to the press team at future AAS meetings.

Please join us in welcoming Lexi as our new Media Fellow and wishing Ben the best in all his future endeavors!

multi-wavelength image of the Bullet Cluster

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.

Plenary Lecture: Scanning the X-ray Sky for Dark Matter, Kerstin Perez (Columbia University) (by Nathalie Korhonen Cuestas)

Throughout the universe, we’ve detected the indirect signatures of dark matter: a hypothetical form of matter that does not interact with normal matter through electromagnetism and makes up most of the matter in the universe. It’s seen in the rotation curves of galaxies, through gravitational lensing in the Bullet Cluster, and in the anisotropies of the cosmic microwave background. Dr. Kerstin Perez (Columbia University), the conference’s last plenary speaker, works to characterize the properties of dark matter through observations of X-ray photons, bringing us closer to understanding the matter that makes up so much of the universe.

It’s possible that dark matter particles interact through forces that we can’t currently understand using the standard model, producing photons with X-ray wavelengths. Perez leverages these interactions to look for “extra” photons as a signature of dark matter. However, it can be difficult to pinpoint which photons are coming from dark matter particles, and which photons are produced by normal, baryonic matter. Ideally, you’d observe a region with a high dark matter density and a low (or very well understood) background of photons from baryonic sources. Even though this technique can be tricky, Perez noted that even when a photon excess doesn’t end up being due to dark matter, it can still tell us something new about the background source.

To make her observations, Perez uses the NuSTAR instrument in a novel way. Normally, astronomers use photons that have traveled through the optics of the NuSTAR telescope, resulting in a small field of view. But one astronomer’s trash is another astronomer’s treasure; Perez uses photons that have come in from very large angles and hit the detector directly, rather than going through the optics system. This results in a larger pacman-shaped field of view, which can be cleverly aligned with a dark matter halo or a star, allowing Perez to search for photons produced by dark matter.

Dark matter particle theories come in lots of different flavors, and in her talk, Perez focused on two: sterile neutrinos and axions. Both types of particles only interact with gravity, and they could address other open questions in particle physics, not just that of dark matter. Perez showed observations of dark matter halos and Betelguese (a well-observed red supergiant) from NuSTAR, and while neither yielded a clear cut detection of dark matter, they do put strong constraints on the properties of dark matter. As these constraints get more stringent, we can get closer to either ruling out a theory or homing in on the true value. Perez ended by highlighting three proposed X-ray missions (HEX-P, GRAMS, and IAXO) that could apply this method with more precision, hopefully bringing us closer to understanding the nature of dark matter.

You can read Astrobites’s interview with Kerstin Perez here.

JWST image of the rho Ophiuchi molecular cloud complex and an illustration of the WL20 star system

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:


Helen B. Warner Prize Lecture: The Lives and Deaths of Star Clusters, and the Black Holes They Make Along the Way, Carl Rodriguez (University of North Carolina at Chapel Hill) (by Catherine Slaughter)

The Wednesday morning plenary lecture was given by this year’s Warner Prize recipient, Carl Rodriguez (UNC Chapel Hill). Rodriguez is a theoretical and computational astrophysicist, whose recent research focuses on the gravitational waves that could be produced by black holes in globular clusters. He opens the lecture emphasizing how our population of observed black holes has changed dramatically since 2015, when LIGO first came online. While gravitational waves have been used to observe a huge number of new black holes, Rodriguez highlighted a smaller set has been identified using radial velocity and (using Gaia) astrometry.

Rodriguez highlighted that newly identified populations often include black holes in the known upper mass gap; there are few black holes found with masses ranging from 65 to 135 times the mass of the Sun. The mass gap is a predicted result of late-stage stellar evolution, when stellar remnants of these masses are torn apart in highly energetic pulsational pair instability supernovae. We simply don’t expect to see isolated black holes of this size. Additionally, the observed astrometric binaries have masses and separations that are largely inconsistent with the expected parameters of common-envelope evolution of isolated binary stars. Rodriguez explained, however, that both of these oddities may be explained by the unique conditions inside globular clusters.

Rodriguez goes on to describe how black holes move throughout a globular cluster. Generally, dynamical friction causes very massive, dense objects to preferentially move toward the center of the cluster over relatively long timescales (~100 million years). Once they’re in generally the same space, black hole binaries can form through three-body system mechanics. In classical Newtonian mechanics, it is not possible for two unbound point particles to enter a bound orbit via standard gravitational interactions — there is simply too much energy in the system. It is possible, however, with the introduction of a third “interloper” star, which experiences a recoil effect, carrying the extra energy away with it. This phenomenon can explain the seemingly strange orbital parameters of the astrometric binaries. The remaining binary is either kicked from the cluster, merges while in the cluster, or gets disrupted by the cluster.

Of course, this all relies on a strong understanding of how globular clusters form in the first place. In order to better understand this, Rodriguez and his research group make use of their Great Balls of FIRE simulations. This project focuses on “daisy-chaining” three types of models. First, a high-resolution cosmological simulation shows how individual molecular clouds form in galaxies. Then, a cloud-collapse simulation takes in that output and models the creation of stars from the material. Finally, an N-body simulation shows how those stars interact and dynamically evolve over time. Their final result is a simulated galaxy, with mass similar to the Milky Way, containing a similar number of globular clusters to the Milky Way. These clusters are shown to have a similar age-alignment relationship to those in the Milky Way, and — most notably — a distribution of black hole masses that includes the upper mass gap. The question then becomes how the simulated mass-gap black holes formed. Rodriguez speaks primarily about two possible mechanisms: black hole mergers and progenitor star mergers.

An image of one of Rodriguez’s slides, outlining the structure of the Great Balls of FIRE simulation. [Slide by Carl Rodriguez]

Analysis of the simulation found that a given black hole is expected to experience, in the most extreme case, two or three mergers. This is because rapidly spinning black holes release gravitational waves in a preferred direction when they merge, causing the merger remnant to be “kicked” in the opposite direction. The more mergers a black hole experiences, the higher its spin, and the harder it gets kicked, eventually getting kicked from the cluster altogether. Indeed, they find only three of these most extreme hierarchical mergers manage to survive in the cluster. It is also possible that stars themselves merge over time, creating very massive objects that could, in turn, form significantly more massive stellar black holes. Using the simulation, Rodriguez and his research group find that because these clusters form hierarchically, they at some point have density profiles that are flat and relatively unstable, leading to runaway merger events.

An image of one of Rodriguez’s slides, showing the output of the Great Balls of FIRE simulation. [Slide by Carl Rodriguez]

Ultimately, Rodriguez explains, new populations of black holes look unlike how we expect because they were likely formed under fundamentally different conditions than we expect. His simulations show that black hole binaries are ten times more efficiently formed in cluster environments, compared to isolated environments. Importantly, recent observations of binary black holes in the upper mass gap can be well explained by the conditions in globular clusters.

You can read Astrobites’s interview with Carl Rodriguez here.

Return to Table of Contents.


Press Conference: More Stars and Distant Worlds (by Ben Cassese)

Wednesday morning, Madison, Wisconsin. As some clouds gathered over Lake Monona just outside the convention center, a comparatively friendly crowd of attendees of the 244th meeting of the AAS assembled to hear the final research-focused press briefing of the conference. Titled “More Stars and Distant Worlds,” this session had presentations split between individual interesting objects and looks towards future observations.

First up was Mary Barsony, who along with collaborators discovered an unusual and striking pair of young stars using the combined powers of ALMA and JWST. The researchers came upon this rare find after noticing something strange in archival images of a triple star system. Although two of the three members appeared about two million years old, measurements indicated that the third was somehow much younger. A closer look at this outlier revealed that what had previously appeared to be one strange star was actually a tightly bound pair, both of which are spewing out long jets of material. Intrigued, they observed the system again, this time using ALMA. This second look revealed nearly edge-on, skirt-like disks of gas around each star. This unique arrangement is an interesting laboratory to test theories of stellar formation and outflows, and a powerful demonstration of the benefits of combining multiple cutting-edge datasets. [Press release]

Next was Breanna Binder, California State Polytechnic University, Pomona, who jumped beyond the cutting-edge facilities of today and instead spoke about the work required to build the next generation of Great Observatories. The Habitable Worlds Observatory (HWO) currently exists only on paper, but by the 2040s, it should hopefully be a real, gigantic space telescope hard at work discovering and characterizing Earth-like planets. Before engineers and technicians can begin bolting together the observatory, however, astronomers need to figure out exactly where they want to aim the thing and what performance specs they need to achieve their ambitious goals. As part of that effort, Binder and collaborators went through a list of about 200 promising target stars to check which of these were amenable to hosting a habitable planet. They found that about a third of them had previously been observed by X-ray telescopes, and in many cases, these archival observations revealed a disappointing but important reality. Although many of their potential target stars appeared docile in the visible wavelengths, a good portion of them are furiously emitting X-rays that are strong enough to (likely) doom any chance of life emerging on the surfaces of their planets. Her presentation emphasized that while the road to HWO will be long, by the time the telescope reaches the launchpad, it’ll be powered on its journey to space both by not only its rocket but also by decades of planning. [Press release]

Next was Roman Gerasimov, University of Notre Dame, who quickly informed the audience that he is “Paid to figure out where the periodic table came from.” He goes about this substantial task by trying to find ancient brown dwarfs and measure their compositions. Brown dwarfs are too small to sustain nuclear fusion in their cores, which means that after being born bright and hot, they fade and cool over time. If one can find a collection of brown dwarfs that all should be around the same age, say a collection that lives in the same globular cluster, then measure their temperatures, the scientist could use them as “galactic chronometers” to estimate the age of the system. That’s exactly what Gerasimov and collaborators did: using images from JWST, they identified three ancient brown dwarfs in a globular cluster named NGC 6397. These puny, sub-Jupiter-sized worlds are likely among the oldest objects in our galaxy, and also likely are just the first of hundreds of similar discoveries. Gerasimov estimates that just one more set of JWST observations taken about three years from now would reveal hundreds more, since the longer baseline would allow the team to distinguish between members of the cluster and faint objects that happen to lie in front of or behind it.

Finally was Juliette Becker, University of Wisconsin-Madison, who described recent modeling of the “perilous” journey a planet with an ocean must embark on as its star grows old. This journey has elements of a good action movie: in order to reach a happy ending where the planet retains its ocean and travels on a stable orbit around its aging white dwarf, it must survive two distinct challenges. First, as its host expands from a typical main-sequence star into a red giant, the planet must avoid getting engulfed by the suddenly enormous central body (for those curious, when our own Sun becomes a red giant, Mercury and Venus will almost certainly fall prey to the ballooning star, though the jury is still out on whether Earth will similarly suffer). Should it successfully avoid getting eaten, then patiently wait out the star’s inevitable shrinkage from a red giant into a puny white dwarf, the planet will now find itself far too far away and cold for anything liquid to remain on its surface. In order to save its ocean, the planet must be kicked inwards towards the white dwarf by some other object in the system, then survive the resulting high-eccentricity migration and tidal dissipation required to land on a close-in, stable, warm orbit.

Becker has practical motivations for fleshing out the odds of each step in this string of hypotheticals, since planets around white dwarfs are significantly easier to characterize than planets around more generic solar-type stars. That’s because the primary technique astronomers use to measure the atmospheres of close-in planets, the transit technique, returns stronger signals as the radii of the star and planet become more similar. So, Becker and collaborators wanted to assess whether it would be worth our time to put the time into surveying these stars in the first place. Their conclusion? Although an ocean could technically survive the journey laid out above, “it’s not an easy process,” and it’s unlikely that a large portion of white dwarf planets have oceans.

You can view a video recording of this press conference or take a look at the presenters’ slides.

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Plenary Lecture: When Data is Not Enough: Illustrating Astrophysics for the Public, Robert Hurt (Caltech/IPAC) (by Will Golay)

Robert Hurt is a researcher at IPAC, an institution based at Caltech that supports four central data archives and 12 different NASA missions. Hurt is a self-described “AstroVizicist,” an expert in visualizing astronomical data for researchers and the public. In his talk, he aimed to motivate the importance of artistic visualization and its role in science communication.

Hurt shows one of the first pieces of acrylic artwork he made early on in his life, an image of a galaxy with several key features aiming to communicate how they are structured. However, Hurt points out that his galaxy painting from 1979 was missing a central bulge region. He noted that this was likely a product of the time: the images of galaxies at the time were being collected on photographic film plates, which would highly overexpose the galaxy’s central regions to have enough sensitivity to capture the lower surface brightness components near the edge. Hurt’s message is that scientific illustration is a sort of hypothesis representing our current understanding of the universe.

To determine if a scientific illustration is successful, we can ask if it is accurate, clear, and, most importantly, amazing. These three components — representing the science, communications, and art “Essential AstroViz Tensions” — can shape how we approach creating a new illustration. In any new science result, there are known facts, known falsehoods, and possibilities consistent with the data but not wholly affirmed. As a scientific illustrator, Hurt aims to capture the most important new known facts of the result, but he also mentions that we can’t possibly know everything. Sometimes, an illustrator must fill in the gaps left behind to paint a complete picture. They might even choose to specifically modify and include some “falsehoods,” such as synthetic colors or rescaling an object so it is visible in the image, to clarify the illustration (trading off accuracy for the value of communication).

Hurt then discusses several case studies of his work and how the scientific illustration process works. In one example, he shows an early image of the Milky Way that resulted in a few inaccuracies as new research emerged. So, he aimed to create a new, better illustration of what our own galaxy might look like to an external observer. Illustrating our galaxy in this way can provide insights that are otherwise challenging to understand with our “inside-out” view of the galaxy. This new image was informed by several scientific results, such as gas simulations, spiral arm models, observations along specific sightlines, and even some unpublished results. The new image ended up being so well-constructed that a feature on the far side of the galaxy, the Scutum-Centaurus Arm of the Milky Way, was so accurate that a different researcher ended up confirming some key details and contacted Hurt because he was concerned he had access to his unpublished data! The artist had simply used some basic symmetries.

The updated illustration of the galaxy incorporates updates to the original image informed by accurate science results. This image is our best guess of the Milky Way's structure.

The updated illustration of the galaxy incorporates updates to the original image informed by accurate science results. This image is our best guess of the Milky Way’s structure. [Slide by Robert Hurt]

Hurt concludes by highlighting his non-traditional career path and the importance of fostering non-traditional and traditional academic career skills in our students. He states that we never know where a student will end up and how their skills outside of the classroom may contribute to a new, unique future role in astronomy that we can’t even predict. It is important for mentors to foster both of these skillsets in their students, even though that might mean a student is working on something beyond their research. Hurt’s illustrations are available online and are free to share with anyone.

You can read Astrobites’s interview with Robert Hurt here.

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Press Conference: Citizen Science from the 2023/2024 Solar Eclipses (by Catherine Slaughter)

Wednesday afternoon brought with it a press conference highlighting citizen science from the 2023 (annular) and 2024 (total) eclipses. Speaking at the conference were Amir Caspi (Southwest Research institute), Angela Des Jardins (Montana State University), Dawn Davies (Hill Country Alliance) and Kate Russo (Being in the Shadow).

A slide from Caspi's press release. It shows a composite image of the solar corona taken by his citizen science teams. The colors indicate the angle of polarization. Caspi's zoom image can be seen on the right.

Composite image of the solar corona taken by his citizen science teams. The colors indicate the angle of polarization. [Slide by Amir Caspi, photo by Catherine Slaughter]

First up was Amir Caspi, reporting on the results of the Citizen CATE project. Citizen CATE featured an observing network of community participants and aimed to study polarization in the solar corona. He highlights that total eclipses provide better ground-based coronal observing than a coronagraph does because eclipses also create pseudo-dark-sky conditions. Because the coronal activity the team was searching for lasts longer than the few minutes an eclipse can be observed at a single site, the Citizen CATE team gave identical, specialized telescopes to 35 teams along the eclipse path. He highlights that the communities that participated were all allowed to keep the equipment for future science and outreach purposes. In all, more than 85% of the sites were able to obtain full or partial eclipse data for the project.

Next up to the podium was Angela Des Jardins, speaking about her eclipse ballooning project, which aimed to measure the atmospheric response to the eclipse leading up to and after totality. Stratospheric ballooning is a multi-disciplinary endeavor, and is useful because it creates space-like conditions without the need for a rocket. For the eclipse project, two teams of researchers — an atmospheric science team and an engineering team — spent the 24 hours preceding the eclipse and 6 hours proceeding, launching stratospheric weather balloons with weather sensors, accelerometers, cameras, and other student-designed experiments. Her primary goal was to observe atmospheric gravity waves (which, she highlights, are not the same as gravitational waves). The experiment was successful, with the first confirmed observations of eclipse-driven gravity waves. [Press release]

Then Dawn Davies stepped up to speak about her project, LightSound. LightSound is a solar eclipse sonification device, made for those in the blind and low-vision community to better experience eclipses. Leading up to the 2023 and 2024 eclipses, LightSound received more than 2,400 requests for devices internationally. Over the course of eight workshops, 420+ volunteers of a broad range of ages and previous building experience created more than 900 devices for libraries, museums, community task forces, blind and low vision services, national parks, senior centers, and more. The team also set up a live-streamed webinar in conjunction with the American Council for the Blind, which reached an audience of more than 2,500 people. As of now, the LightSound team is looking ahead to the 2026 and 2027 eclipses, and are hoping to implement a haptic feedback feature to the device. [Press release (PDF)]

Finally, Kate Russo took the stage to describe her project, Being in the Shadow. A clinical psychologist by trade and eclipse chaser by hobby, Russo and her collaborators work to observe the feeling of awe inspired by viewing a solar eclipse through brain wave signatures. She defines awe by two specific experiences. The first is vastness, an understanding of something greater than ourselves, and the second is accommodation, the way we re-align our perspectives accordingly.  In previous phenomenological research, Russo identifies six experiences that people most often report experiencing during a total eclipse: a sense of wrongness, a primal fear, awe, connected insignificance, euphoria, and a desire to repeat (yielding the appropriately themed acronym “SPACED”). In a pilot project conducted during the 2023 annular eclipse, their primary goal was to simply test the efficacy of the brain-wave mapping technology. What Russo found, however, was that even in a non-total eclipse, they were able to observe awe in every single participant’s data. Looking forward, they are hoping to repeat the experience at the 2028 eclipse in Australia (where Russo primarily works), and possibly extend the project to other astronomical events. [Press release (PDF)]

An image of the panel at the eclipse outreach press conference

An image of the panel at the eclipse outreach press conference. Shown (left to right) are Susanna Kohler (at the podium), Angela De Jardins, Dawn Davies, and Kate Russo. Amir Caspi presented from zoom and is not shown. [Photo by Catherine Slaughter]

You can view a video recording of this press conference or take a look at the presenters’ slides.

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Royal Astronomical Society Gold Plenary Lecture: Challenges to the Cosmological Model, John Peacock (University of Edinburgh) (by Nathalie Korhonen Cuestas)

Over the course of 67 years, modern cosmology was born and matured into the current standard model, known as Λ cold dark matter (ΛCDM). In his plenary lecture, Dr. John Peacock laid out the history of cosmology, highlighting the measurements that got us to where we are now, explained some of the possible problems with ΛCDM, and outlined how recent results address these challenges.

There’s a plethora of evidence supporting ΛCDM. From redshift measurements of Type Ia supernovae, to the large-scale structure of the universe, to the anisotropies of the cosmic microwave background (CMB), many signs point towards ΛCDM. However, there are some areas of the model that we don’t fully understand — including but not limited to the nature of dark energy and dark matter — and some areas of the model that appear to be in conflict with observations. Peacock touched on four major sources of tension — large-scale streaming velocities, the CMB dipole, Hubble tension, and lensing of the CMB — and focused primarily on the last two.

You may know that the universe is expanding at an ever increasing rate, and the Hubble constant describes the speed of this expansion. There are a number of different ways you can estimate the Hubble constant, but they generally fall into two categories. One method involves measuring the distance to and velocity of distant galaxies. These two quantities are linearly related and the slope of the line can give you the Hubble constant. Alternatively, you can calculate the Hubble constant from the temperature of the CMB, which is very precisely measured. But there’s a problem: these two methods yield different values for the Hubble constant. Typically, Type Ia supernovae or Cepheid variable stars are used to calculate the distance measurements, but, Peacock said, these methods might be introducing unknown systematic uncertainties. He also showed that when a different standard candle (J-region asymptotic giant branch stars in this case), you can get a value for the Hubble constant that more closely agrees with the CMB value.

The second source of tension Peacock discussed was the results from weak gravitational lensing studies. Mass warps spacetime, and this leads to a lensing effect that produces distorted images. If you know what the undistorted image should look like, you can use the distortions to calculate the mass that must have been along the line of sight and produced the lensing. The technique can be applied to the CMB; by measuring distortions in the CMB, you can back out the amount of mass that must have been along the line of sight. Since the CMB is the edge of the visible universe, the mass along the line of sight probes the distribution of mass throughout the universe, which is fundamentally determined by cosmology.

Peacock showed that we do in fact observe slight distortions to the CMB, and the overall distortion is in good agreement with ΛCDM. However, when distortion was broken down into different redshift intervals, astronomers found something different. When only considering the mass at high redshift, the results were consistent with ΛCDM, but this was not the case at lower redshifts, in the local universe. The result might point towards a potential time evolution in ΛCDM, specifically in the dark energy component of the model (that’s the Λ). However, Peacock was careful to emphasize that these results are still in their early stages, and further study is needed before we make any major adjustments to our cosmological models.

You can read Astrobites’s interview with John Peacock here.

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Solar Physics Division Harvey Prize Plenary Lecture: Dissipation and Excitation: The Role of Kinetic-Scale Waves and Instabilities in the Evolution of the Solar Wind, Kristopher G. Klein (University of Arizona)

The Karen Harvey Prize is awarded by the Solar Physics Division of the AAS in recognition of significant contributions to solar physics early in one’s career. This year, the award went to Kristopher Klein of the University of Arizona. Klein studies the solar wind — the tenuous plasma that constantly streams out from the Sun and fills the solar system. Because the Sun is by far the closest star to Earth, there are types of data that we can collect from the Sun that we simply can’t get for any other star or distant plasma environment. While Klein jokingly laments that many solar physicists interact not with pretty pictures of the Sun but instead with densely packed plots of particles and electric and magnetic fields, studies of the Sun have far-reaching implications.

Klein’s work uses simulations to understand how energy is transferred within the solar wind plasma. Energy can be transmitted by waves, instabilities, and turbulence, which transfers energy from large spatial scales to small spatial scales. Studying these factors can help researchers understand electron and proton heating, which can in turn help to interpret observations of distant plasma environments, such as the pictures of Sagittarius A*, the supermassive black hole at the center of the Milky Way.

In addition to simulations, solar physicists work with an abundance of spacecraft data: there are currently 20 missions (27 spacecraft in total) capable of making in situ measurements of the solar wind, and 14 more missions are currently being formulated or implemented. Using this fleet of spacecraft, researchers can extract the basic properties of the solar wind and derive more complex parameters, like the plasma beta (the ratio of the thermal pressure of a plasma to its magnetic pressure). Because the plasma beta varies greatly with position in the solar system, different locations within the solar wind can be used as analogs for many different plasma environments across the universe.

Klein expanded on the projects that he and his research team have undertaken to track down the ways in which energy flows within the solar wind. While important advances have been made with existing data and simulations, most current spacecraft missions measure the properties of the solar wind at a single point, taking measurements as the solar wind blows across the spacecraft. (A few missions like the Magnetospheric Multiscale mission involve multiple spacecraft working in tandem.) Klein introduced the upcoming HelioSwarm mission, which will be composed of nine spacecraft that explore the solar wind, magnetosheath, and foreshock on a variety of spatial scales to study these regions in an entirely new way. With new views of the solar wind incoming, we can expect our knowledge of the solar wind and other plasma environments across the universe to increase in leaps and bounds!

image summarizing current heliophysics missions

A summary of the current (as of 2022) fleet of heliophysics missions. [NASA’s Goddard Space Flight Center]

You can read Astrobites’s interview with Kristopher Klein here.

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ten spiral galaxies imaged by JWST

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:


Plenary Lecture: Dark and Quiet Skies for the Future of Astronomy and of the Space Environment, Aparna Venkatesan & Teznie Pugh (University of San Francisco and McDonald Observatory, UT Austin) (by Will Golay)

Aparna Venkatesan (University of San Francisco) and Teznie Pugh (McDonald Observatory, UT Austin) started the second day of the AAS by discussing the exponentially growing challenges of protecting dark and quiet skies. Venkatesan and Pugh are co-chairs of COMPASSE (Committee for the Protection of Astronomy and the Space Environment), an AAS committee dedicated to preserving the viability of ground-based, orbital, and lunar astronomy.

There are growing threats to astronomy across the electromagnetic spectrum, the most well known being light pollution. A recent paper used citizen science reports of star visibility and found that the reduced number of visible stars can be explained by the sky brightness increasing between 7% and 10% every year for the last 11 years. If this trend continues, the number of visible stars in the night sky will halve every 10 years, an existential threat to ground-based optical astronomy. The impact on major astronomical observatories is also profound. Another recent result showed that about two-thirds of major astronomical observatories have sky brightnesses exceeding the International Astronomical Union’s recommended 10% above natural levels.

However, the threat does not end in the optical or on the ground. Radio-frequency interference is another rapidly growing problem that could wipe out ground-based radio observatories. At the other end of the spectrum, space-based nuclear power could threaten space-based high-energy observatories like Chandra (#SaveChandra). Also in space, the growing number of satellites has posed a major problem for ground-based observation. Eighty percent of all active satellites have been launched in the last four years, and 60% of active satellites are part of the Starlink constellation. As of 29 May 2024, there are 547,267 combined International Telecommunications Union (ITU) & Federal Communications Commission (FCC) applications for new frequency allocations for space-based satellites. The impact of these satellites is manyfold: from increasing the sky brightness, streaking in images, and the impact of launches (which are not yet well known), 500,000 satellites would make ground-based astronomy almost impossible. Given current predictions on satellite launchers, the Vera Rubin Observatory anticipates streaking in 30% of images during twilight hours.

A zoom-in of the radio frequency allocation plot showing the location of the 21-cm line relative to the frequency allocations

A zoom-in of the radio frequency allocation plot showing the location of the 21-cm line relative to the frequency allocations. The 21-cm line is not a frequency protected for astronomy. [Slide by Aparna Venkatesan and Teznie Pugh]

The impact of brighter skies extends far beyond professional astronomers. Amateur astronomers will also suffer the same effects, and the implications on animal and bird migration patterns are just starting to be understood. Some Indigenous populations, which have already disproportionately been impacted and repeatedly displaced, rely on wayfinding with constellations and asterisms. The rising sky brightness already has measurable impacts on this navigation method by reducing the number of visible stars.

However, all is not lost! COMPASSE is taking many steps to combat these challenges. COMPASSE provides templates for local ordinances and advocates for dark skies, education, and outreach in local communities. The committee also works with government organizations like the FCC, the Federal Aviation Administration, the US State Department, etc., to provide comments on the impact of new policies on dark and quiet skies. They are increasing awareness by publishing in scientific journals and popular media outlets, and they’ve taken many more steps to begin combating this issue. Venkatesan and Pugh highlighted that the story is not complete yet, and that it is our story to write by getting involved in advocacy for dark and quiet skies.

You can read Astrobites’s interview with Venkatesan and Pugh here.

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Press Conference: From the Galactic Center to the Galactic Disk (by Nathalie Korhonen Cuestas)

The first press conference of the day included five different speakers who described their work on Sagittarius A* (Sgr A*) — the supermassive black hole (SMBH) at the center of our galaxy — and its surroundings. Sgr A* gives us a rare chance to study inactive black holes, which are otherwise too faint to observe with much detail.

The first speaker, Grace Sanger-Johnson (Michigan State University), presented X-ray observations of Sgr A*, which were taken over a period of eight years by the NuSTAR telescope. A puzzling characteristic of Sgr A* is that it flares in X-ray wavelengths. Over a period of a couple hours, Sgr A* can become up to 600 times brighter than it normally appears. The origin of these cosmic fireworks is currently unknown, but there are two main hypotheses: the flares could originate from the magnetic fields in plasma very close to the black hole, or they could be the result of a star coming too close to the black hole and losing some of its mass. Sanger-Johnson’s observations show that there is a correlation between the brightness of a flare and the hardness of a flare. Here, “hardness” refers to how much of the light emitted is at shorter, more energetic wavelengths. A harder flare has more energy at shorter wavelengths, and Sanger-Johnson found that harder flares were generally brighter. This correlation could point to two different origins for these X-ray flares: one that produces dimmer, softer flares, and another that produces brighter, harder flares. Further observations of Sgr A*’s flares will help astronomers determine if this is indeed the case. [Press release]

Next up was Jack Uteg, a rising sophomore at Michigan State University. His talk shifted focus from Sgr A* to the ring of molecular gas that resides around 100 parsecs from the galactic center. This gas, known as the central molecular zone (CMZ), can be observed in X-ray, but we know that molecular gas cannot emit at this wavelength by itself. Therefore, these X-rays may have originated from Sgr A*, and are now being reflected by the CMZ. Uteg specifically studies the emission from a region known as the Bridge Cloud. The distance between Sgr A* and the Bridge Cloud means that light takes about 200 years to travel from Sgr A* to the Bridge Cloud, where it can be reflected. This means that any observations of the Bridge Cloud tell us what Sgr A* was up to 200 years ago. Using X-ray observations taken over 24 years, Uteg reconstructed the X-ray emitting history of Sgr A* and found that around 200 years ago, Sgr A* underwent an outburst that made it 100,000 times brighter than it normally is! [Press release]

Continuing with the theme of the CMZ, Dylan Paré (Villanova University) discussed his observations of the magnetic fields in the CMZ. The FIREPLACE (Far-Infrared Polarimetric Large-Area CMZ Exploration) survey used the polarization of light from the CMZ to map the magnetic fields that thread the clouds. Paré found that the magnetic field was preferentially oriented in two directions, and that higher density regions such as The Brick (see the first inset panel in the image below) have more well-aligned magnetic fields. In the galactic disc, the opposite is observed to be true — denser clouds are less likely to have well-aligned magnetic fields. While further analysis of the different regions of the CMZ is needed, it’s possible that the observed magnetic fields are the result of a large-scale magnetic field, running perpendicular to the galactic plane, being sheared by the molecular clouds.

This image shows the structure and magnetic fields of the CMZ. Cloud-like structures are shown in purple and cyan, and thin yellow streaks can be see crossing the clouds vertically. The direction of the magnetic field is also shown using short white lines which are aligned with the field direction. There are three inset panels which show zoom-ins of three regions: The Brick, the 20 km/s cloud, and Sgr C. In these insets, the magnetic field lines are well-ordered and appear to align with the cloud.

This picture shows you the CMZ, and the inset panels zoom in to the larger image. Radio emission is shown in yellow, emission from warm dust is shown in purple, and emission from cool dust is shown in cyan. The direction of the magnetic field is shown by the white lines. [Paré et al. 2024]

Another region observed by the FIREPLACE survey is Sagittarius C (Sgr C), an intriguing region with unusually high star formation. Jianhan (Roy) Zhao (UCLA) described the various components of Sgr C and how we can use them to learn more about the mechanisms at play in the CMZ. In the image you can see bright yellow streaks, which are radio filaments. One of these filaments originates in Sgr C, appearing to emanate from a shell of ionized gas that surrounds a molecular, star-forming cloud. One possible source of radio filaments is magnetic reconnection, a high-energy phenomenon that can accelerate electrons and cause them to emit in the radio wavelengths. In Sgr C, Zhao found that the magnetic field lines are converging towards the radio filament, supporting the idea that magnetic reconnection is powering the radio emission. The fact that the radio filament is seen to originate in an ionized region further supports this idea, since in order for electrons to be accelerated, they have to be free.

Last but not least was Dr. Anthony Minter (Green Bank Observatory), who discussed his search for dust and molecules in Smith’s high-velocity cloud. High-velocity clouds are clouds that are flying towards the Milky Way, potentially providing the fuel needed to sustain star formation. Clouds in the Milky Way contain different molecules and dust grains, but Smith’s high-velocity cloud was observed to contain no dust or molecules. It could be that the cloud originally did contain dust and molecules, but over time, they became dissociated, or, it could be that the cloud was formed from a pristine environment. In the galactic disc, we know that clouds further from the galactic plane have less dust and molecules. Minter found that clouds near the galactic center have a similar, but steeper gradient. This means that a cloud at the galactic center will have fewer molecules and dust grains than a cloud at a similar height from the galactic plane, but over the galactic disc. These kinds of abundance patterns help us to understand the structure of the Milky Way and potentially help reconstruct the events that determined the evolution of our galaxy. [Press release]

You can view a video recording of this press conference or take a look at the presenters’ slides.

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Unlocking the Mysteries of Exoplanets: The Crucial Role of Laboratory Research, Erika Kohler (NASA Goddard Space Flight Center) (by Catherine Slaughter)

This summer’s AAS meeting is a joint session with the Laboratory Astrophysics Division (LAD). As part of this joint meeting, Dr. Erika Kohler (NASA Goddard Space Flight Center) gave Tuesday’s midday plenary lecture. In this talk, Kohler promoted the use of lab-based experiments in astrophysical research and highlighted a number of her group’s projects, including the prep work for the forthcoming Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission.

The talk starts out posing a question that motivates much of the work we do as scientists: “We found it, why not study it?” Kohler describes how recent technological innovation has allowed us to develop advanced spacefaring probes and respond to this question using in situ measurements of solar system planets. The catch, she notes, is that even the most advanced tech could not make in situ measurements of exoplanets. From this, Kohler outlines her talk’s key takeaways: that lab research is fundamental and complements all other astrophysics work, and that (given the cross-disciplinary nature of exoplanet research) communication pathways and user engagement propel us forward. To underscore these ideas she gives two examples from her own research.

The first comes from a study of cloud formation in exoplanet atmospheres. Solar system planets, Kohler explains, represent a very limited region of possible exoplanet parameters, especially in terms of atmospheric pressure and temperature. “If you’re only designing experiments to describe [the solar system planets],” she says, “you’re missing a whole universe out there.” In the project, Kohler and her team used lab-based experiments to recreate the very extreme atmospheric environments found on distant exoplanets. Their goal was to experimentally determine saturation vapor pressure curves — mathematical descriptions of the pressures and temperatures at which a given material will form clouds — for a number of known and expected molecules in exoplanet atmospheres. The preexisting curves were created using calculations based on Earth-like conditions. They found that the heights at which clouds form in a given atmosphere are different in extreme environments, which changes our interpretation of possible exoplanet atmosphere observations. This is a result that could only be reasonably obtained in a lab setting.

A slide from Kohler's talk, showing the Orbital Distance-Mass parameter space scatter plot for identified exoplanets at present. The plot is lined in white with white text on a black background, and the data points are colored according to discovery method (solar system planets, transit, radial velocity, microlensing, and imaging). The sections of parameter space spanned by the solar system planets is highlihgted in purple.

A slide from Kohler’s talk, showing the orbital distance–mass parameter space scatter plot for identified exoplanets at present. [Slide by Erika Kohler]

The second example is a study conducted in preparation for the launch of DAVINCI. The mission will include a probe that descends down to the surface of Venus, taking images of the surface in near-infrared and making atmospheric measurements along the way. In order to obtain usable images, however, it is important to ensure that the atmosphere of Venus is reasonably transparent to infrared light. Kohler’s group began by studying the changing opacity of CO2 in the varying temperatures and pressures of Venus’s atmosphere. They conducted a simulated descent, taking observations of infrared transmission through CO2 at conditions mimicking the atmosphere from 55 to 7 km above the surface. In doing so, they are able to identify the wavelengths at which the atmosphere can be expected to become opaque at some point in the probe’s journey. Along with being foundational work for the future DAVINCI mission, these experimental results have huge implications for JWST, which observes in the mid-infrared, highlighting the necessity of lab work as a supplement to distant observation.

A slide from Kohler's talk showing a sprawling graph-map diagram of the many features studied in exoplanet research. They are spacially organized into broad groups labled "Stellar Effects," "Planetary Systems," and "Planetary Properties." Each feature is colored according to whether it is directly observable, modeled in a way that is constrained by observations, or accessible through direct modeling only.

A slide from Kohler’s talk showing a sprawling graph-map diagram of the many features studied in exoplanet research. [Slide by Erika Kohler]

Kohler finishes the talk encouraging the crowd to pursue three actionable challenges: 1. Talk to people in other subfields. 2. Look at the assumptions in our own research, and see if they’ve ever been verified in the lab. 3. Take a multi-method approach to research, combining lab-based, modeling, and observational techniques. She leaves us with a reminder that lab-based research allows us to both describe and predict astrophysical observations, and that we want to be prepared before first light. 

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Press Conference: Massive Black Holes and Surprising Spirals (by Kerry Hensley)

Fan Zou (Penn State University) opened the afternoon press conference with a discussion of supermassive black hole growth. Despite nearly all massive galaxies having supermassive black holes, it’s still not known exactly how these objects get so massive. Accretion and mergers are the two possible growth mechanisms, and researchers need to understand both processes to reconstruct the growth history of black holes. Zou explained that astronomers study black hole accretion through X-ray observations, and they study mergers through supercomputer simulations. Combining results from Chandra X-ray Observatory, eROSITA, and XMM-Newton — three premier X-ray observatories — with output from the IllustrisTNG simulations, Zou’s team found that accretion played a larger role in black hole growth than mergers did under most circumstances. The growth rate due to both mechanisms was higher in the early universe, although the two mechanisms have declined at different speeds. Today, mergers play a larger role relative to accretion than in the early universe. [Press release]

illustration of a quasar with outflowing winds

Illustration of a quasar with outflowing winds. The spectra at the top right shows how the absorption line has shifted to bluer wavelengths over time. [NASA/CXC/M. Weiss, Catherine Grier and the SDSS collaboration]

Robert Wheatley and Catherine Grier (University of Wisconsin-Madison) reported on their study of a quasar: a supermassive black hole with a hot, luminous accretion disk that emits radiation across most of the electromagnetic spectrum. Quasars often have powerful winds or outflows that travel at millions of miles per hour out from the accretion disk. Because these winds can block the light from the hot accretion disk, they are visible in quasar spectra as absorption lines. Using observations from the Sloan Digital Sky Survey Black Hole Mapper Reverberation Mapping Project, Wheatley, Grier, and collaborators demonstrated that the outflows from the quasar SBS 1408+544 (also called SDSS-RM 613) have been accelerating over the past eight years because of radiation pressure from the luminous accretion disk. This acceleration was evident from the blueward shift of an absorption line of carbon. While previous observations have hinted at accelerating quasar outflows in a handful of spectra, this new work uses 130 spectra, providing an unprecedented new look at this phenomenon. [Press release]

Next, Riccardo Arcodia (MIT) presented a study on massive — not supermassive! — black holes in low-mass galaxies. Studying these somewhat-less-than-supermassive black holes in the nearby universe can help researchers understand how supermassive black holes grew from lower-mass seeds in the early universe. Accreting black holes emit light across the electromagnetic spectrum and can be highly variable, so Arcodia’s team searched for low-mass galaxies that are variable in the optical and infrared to identify candidate massive black holes. Of the 200 candidate massive black holes, only 17 emitted X-rays. This result is unexpected because accreting supermassive black holes are extremely luminous in X-rays, and the team estimated that X-rays from the black holes in their sample should have been detectable. This might mean that lower-mass black holes have a different accretion mode compared to supermassive black holes, possibly because of the lower gravity, clumpier interstellar medium, or other factors. [Press release]

Lastly, Vicki Kuhn (University of Missouri Columbia) presented some new results from JWST on spiral galaxies. Previous studies using the Hubble Space Telescope have found that there are very few spiral galaxies earlier than a redshift of z = 2, which corresponds to when the universe was just a few billion years old. Kuhn’s team identified 873 galaxies with high stellar mass and redshifts between 0.5 and 4 in observations from JWST, which can look farther back in time than Hubble can. A team of six researchers visually classified each galaxy in the sample as spiral or not, and they found that JWST sees more spirals than Hubble did, especially at low redshift. To account for the fact that spiral structure is harder to discern at high redshift, Kuhn’s team created a sample of mock high-redshift galaxies. After determining how redshift affects the fraction of galaxies in which spiral structure is visible, the team found that about 30% of galaxies are spirals out to a redshift of z = 3. This is far more spirals than found in previous studies, suggesting a need to recalibrate our expectations for when and how spiral structure formed in early galaxies. [Press release]

You can view a video recording of this press conference or take a look at the presenters’ slides.

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Plenary Lecture: Leveraging AI to Transform the Astronomy Data Revolution into a Discovery Revolution, Cecilia Garraffo (Center for Astrophysics | Harvard & Smithsonian) (by Will Golay)

Cecilia Garraffo is a researcher at the Center for Astrophysics | Harvard & Smithsonian and the director of AstroAI. She is an expert in machine learning (ML) and artificial intelligence (AI) data analysis methods. She has developed novel techniques for using machine learning to uncover unique and exciting results from large astrophysical datasets. In her talk, she aimed to highlight what AI can contribute to research in astrophysics.

Garraffo motivated the need for AI methods by reminding us of an important point: although we are building massive observatories that will be coming online in the next five to ten years, are we, as a community, prepared for the immense data influx that will ensue? Once observatories like the Vera Rubin Observatory and the Square Kilometre Array begin observing, we will generate more data in one year than all currently existing astrophysical data. We are entering the era of petabyte astrophysics, an era we are not yet prepared to begin. The data volumes are not the only consideration: as astrophysics research becomes increasingly multi-wavelength and multi-messenger, causing datasets to become heterogeneous, it is even more critical that we have methods that can unify the picture and maximize the scientific value of such unique datasets.

AI is one tool we can apply to begin preparing for the upcoming massive influx of data. Garraffo argues that AI has the unique ability to search for patterns and classes intentionally (even if we don’t know what those patterns are a priori), enabling a chance for discovery spaces that would otherwise be inaccessible in smaller datasets. Even the most basic dimensionality reduction and clustering methods have successfully identified new anomalies in large datasets that we can later follow up on.

How exactly do we execute such a search using ML methods? The astronomy community needs experts in AI to help develop strategies specific to our kind of data. Astronomical data often differs from the data used to train large language models (LLMs) in several ways. Our data are biased and complex, could be multimodal, almost always incomplete, and undoubtedly sparse. To address these issues, we need to take specific steps to prepare our data and our ML models, which require user expertise in identifying methods and successfully applying them in the context of astrophysical research.

Garraffo then shared several examples of how AI has been used in various research contexts inside the AstroAI collaboration. One particularly striking example she shared was using ML methods to generate new “realistic” images of a black hole accreting material for comparison with images from the Event Horizon Telescope (EHT). Since general relativistic magnetohydrodynamic simulations are costly to run, we can use ML methods to interpolate between the model’s parameters. In the case of EHT, they are interested in using these methods to generate images of a black hole with differing spins, significantly affecting how the accretion will appear in EHT images.

A slide from Cecilia Garraffo's presentation showing two images of a black hole that were generated by simulation and one image that was generated from ML methods. Garraffo is illustrating that the human eye is not well-suited to distinguish between these cases.

A slide from Cecilia Garraffo’s presentation showing two images of a black hole that were generated by simulation and one image that was generated from ML methods. Garraffo is illustrating that the human eye is not well suited to distinguish between these cases. [Photograph by Will Golay]

Although ML astrophysics methods are just starting, Garraffo is excited to continue sharing them and educating the community via the AstroAI collaboration. The collaboration aims to educate students about how AI methods can be used in astrophysics research and begin developing a new era in which these methods are common throughout a wide variety of subfields. Stay tuned for more updates about the AstroAI collaboration at the Center for Astrophysics on their website!

You can read Astrobites’s interview with Cecilia Garraffo here.

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Plenary Lecture: With a Wild Surmise: A New Era of Exoplanet Exploration, Tom Beatty (University of Wisconsin at Madison) (by Jessie Thwaites)

Wrapping up today’s talks was Dr. Tom Beatty, whose plenary lecture explored exoplanets, specifically how we can classify them. We already know of more than 5,600 exoplanets, and that number just keeps growing! He discussed how we can measure a planet’s atmosphere to learn how exoplanets form, explore what makes a planet habitable, and search for signatures of water and oxygen that would be necessary to support life.

The attempt to classify exoplanets is multifaceted, he says, including searching for trends in their mass, gravity, age, metallicity, clouds, specific elemental abundances, and more. But these quantities have complicated relationships; for example, he discusses how ambiguity in cloud models on the planet’s surface can change the abundance measurement we get. These measurements of the spectra of these planets are made via transmission (seeing the spectral lines that appear when the planet passes in front of its star) and emission (seeing the spectral lines than disappear when the planet passes behind its star).

Central to the themes of his talk were how improvements in technology have made these detailed and accurate measurements possible. Initially, these measurements were done with the Spitzer Space Telescope, and massively improved upon with the Wide Field Camera 3 instrument on the Hubble Space Telescope, which allowed for more precise and spectroscopic measurements. And now, with JWST’s improved sensitivity, we can measure carbon and oxygen molecules in exoplanet atmospheres for the first time, get spectroscopic measurements of clouds, and even search for signatures of life on exoplanets!

slide describing what we could learn using JWST observations in the near future, and a graphic with properties of exoplanets that should be included in their classifications, including age, gravity, clouds, mass, irradiation, bulk metalicity, and mixing.

New questions about our understanding of exoplanets, and properties of exoplanets that are currently being studied. [Slide by Tom Beatty]

But searching for biosignatures requires more than just understanding the atmosphere on these planets, he says, so researchers have formed the Wisconsin Center for Origins Research (WiCOR) to bring together astronomy, chemistry, integrative biology, geoscience, bacteriology, botany, and atmospheric and oceanic studies to search for life on exoplanets in a multidisciplinary way.

You can read Astrobites’s interview with Tom Beatty here.

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Space telescope image showing hundreds of galaxies and other stars

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) (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.

diagram demonstrating the bending of light by a massive galaxy cluster

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]

UNCOVER uses the power of gravity to unlock a Pandora’s box of high-redshift galaxies. Normally, light travels in a straight line, but this can change if a heavy enough object warps spacetime enough to bend light. This effect is known as gravitational lensing and results in the images of galaxies being distorted and, more importantly, magnified. Gravitational lensing allows us to see galaxies that would otherwise be too faint and resolve galaxies that would otherwise be too small.

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.

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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]

spectra of Beta Pictoris

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 forward in the planet-formation process, Christine Chen (Johns Hopkins University/Space Telescope Science Institute) reported on JWST observations of a debris disk around the young, nearby star Beta Pictoris. In the debris disk phase, the original gas and dust of the disk have mostly dissipated, and planet formation is underway; as planetesimals form, they collide and create rocky rubble and dust. Twenty years ago, the Spitzer Space Telescope detected several types of dust around the star Beta Pictoris, which is known to be orbited by two giant planets. Looking at the star again with JWST in 2023, Chen’s team saw that two of the dust components — hot dust and small, cold forsterite dust grains — had disappeared. Piecing together the clues, Chen’s team proposed that a collision between giant asteroids some 20–30 years ago created the dust seen by Spitzer; by the time JWST turned toward the system, radiation pressure had whisked the small dust grains out of the system, resulting in the less-featured spectrum seen today. Other data support the collision scenario, including 2022 JWST observations of a “cat tail” feature in the disk’s emission and 2014 ALMA observations of carbon monoxide gas. [Press release]

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 a prematurely deployed antenna

“Selfie” by ROLSES showing the prematurely deployed antenna, circled. [Intuitive Machines]

Lastly, Jack Burns (University of Colorado Boulder) presented the results of a recent mission to land a radio telescope near the Moon’s south pole: Radio wave Observations at the Lunar Surface of the photo Electron Sheath (ROLSES). For the first time in more than 50 years, NASA landed a scientific payload on the Moon in February 2024. While there were a few bumps along the way — a 2.5-meter antenna deployed unexpectedly in transit, and a failure of the laser-guided navigation system resulted in a too-hard impact that snapped one of the landing legs and tilted the lander nearly on its side — the mission was a success. The lander, observing Earth as would a distant observer for whom our planet is an exoplanet, collected Earth’s radio signals. This is essentially a redo of Carl Sagan’s SETI experiment, which used a close flyby of Earth by the Galileo spacecraft to understand how our planet might look to an extraterrestrial observer. The ROLSES radio spectrum greatly improved upon the measurements from Galileo, providing crucial data to be compared to future observations of exoplanet radio emissions made from telescopes on the far side of the Moon. The future of lunar radio astronomy is bright: NASA has already funded a successor to ROLSES that will fly in 2026, along with the Lunar Surface Electromagnetics Experiment-Night (LuSEE-Night) mission (also in 2026), which will perform cosmological observations from the lunar farside, shielded from terrestrial radio emissions. [Press release]

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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.

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]

Pinilla-Alonso shared preliminary results from her Cycle 1 JWST program, DISCo. In this program, her collaboration used the NIRSpec and MIRI instruments to collect infrared spectra of ~60 TNOs that they identified as having various properties. With these observations, they found that the spectra of TNOs fall into three major groups: bowl-type, double-dip-type, and cliff-type. These three categories are physically characterized by the molecules that create these features in the infrared spectra. The bowl-type TNOs are rich in water ice, with some carbon dioxide. The double-dip-type has lots of carbon dioxide and carbon monoxide ice and evidence of more complex organics. Finally, the cliff-type sources have many organic molecules but less carbon dioxide and carbon monoxide.

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. The presence and absence of certain molecules are shown relative to their "ice lines," where those molecules can freeze based on the star's temperature and the distance.

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]

Although previous observations had only hinted at a transition in the composition of TNOs based on where they formed relative to the “ice lines” (or the distances at which a particular molecule freezes), these JWST observations provide a much stronger case for the origin of TNO diversity. Pinilla-Alonso highlighted that these results indicate we can use the properties of TNOs to learn about the primordial planetesimal disk in a new way. Her collaboration is completing additional analyses of their JWST data, and we should expect more results to come soon.

You can read Astrobites’s interview with Noemí Pinilla-Alonso here.

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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]

An artist's concept of the binary star system HM Sge

Illustration of the symbiotic nova system HM Sagittae. [NASA, ESA, Leah Hustak (STScI)]

Next was Ravi Sankrit, Space Telescope Science Institute, who shared his work on a symbiotic nova named HM Sagittae. This star, though “nondescript” when viewed in a contemporary single snapshot, has led an interesting life over the past half-century. Back in 1975, this star loudly announced to the world that it was actually a pair of tightly bound stars: an accreting white dwarf and a pulsating red giant called a Mira variable. This announcement came in the form of an explosion: material that had been siphoned off the Mira and onto the surface of the white dwarf ignited, and the system grew hundreds of times brighter thanks to the thermonuclear fireball. The pair have felt the effects of the explosion ever since and have been slowly fading towards their original brightnesses. Sankrit shared a comparison of observations taken each decade, including recent ones collected by the Cosmic Origins Spectrograph aboard the Hubble Space Telescope. By watching how different emissions lines have evolved over time, the researchers are beginning to model the long-term relaxation of this feisty system. [Press release]

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]

six JWST images showing the disappearance and appearance of transient supernovae

Three examples of transients discovered through the JADES program. [NASA, ESA, CSA, STScI, Christa DeCoursey (University of Arizona), JADES Collaboration]

Christa DeCoursey, University of Arizona, and Justin Pierel, Space Telescope Science Institute, rounded out the session with an update on the JADES transient survey. JADES, or the JWST Advanced Extragalactic Survey, is an enormous collaborative effort that involves aiming JWST at a tiny patch of sky for more than 100 hours, waiting a year, then imaging that same patch again. The resulting ultra-deep images contain some of the most distant galaxies ever discovered. Equally interesting, however, are the smaller objects that appear in just one of the two photographs. A few dozen (relatively) bright dots appear in one image but not the other, meaning they must have flared up or died down quickly. The team identified these as supernovae, and given the locations and properties of their host galaxies, they must be some of the most distant eruptions seen to date. The Hubble Space Telescope managed to find about 20 truly faraway supernovae in 20 years, and in just one year of observations, the JADES team has already found 83 comparable events. It’s still early days, but JWST has already proven itself a capable supernova hunting machine, and the community can look forward to more observations of ancient explosions in the coming years. [Press release]

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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.

An image of one of the slides from Sam Hale's AAS 244 plenary. The slide is an image of Yerkes observatory from when it first opened in 1987. It features three large telescope domes attached tp the same building, with a large lawn in the foreground. An image caption reads "Yerkes Observatory 1897". Credit: Sam Hale

Yerkes Observatory, when it first opened in 1987. [Slide by Sam Hale]

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!

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Solar Physics Division George Ellery Hale Prize Lecture: Solar Irradiance: Earth’s Energy Source, Judith Lean (University of Colorado) (by Jessie Thwaites)

plots showing the 11-year solar cycle. As the irradiance increases, so does the number of faculae and sunspots on the sun, indicating solar maximum.

Slide showing the total solar irradiance, along with the presence of faculae and sunspots. Click to enlarge. [Slide by Judith Lean]

Following Sam Hale’s plenary discussing the life and work of his grandfather, the George Ellery Hale Prize was awarded to Dr. Judith Lean, for her work on solar irradiance. When you look up “total solar irradiance,” you’ll find that people once thought the total radiative output of the Sun was a constant — but as Dr. Lean describes, it’s anything but!

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.

multiple plots, showing the contributions of different effects to the rise in global surface temperature. first there is ENSO and volcanic influences, which are fairly random, then solar irradiance, which has a regular cyclic contribution from the solar cycle, and then anthropogenic influence, which increases dramatically after around 1960.

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

This is also inherently connected to climate on Earth, and an important part of understanding climate change. Although the Sun is variable, and can raise or lower Earth’s temperature depending on the solar power output, this and other natural factors alone cannot explain the full increase in global surface temperature. The global change in temperature has already surpassed the 1.5-degree Celsius “climate threshold,” and with every 0.1 degree of additional warming we will begin to see exponential effects. By understanding the solar cycle, we can better understand the trends happening in our changing climate.

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banner announcing the 244th meeting of the American Astronomical Society in Madison, WI

This week, AAS Nova and Astrobites are attending the American Astronomical Society (AAS) summer meeting in Madison, WI, and online.

AAS Nova Editors Kerry Hensley and Susanna Kohler and AAS Media Fellow Ben Cassese will join Astrobites Media Intern Nathalie Korhonen Cuestas and Astrobiters Will Golay, Catherine Slaughter, and Jessie Thwaites to live-blog the meeting for all those who aren’t attending or can’t make it to all the sessions they’d like. We plan to cover all of the plenaries and press conferences, so follow along here on aasnova.org or astrobites.org! You can also follow Astrobites on Bluesky at astrobites.bsky.social for more meeting content.

Where can you find us during the meeting? We’ll be at the Astrobites booth in the Exhibit Hall all week — stop by and say hello! You can also find Kerry, Susanna, and Ben at the press conferences Monday through Wednesday. AAS press conferences are open to all, and they can also be viewed on the AAS Press Office YouTube channel for anyone not attending the meeting.

Finally, you can read the currently published AAS 244 keynote speaker interviews here. Be sure to check back all week as the remainder are released!

banner announcing the 244th meeting of the American Astronomical Society in Madison, WI

AAS 244 is nearly here! The AAS Publishing team looks forward to connecting with meeting attendees in Madison, WI, and we’re excited to share a preview of upcoming publishing-related events. Attending the meeting will be Julie Steffen (AAS Chief Publishing Officer), Ethan Vishniac (AAS Journals Editor in Chief), Gus Muench (AAS Journals Data Editor), and Katie Merrell (AAS Journals Data Editor). Several of the editors of the AAS journals, including Fred Rasio (Editor of the Astrophysical Journal Letters) and Steve Kawaler (Lead Editor of the Stars and Stellar Physics research corridor) will be in attendance as well. Be sure to stop by the AAS booth in the Exhibit Hall to say hello, chat about the journals, have your data questions answered, and pick up some swag!

AAS Nova Editors Kerry Hensley and Susanna Kohler, AAS Media Fellow Ben Cassese, Astrobites Media Intern Nathalie Korhonen Cuestas, and the rest of the Astrobites team will also be available periodically at the Astrobites booth in the Exhibit Hall.


Open Science at AAS 244

Note: The following section contains links to the AAS 244 block schedule. You must be logged in for these links to direct you to the correct session; otherwise, they will take you to the main block schedule page.

On Tuesday, an oral session on outreach and education will take place in Ballroom D from 2:00 to 3:30 pm CDT. One of the talks in this session will introduce a recent special issue of the Bulletin of the American Astronomical Society that provides “eclipse science and investigations, resources for safe viewing, astrophotography, education tools and resources, personal reflections, peer-reviewed papers, explorations of individuals’ reactions to solar eclipses, descriptions of events, and discussions of logistics” for the three most recent solar eclipses to cross North America. As a bonus, this session also includes a talk by Tom Rice (AAS Education Specialist) on eclipse-related outreach to Deaf, hard-of-hearing, and signing audiences.

On Wednesday, be sure to attend the Astrophysics and Open Science splinter session. This session will bring together members of the NASA Astrophysics Division and the NSF on a panel to speak on NASA and NSF efforts to enable Open Science and take questions on this topic. You can submit your questions ahead of time; the link to submit questions is available in the abstract linked above. The session will take place 11:00 am – 12:30 pm CDT in the Hall of Ideas I.

photo collage showing two previous AAS Media Fellows emceeing press conference alongside an image of the Carina Nebula

Are you an astronomy graduate student who’s interested in science communication? Do you wish you had the opportunity to explore that interest and gain professional development without having to take time off from your graduate studies? Do you want to write for AAS Nova, report on astronomy meetings, help organize and run press conferences, and learn the ins and outs of academic publishing?

Then the AAS Media Fellowship might be for you! This position was developed in 2017 by the American Astronomical Society to provide training and experience for a graduate student in the astronomical sciences interested in science communication. The fellowship is a remote, quarter-time, one-year (with the possibility of extension to two years) position intended to be filled by a current graduate student at a US institution. The new AAS Media Fellowship term will begin in Fall 2024.

If this sounds like a good fit for you, you can get more information below or at the job register posting. Apply by 21 June 2024 by submitting your contact information, a cover letter, and a short CV to personnel@aas.org. See the job register posting for the full application details.


Essential Duties & Responsibilities

The AAS Media Fellow will report to the AAS Communications Manager. The Fellow will work the equivalent of one day per week (on a schedule that will be jointly developed and agreed upon by the Fellow, the AAS Communications Manager, and the AAS Communications Specialist) and be responsible for a wide range of duties. The Fellow will be expected to:

  • Assist in sharing astronomy press releases via AAS press office channels.
  • Regularly write and publish articles for AAS Nova.
  • Occasionally help to prepare other written communications such as AAS or Division press releases.
  • Assist in managing AAS communications such as social media accounts, postings to the AAS website, and emails to members or authors.
  • Serve as backup to the AAS Communications Manager or the AAS Communications Specialist during absences for daily tasks like distributing press releases and publishing AAS Nova posts.
  • At the AAS winter and summer meetings, help the AAS Communications Manager plan and run press conferences, help represent AAS Nova, and help organize live-blogging coverage of the meeting by Astrobites and AAS Nova.

Qualifications

The Fellow must:

  • Be a graduate student in good standing in the astronomical sciences or a related field at a US institution.
  • Receive the approval of their advisor or department chair to apply.
  • Receive their primary support from their home institution.
  • Have a keen eye for detail and accuracy.
  • Have the ability to absorb complex material, synthesize information, and write short articles that concisely reflect key points of the material to a target audience.
  • Have good working knowledge of, and/or ability to quickly master, tools such as WordPress, Drupal, Microsoft Office, and Adobe Creative Suite.

Compensation

The stipend for this position is $7,500 per year for the equivalent of one day of work per week, payable on a quarterly basis. Travel support will also be provided for travel to the summer and winter AAS meetings.

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