Hubble image of a Wolf–Rayet star

Editor’s Note: This week we’re at the 242nd AAS meeting in Albuquerque, NM, 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 on Twitter for live coverage. The usual posting schedule for AAS Nova will resume on June 12th.

Table of Contents:

Hale Prize Lecture: George H. Fisher (University of California, Berkeley) (by Emma Clarke)

The Solar Physics Division awarded this year’s Hale Prize, which recognizes “outstanding contributions over an extended period of time to the field of solar astronomy,” to George Fisher of the University of California, Berkeley. His talk, “Understanding the Dynamics of Magnetic Field and Plasma in the Interior and Atmosphere of the Sun,” reviewed the contributions to the field by himself and collaborators.

He began by discussing solar flares. First he described what happens when a solar flare occurs. This begins with the reconnection of magnetic field lines in the solar plasma. These newly reconnected field lines are filled with energetic electrons (which we can see due to their collisions with ions in the solar atmosphere and subsequent bremsstrahlung radiation). An enormous amount of energy is released in the reconnection event and transported into the solar chromosphere. An outstanding question many years ago was what happened to the solar atmosphere when heated by the energetic electrons. In 1989, Fisher described the downflows of chromospheric plasma driven by these energetic electrons and developed a generalized theory for the flare-driven chromospheric downflow’s amplitude and time variation. These predicted downflows are now routinely observed. Later, researchers wondered whether the solar flare models could be applied to stellar flares — flares on other stars. Working with Suzanne Hawley, originally a grad student and now a professor at the University of Washington, Fisher applied solar flare models to stellar flares more generally.

An illustration of the regions of the Sun's atmosphere and interior.

An illustration of the regions of the Sun’s atmosphere and interior. Click to enlarge. [NASA/Goddard]

Dr. Fisher’s second topic was magnetic fields on the solar surface. These fields most likely come from the tachocline, a transition region at the base of the convection zone with large shear. From the tachocline, magnetic active regions emerge at the solar surface as magnetic flux tubes. In the flux-tube model, the magnetic field is concentrated in a thin tube. The dynamics of the tube can be described by the forces acting on a thin 1D tube embedded in a 3D model of the solar interior. Fisher said that the flux tubes do an excellent job of explaining the observed relationship between how sunspots are “tilted” and their solar latitude (known as Joy’s law). Sunspots have the property where the leading side (in the sense of the rotation of the Sun) is more compact relative to the more broken-apart side that follows. He has argued that the higher field strength of the leading side allows the tube to better resist being broken apart by turbulent convection.

Next Dr. Fisher discussed work on determining which magnetic quantity best correlates with observed X-ray output of active regions on the Sun. With collaborators he found that X-ray output is best correlated with the unsigned (think absolute value) magnetic flux. Despite advances in understanding the relationship between solar magnetic fields and X-ray emission, reproducing an observed X-ray image with simulations has been a challenging problem; observed and computed images still do not show compelling agreement. Fisher and collaborators speculate that the main cause of the disagreements is in how the coronal loops are heated.

The final part of the talk was about efforts to develop a data-driven physics-based model of the 3D magnetic field above the photosphere. Dr. Fisher explained that such a model would require (1) a model for the evolution of the 3D magnetic field — such as a magnetohydrodynamic model or magnetofrictional model — and (2) a method to derive the electric field and/or velocity field from the photospheric magnetic field data in order to implement Faraday’s law, which describes the evolution of the magnetic field in time. Dr. Fisher discussed the challenges of the second requirement. While velocity along the line of sight can be determined with Doppler shift methods, the other two “horizontal” components are more difficult to estimate. In 2008, Fisher and Welsch developed the FLCT code, based on the Local Correlation Tracking (LCT) technique, to find the horizontal components of the velocity from magnetogram data. Their code can construct the velocity field using two images taken at slightly different times. FLCT has been applied to find flows in many different settings, some of which Fisher never imagined it would be used for! Two applications that he found surprising were deriving streamline maps of the flows and deriving proper motion flows from nebula images taken years apart.

The other approach to the second requirement is to determine the electric field. One option is to compute the poloidal–toroidal decomposition electric field from all three components of the magnetic field. Fisher and collaborators do this using a technique called PDFI, which stands for “poloidal–toroidal decomposition (PTD) plus Doppler plus Fourier local correlation tracking (FLCT) plus ideal.” Fisher says that this technique does a “pretty decent job” of reproducing the electric field. The electric field has now been computed using PDFI for most emerged active regions observed by the Solar Dynamics Observatory.

Dr. Fisher concluded by sharing his excitement for solar physics research and the many unsolved problems in the field. He proposed that we are entering a “golden age” of solar physics, especially with regards to solar magnetism.

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Press Conference: Resolving Stars and Hunting Nearby Galaxies (by Junellie Gonzalez Quiles)

composite X-ray and optical view of the Triangulum Galaxy

A composite X-ray and optical view of the Triangulum Galaxy. [X-ray: NASA/CXC/SAO/P. Plucinsky et al.]

The first press conference of the day was moderated by Dr. Kerry Hensley, AAS Deputy Press Officer, and she introduced the three speakers for the session. First up, we had Olivia Gaunt, a PhD student from Tufts University speaking about “Rare Signals from Stars in Triangulum Galaxy.” Olivia used the Keck II telescope and specifically the Imaging Multi-Object Spectrograph (DEIMOS) to observe the Triangulum Galaxy. The Triangulum Galaxy (Messier 33), is 2.73 million light-years from Earth and has an estimated 40 billion stars. Out of these stars, Olivia is interested in Wolf-Rayet stars, which are a rare class of emission-line stars that exist in an intermediate stage between big and hot O-type stars and Type Ibc supernovae. These stars are also typically characterized by an expanding bubble of ionized gas. Olivia specifically looked at Broad Emission Line Luminous Sources, also referred to as BELLS, in the Triangulum Galaxy. In one object (BELLS 1), the team saw exciting changes to the star’s emission over a 4-year timescale, which has not been observed before! Lastly, some of these objects are even an even more rare type of Wolf-Rayet stars, which gives a new insight to this area of astrophysics.

Next up, we had Jim Jackson from the Green Bank Observatory who talked to us about star formation triggered by an expanding bubble in the Nessie Nebula. The birthplaces of baby stars (protostars) are dense, cold, filamentary molecular clouds. When high-mass (greater than 8 times the mass of our Sun) stars are formed, they put large amounts of energy into the surrounding gas, which ionizes it and forms expanding bubbles (H II regions). This phenomenon drives the main question of the study: does this energetic feedback trigger or hinder star formation? To answer this question, Jackson’s team looked at the Nessie Nebula, an extremely filamentary infrared dark cloud, which is cold, dense, and opaque. The Nessie Nebula also contains the Nessie bubble in which they see a feature that looks like a question mark. They see the expanding bubble, which interacts with the filament and at their intersection they see a luminous protostar. Its location strongly suggests that the collision between the expanding bubble and the Nessie filament triggered star formation. To determine this, they used the Stratospheric Observatory for Infrared Astronomy (SOFIA) and the Australia Telescope Compact Array (ATCA) to observe the Nessie Nebula. Through detection of ammonia, they were able to see that there are signs of shock, which means the expanding bubble is slamming into the filament at supersonic speeds and the collision triggered a star to form. [Press release]

To finish off the press conference, we had Stephen Walker from University of Alabama in Huntsville talking to us about X-ray observations of a group of galaxies falling into the Coma Cluster. X-rays provide us with a view of the hot (100 million K) intracluster medium filling clusters. They allow us to observe how galaxies move and merge into clusters. The team used XMM-Newton to observe the Coma Cluster. They observe the infalling group NGC4839 that has a 1.5 million light-year-long tail behind it, and their new observations are the most detailed of an infalling group! The Coma Cluster is preceded by a shock front traveling at around 3 million mph. Their edge detections show ripples like Kelvin Helmholtz instabilities. Through studying the shape of its tail, they are able to constrain the properties of the gas such as viscosity, which is important for understanding how galaxy clusters grow through mergers. [Press release]

X-ray images of the Coma Cluster

XMM-Newton (left) and Chandra X-ray Observatory (right) images of the Coma Cluster. [From slides by Stephen Walker]

Twitter thread for press conference by Junellie Gonzalez Quiles.

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Plenary Lecture: Julia Blue Bird (National Radio Astronomy Observatory) (by Wei Vivyan Yan)

This plenary talk today was delivered by Dr. Julia Blue Bird from the National Radio Astronomy Observatory, sharing the latest discoveries on galactic properties and evolution with CHILES. Thanks to all the amazing instruments to study both neutral hydrogen (HI) and molecular hydrogen, “It is really an amazing time to be a radio astronomer,” says Dr. Blue Bird.

Dr. Blue Bird first introduced CHILES as “a pathfinder for future radio astronomy surveys.” CHILES is short for COSMOS HI Large Extragalactic Survey, a blind survey on the HI emission using the Karl G. Jansky Very Large Array (VLA), covering the part of the COSMOS field with no strong ratio continuum sources (Figure 1). Since the HI emission line is faint and requires long integration times to observe, HI studies with previous large surveys are mostly limited to the nearby Universe (up to z = 0.06). Anything beyond z = 0.25 is considered high redshift. With a 1000-hour single pointing, CHILES could observe the HI line up to z = 0.5, which is a huge step forward.

The redshift (left) and sky coverage (right, black circle, as big as the Moon) of CHILES. [Slide by Dr. Julia Blue Bird]

The primary goal of CHILES is to tell the story of individual galaxies. Here, Dr. Blue Bird used CHILES observation to examine the connection between the comic web and galaxy gas. Since CHILES provided us with the opportunity to study both local and large-scale environments beyond z = 0.1 for the first time, Dr. Blue Bird was able to extend this discussion to higher redshift regimes.

CHILES observed the filamentary network of the cosmic web at z < 0.1 The blue filament lines overlaid the distribution of galaxies (top-down view). [Slide by Dr. Julia Blue Bird]

By identifying the filamentary network of the cosmic web over CHILES’ field of view, we can locate the distance between a galaxy and the filaments (Figure 2). The closer a galaxy lies from the filament, the less HI gas this galaxy owns. Therefore, in the regions close to the filaments, we tend to find redder, passive, and more massive galaxies. In addition to this HI gas fraction, galaxy orientation is also related to the galaxy location to the surrounding filaments. CHILES showed that low-mass galaxies generate spins that align with filaments by accreting onto the filaments, while high-mass galaxies generate spins perpendicular to filaments by merging along filaments, which agreed with theoretical predictions.

Very tight correlation between HI mass and disk diameter values directly from CHILES data (Dr. Blue Bird’s favorite scaling relation!), suggesting a nearly constant HI surface density. Click to enlarge. [Slide by Dr. Julia Blue Bird]

Dr. Blue Bird also examined the connection between star formation histories and galaxy gas, which appears as scaling relations. These relations also serve as excellent “sanity checks” for the data! Among all scaling relations (HI & stellar mass, specific star formation rate & stellar mass…) checked with CHILES data, Dr. Blue Bird’s favorite one is a very tight correlation between HI mass and disk diameter values directly from CHILES data (Figure 3). This relation suggests that the HI surface density remains nearly constant as the disks grow.

At higher redshift, Dr. Blue Bird also found some fascinating individual sources at high redshift. For example, a very exciting starburst galaxy at z = 0.38 observed with CHILES shows a large amount of CO and a surprisingly high star formation ratio. More like galaxies at z > 2! Although most detections of individual distant galaxies are generally limited compared to nearby galaxies, stacked spectra of those distant samples can demonstrate the average properties at high redshift. Stacked gas fraction seems to rise along higher redshifts, indicating a possible evolutionary trend. More tests are needed for these hints of the galaxy evolution!

CHILES filled in gaps of missing data points. [Slide by Dr. Julia Blue Bird]

Dr. Blue Bird concluded this talk with the potential and capability of CHILES. CHILES is ongoing and has already filled in many missing measurements and data points (Figure 4). It will make more significant contributions to the scientific community. Dr. Blue Bird also offered acknowledgments not only to the land but also to the students of the land at the end of this presentation.

Live tweets of this session by Wei Vivyan Yan.

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Press Conference: Hot Jupiters and Hungry Black Holes (by Lucas Brown)

Today’s second press conference was massive — ranging from investigations of massive Jupiter-like exoplanets and explosive nova events to new observations of a famous black hole binary and studies exploring the behavior of supermassive black holes in cosmic voids.

Plot showing the semi-major axis versus mass for planets within our solar system as well as the observed population of exoplanets. “Hot Jupiters” are exoplanets with small semi-major axes but large masses, and they appear in this plot towards the top left. It is not completely understood how these planets migrated to be so close to their host stars. Click to enlarge. [Songhu Wang]

In the first of four presentations, Songhu Wang from Indiana University spoke on the aforementioned “hot Jupiters.” First showing a plot of semi-major axis versus mass for each of the planets in our solar system, Wang noted the prevalence of gas giants in our outer solar system led researchers to believe for a long time that the temperature gradient of our solar system allowed larger amounts of icy, solid material to exist farther from the Sun, causing the larger planets to form there. However, in exoplanet systems, it is actually incredibly common for Jupiter-sized planets to exist extremely close to their host star — hence, “hot Jupiters.” This discrepancy suggests that some additional mechanism must be bringing these planets inwards over time. Two popular models exist for this mechanism: “disk migration” and “high-eccentricity migration.” The latter method typically doesn’t permit hot Jupiters to end up in orbits close to other planets, so it has been of much interest to researchers to determine how “lonely” hot Jupiters are. While previous research has suggested hot Jupiters are indeed lonely, Wang and his team recently employed a method called transit timing variation to search for planets in orbits close to hot Jupiters, and they found evidence that such companion planets might be much more common than previously thought! Further research is needed to confirm this finding and explore its implications for planetary migration models, but it’s nice to think those hot Jupiters out there aren’t so lonely after all.

Next up was something much hotter than a hot Jupiter — a nova! Montana Williams from New Mexico Tech presented on new observations of a particularly strange nova. A nova is an astrophysical event that occurs when hot plasma accreting onto a white dwarf in a binary star system becomes hot enough to temporarily sustain a fusion reaction. The nova in question, dubbed V1674H, was imaged by a collection of radio telescopes collectively known as the Very Long Baseline Array (VLBA). This event was remarkably fast for a nova, as it dimmed 2 magnitudes over the course of just around one day. This observation marked only the second time a system like this was observed using the VLBA, and as a result the researchers were able to learn about the structure and dynamics of the ejected stellar material.

Artist’s impression of the OJ287 black hole binary system. When the smaller secondary black hole crosses the accretion disk of the primary black hole, the system increases in brightness. [S. Zola & NASA JPL]

Stepping up in mass once again, Mauri Valtonen from the University of Turku announced a possible first-ever direct detection of light coming from a secondary black hole in a black hole binary. The binary system, denoted OJ287, has been studied for a very long time. There are even images on photographic plates of the system that date back to the late 1800s! Part of what makes this system interesting is that the ~12-year orbit of the secondary black hole means that astronomers can predict when the secondary black hole will cross the accretion disk of the primary black hole. Whenever this happens, the system gets significantly brighter. However, up until now it has been impossible to distinguish between light coming off of the accretion disk or jets of the primary black hole and light coming off of the secondary system. Valtonen’s team performed an analysis of recent disk crossings and believes a particular set of variable flares they found corresponded to gas rushing into a stable area around the secondary black hole known as its Roche lobe. If this is indeed what the team spotted, it would mark the first direct detection of light from the secondary black hole in a black hole binary system.

Following the theme of hungry black holes accreting gasses, the final presentation of the day was a report on initial results from a research project lead by Anish Aradhey, a student at Harrisonburg High School, on the properties of supermassive black holes (SMBHs) at the center of galaxies in cosmic voids. Cosmic voids are huge underdense regions that occupy around 50% of the universe’s volume while containing less than 20% of the universe’s galaxies. The motivation for this work was to explore the hotly debated theory that galaxy interactions and mergers cause central SMBHs to accrete more material (or as Aradhey puts it — ”snacking”). Galaxies in cosmic voids are the loneliest of them all, so they provide an interesting point of comparison for this theory. Aradhey and his team used more than 8 years of NASA WISE data to look for the variability of mid-infrared light galaxies, which is a different method than is commonly employed in looking for “snacking” SMBHs. Typically, measurements are made of a galaxy’s mid-infrared light at one moment, and researchers look for bright red signatures associated with accretion onto SMBHs. This method can misclassify systems which are active but highly variable, so this new work attempts to avoid this issue by focusing on variability in this part of the spectrum. Aradhey and his team ultimately discovered that midsize and dwarf galaxies tend to have more “hungry” black holes in cosmic voids than in the general population, possibly because their isolation allows gas to more efficiently transfer to the center. On the other hand, central SMBHs appeared less active in the cosmic voids for larger galaxies.

Live tweets of this session by Lucas Brown.

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Harvey Prize Lecture: Bin Chen (New Jersey Institute of Technology) (by Sumeet Kulkarni)

Every year, the AAS Solar Physics Division awards the Karen Harvey Prize to an early-career scientist who shows outstanding productivity within ten years of their dissertation. This year’s winner is Dr. Bin Chen, an associate professor of physics at the New Jersey Institute of Technology. Chen gave a plenary talk on using the Sun as a laboratory to study some of the most energetic plasma physics phenomena.

A diagram representing the the shape and structure of a solar flare

A diagram representing the the shape and structure of a solar flare. [Alexandra Angelich, NRAO/AUI/NSF]

Chen said our closest star is a stepping stone to studying all stars in astronomy. Indeed, we use units such as solar mass and luminosity to base our understanding of various happenings in the universe. While we can’t go there in a lab coat, the Sun also serves as a great laboratory for all of stellar physics. First and foremost, it is BRIGHT, making it easy to track dynamic phenomena happening on its surface in human timescales. For example, a one-second exposure time is enough to image a rising solar flare that can change its shape and form within seconds. In contrast, other dynamic phenomena such as supernova outflows need hours of observing time to collect data and show changes over a timescale of years.

Additionally, we can study the Sun at multiple wavelengths and resolve it extremely well spatially as well as temporally. Chen and his solar physics colleagues have leveraged these abilities to understand solar flares in exquisite detail.

Solar flares release humongous amounts of energy, totalling up to 1032 erg — 10 million times greater than a volcanic explosion. The size of the corona participating in this release is equivalent to a large fraction of the size of the Sun, with the flare rising as high as 0.1 times its radius. The cause of this energy release is magnetic reconnection, a process wherein magnetic field lines of opposite poles approach each other, increasing the electric field and current density in a very thin layer called the “current layer.” This process also accelerates particles such as electrons up to very high speeds, close to the speed of light. Combining theoretical models and observations using the Very Large Array (VLA) and the Expanded Owens Valley Solar Array (EOVSA), Chen has added new insights to where and how this particle acceleration occurs in solar flares.

According to current theoretical models, a standard solar flare forms a long and thin current sheet that tapers in the middle, leading to high velocities of particles in this region. EOVSA can take frequent, broad-band microwave spectra of solar flares, from which it is also possible to distinguish spectra coming from within each region of a flare. This helps us study how magnetic fields vary within the flare structure.

Based on these data, Chen said the magnetic field profile of the observed current sheet matched very well with theoretical models. The field had a local maximum (around 500 Gauss) and minimum (called the “bottle”). The bottle portion had a lower magnetic field at the center surrounded by high fields at two ends. But unexpectedly, the spot with the maximum high magnetic fields has lower concentrations of energetic electrons, which are more prevalent in the bottle region.

Magnetic reconnections are seen in other places too: the Tokamak nuclear fusion prototype reactor and neutron stars. But they are especially important with planetary magnetic fields such as the Earth’s magnetosphere, which protects our atmosphere from evaporation due to solar winds and is thus crucial to sustaining life on our planet.

That is why it is important to study this physical process in further detail. Chen said the future observatories such as the Frequency Agile Solar Radiotelescope (FASR) would have the ability to resolve the shapes of solar flares like never seen before, as seen in the simulated image below. It is sure to flare up as many new questions as it answers!

A comparison of EOVSA observations and simulated observations of solar flares using the proposed FASR telescope [Slide by Bin Chen]

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Plenary Lecture: Linda Shore (Astronomical Society of the Pacific) (by Ben Cassese)

The final plenary of the day offered something new for those who remained in the largest exhibition hall into the early evening: a talk not on astronomy research, but on public outreach and science communication. Dr. Linda Shore, the CEO of the Astronomical Society of the Pacific and winner of the 2023 AAS Education prize, split her time between a discussion of principles on how to effectively communicate with the public and anecdotes/examples from throughout her career as an educator.

After noting that science communication is more important than ever in the age of misinformation and proliferating conspiracy theories, Dr. Shore shared three keys to effective science education: all activities, whether hands-on museum demonstrations or sit-down lectures, should aim to foster participants’ Science Identity, Science Agency, and  Science Capital.

An effective way to hit all three areas is to let participants explore somewhat on their own and reach a conclusion through their own questioning. The Exploratorium, a museum in San Francisco where Dr. Shore worked for many years before joining the ASP, takes this concept to the extreme. From the moment they arrive, guests of all ages are presented with interactive exhibits that come with very few instructions. For example, a giant concave mirror that sat along one wall was not accompanied by any text explaining the concepts of basic optics, like a focal point or magnification. Even so, by approaching the mirror from different directions at different distances, visitors learned that the image flipped and warped depending on their viewing geometry. Many also discovered that sound behaves like light and can be focused as well, allowing them to whisper to a friend across the hall if they stood just the right distance from the mirror.

Although the Exploratorium educates the public about science, it also is a hub for teachers to teach teachers. Dr. Shore shared several classroom experiments developed during the long-running Exploratorium Teachers Institute, a forum for teachers to develop their own strategies for effective communication, often under the guidance of veteran teachers who went through the programs themselves.

Short on time, Dr. Shore unfortunately had to skip some of the recent initiatives she has spearheaded for practicing astronomers to better their own science communication abilities. But, they are many, and include the AAS-ASP Ambassadors Program and On-The-Spot Feedback Program.

We thank Dr. Shore for her informative and enjoyable presentation, and congratulate her on the well-deserved 2023 AAS Education Award!

[Slide by Linda Shore]

Live tweets of this session by Ben Cassese.

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an enormous field of galaxies as seen in the infrared by JWST

Editor’s Note: This week we’re at the 242nd AAS meeting in Albuquerque, NM, 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 on Twitter for live coverage. The usual posting schedule for AAS Nova will resume on June 12th.

Table of Contents:

Fred Kavli Plenary Lecture: Dan Scolnic (Duke University) (by Lucas Brown)

AAS started off tense this year — that is, it started with a presentation about two measurements that are in tension with each other. Professor Dan Scolnic of Duke University took the stage to give this meeting’s Fred Kavli Plenary Lecture, which focused on his work measuring the expansion of the universe with Type Ia supernovae. Over the past ten years, these sorts of “direct” measurements of the expansion rate (denoted “H0”) have honed in on a value around 73 km/s/Mpc while precise measurements of the cosmic microwave background (CMB) combined with the standard model of cosmology have suggested a value around 67.5 km/s/Mpc. What gives?

The first portion of Prof. Scolnic’s talk helped bring us up to speed on the history of the Hubble constant and the idea of the expanding universe itself. More than 100 years ago, Einstein completed his general theory of relativity, and he set out to apply his new theory to the universe as a whole to understand its cosmological implications. Quickly, he found that in order to have a static, eternal universe, a constant term had to be added to his field equations — the “cosmological constant.” Einstein insisted for much of his life that any non-static models of the universe derived from his theory had to be wrong in some way, Prof. Scolnic noted, but the idea of a dynamic universe was eventually vindicated through observations. Those observations, carried out initially by Harvard astronomer Henrietta Leavitt and then expanded upon by Edwin Hubble, involved measuring the distances to far away galaxies using Cepheid variable stars, whose intrinsic brightness can be deduced from their period of brightening and dimming. By tracking the relation between the distance to a galaxy and the velocity at which it recedes from us, Hubble and his successors demonstrated the expansion of the universe.

This plot demonstrates the distance ladder technique used by cosmologists to measure the scale of the universe as well as cosmological parameters like the rate at which the universe is expanding. Local measurements using stellar parallax are used to calibrate distance estimates for Cepheid variable stars, which are then used to calibrate distance estimates for Type Ia supernovae. Click to enlarge. [Reiss et. al. 2021]

Type Ia supernovae, like Cepheid variables, have an intrinsic brightness that can be tightly constrained. This, combined with their extreme luminosities, makes them ideal for measuring the expansion of the universe on even larger distance scales. Precise measurements of this expansion using supernovae revealed that the universe is not only expanding but accelerating, which encouraged the re-introduction of Einstein’s cosmological constant into cosmology. Today, measuring the expansion rate of the universe H0, as well as the value of the acceleration, are major aspects of observational cosmology. Prof. Scolnic works in large collaborations like Pantheon+ and SH0ES to measure these values using Type Ia supernovae and other objects with well-constrained intrinsic brightness, known as “standard candles.” The process of combining distance measurements from different types of standard candles to estimate farther and farther distance scales is known as the “distance ladder” method. In contrast, one can also infer H0 from measurements of the CMB. Prof. Scolnic likened this approach to looking at a human growth chart: the CMB acts as a “baby picture” of our universe, and when we combine this picture with a cosmological model we can generate an expected growth-chart to predict the properties of the universe today. However, in recent years it has become clear that CMB measurements are predicting a lower value of H0 today than is actually measured using the distance ladder technique.

This discrepancy, known as the “Hubble tension,” has led to large amount of criticism being levied at the work of Prof. Scolnic and his collaborators, as some believe the tension is most easily explained as being the result of systematic errors in their analysis. However, Prof. Scolnic and his teams have worked diligently over the past several years to address these concerns. In his presentation, Prof. Scolnic demonstrated how even tweaking over a dozen aspects of their analysis couldn’t get H0 below about 72.5 km/s/Mpc, still far from the 67.5 km/s/Mpc derived from CMB measurements. Removing entire “rungs” on the cosmic distance ladder also fails to resolve the tension. Prof. Scolnic believes that their measurements are indeed correct, and that part of why other physicists are so apprehensive about the analysis is that there isn’t anything immediately obvious on the theoretical side that can fix the tension. In many theoretical explanations, a radical change in the dynamics of the universe must occur at either very early or very recent times. Prof. Scolnic largely dismisses the latter conclusion, highlighting a paper that speculates on the possibility that a rapid change in the gravitational force ~100 million years ago may have occurred, coinciding with the extinction of the dinosaurs. The bizarre connection here is meant to demonstrate how sparse the evidence is for these recent-universe changes. On the other hand, Prof. Scolnic thinks some theories which modify early-universe dynamics may be promising, such as “early dark energy.” Regardless of what exactly turns out to resolve the Hubble tension, there is clearly a lot left to learn about the history of our universe.

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Press Conference: Discoveries in Distant Galaxies (by Sumeet Kulkarni)

The press office at AAS 242 decided to begin their press conference schedule from a long, long time ago and in galaxies far away, with subsequent press conferences bringing us gradually closer to home by Wednesday. This first one, though, was all about discoveries in distant galaxies using new-age probes that extend humanity’s sense-making capabilities almost beyond comprehension — through gravitational wave detectors such as LIGO and Virgo and telescopes like JWST.

Artist’s impression of a cocoon debris emitted from supernovae that could generate gravitational waves [Ore Gottlieb/CIERA/Northwestern University]

First up, representing the “audible” sector of astronomy — listening to the “sounds” of spacetime via gravitational waves — was Ore Gottlieb from Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics. While detectors such as LIGO and Virgo now regularly catch the chirps from merging binary neutron stars and black holes, there are other, yet undiscovered sources of gravitational waves that researchers hope to uncover in their fourth observing run (O4). One of these is catching the combined cacophony of gravitational wave sources, also known as the “stochastic gravitational wave background,” as opposed to hearing individual events. While compact binaries also contribute to this background, Gottlieb focussed on two additional possibilities that can set spacetime in motion: Supernovae and the progenitors of gamma ray bursts (GRBs). The latter can create extended “cocoon” structures powered by jets in 20-40-solar-mass stars, and these promise to be the most likely stochastic background candidate. However, Gottlieb noted that there is only about 1% chance of detecting cocoon signatures in O4, and realistically, we will need third-generation observatories. [Press release]

Next up was a trio of presenters unveiling new results from the JWST-JADES project. JADES, short for the JWST Advanced Deep Extragalactic Survey, is a massive hunt for galaxies especially from the early universe (when it was only around 600 million years old). In late 2022, the team broke the record for the earliest discovered galaxy, and they expect to keep breaking milestones as new data rolls in.

The first speaker, Marcia Rieke from Arizona State University introduced the JADES project and its latest data release. This was followed by Kevin Hainline from the Steward Observatory who gave an outline of exactly how early of an universe their team is probing. JADES’ dataset of galaxies from less than 600 million years since the Big Bang now numbers at 717, up from only a dozen or so before JWST! “It’s exciting that we can even talk about these (early) times,” Hainline said. More than 93% of these galaxies, which formed the early hydrogen and helium crucial for the evolution of our universe, were never seen before JWST. But now, not only can we detect these infant galaxies, but we can also see complex structures in them, including one dumbbell-shaped early galaxy which is Hainline’s favorite. [Press release]

Ryan Endsley from UT Austin gave the next JWST update about dwarf galaxies. He said that ultraviolet emission lines from the recombination of hydrogen ions are valuable probes of star formation in early galaxies. In particular, they are great probes to study dwarf galaxies, given JWST’s ability to detect emission lines from galaxies that are 50 times fainter than what was possible before. It is now also possible to compare whether bright and faint galaxies from the early universe developed differently. And indeed, the JADES team found that the brightest galaxies underwent more star-formation bursts — events wherein matter equivalent to several tens of Suns formed at once. [Press release]

JWST image of the Einstein ring of a lensed galaxy 12 billion light-years away (in red) surrounding a foreground galaxy (in blue) 3 billion light-years away. Click to enlarge. [Slide by Jane Rigby]

The next presentation emitted smoke, not quite from fireworks, but from a new discovery that definitely warrants setting some off — that of complex organic molecules in early galaxies. Jane Rigby presented these results from the TEMPLATES project, which uses JWST observations of four distinct galaxies. She made sure to spotlight two researchers to be credited with this discovery: Justin Spilker from Texas A&M University and Kedar Phadke from the University of Illinois. Through observing a galaxy 12 billion light-years away that got bent, warped and magnified by a closer clump of galaxies 3 billion light-years away in what is known as gravitational lensing, the team could make out signatures of organic molecules that lead to smoke or smog-like structures in their images. [Press release]

The final press briefing of this morning was given by Patrick Kamieneski from Arizona State University, who talked about a dusty and warped Milky Way-like galaxy nicknamed “El Anzuelo.” Spanish for a fish-hook, this term aptly describes the shape of this galaxy which is 11 billion light-years away. While similar in size and a dustier version of our own galaxy, El Anzuelo forms stars at more than 80 times faster than the Milky Way. JWST’s incredible infrared detection capabilities have made it possible to dramatically improve the way in which we can study such objects, as emphasized by the image below.

Animated gif comparing Hubble and JWST images of El Anzuelo galaxy. [Patrick Kamieneski]

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Oral Session: Daytime & Dark Sky Heritage in American Southwestern Archaeoastronomy (by Emma Clarke)

Example of a gnomon — a vertical construction that casts a shadow. Pebbles mark the shadow’s trajectory over time as the Sun makes its daily path across the sky. [From slide by Tony Hull]

Tony Hull from the University of New Mexico started this session by discussing a simple and accurate method to define cardinal directions. In an experiment in Chaco Canyon, New Mexico, researchers used a portable light stand constituting a gnomon and pebbles to track the trajectory of the gnomon shadow. They showed that on the equinox, the tip of the shadow follows a straight line, oriented accurately east–west. They concluded that the equinox gnomon is sufficient to establish the cardinality of the Great House Pueblo Bonito in Chaco Canyon. However, this is not ethnographic evidence that the method was used, rather that it could have been used.

Next up, Cherilynn Morrow discussed the outreach program associated with NASA’s PUNCH mission: four “suitcase-sized” spacecraft focused on the inner heliosphere between the Sun and Earth that is scheduled to launch in 2025. The PUNCH outreach program focuses on the sun as a natural extension of the human understanding of the sun and its rhythms. The program shares the interconnections between historical sun watching, such as interpreting the “eclipse” petroglyph site at Chaco Canyon, and modern Sun-watching, both by NASA missions and all contemporary people observing sunrise, sunset, light and shadow cast by the Sun, and eclipses.

The “eclipse” petroglyph in Chaco carved by the Ancestral Puebloan people may have been inspired by the total solar eclipse in 1097. [From slide by Cherilynn Morrow]

The third speaker, J. McKim Malville, discussed the astronomy connected with the Great Houses in Chaco Canyon and what it meant for the inhabitants, residents, and visitors during astronomical events. One unanswered question is why the 15 Great Houses were built in such a resource-poor location and not totally abandoned when leaders moved northward. Perhaps the canyon and buildings were sacred places with astronomical significance.

Closing the session, Michael Rymer spoke briefly about archaeoastronomy and international dark sky places. The International Dark-Sky Association’s International Dark Sky Places Program encourages areas around the world to preserve dark sites through policies and public education. Two dark sky places in the US — Chaco Culture and National Historic Park in New Mexico, and Hovenweep, on the border of Utah and Colorado — are also archaeoastronomical sites. Protection of the dark night sky at these places not only makes better stargazing, but is also important for preservation of wildlife and plants. There is a growing list of potential future sites of dark-sky parks in the US.

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Plenary Lecture: Edwin “Ted” Bergin (University of Michigan, Ann Arbor) (by Junellie Gonzalez Quiles)

Murthy Gudipati from the Jet Propulsion Laboratory (JPL) introduced the Laboratory Astrophysics Division and invited everyone to become familiar with the division and join as members. He then introduced the plenary speaker, Prof. Edwin “Ted” Burgin from the University of Michigan, Ann Arbor. His talk titled “The Birth of Planets and the Story of Carbon” started with his recognition of laboratory astrophysicists and their role in helping understand the fundamentals needed to study astrophysical phenomena. Ted then transitioned to mentioning how the search for life has driven the connection between chemistry in protoplanetary disks to the atmospheric composition of exoplanets. This link is essential if we want to fully understand how planetary systems are formed and, therefore, how individual exoplanets are formed.

Shown here is the bulk carbon to silicon ratios for the Earth and solar system bodies. Click to enlarge. [Slide by Ted Bergin, from Bergin et al. 2015]

Throughout his talk, he took us on a journey where he explained what protoplanetary disks look like, how there are dark gaps or rings, which can mean that planets may be forming in that region, and explained to us one of the ways you can create exoplanets: pebble accretion. Through planet formation, exoplanets can have different bulk compositions depending on where they form and whether they are mainly made of refractory, semi-volatile, or volatile elements. Öberg et al. 2011 shows the relationship between the carbon to oxygen ratio (℅ ratio) and the snowlines in a planetary system, and Ted mentioned that in systems that have a ℅ ratio higher than 1, we know that oxygen must be present as ice on grains. Knowing the carbon to oxygen ratio is important to understand in the context of planet formation.

Here you can see the TW Hya system and their C2H detection from the Bergin et al. 2016 paper. Click to enlarge.

During his plenary, he also spoke about isotopic fractionation and how it offers a new window into planet formation. He showed the TW Hya system, where they looked at the ratio of 12C to 13C. This can be done for other planetary systems to say whether the system could be carbon rich (see Figure 1). He then ended his talk by talking about our own planet. Earth is relatively carbon poor compared to our Sun, Venus, and other types of chondrites (see Figure 2). Earth was formed of mainly refractory materials with small amounts of soot and water, and he aims to understand soot in the context of exoplanets. He also studied the geological processes that could lead to outgassing on exoplanets and how the carbon inventory can lead to methane in their atmospheres and potentially hazes as well.

He is very interested in how all of these aspects of planetary formation and evolution could impact the habitability of exoplanets, and it is certainly something to look out for in our search for life in other worlds!

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Press Conference: Solar Swirls, Satellites, and Saving the Night Sky (by Lucas Brown)

The second press conference of the day switched gears from the distant reaches of the universe to our local corner of space, with presentations on a new solar weather phenomenon, the positives and negatives of artificial satellites for astronomy, and updates on efforts to preserve the night sky.

First up was Oana Vesa from New Mexico State University, who spoke on new research into solar tornadoes. That’s right — there are tornadoes on the Sun. Only discovered in 2008, there is little known about the formation mechanisms behind these tornadoes or their overall role in the solar environment. Vesa explained that these tornadoes, consisting of hot, swirling plasma, are bound to the surface of the Sun magnetically, and can channel mass and energy up through different levels of the solar atmosphere. And like most things on the sun, their scale is massive. These chaotic solar vortexes vary from the size of a city all the way up to the size of Earth. Through new observations performed at the Dunn Solar Telescope, Vesa’s team has tracked dozens of these events, and they have begun the process of cataloging and analyzing their behaviors. So far, the team has found the tornadoes to have an average lifespan of about 8 minutes, and some have been seen to form in pairs or exhibit chaotic spiraling patterns. There’s a lot left to learn about these fiery storms. [Press release]

An image of the main science component of ORCASat, containing a laser module, photodiodes, and an integrating sphere, also known as a Lambertian sphere. ORCASat is designed to help calibrate ground-based telescopes. Click to enlarge. [From ORCASat/University of Victoria Centre for Aerospace Research]

Next up was Justin Albert from the University of Victoria, who gave an overview of ORCASat, a recent cubesat mission that intends to demonstrate the utility of specialized satellites for calibrating ground-based telescopes. ORCASat contains a specialized cavity known as a Lambertian sphere, which evenly disperses incoming laser light before some of that light reflects down towards Earth. This system allows for on-board photodiodes to very accurately measure the intensity of light which will be beamed through the atmosphere. In turn, ground-based equipment can observe the satellite in orbit and determine how much light was lost as it passed through the atmosphere, providing a very sensitive method of calibration. The satellite has been in orbit since November of last year, and in the ensuing months, one complete exposure (in good lighting conditions) has been taken of the satellite streaking across the sky, providing a first proof-of-concept of the method. NASA and NIST are expected to develop a more advanced satellite for this purpose in the future, which will hopefully help increase the accuracy of measurements taken by ground-based telescopes. [Press release]

Plots showing how the Median Radon Transform algorithm can identify satellite trails in imagery from the Hubble Space Telescope (HST). The top plot is a HST image containing a satellite trail, while the bottom right image is produced by applying a Median Radon Transform. The satellite trail now appears more similar to a point source. [Figure 3 in Stark et. al. 2022]

While satellites like ORCASat may help increase the accuracy of ground-based astronomy through its intentional emission of light, most satellites in orbit are actually detrimental to ground-based astronomy due to their reflection of light, occasionally creating bright streaks in astronomical imagery. For this reason, astronomers around the world have been working on developing algorithms to automatically detect such streaks and remove them or toss out the affected imagery. David Stark from the Space Telescope Science Institute (STScI) spoke on this in his talk, highlighting the development of a new algorithm which greatly increases the accuracy of satellite-trail detection. The algorithm employs a method known as a “Median Radon Transform,” which essentially looks for the median pixel brightness in every possible straight line one could trace within an image. A large outlier in a given line’s median value is a strong sign that that line contained an abnormal amount of light, often due to a satellite trail. This method significantly improved satellite-trail detection over previous methods developed at STScI. In testing the method on Hubble Space Telescope (HST) data, Stark and his team found that the number of satellite trails in HST imagery had roughly doubled over its lifetime, but noted that the rate was still so small that it did not hinder HST’s ability to do science. [Press release]

Closing out today’s second press conference, James Lowenthal from Smith College spoke about efforts to protect the night sky from light pollution. He noted that terrestrial light pollution from cities is in many ways a more significant threat to astronomy than satellite trails, and has many other negative effects such as harming plants and animals which are all used to a particular day-night cycle that has been disrupted in recent years. He also highlighted the spiritual significance of the night sky to many native communities. Lowenthal noted that dark sky advocacy groups have grown in recent years thanks in part to renewed interest due to the growth of satellite mega-constellations like SpaceX’s Starlink. Through the efforts of dark sky groups and their partnerships with native communities, local governments, and industry, some strides have been made towards preserving the night sky, such as creating new lighting standards centered around preserving the night sky while still illuminating cities. However, much more work has to be done given that recent research has shown that light pollution is increasing at much higher rates than previously thought due in part to the proliferation of LEDs. One of the success stories Lowenthal highlighted in his talk was the protections enacted in Coconino County, Arizona, home to numerous historic observatories. Another recent example given was the enacting of official dark sky protections in central Maine, one of the last remaining dark sky sites east of the Mississippi River. [Press release]

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Plenary Lecture: Greg Taylor (University of New Mexico) (by Ben Cassese)

Greg Taylor of the University of New Mexico delivered the third plenary of the day. Over the course of 45 minutes, Prof. Taylor took the denizens of Ballroom C and the Zoomiverse on a whirlwind tour of science conducted with the Long Wavelength Array (LWA) over the past decade. This instrument, a collection of 256 individual antennae spread throughout a 100-meter ellipse, has touched an impressive number of subfields in that time: From pulsars to the solar wind, the LWA has seen (and measured) it all.

A schematic of how the LWA detects an incoming meteor. [Prof. Greg Taylor, University of New Mexico]

After joking that his talk would last 6 hours and cover each of the roughly 80 papers built on LWA data, Taylor settled for summaries of some of the highlights. Many of these centered on the detection and characterization of meteors as they streak through the atmosphere and leave a wake of radio-bright ionized material trailing behind. There was a satisfying arc to this line of research: When Taylor and collaborators first saw these brief signals, they did not know what to make of them. They could think of no astronomical source for these transients scattered evenly throughout the sky, and only with careful analysis and cross-checking with other techniques did they realize that they had built a uniquely capable meteor detector. The team has since made the study of disintegrating meteors and their fireballs a major research focus.

Taylor also shared an overview of observations designed to test models of the solar wind. Here, the LWA stared at a pulsar (during the day! Radio astronomy is great like that) and measured how its signal changed as the Sun edged closer and closer to their line of sight. This let the team probe different regions of interplanetary space and constrain the ionized material that hovers within the solar system and slightly distorts radio signals.

Plans for the “swarm” of detectors to complement/supplement the LWA. Click to enlarge. [Prof. Greg Taylor, University of New Mexico]

After including very brief overviews of a few other projects, Taylor pivoted to the future of the LWA. The team has already constructed a second, similar array far from the original, which they can connect to form a longer baseline and better angular resolution. In the coming years, they hope to repeat this improvement in the extreme and build a “swarm” of small arrays dispersed across the United States. Some of these sites are purely aspirational, but some already have committed funding; in all, it looks like the next decade will be even more productive than the last.

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Plenary Lecture: Jeyhan Kartaltepe (Rochester Institute of Technology) (by Sumeet Kulkarni)

“Far and wide eyes of the JWST” was the theme of the final plenary session at AAS 242 on Monday. Prof. Jeyhan Kartaltepe from the Rochester Institute of Technology talked about results from two wide-ranging projects from the first JWST observing cycle and how they are constantly molding our knowledge of cosmic history.

Kartaltepe began with a brief overview of JWST’s capabilities and how its infrared eyes unlock the deepest reaches of the universe by detecting light that has been redshifted to those wavelengths due to cosmic expansion. JWST was always going to be pathbreaking, and all astronomers knew it. When asked how many in the plenary woke up early (in US time zones) to watch it launch on Christmas day in 2021, 90% of the hall raised its hands.

The reach of different deep field images towards the early universe in terms of redshift. [Prof. Guinevere Kauffmann, MPA Garching]

The first project Kartaltepe’s plenary featured was CEERS, which observes a 100 square arcminute patch of the sky to demonstrate, test, and validate efficient extragalactic surveys. An early science result from CEERS was the discovery of a faraway galaxy, now known as Maisie’s galaxy after the daughter of one of the project PIs. Maisie’s galaxy looks like a red blob among a sea of usual-looking galaxies, as is typical for such early galaxies. But the interesting thing was that it wasn’t a standalone galaxy in CEERS data! There were several more candidates found in JWST images, challenging our understanding of how quickly galaxies started to form and mature in our universe.

But among the exciting early galaxy candidates also hide several mimickers: nearby, dusty galaxies also have the same red, blobby appearance which can be mistaken to be one due to high redshift by photometry (studying properties of the images) alone. But JWST does much more than just click pictures of these galaxies. It can also study their character using a spectroscope, or a prism that splits light to unveil the telltale signatures of molecules within it. The spectroscopic data from JWST of Maisie’s galaxy was so clean, that it “looked just like that of a nearby galaxy,” said Kartaltepe. This helped them confirm its age of being only around 390 million years after the Big Bang! Spectroscopy also helps confirm (or reevaluate) the age of early galaxy candidates. Kartaltepe gave an example of a galaxy first believed to have a redshift of 16 (placing it among the earliest ever detected galaxies), which was then reduced to 4.9 thanks to the JWST’s NIRSpec data.

The scale of COSMOS-Web observations [Jeyhan Kartaltepe]

The second project that Kartaltepe is excited about is Cosmos-Web. This project covers a relatively big patch of the sky, just larger than the full Moon, but goes deep into it with JWST’s far-reaching eye to record all galaxies near and far that lie within. This patch of the sky was chosen because part of it has been extensively studied by the Hubble space telescope, allowing for extracting science out of the two sets of observations in tandem. As of today, Cosmos-Web has completed about half of its observations and is already finding large numbers of high-redshift galaxy candidates, dusty star-forming galaxies, and more!

Kartaltepe concluded her plenary by stressing the importance of mentorship in furthering our field and supporting the progress of students and early career researchers. “I wouldn’t be here if not for excellent mentors,” she said, and urged all students today to pick an advisor who prioritizes seeing them as a person first.

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photograph of a booth with astrobites posters, stickers, and pins

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

AAS Nova Editors Kerry Hensley and Susanna Kohler and AAS Media Fellow Ben Cassese will join Astrobites Media Intern Sumeet Kulkarni and Astrobiters Lucas Brown, Emma Clarke, Wei Vivyan Yan, and Junellie Gonzalez Quiles to live-blog the meeting for all those who aren’t attending or can’t make all the sessions they’d like. We plan to cover all of the plenaries and press conferences, so follow along here on aasnova.org or on astrobites.org! You can also follow @astrobites on Twitter for the latest updates.

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! In addition, you can catch Kerry, Ben, and Sumeet at the press conferences all week, and Sumeet will be presenting an iPoster on Astrobites as an educational resource at 5:30–6:30 pm MT on Tuesday, 6 June.

You can read the currently published AAS 242 keynote speaker interviews here. Be sure to check back all week as the remainder are released!

banner announcing the 242nd AAS meeting

AAS 242 is nearly here! The AAS Publishing team looks forward to connecting with meeting attendees in Albuquerque, NM, and online, and we’re excited to share a preview of upcoming publishing-related events. Also, be sure to stop by the AAS booth in the Exhibit Hall, which will be staffed by several members of the publishing team, including Julie Steffen (AAS Chief Publishing Officer), Ethan Vishniac (AAS Journals Editor in Chief), Frank Timmes (AAS Journals Associate Editor in Chief), and Gus Muench (AAS Journals Data Editor). We’re also happy to announce that the newest member of the Publishing team, Journals Data Editor Katie Merrell, will be attending the meeting — be sure to stop by and say hello!

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

AAS Peer Review Workshop

Sunday, June 4, 8:00 am – 12:00 pm MT

Building on the successes of the first peer review workshop, which was organized by the AAS and IOP Publishing and held remotely in February 2023, the AAS is holding its first-ever in-person peer review training at AAS 242. This workshop, led by the scientific editors of the AAS journals, will teach participants about the peer review process, give them the opportunity to see both poor and exemplary referee reports, and provide them with hands-on experience in writing a peer review report. Participants will receive a graduation certificate.

While signups for this instance of the peer review workshop are closed, more workshops are planned for the future, so keep an eye out for more information about upcoming opportunities!

“The What and Why of Open Science”

Tuesday, June 6, 10:00 – 11:30 am MT | Meeting Room 220

This Meeting-in-a-Meeting will explore the benefits of open science practices, diving into the implementation and impact of creating accessible archives for data and software, making journal articles open access, and much more. Presenters will include AAS Journals Data Editor Gus Muench and program officers from NASA and the National Science Foundation.

Want to learn more about implementing open science practices? A second Meeting-in-a-Meeting taking place on Wednesday, June 7, at 10:00 am MT in Meeting Room 220 will provide opportunities for members of our community to share their experiences, successes, and challenges with open science.

Hubble image of the Butterfly Nebula

Editor’s Note: This week we’re at the 241st AAS meeting in Seattle, WA, 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 on Twitter for live coverage. The usual posting schedule for AAS Nova will resume on January 18th.

Table of Contents:

Plenary Lecture: John Mather (NASA Goddard Space Flight Center) (by Briley Lewis)

John Mather’s plenary was a celebration. He opened by thanking the 8 billion humans on Earth, 10,000 observers, 20,000 engineers, and 100 scientists worldwide for making the huge endeavor of JWST happen, and then took the audience on a whirlwind tour of JWST’s history and the highlights of its first year of discovery. From tracing dark matter to revealing the earliest galaxies, taking photos of planet-forming disks to peering into Titan’s hazy atmosphere, watching an asteroid attack to puzzling over shells around a star, it’s truly been a year of great scientific progress and a whole lot of gorgeous images, too.

Mather also looked towards the future, with shout-outs to so many exciting ongoing projects: Euclid, NGRST, the Vera Rubin Observatory/LSST, thirty-meter class telescopes (TMT, eELT, and GMT), and the Decadal-recommended Habitable Worlds Observatory (also sometimes known as LUVEx, a portmanteau of the telescopes that inspired it — LUVOIR and HabEx). He even speculated beyond that, sharing future concepts like hybrid ground-and-space-based observatories using artificial satellites as orbiting guide stars for adaptive optics systems or as stations for very-long-baseline interferometry (VLBI).

The big takeaway here is that we’ve done some incredible things as a community, and we have so much more to come. “Celebrate, and then write proposals!” he told the astronomers in the audience. “We’re just getting started.”

Live tweets of this session by Briley Lewis.

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Press Conference: Clouds and Nebulae (by Pratik Gandhi)

One of the final press conferences of the 241st AAS was focused on clouds and nebulae, and by extension supernovae and other processes that lead to the formation of clouds and nebulae.

Dr. Gerrit Verschuur and Dr. Joan Schmelz were first up, showing new results on distance measurements to the high-velocity cloud (HVC) complex M. This year marks the 60th anniversary of the discovery of this HVC in the Milky Way, and its velocity is much higher than the rotational velocity of the galaxy. Their team made the first-ever distance estimate for any HVC, and they found that there is a stream of gas between the star MI and the gas filament (which is now called Complex M). Radio data also shows that there is a large cavity associated with the complex, which appears to be the result of a supernova that exploded 4 million years ago! The team also inferred a distance of 307 parsecs and a total supernova energy output of 3.5 x 1050 erg. Finally, they concluded by mentioning that the “Local Chimney,” a low-density extension of the well-known “Local Bubble,” likely came from this progenitor supernova.

Next, Dr. Robert Fesen talked about the exceptional supernova remnant Pa 30. This remnant is really interesting because it was discovered in 2013 by amateur astronomer D. Patchick using data from the WISE mission. In recent years, different teams from Hong Kong, France, and Russia discovered a really unusual massive white dwarf star at the center of the remnant, with some astounding properties like really high-velocity winds and high luminosity. This star could be the product of the merger of two white dwarfs, resulting in a rare Type Iax supernova. The other really fascinating thing about this supernova is that it likely happened only a thousand years ago, which is really recent on galactic timescales!

Dr. Bruce Balick continued the press conference with a talk on “The tempestuous life of the Butterfly Nebula, NGC 6302.” Although his take on it was that it “doesn’t look like much of a butterfly, but rather a dragon sneezing fire all around it.” This nebula is an example of an unexpected stellar evolution result. While most planetary nebulae are symmetrical and formed gently (not from explosions), the Butterfly Nebula is asymmetric, much bigger, and a lot more chaotic. Their team compared Hubble Space Telescope images from 2009 and 2020 and found that there appear to be multiple outflows of gas and other material from the central regions, with different outflows having different directions and different ages. Dr. Balick concluded by saying that observations of the Butterfly Nebula are compatible with a rare triple-star accretion disk model, while single and binary star models are too simplistic to be applicable and do not explain all the observed features.

The final presentation was by Dr. Peter Barnes, who talked about “the case of the masquerading monster in BYF 73.” Cloud BYF 73 is a massive cloud about 8,000 light-years away, with an associated nebula. The mystery associated with it is an inflow of material towards the center, which happens to be the highest rate of mass inflow towards a protostellar object ever seen! Their team used observations from the SOFIA and ALMA observatories, and found strong polarization of magnetic fields in the nebula, and weak polarization in the protostellar core. They also found that the gas infall towards the center is faster than expected, implying a 4–6 times larger protostellar mass than thought, of about 1,000 solar masses. Thus the central protostellar object has been labeled a “masquerading monster”!

Live tweets of this session by Pratik Gandhi.

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Plenary Lecture: Sangeeta Malhotra (NASA Goddard Space Flight Center) (by Isabella Trieweiler)

Dr. Sangeeta Malhotra kicked off her plenary talk, “Tiny Mighty Galaxies,” by promising many vegetable puns and a little bit of science. Dr. Malhotra is a researcher at the NASA Goddard Space Flight Center and works on low mass galaxies. She grew up in Delhi, earned her PhD in Astrophysics from Princeton University (becoming the first woman of color to do so!), and was part of the inaugural class of American Astronomical Society fellows. She was previously a professor at Arizona State University and moved to Goddard to work on the Nancy Grace Roman Telescope (formerly WFIRST).

Dr. Malhotra’s research focuses on Lyman-alpha (Lya) galaxies. The Lyman-alpha line is a spectral line of hydrogen; Lya photons are created when electrons fall from the second energy level down to the ground state. Any star-forming galaxy can make Lya photons, so Lya galaxies are just the particular cases where Lya photons are able to escape the galaxy and be observed. Figuring out exactly what allows Lya to escape some galaxies but not others is an open question. Dr. Malhotra showed that Lya galaxies have some common characteristics — they tend to be small in size, with low metallicity and low dust content. Additionally, many Lya galaxies are young, with low stellar masses but high gas pressure and strong emission lines, hence the label “Tiny Mighty Galaxies.”

Lya galaxies are cosmologically important because they help us understand the process of reionization by providing constraints on the amount of neutral hydrogen present at a given time. Connecting the galaxies with reionization requires a really good understanding of the physics of Lya escape, and that’s where the vegetables come in! Over the course of Galaxy Zoo, a citizen science project tasked to identify and categorize galaxies, members of the public helped find a new kind of galaxy, affectionately named “Green Peas.” Green Pea galaxies are small, round, and green in color, hence the name. They have very strong emission lines, particularly ones produced by oxygen. They also happen to be a very good local universe counterpart to the high-redshift Lya galaxies used for reionization studies. Dr. Malhotra’s group uses Green Peas to test their models of Lya escape and have found that factors such as dust content and peak velocities are some of the best determinants of Lya escape.

The other component needed to connect Lya galaxies and reionization is a large sample of Lya galaxies at high redshift. Dr. Malhotra is working on this via the LAGER survey, which aims to find Lya galaxies at a redshift of 7. The survey is an international collaboration and uses a narrow band approach to identify the bright Lya lines in galaxies. Dr. Malhotra’s involvement in the Roman telescope will also be crucial to reionization research as the telescope’s extremely wide field of view will help astronomers understand how reionization occurs on scales spanning many clusters of galaxies.

slide from Sangeeta Malhotra's plenary talk

[Slide by Sangeeta Malhotra]

Finally, Dr. Malhotra closed her talk by urging senior scientists to put effort into the retention of students of marginalized identities. She presented a summary of her own previous mentees and showed that the majority of women and students of color have since left the field. She reminded students to prioritize their own mental and physical health, and to ask for help as needed, but stressed that the responsibility for the problem is absolutely on senior faculty. She called on mentors to take notice of any similar trends amongst their own students and to get to work solving this issue in astronomy.

Live tweets of this session by Isabella Trierweiler.

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Press Conference: Signals from Neutron Stars and Black Holes (by Graham Doskoch)

The final press conference of AAS241 focused on compact objects: black holes and neutron stars. Four speakers took the podium, presenting discoveries of several new types of astronomical objects — and a couple of old favorites. First up was Prof. Eric Coughlin of Syracuse University. Prof. Coughlin and collaborators studied a tidal disruption event, or TDE, called AT2018fyk. TDEs occur when a supermassive black hole tears apart a nearby star, feasting on its gas and emitting a high-energy outburst. These are usually cataclysmic events, but the group noticed that 600 days after the outburst, AT2018fyk dimmed — and then experienced another, similar outburst 600 days later.

This isn’t supposed to happen with TDEs! The group proposed a model to explain this repetition: a partially disrupted TDE. A star near the supermassive black hole was tidally disrupted, but only partially; some of its gaseous envelope was accreted, leaving a partially-stripped remnant that kept circling the black hole on a 1,200-day orbit. One orbit later, it was once again disrupted. The model predicts that there should be another event this coming August. Will it happen? We’ll have to wait and see.

The next speaker was Emily Engelthaler, of the Center for Astrophysics | Harvard & Smithsonian. She had performed ultraviolet spectroscopy of another TDE (this time not a repeater!). The emission showed a number of expected features, including carbon lines, showing the fast-moving material in the black hole’s accretion disk. What was interesting was the amount of variability, and the eventual disappearance of this carbon emission. Engelthaler proposed that the “puffy doughnut” of material is getting less “puffy,” leading to changes in the spectral absorption and emission.

Engelthaler was followed by Rose Xu, an undergraduate at Bard College. Xu presented results on X-ray flares from Sagittarius A*, the supermassive black hole at the center of the Milky Way. While Sgr A* isn’t as active as many others of its kind, it does exhibit X-ray and infrared flares on a roughly daily basis. Xu was interested in addressing an unresolved question: What’s the mechanism behind these flares? She and her collaborators searched data from the NuSTAR X-ray telescope, discovering seven new flares from 2016 to 2022, including a double-peaked flare. The ground found tentative evidence that bright flares and faint flares may have spectral differences, a hint that they could be caused by different processes.

The final speaker, Dr. Amruta Jaodand of Caltech, presented new results on an unusual pulsar, J1023+0038. Pulsars are the dense, rapidly rotating remains of massive stars, and they emit beams of electromagnetic waves, which sweep across our line of sight, like a lighthouse. This appears as periodic emission, usually at radio wavelengths but occasionally in X-rays and the optical. A subclass of pulsars, millisecond pulsars, spin several hundreds of times per second, after accreting material — and angular momentum — from a companion.

J1023+0038 is a type of millisecond pulsar called a transitional millisecond pulsar. It’s in the process of this accretion, and switches between different modes, one involving X-ray emission and one involving radio emission. Jaodand found that the pulsar also emits ultraviolet pulses; while it’s not the first known UV pulsar, it is the first known UV millisecond pulsar. Coupled with its strange X-ray and radio behavior, this may give insight into pulsar emission mechanisms.

Live tweets of this session by Graham Doskoch.

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Plenary Lecture: Dan Foreman-Mackey (Flatiron Institute) (by Mark Popinchalk)

When Dr. Dan Foreman-Mackey showed a functioning code block on one of his first slides, he whimsically remarked “I don’t think any other plenary has put Python code in their talk,” which was met with a round of laughter. And it’s probably because no other plenary was trying to do what Foreman-Mackey did — spend 40 minutes presenting the motivations, grand ideas, and power of the open source software he’s worked on in his career.

The scientific example that was used was using Gaussian processes to fit a Kepler light curve showing a transiting planet. But that quickly became a background feature to the three Gaussian-process libraries that Foreman-Mackey had created at different stages in his career; george, celerite, and tinygp.

With his natural charm he carefully laid out the major improvements that each of the three packages incorporated into the computation of Gaussian processes. george made a step away from rote implementation, instead offering a library of kernels (tools used to construct the Gaussian-process model). celerite (“Imagine there are accents if you want to pronounce it properly [i.e., celerité]”) used linear algebra to speed up the Gaussian-process calculation, and tinygp used JAX at its core to speed it up even further.

But it wasn’t the technical achievements that were the most impressive. It was the intention behind the packages that truly shined the brightest throughout the plenary. Foreman-Mackey is a champion of open-source software, where the codebase is public, documented, and easily accessible. Some might cringe at the thought of all their work laid bare for anyone to scrutinize. However, it was clear that Foreman-Mackey thought this was a strength. That a code was made for others meant that it needed to be flexible, that public eyes would find the room for improvements and innovations, that there is a strength in trusting the community of your peers.

This wasn’t a plenary on a topic so much as it was a plenary on a way of working. Littered with little jokes, personal anecdotes, and even more lines of code, the talk wasn’t about empowering the audience with knowledge, but encouraging them to try new code and ultimately experience the ecosystem of open-source coding of which Foreman-Mackey is a clear and vocal champion.

Full slide deck: https://speakerdeck.com/dfm/open-software-for-astrophysics-aas241
Live tweets of this session by Mark Popinchalk.

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Berkeley Prize Lecture: Anthony Brown (Leiden University) (by Ali Crisp)

Dr. Anthony Brown gave his plenary on the Gaia mission, for which he and his team were being awarded the AAS Berkeley Prize. He began with an overview of the mission, including a joking remark thanking the JWST team for putting their telescope at L2 (where Gaia is also located) so he doesn’t have to explain what that means in his talks anymore. He emphasized the teamwork aspect of the Gaia mission, listing all the different teams in the Gaia Data Processing and Analysis Consortium (Gaia DPAC) and their contributions to the project.

A group picture of the Gaia collaboration

A group picture of the Gaia collaboration. [Slide by Anthony Brown]

Dr. Brown then gave an overview of the data Gaia has collected so far and all the different astrophysical parameters it gathers. To date, Gaia has measured fundamental parameters such as stellar radii and temperature for over 471 million stars. Of those 471 million stars, there are also 2.5 million stars with detailed chemical abundance measurements, 1 million stars with high-resolution spectra, and 219 million star with low-resolution spectra. 800,000 binary systems have also been cataloged in the mission!

Dr. Brown continued by highlighting Gaia science contributions, starting with providing astrometric measurements of Arrokoth to the New Horizons team, so they could make accurate orbital calculations for the spacecraft’s approach. Gaia data were also used to calculate the precise luminosity functions required to confirm that carbon–oxygen white dwarfs undergo crystallization in their interiors. Gaia’s precise astrometry has also been used to confirm the existence of a black hole, to make 3D maps of nebulae such as Orion, and to build clearer pictures of how different elements are distributed in the Milky Way, which in turn give us a better idea of the galaxy’s formation history.

Dr. Brown ended his talk by listing what new data products will be included in the fourth and fifth Gaia data releases, including updated astrometry, time-series data, and much, much more. He kindly requests that — should you use Gaia data for your research — you give the team credit for their hard work. Specific information on how to acknowledge Gaia can be found here.

Live tweets of this session by Ali Crisp.

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artist's impression of a rocky exoplanet

Editor’s Note: This week we’re at the 241st AAS meeting in Seattle, WA, 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 on Twitter for live coverage. The usual posting schedule for AAS Nova will resume on January 18th.

Table of Contents:

Royal Astronomical Society Gold Medal Lecture: George Efstathiou (University of Cambridge) (by Yoni Brande)

Professor George Efstathiou is the 2022 Royal Astronomical Society Gold Medal awardee, and as part of this honor, he was invited to give one of the plenary talks here at the winter AAS meeting. Prof. Efstathiou is Professor of Astronomy at the Institute of Astronomy at Cambridge, and he was director of the Institute from 2004 to 2008. His research focuses on cosmology, ranging from simulations of large scale cosmic structure formation to anisotropies in the cosmic microwave background.

Prof. Efstathiou structured his talk around paradigm shifts in cosmology. Fifty-seven years ago, in 1965, Penzias and Wilson discovered the cosmic microwave background (CMB), providing the strongest evidence for the Big Bang theory of the origin of the universe. When Prof. Efstathiou started his PhD a decade later, he worked on early computational models of cosmological structure formation, taking weeks to run on room-sized computers. For comparison, he re-ran some of those models on his laptop, but they only took 30 seconds!

Soon after, inflationary theory was the next paradigm shift in cosmology, which preserved causality in the early universe, linking now-unrelated areas of space with each other just after the universe’s formation. However, while inflation explained the current scale of the fluctuations in the CMB, their origin was still unclear, leading to the development of the modern theory for the quantum generation of those fluctuations, giving modelers initial conditions to tweak for their simulations!

Working from the cold dark matter (CDM) model, Prof. Efstathiou and his group produced a suite of simulations of current-day large scale structure and then conducted a big photometric survey to test their assumptions. They found even more structure in the current universe than they’d predicted, which could only be resolved by a positive cosmological constant, the simplest explanation for dark energy (the Lambda-CDM model).

These theoretical models were quickly tested with even more sophisticated observations, with COBE, WMAP, and Planck measuring the CMB at incredible resolutions, showing spatial invariance and causal connection across the entire sky, with the amplitudes of the fluctuations lending even more support for LCDM and closely matching theoretical predictions.

So, do we actually have a standard model of cosmology? Yes, with some caveats: we don’t really understand inflation, we don’t have a dark matter particle, and we don’t understand dark energy. This raises an uncomfortable question: Is LCDM just a fitting function? Prof. Efstathiou is a bit more optimistic. Each point in the model has lots of indirect observational evidence, so there should be some truth in the model even if we don’t deeply understand the individual ingredients.

A lot of the observational problems need to be resolved. It’s been 25 years since dark energy, the last paradigm shift in cosmology, and who knows where the next one will come from. It’s unlikely that a theorist will come up with something groundbreaking out of nowhere. The Hubble tension still needs to be resolved, and it might be impossible to detect primordial gravitational waves from the CMB. Prof. Efstathiou’s best bet is that the next paradigm shift will be the detection of dark matter. Hopefully, in another 57 years, the RAS Gold Medal winner will step onto the stage at the AAS meeting and give a similar talk, all about how we used to not understand inflation!

Live tweets of this session by Yoni Brande.

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Press Conference: Building Systems in Our Local Universe (by Briley Lewis)

This morning’s press conference tackled the building blocks of our universe, from star-forming regions to planet-forming debris disks — including multiple new exciting results from JWST.

JWST images of the AU Microscopii debris disk

JWST images of the AU Microscopii debris disk. [Kellen Lawson]

Kellen Lawson (NASA Goddard Space Flight Center) presented JWST NIRCam observations of the debris disk AU Mic, a well-studied edge on disk with a few planets known from transits. The new JWST images reveal the disk in never-before-seen wavelengths, which are still undergoing analysis. The team didn’t spot any planets, but their sensitivity curves revealed that JWST is now sensitive to solar-system-mass planets at solar system scales, which is exciting!

Jacob Lustig-Yaeger and Erin May (Johns Hopkins University Applied Physics Laboratory) presented new observations of transiting rocky exoplanet LHS 475b, JWST’s first exoplanet discovery and a previously unconfirmed TESS Object of Interest (TOI). This planet is very similar in size to Earth, but much warmer — and with transmission spectroscopy, they peered into its atmosphere. Its spectrum is remarkably flat, consistent with either a fully carbon dioxide atmosphere or even no atmosphere at all. More observations are needed to figure it out!

Margaret Meixner (Universities Space Research Association) revealed a gorgeous new image of star-forming region NGC 346. NGC 346 is the brightest most massive star forming region in the Large Magellanic Cloud, and her team searched for young stellar objects (YSOs) embedded within it. They found so many that the YSO count has grown by a factor of three!

Ümit Kavak (Universities Space Research Association) continued on the theme of star formation, showing data from the airborne observatory SOFIA that reveal huge outflows from the Trapezium stars within the Orion Nebula moving over 60,000 miles per hour. And last but not least, Theo O’Neill (University of Virginia) displayed a new map of the local bubble’s magnetic field. The local bubble was created a long time ago from supernovae (not from the Sun!), and the Sun just happens to be in the middle of it. This map is going to be a useful new tool for astronomers exploring how magnetic fields affect star formation.

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Dannie Heineman Prize Lecture: Norman Murray (CITA) (by Graham Doskoch)

Here’s a simple question: Why does one day on Earth last 24 hours? That was the focus of the plenary lecture by Prof. Norman Murray, winner of the Dannie Heineman Prize. It might seem easy to answer, but half a century of work has shown it to be anything but. The solution requires an understanding of tidal forces, atmospheric modeling, and a willingness to think about clams.

Prof. Murray took us to the Pacific Northwest. Clams there grow their shells at different rates depending on nutrient and sediment deposition in the shallows of the ocean; if a clam is eating, it’s growing. This in turn is connected to the height of the tides. By looking at the size of bands in a clam’s shell, you can learn about how the tides have varied over time — which in turn tells you about the orbit of the Moon, since it’s one of the two celestial bodies that cause gravitational tides on Earth.

Clams haven’t lived on Earth since the dawn of time, so if you want to go back further, you need to check the geologic record. By probing the composition of strata, you can grab information about the history of Earth’s climate, from which you can in turn extract data showing the precession of Earth and the Moon. More analysis then lets you model the change in the Moon’s semimajor axis.

If that wasn’t complicated enough, Prof. Murray pointed out that there’s another force affecting Earth’s angular momentum: thermal tides. As the Sun heats Earth’s atmosphere, more complex interactions cause changes in pressure, giving rise to a tidal perturbation. In short, gravitational tides from the Moon extract angular momentum from Earth; thermal tides, on the other hand, add angular momentum.

Some fluid dynamics modeling shows how waves can propagate in the atmosphere, driven by these effects. Prof. Murray showed that they’re subject to a particular resonance determined in part by the speed of sound in the atmosphere. This resonance, coupled with thermal and gravitational tides, eventually drove Earth’s angular momentum to its current point, corresponding to a day of roughly 24 hours. The balance has lasted about 1 billion years, give or take.

There are other interesting facts you can derive from modeling; for example, there’s a temperature dependence on all of this. Plus, by simulating the angular momentum transfers, you can model evolution of the Moon’s orbit — in particular, the change in the Moon’s semimajor axis over time. It’s model-dependent, but the results Prof. Murray presents match experimental data points, to varying degrees of success.

plot of the lunar orbital semimajor axis over time

The lunar orbital semimajor axis as a function of time. [Slide by Norman Murray]

Live tweets of this session by Graham Doskoch.

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STEM Mentorship and Underrepresented Minoritized Students (by Isabella Trierweiler)

This special session included four views on the intersections of mentoring, mental health, and diversity, equity, and inclusion (DEI) work. The first speaker was Jennifer Bates, a social worker and program manager for the Broadening Participation initiative at the National Radio Astronomy Observatory (NRAO). She introduced the motivations for the Broadening Participation Programs, which include five research and mentoring programs to increase representation of students with underrepresented identities in the sciences. She pointed out multiple studies of stress and anxiety amongst college students in general, as well as specifically for BIPOC and LGBTQIA+ students, showing that students or marginalized identities are much more likely to experience discrimination and exclusion but less likely to receive adequate mental health care. Danielle Rowland, who also works on the Broadening Participation Programs at NRAO, then spoke about the NAC (National Astronomy Consortium) program. The program places students into cooperative teams to work on summer research projects. Students also receive mentoring and professional development support and are eligible for further research projects, travel grants, and bridge support for graduate school after their participation in the program.

Timothy Paglione shared his experience running AstroCom NYC, a CUNY program to provide support and mentoring for astrophysics students. The students are paired with research and career mentors and work on research at the American Museum of Natural History. The CUNY system is very extensive, with 25 campuses including senior and community colleges, graduate programs, and professional colleges. The program has grown along with its students’ needs, evolving the approaches to preparing students for graduate school as well as industry jobs and adding a focus on mental health. One of the unique aspects of AstroCom NYC is that the program has a counselor available to serve students’ mental health needs, so that students can attend one-on-one counseling sessions or join a “Solidarity Group.”

Finally, David Morris spoke about his experience growing the physics and astronomy program at the University of Virgin Islands (UVI). UVI is a relatively small university with about 1,500 students, most of whom grew up locally. The degree program in physics, with a concentration in astronomy, just started in 2015 and grew rapidly in its first few years. However, the program faced difficulties when Covid began, and both enrollment in UVI and in the physics program went into a decline. In order to get students involved again and improve recruitment to the physics major, the department started a student-run High Altitude Balloon project. The intensive hands-on experience helped to renew enthusiasm for research amongst the students while giving them the opportunity to work with scientists at other institutions.

Live tweets of this session by Isabella Trierweiler.

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Press Conference: Discoveries in the Milky Way’s Backyard and in the Universe at Large (by Mark Popinchalk)

If you are feeling pedantic, you might point out that a press conference called “Discoveries in the Milky Way’s Backyard and in the Universe at Large,” could be more simply called “Discoveries.” But a better name might have been “Galaxies,” as that was the through line between all the presentations.

First was Burçin Mutlu-Pakdil who announced the discovery of three ultra faint galaxies beyond the local group. Ultra faint dwarf galaxies are the most dark matter dominated objects in the galaxy, but are (by definition) faint and small, which makes them challenging to observe. All the previous examples were around galaxies in our local group (essentially the Milky Way, Andromeda, and smaller friends), but the authors identified three new ones around NGC 253 using Hubble images.

Then Dong-Woo Kim introduced us (or at least me) to XBONGs, X-ray Bright Optically Normal Galaxies. They are just that, galaxy-like objects that look normal in optical light, but are extremely bright in X-ray. By combining Chandra data with objects classified as galaxies in SDSS, they found 820 XBONGs and attempted to understand what they were. 50% of them are almost certainly obscured active galactic nuclei, where the optical light is blocked by gas and dust but the X-ray light is penetrating through. The other half is split between likely being hot gas clouds and maybe diluted active galactic nuclei. In the future, they will use more Chandra observations and double the number of XBONGs (so fun to write) for them to classify, and hopefully understand the phenomenon.

Kaixiang Wang then set about revealing the origin of ultra compact dwarf galaxies (UCDs). These objects seem to blur the definition between globular clusters and dwarf galaxies; they have a similar mass to the latter, but their size is an order of magnitude smaller, closer to the former. One theory is that they are former dwarf galaxies that have had their outer layers stripped by a violent tidal interaction in the past, leaving only the nuclear star cluster. The main result is that they found some objects with tidal disruptions and envelopes — smoking-gun evidence that at least some UCDs originate from disrupted nucleated dwarf galaxies.

We then moved from smaller galaxies to some of the bigger players in our own Local Group, the galaxies that are near the Milky Way. Kat Barger started by warning us about the dangers of supernovae winds pushing out gas in the Large Magellanic Cloud galaxy (LMC). Really the danger is to the LMC, as she showed that the winds were heating up gas and shooting it out of the LMC, at least 4.5 times the amount of gas that the LMC is using to make stars and planets! That’s not necessarily bad for its future star formation rate, as the gas might cool and fall back towards the small galaxy, except there is a much bigger galaxy nearby — our own Milky Way! The presentation ended by showing that there is already a large outflow from the LMC that is being tidally pulled by the Milky Way. Thanks for the gas, LMC!

Finally, Adam Smercina wanted to look at spiral structure in low-mass galaxies, such as the LMC, but it’s not a good example in part because of the tidal influences of the Milky Way. So instead he focused on the Triangulum galaxy, another diminutive neighbor. Using a Hubble survey program called PHATTER, he was able to identify 22 million stars individually, and sort them into rough bins of youngest, young, intermediate and old. When he looked at how those populations were positioned in space, the young stars show a clear spiral structure, while the older ones lose their spiralness! This isn’t necessarily an evolutionary sequence, as the older ones might have been disrupted into their blobby distribution. Rather, it’s more likely a trace of the gas in the galaxy, which behaves differently than the stars do.

Overall it was great to see some new results from galaxies that were indeed in the Milky Way’s backyard and beyond!

Live tweets of this session by Mark Popinchalk.

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Plenary Lecture: Chanda Prescod-Weinstein (University of New Hampshire) (by Isabella Trierweiler)

The theme throughout Dr. Chanda Prescod-Weinstein’s plenary talk was that astrophysics and particle physics will become increasingly entangled as the quest to understand dark matter moves forward. Dr. Prescod-Weinstein is a Professor of Physics and a Core Faculty Member in Women’s and Gender Studies at the University of New Hampshire, and author of the popular science book “The Disordered Cosmos: A Journey into Dark Matter, Spacetime, and Dreams Deferred.” She focused her plenary talk on the role of astrophysics in some of the most pressing open questions regarding dark matter.

Dr. Prescod-Weinstein began her talk by introducing dark matter, the mass that we know is prevalent throughout the universe due to its gravitational influence but which does not seem to be explained by any particles in our current standard model. Astrophysical proof of dark matter has existed for some time — we see it in the flattening of galaxy rotation curves, in lensed galaxies imaged by Hubble and JWST, and in the features of the cosmic microwave background. Based on these observations, and through testing dark matter in cosmological simulations, we know that dark matter doesn’t interact with photons and is cold and slow moving.

She stressed that understanding dark matter is not just a goal for particle physicists — astronomers have stakes in the outcome, too. One of the main examples lies in galaxies, whose formation and evolution is deeply dependent on the dark matter halos they reside in. To truly understand the physics of galaxies and their satellites, we need to understand what dark matter is and how it influences its environment.

Amongst the possible components of dark matter, which span in scale from miniscule particles to multiple-solar-mass black holes, Dr. Prescod Weinstein spoke about two promising options: axions and asymmetric dark matter. Axions are theoretical particles that were proposed to solve symmetry issues in quantum field theory. The particles were proposed in the 1980s, but experiments have just recently become capable of searching for them. The idea behind asymmetric dark matter is that, much like particles and anti-particles, dark matter and anti-dark matter both formed in the universe, and in the process of colliding and annihilating, only dark matter was left to survive to present day.

Venn diagram of the possible theories of dark matter.

Venn diagram of the possible theories of dark matter. [Slide by Chanda Prescod-Weinstein]

Dr. Prescod Weinstein presented a few astrophysical probes related to each of these potential dark matter components. Interestingly, astronomers can expect neutron stars to play a big role in future dark matter studies. The inner cores of neutron stars are very mysterious, but it could be that they contain dark matter, not just nuclear matter. Additionally, it’s possible that asymmetric dark matter can be made within neutron stars. More higher-energy missions could help us clarify the neutron star/dark matter relation!

Illustration of a neutron star's interior

Illustration of a neutron star’s interior. [Slide by Chanda Prescod-Weinstein]

Regarding axions, Dr. Prescod Weinstein showed that astronomical-scale manifestations of the particle are certainly possible! Axions are a type of particle called bosons, and because they are bosons they have a special property when cooled to very low temperatures. When bosons (and axions) are near 0 Kelvin they become Bose-Einstein condensates, a particular state of matter where many individual particles group together so that quantum systems can be viewed macroscopically. The exact size of the condensate would depend on the mass of the particle, but axion Bose-Einstein condensates are theorized to be at least as large as an asteroid!

To move forward in these theories, Dr. Prescod Weinstein emphasized the importance of new instruments such as STROBE-X and the Vera Rubin Observatory. Observations from these telescopes will be crucial in fully utilizing astrophysical probes in the search for dark matter!

Live tweets of this session by Isabella Trierweiler.

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Plenary Lecture: Sabrina Stierwalt (Occidental College)

Dr. Stierwalt began her talk with an overview of dwarf galaxies. She explained that we have recorded evidence of our ancestors observing the Small and Large Magellanic Clouds — two of the most famous dwarf galaxies — dating back to prehistoric times. However, we didn’t know what they or other dwarf galaxies were until Harlow Shapley observed the Sculptor Dwarf Galaxy in 1937.

Moving into the bulk of her talk, Dr. Stierwalt outlined four reasons why dwarf galaxies are both very hard and very important to study:

  1. Dwarf galaxies are both small and faint — two characteristics that can greatly limit the observability of an astronomical object. However, because they are small and faint, we can use them to place stricter constraints on galaxy structure. For instance, we know roughly where dwarf galaxies should be in relation to the Milky Way and how many of them there should be, so if we compare the theoretical distribution to what we actually observe, we can determine how much dark matter must be present to reconcile the difference.
  2. Dwarf galaxies are strongly affected by stellar feedback because their gravitational wells are shallow. In other words, since they’re smaller than other galaxies, they have less gravity and are more affected by events such as supernovae that create turbulence in the interstellar medium. Studying the effects of stellar feedback can tell us more about both the mechanisms creating the feedback and the structure of the dwarf galaxies themselves. This is especially true in relation to dark matter, since we see dwarf galaxies with both low and high amounts of dark matter, and those with seemingly high amounts of dark matter tend to be more isolated, leading astronomers to wonder if stellar feedback is somehow stripping the dwarf galaxies of dark matter.
  3. Dwarf galaxies have low metallicities, so their compositions are similar to those of the highest redshift — i.e., the oldest — galaxies. This similarity means they can give us an idea of how star formation and stellar feedback occurred in the earliest populations. They can also give us insight into how mass loss occurs in low-metallicity stars, and help us discover techniques to find intermediate active galactic nuclei.
  4. Dwarf galaxies are heavily influenced by their environment. In other words, they’re very sensitive to what’s happening around them chemically and dynamically. Mergers of dwarf galaxies, for example, are much more likely to occur than mergers of large galaxies, and have different results. Dwarf galaxy mergers have starbursts occurring earlier in the merger than in mergers of larger galaxies, for example, and create more evenly distributed stars.

In closing, Dr. Stierwalt briefly discussed how upcoming surveys with the Rubin Observatory and the Nancy Grace Roman Space Telescope will increase the number of known dwarf galaxies. Additionally, follow-up observations of known dwarf galaxies using JWST will tell us even more about their dynamics and characteristics. Simulations of dwarf galaxy mergers — thought to be the progenitors of larger galaxies such as the Milky Way — are also becoming more and more accurate as we learn more. It’s an exciting time to be studying these small but mighty galaxies!

Live tweets of this session by Ali Crisp.

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Astronomy in Indigenous Communities Special Session [from Tuesday, January 10th](by Macy Huston)

This session was the third of three events at AAS 241 relating to Community Models of Astronomy, following a workshop January 5–6 and the plenary panel on Monday.

Christine Matsuda (Maunakea Observatories) introduced the session, establishing the context of this work from the Astro 2020 decadal survey part 3.4.1. The Community Models of Astronomy workshop focused on strengthening relationships between indigenous communities and the astronomy institutions that exist on their land. The 30-person workshop was hosted by the ‘Imiloa Astronomy Center and Maunakea Observatories, with representation from multiple indigenous communities, as well as indigenous and non-indigenous astronomers and other scientists. Major discussion topics included the difficulty of such relationships, establishing mutual stewardship as opposed to a benefactor/beneficiary relationship, and the misalignment of the pace of this work and institutional timelines. Next steps following the workshop will summarize the ideas discussed and recommendations for the future.

Next, Yuko Kakazu, education and outreach specialist at Thirty Meter Telescope (TMT), spoke about connecting astronomers with Hawaiian students through tutoring. TMT and Mauna Kea have been a source of community division and a symbol of colonialism and injustice since before the 2019 protests. The start of the pandemic in 2020 paused previous interactions. The TMT project manager moved to the community to listen and learn, and a new education and outreach team was established in the area. The pandemic’s impact on education (as Hawaiian schools closed for over a year) saw a decrease in science and math proficiency, particularly among native Hawaiian students and other marginalized groups. The TMT education and outreach group started a tutoring program that reduced the number of students failing classes and helped to establish a sense of community between the astronomers and locals.

The third speaker, Ku’ulei Bezilla (’Imiloa Astronomy Center) presented A Hua He Inoa, which means something like “calling forth a name.” This project at the ‘Imiloa Astronomy Center has worked to reclaim cultural practices in Hawaii, including naming astronomical objects. So far, five student cohorts have gone through the naming process, resulting in six official names: the quasar Pōniuāʻena, the interstellar object ‘Oumuamua, the black hole Pōwehi, the asteroids Kamo’oalewa and Ka’epaoka’āwela, and the dwarf planet Leleākūhonua. The current cohort has submitted the names Leimakua and Kawelo to the 2023 International Astronomical Union ExoWorld naming competition for HAT-P-26 and HAT-P-26b, inspired by a story about family relationships. The group is also working to build an exhibit about light pollution in their community.

The next presentation was about the One Sky Project, given by Ka’iu Kimura (’Imiloa Astronomy Center). This project, which is sponsored by TMT, is bringing together different communities to share stories in planetaria, with the guiding principle: “Everyone sees something a little bit different, but we all see one sky.” Six films have been created so far, based on cultures from Hawai’i, Japan, Navajo, Greece, Canada, and India. The first five films will be released after the final premiere next month, and they will be freely available to planetariums, along with materials to prompt discussion. Ka’iu closed with a mention of the difficulty around this project’s TMT sponsorship given the opposition against its construction on Mauna Kea. But, One Sky Project has appreciated their support and editorial freedom.

The second to last presentation of the session was from Jacelle Ramon-Sauberan. Jacelle is a full-time faculty member at Tohono O’odham Community College who spoke about her work as a part-time communication specialist for NOIRLab/Kitt Peak National Observatory (KPNO). The role provides cultural competency education and helps with relationships between the Tohono O’odham community and KPNO. She showed the new NOIRLab education program logo created by Jeffery Antone Sr., a Tohono O’odham artist. Jacelle also arranged for tribal leaders to visit KPNO for the first time in many years, including Tohono O’odham Nation Chairman Ned Norris Jr., Vice Chairwoman Wavalene Saunders, and Schuk Toak District Leadership. During the Contreras fire at KPNO, the Tohono O’odham nation’s fire department, police, and other entities assisted. Additionally, a medicine person cleansed the mountain and staff after the fire. Jacelle wrapped up with a discussion in-progress updates to KPNO’s land acknowledgement, involving community input, including elders and youths, and translating it to O’odham.

Aparna Venkatesan wrapped up the session with a discussion about the problem of satellite constellations (SatCons). During our ongoing global crises, we have the opportunity to work together and establish better ways of doing things. The SatCon crisis involves the dramatically growing number of satellites in low Earth orbit, threatening astronomy and dark skies everywhere. They cause streaks in images but also contribute to a rise in global brightness, wiping out the “dark sky” regions of the planet. In addition to astronomy, these issues affect cultural sky traditions, human health, and animal behavior, including bird migration. Aparna took part in the Community Engagement working group from the SATCON2 workshop in July 2021. The group examined the future of orbital space in partnerships with indigenous communities, identifying ethical, cultural, and legal issues in the SatCon crisis. She closed with an emphasis on the importance of setting precedents today to work ethically, based on communities, not conquest.

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Optical image of the Pleiades star cluster

Editor’s Note: This week we’re at the 241st AAS meeting in Seattle, WA, 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 on Twitter for live coverage. The usual posting schedule for AAS Nova will resume on January 18th.

Table of Contents:

Plenary Lecture: Allison Kirkpatrick (University of Kansas) (by Yoni Brande)

Everything I Need to Know About AGN I Learned in this Plenary – Allison Kirkpatrick (Univ. Kansas)

Prof. Allison Kirkpatrick is an expert in active galactic nucleus (AGN) observations and is currently a professor at the University of Kansas, where she leads a vibrant research group and heads the KU REU program. Prof. Kirkpatrick is also deeply involved with early JWST AGN science through the JWST Cosmic Evolution Early Release Science (CEERS) collaboration. Astrobites’s live tweeting of her plenary talk can be found here.

Prof. Kirkpatrick began by highlighting her close collaborators, postdocs, and students, without which none of the groundbreaking work happening in her group would be possible.

AGN are the accreting supermassive black holes (SMBHs) at the centers of galaxies. For example, the SMBH in Messier 87, the first target of the Event Horizon Telescope’s imaging campaign, is roughly the size of the solar system (~300 AU), while its host galaxy is more than 10 million times larger. Despite this disparity, SMBHs often have significant impacts on their host galaxies. Observationally, we can see their indirect effects, such as jets and radio lobes, but we can also classify AGN by their direct properties, such as the presence or absence of broad emission lines.

Finding AGN

We can find AGN by observing in several different bands, anything from the X-rays down into the radio. Different parts of the AGN structure (the dusty torus, corona, BH accretion disk, or clouds in the broad and narrow line regions) tend to emit in specific regions of the electromagnetic spectrum. High X-ray emission from the incredibly hot corona is a good specific tracer of AGN, but X-rays are often absorbed by gas in the interstellar medium, making this method relatively incomplete. Cooler temperatures in ionized clouds lead to broad optical emission lines, but can also be obscured, and spectra are expensive. Narrow lines come from the accretion disk, but some (like H-alpha and H-beta) are also characteristic of star formation, requiring specific line ratios to diagnose AGN versus star forming galaxies. The hot dust in the torus is an infrared emitter (with a classic power law), but it needs to be separated from cold dust in the rest of the galaxy. A major benefit is that infrared AGN aren’t obscured by geometry or other structures in the host galaxy. JWST photometry will be able to tease these apart, so stay tuned for new samples of AGN from Prof. Kirkpatrick’s group!


The observational types of AGN have historically been thought to be geometric effects, where different viewing angles give us clearer or obscured views through the AGN’s own structure down towards the black hole. However, this isn’t the only explanation: non-unified models posit that, for example, high AGN accretion rates can blow the torus further away, removing it as a source of emission entirely. High galaxy masses and mergers can also deliver more obscuring gas into the galaxy, blocking emission from the AGN externally. These processes can also change over a galaxy’s lifetime, where initially obscured AGN may clear away the gas and dust blocking them, eventually transitioning to an unobscured state.


When two gas-rich galaxies collide, the merger process compresses their gas and triggers bursts of star formation. In addition, the merger shunts gas towards their centers, massively growing their SMBHs. Recent studies have shown that this gas also obscures the AGN and is correlated with the dust content of the merging galaxies. However, recent studies have also shown that while mergers are sufficient to fuel AGN, they’re not necessary, with half of the observed low redshift quasars in the Stripe82 sample not present in merging galaxies.


Strong AGN emission isn’t just a good observational tracer, but it can also drive powerful winds throughout the galaxy. These winds have been theorized to be able to quench star formation, but it’s hard to definitively measure the mass outflows from these winds. Since star formation also consumes lots of gas mass, AGN winds may not actually be sufficient to quench galaxies, especially at high redshift. AGN can also heat dust throughout the rest of the galaxy, and this itself may also be enough to quench star formation. Since dust and gas tend to coincide, AGN-heated gas may also be present, which has been shown observationally. Each of these feedback mechanisms could explain star formation quenching. While this assumes star formation declines in AGN host galaxies, observations of infrared AGN and X-ray AGN imply that both populations may form stars at typical rates.

The Oddballs

Not all AGN are typical or well-behaved. Prof. Kirkpatrick’s group has identified a population they call “Cold Quasars”: high-luminosity AGN with significant amounts of cold gas and lots of dust (but totally unobscured!)


Closing out her plenary, Prof. Kirkpatrick highlighted some major societal concerns in our field. We can’t separate scientists from their science, and who gets to do science is as important as the discoveries they make. Diversity in the field is low, and historical trends have made astronomy a less-than-hospital place for astronomers of marginalized identities, including but not limited to non-white, non-male, neurodivergent, disabled, queer scientists. These scientists often shoulder disproportionate service efforts, are intentionally or implicitly devalued, and have harder times getting funded.

Luckily, this is a solvable problem. There are great resources available to marginalized students to help find their cohorts, including Black in AstroNSBPSACNAS, the Astro Outlist, and others! Allies can also do their best to amplify the voices of our marginalized peers, make our conferences and classrooms more inclusive and accessible, value service work alongside research and teaching for hiring, tenure, and funding, educate ourselves on institutional barriers and how to dismantle them, and learn how to mentor all students effectively. Prof. Kirkpatrick closed with a strong statement: “Our field will only be truly accessible when we decide that people matter more than black holes.”

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Press Conference: New Developments in the World of Planets (by Isabella Trierweiler)

Patrick Taylor, discussing radar on the Green Bank Telescope

Patrick Taylor kicked things off by introducing the new radar capabilities of the Green Bank Telescope (GBT). The GBT is currently the world’s largest steerable radio telescope, and it recently got its first prototype radar system, built in collaboration with Raytheon. The new transmitter has less power than a microwave but has already generated some impressive results! To image objects, the GBT works in conjunction with the Very Long Baseline Array (VLBA), with the GBT as a transmitter and VLBA as the receiver. This system resulted in the highest resolution image of the Moon ever taken from Earth, as well as a detailed image of the Tycho crater. The team also demonstrated the GBT transmitter’s use in small-body science by detecting an asteroid five times farther away than the Moon!

Many in the audience were curious about how the GBT system will compare to the recently collapsed Arecibo telescope. Dr. Taylor noted that the GBT is a much smaller telescope, but it does have more flexibility as it is fully steerable (Arecibo had a steerable receiver but the base was built into a sinkhole). He also pointed out the GBT will continue to be used in partnership with the VLBA and eventually the ngVLA. which will bring the whole system’s capabilities in range of Arecibo’s. Designs for the final radar system for the GBT are still in the works, but once the radar system is completed, the GBT could be used for detailed geology and dynamics studies, tracking of space debris and planetary defense, small-body science, and more!

Emily Gilbert, sharing a TESS earth-sized planet in the habitable zone

Emily Gilbert, a postdoc at NASA’s Jet Propulsion Laboratory, presented the exciting discovery of the second known Earth-sized planet in a star’s habitable zone! The habitable zone is the area around a host star that is warm enough for planets to host liquid water. Dr. Gilbert used data from TESS to study the planetary system TOI 700. There were previously three known planets in the system, including planet d, the first Earth-sized planet discovered in the habitable zone. Dr. Gilbert analyzed 14 transits’ worth of data in order to detect the new habitable zone planet, which is slightly smaller than Earth and has an orbital period of 28 days.

TOI 700 is scientifically interesting because the host star is very bright and relatively nearby, and the star appears to be fairly inactive, so it should be a very good candidate for follow up observations! Since the system has planets both within and outside of the habitable zone, detailed studies of this system could help astronomers better understand how planets can follow very different evolutionary tracks after being born in the same protoplanetary disk. Dr. Gilbert says further observations of the system are already in the works! She already has 100 hours on ESPRESSO, a spectrograph at the VLT, to calculate masses for the four planets.

Rob Zellem, announcing the launch of Exoplanet Watch, a citizen science program

Exoplanet Watch is now open to general audiences! The program involves amateur astronomers and members of the general public in the search for exoplanets, with the goal of combining the power of many small telescopes to more efficiently monitor exoplanet transits. Precise transit timings are really crucial for studying exoplanet atmospheres, and now anyone can help out with these studies! Folks with their own telescopes can sign up to contribute data to the project, and anyone without telescope access can help to process the data. All data contributed to the project will be immediately available to everyone, and anyone who volunteers to observe for Exoplanet Watch will be a co-author on any scientific papers that use the data. Exoplanet Watch carried out a test campaign in 2021, combining data from 24 facilities to construct a transit light curve, something that would have taken 2 hours of JWST observing time! Now that the program is open, astronomers will even be able to request observations for particular systems, and will get results more quickly without needing to wait to receive time on a major telescope. The whole system is a really novel way to approach research, allowing astronomers, amateur observers, and the public to all work more closely and collaboratively on astronomy projects. If you would like to get involved in the citizen science project, you can sign up for the Exoplanet Watch Slack here to get started!

Sasha Hinkley, presenting the first directly imaged Gaia Exoplanet

Finally, Sasha Hinkley showed the first direct images of a Gaia Exoplanet, HD206893c. The host star was known to have a circumstellar disk, so it was a promising place to look for exoplanets. The Gaia mission takes very precise measurements of stellar positions in the sky, finding planets based on whether the stars wobble. HD206893 was already known to host one planet, but Gaia data suggested there might be another one, so the team turned to precise imaging to find it. They used the GRAVITY instrument on the VLT to image the system, confirming the orbit of the previously discovered planet and making the discovery of the second planet! The new data is incredibly precise — Dr. Hinkley likens it to observing a dime from 60,000 miles away. The discovered planet is very unique — in size it is right on the border between planets and brown dwarfs (and will hopefully help astronomers better understand the differences between the two groups), and there is evidence that it may have nuclear burning ongoing in the core!

Live tweets for this session by Isabella Trierweiler.

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Plenary Lecture: Nia Imara (University of California, Santa Cruz) (by Pratik Gandhi)

In her tour de force plenary talk, “A Star is Born,” Prof. Nia Imara provided a comprehensive review of the complex and important field of star formation out of molecular clouds, the relevant open questions, and potential resolutions to those questions. Dr. Imara, a professor at UC Santa Cruz, was the first Black woman to get an astrophysics PhD from UC Berkeley, and she is also an artist, community organizer, and founder of the non-profit Onaketa, which provides free STEM tutoring to Black and brown youth. In a fun yet poignant moment, she kicked off her plenary by taking a selfie with the entire audience and then acknowledged her ancestors, family, and teachers/mentors who have guided her over the years.

Molecular clouds are the birthplaces of stars and an important intermediate regime between galaxies and stars. Dr. Imara pointed out how difficult star formation is to fully understand, because it’s a complex, multi-scale process involving many different physical processes like gravity, fluid dynamics, magnetism, and chemistry. Molecular clouds are the first steps in the process of star formation, as the coldest and densest, and thus self-gravitating, regions of the interstellar medium. A typical molecular cloud is composed of atomic hydrogen (HI), molecular hydrogen (H2), other molecules like carbon monoxide (CO), and dust.

Next, Dr. Imara posed some of the biggest open questions in the field of star formation, such as:

  1. How do stellar nurseries form and evolve?
  2. What is the role of galaxy environment in star formation?
  3. What is the nature of star formation in the early universe?
  4. Why do stars have the masses they do?
  5. How does star formation depend on the structure of molecular clouds?

A really important idea in the field of star formation is the Kennicutt–Schmidt Law, the idea that star formation rates in galaxies are correlated with the distribution of hydrogen gas in them. Molecular clouds tend to be associated with the highest-surface density of HI gas, and thus are thought to be the setting for most of the star formation in galaxies. Dr. Imara’s work in 2016 implied that turbulence in atomic gas is sub-sonic or trans-sonic, and that HI surface density plays a key role in setting the total mass of molecular clouds. Additionally, although the Kennicutt–Schmidt relation applies to galaxies on large scales, it breaks down when you look at smaller scales. The answer here might lie in cloud ages/lifetimes and whether stellar feedback has had enough time to disperse the cloud after star formation.

Dr. Imara highlighted the PHANGS collaboration, one of the most important surveys of molecular clouds and molecular gas in star-forming galaxies outside of the Milky Way. The image below shows the massive improvement in resolution that PHANGS provides relative to older surveys! One of the key results from PHANGS shows higher surface densities of gas in galactic centers, possibly due to bars funneling gas into the centers. Similarly, PHANGS sees higher gas densities in spiral arms relative to the inter-arm regions.

images from the PHANGS survey

A slide from Dr. Imara’s plenary talk at AAS 241. Comparing PHANGS survey with previous images, it highlights the increase in spatial resolution. [Adapted from Leroy et al. 2021]

Switching gears, Dr. Imara discussed star formation in dwarf (low-mass) galaxies. Dwarf galaxies are excellent labs for studying star formation in chemically young environments because their properties are so different from larger, Milky Way–like galaxies. Dr. Imara hopes that a future PHANGS-like survey focusing on molecular clouds and star formation in dwarf galaxies will transform the field.

Next, Dr. Imara highlighted the rapid onset of star formation in the early universe, which has been discovered in recent years and was unexpected. ALMA and JWST have observed galaxies at very early times with large masses, lots of dust, and rapid star formation.

On a related note, she highlighted the important concept of the initial mass function (IMF). IMF refers to the distribution of stellar masses at formation, which “impacts nearly every area in astronomy,” says Dr. Imara. Its importance cannot be understated, but we still don’t fully understand all of the ideas behind what causes it! STARFORGE, a suite of cutting-edge simulations of molecular clouds and star formation, has shown that stellar feedback and jets from protostars is crucial for determining the resultant IMF of the stars being born, thus making it a self-regulating process.

Segueing into discussing her recent work, Dr. Imara mentions a major challenge in the field: how do we infer 3D properties of molecular clouds from 2D observations? Well, she and her team had the idea of creating 3D-printed stellar nurseries to visualize the properties of molecular clouds! Dr. Imara is looking at the intersection of art and science to understand how various physical properties affect star formation and the structure of molecular clouds. She and her team ran simulations and then used them to generate the 3D prints. This process helped them determine that what appears to be a gas filament can often be a 3D sheet or pancake-like structure of gas.

In her concluding remarks, Dr. Imara highlighted her nonprofit Onaketa that provides free STEM tutoring to Black and brown children. She also highlights the astronomy that her ancestors and people started studying thousands of years ago. “Star formation provides us with a compelling metaphor — we’re all connected across large scales of space and time,” she concluded.

photographs of stones arranged in one of the world's oldest astronomy sites

[Slide by Nia Imara]

Live tweets of this session by Pratik Gandhi.

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ExoExplorers Special Session (by Briley Lewis)

This afternoon, early career scientists from the NASA ExoExplorers program gathered to discuss their perspectives on diversity, equity, and inclusion efforts in astronomy. These talks explored various dimensions of diversity in astronomy, including race, socio-economic status, disability, gender identity, first-generation status, and more.

Caprice Phillips, graduate student at The Ohio State University and vice president of Black In Astro, shared recent updates on the Black In Astro (BIA) organization and how people can get involved in upcoming events. You may be familiar with BIA from their collaborations with us here at AstrobitesDavid Coria, graduate student at University of Kansas, highlighted minority-focused academic success programs, including a few important to his career: the K-State Developing Scholars Program, the McNair Postbaccalaureate Program, and the Hagan Scholarship Foundation. Coria recommended that faculty build trust with their students and be understanding of obstacles they have faced, and be willing to take on students from academic success programs.

Kiersten Boley, also a graduate student at The Ohio State University, discussed the classic description of the “pipeline” in academia, suggesting that not only is it leaky, but also that it begins even before college. Income and opportunities for science education are deeply intertwined, and begin affecting kids at a young age — the same young ages when they are forming their science identities. Boley suggested that outreach efforts should target these younger kids at lower-income schools, providing them opportunities they may otherwise not experience.

Dr. Kaitlin Rasmussen (who has been featured before on Astrobites!) explored the experiences of trans, non-binary, and other astronomers beyond the gender binary, as also discussed in their Astro2020 White Paper. Rasmussen listed five flaws in astronomers’ studies of gender in the field: that in these studies gender is white, observable, discrete, a statistic, and inconsequential. They recommend involving sociologists in any studies of gender in the field and compensating marginalized students / colleagues for their expertise on their lived experiences.

UCLA grad student and Astrobites writer Briley Lewis (yep, that’s me!) spoke on disability and accessibility, which Astrobites has great resources on in our Beyond bites. I shared my experiences organizing planetarium shows for Deaf and blind audiences, and with the recent University of California strike. Lastly, UNC Chapel Hill grad student Amy Glazier talked about her experiences as a first-generation college student, and the variety of barriers faced by those without the institutional know-how and lots of unknown unknowns about how to navigate higher education. “Why is it on us to justify our [marginalized students’]presence instead of institutions to justify our absence?” Glazier said. “Stop treating students from marginalized groups as problems, and start treating them as people.”

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Press Conference: Stars and Their Activity (by Macy Huston)

Chih-Chun “Dino” Hsu (Northwestern University) kicked off this afternoon’s press conference with the “Discovery of the Shortest-Period Ultracool Dwarf Binary.” Ultracool dwarfs are low-mass stellar/sub-stellar objects with temperatures below 3000K. Binary systems, particularly those with short periods, are important for creating accurate theoretical models. Only three short-period ultracool dwarf binaries were known before this discovery. Keck observations of the LP 413-53 AB system show a radial velocity signal indicating a 20.5-hour orbital period. This pair’s close-in orbit is comparable to the distance between Jupiter and the Galilean moons. It is unlikely that the objects formed this close together. Two more likely scenarios are orbital evolution and scattering caused by an (ultimately ejected) tertiary companion.

Next up was “To Rain or Not to Rain: Correlating Solar Flare Class and Coronal Rain Statistics” from Kara Kniezewski (United States Naval Academy). Magnetic field line reconnection causes solar flares that heat up plasma, causing it to expand then “rain” back down to the surface. The team analyzed 240 solar flares from 2011 to 2019 (Solar Cycle 24) to track post-flare rain occurrence and duration. The data show a correlation between higher flare strength and higher rain occurrence and duration. They also found that these post-flare rains can predict future solar activity. More powerful flares correspond with higher starspot coverage. While this “rain” effect was known to exist for a while, this work finally examined the issue in detail and established the statistics of post-flare rain in the astrophysical literature.

The third presentation came from Marina Kounkel (Vanderbilt University): “Relating Angular Momentum Evolution and Gyrochronology for Young Stars in the Field.” Stellar ages are typically measured in the context of a cluster of stars that formed together. Based on the population’s evolution, best visualized on an HR diagram, the cluster’s age can be estimated. Gaia has identified thousands of new clusters, allowing for more of this type of study. However, billions of main sequence stars exist in the field, rather than their birth clusters, so we need another method to measure their age. By tracking brightness variability due to starspots, we can measure the rotation periods of stars with telescopes like TESS. With mass and radius data, in addition to period measurements, angular momentum can be estimated. Angular momentum decreases with stellar age, which allows these “gyrochronology” measurements to predict the ages of field stars. This project produced an empirical grid for gyrochronology based on TESS data.

Next, Anastasios Tzanidakis (University of Washington) presented the “Discovery of the Deepest and Longest Known Blinking Giant Star Gaia17bpp.” (Press release) The star’s interesting activity was detected with Gaia, which measures the position and brightness of millions of stars in the galaxy. The cool M-giant star was notable for its odd optical light curve, where it gradually brightened ~4 magnitudes over ~3 years. Archival data back to the 1950s showed a relatively flat light curve for the star until 2013, when it very gradually dimmed. This dramatic dimming event may be explained by a dusty disk eclipsing it, where the disk may host a hot star in its center. If the two stars are gravitationally bound, the orbital period should be ~100–1000 years, so these eclipse events are very rare. This calls back to a similar system, Epsilon Aurigae, which shows dramatic 2-year eclipses every 27 years. These two systems (along with two others) belong to an emerging population of binary stars with dramatic dimming events which future surveys like LSST should help characterize.

The final presentation of this session was “Starspots and Magnetism: Testing the Activity Paradigm in the Pleiades and Messier 67 Star Clusters” from Lyra Cao (The Ohio State University). Cool stars show a lot of magnetic activity and starspots, which can affect their interior structure. In order to create accurate models of these stars, magnetism has to be accounted for. The team developed a method to directly measure the magnetism of stars by separating out the ambient surface and the starspot signatures in their spectra. This allows for magnetic studies in open clusters, where stars all have similar ages and compositions. Rapidly rotating stars show stronger magnetism and starspot coverage, but at a high enough speed, this effect saturates, and starspot levels remain flat. The team found some anomalous stars whose starspot coverage appears too high for their relatively slow rotation periods. When modeling eclipsing binary stars, their radii can appear inflated compared to real radius values. Accounting for starspots can allow for more accurate radius and temperature estimates, which also enables more accurate radius measurements for transiting planets. Starspot activity is most powerful for low-mass stars and stars turning off of the main sequence, then fades away in the stellar evolution process as stars dramatically expand and slow their rotation.

Live-tweet thread by Macy Huston

YouTube recording

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Henry Norris Russell Lecture: Richard Mushotzky (University of Maryland) (by Graham Doskoch)

The Henry Norris Russell Lectureship is presented to an astronomer who has distinguished themself throughout the course of their scientific career. This year’s recipient was Prof. Richard Mushotzky, of the University of Maryland, whose career has paralleled the course of the field he has dedicated his life to: X-ray astronomy. He has seen everything from its serendipitous arrival and exciting early years to the earliest X-ray observatories to the leaps and bounds achieved by the Chandra and XMM-Newton missions. Prof. Mushotzky summarizes where the field is right now as we move into an age of X-ray astronomy heralded by several new instruments.

He began his talk by taking us back to the early days of X-ray astronomy with the launch of the Uhuru satellite. Its X-ray observations gave astronomers a new toy in their toolkit to study active galactic nuclei (AGN), supermassive black holes which are accreting matter and spewing out relativistic jets, high-energy emission, and more. When Uhuru was launched in 1970, AGN were still poorly understood; while we know much more about them today, plenty of questions remain. How are the different kinds of AGN related? How do they interact with their host galaxies? How common are they?

More progress on these problems was made with the HEAO program in the late ‘70s and early ‘80s, which Prof. Mushotzky worked on after finishing graduate school. The HEAO missions studied, among other things, the variability of AGN and were also able to take — in Prof. Mushotzky’s words — “boring” spectra. More progress was made on the spectroscopic front towards the end of the century when Chandra and XMM-Newton launched; over the past couple decades, they have remained stalwarts of the field.

Prof. Mushotzky turned to some of today’s state-of-the-art X-ray astronomy, focusing on the work he and his colleagues have done recently on AGN, much of which has been enabled by the Swift Observatory’s Burst Alert Telescope (BAT). Some of his work has involved studying emission from what are called radio-quiet AGN – many of which can, nevertheless, be detected with radio telescopes like ALMA. Their observations at high frequencies (for radio waves, at least) showed an unexplained component of AGN spectra not easily attributed to known high-energy processes.

They also noticed interesting relationships between active supermassive black holes and their host galaxies. A galaxy is more likely to host an AGN if it contains more molecular gas; conversely, it also turns out that galaxies with AGN are more likely to have large molecular gas reserves. Prof. Mushotzky and collaborators also found that AGN hosts tend to have undergone more mergers with other galaxies; he showed the mosaic below as an example of how spectacular these mergers can be.

A collage of different galaxy merger remnants.

Merger remnants, some of which host AGN. [Koss et al. 2010]

The final section of Prof. Mushotzky’s lecture was dedicated to what the future holds for X-ray astronomy. Two major missions headline the decades to come. This May, the XRISM mission will be launched, equipped with imaging and spectroscopic instruments to study soft x-ray emission. It will be followed in 2032 by the AXIS satellite, which will be roughly 10 times as sensitive as Chandra. AXIS will address many of the priorities of x-ray astronomy determined by the Astro2020 decadal survey — truly a telescope for the 21st century.

Live tweets of this session by Graham Doskoch.

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HEAD Bruno Rossi Prize Lecture: Keith Gendreau and Zaven Arzoumanian (NASA Goddard Space Flight Center) (by Ryan Golant)

Each year, the Bruno Rossi Prize is awarded for “a significant contribution to High Energy Astrophysics, with particular emphasis on recent, original work.” This year, the Rossi Prize was given to Keith Gendreau, Zaven Arzoumanian, and the team responsible for the Neutron Star Interior Composition Explorer (NICER), a revolutionary X-ray telescope launched in 2017. In this plenary lecture, Dr. Gendreau and Dr. Arzoumanian summarized NICER’s capabilities and goals and provided a glimpse into the deluge of fascinating results emerging from NICER’s data.

Dr. Gendreau opened the talk by thanking the whole NICER team, including the nearly 100 scientists in the science working group; later in the talk, Dr. Arzoumanian expressed similar gratitude, stating that “it’s a privilege everyday to work with the talented people who work with NICER.”

Dr. Gendreau’s portion of the talk largely focused on NICER’s unique design specifications. All of NICER’s optics are contained within a small box of roughly one cubic meter, deemed the X-ray Timing Instrument (XTI); the XTI contains 56 densely-arranged concentrator mirrors and sunshades, focusing X-ray emission onto an array of 56 detectors. Since NICER’s original goal was to observe point sources like neutron stars — and not to produce large-area images — the telescope’s instrumentation sacrifices field of view in favor of high throughput and mobility, collecting as many X-ray photons as possible; the XTI can detect individual photons with an energy resolution on par with the best CCD detectors and a time resolution of less than 100 nanoseconds. The XTI is also attached to a highly flexible mount, allowing the instrument to slew quickly and precisely to capture a target’s position down to an arcminute or better.

A detailed schematic diagram of NICER

A detailed schematic diagram of NICER. [Slide by Keith Gendreau]

photograph of the NICER telescope on the International Space Station

A view of the Neutron star Interior Composition Explorer (NICER), seen at the center of this image, in its berth on the International Space Station. [NASA]

NICER is installed on the International Space Station (ISS) and remains the largest producer of peer-reviewed papers of any experiment on the ISS. While the space station presents a number of large obstructions to NICER’s view (including solar panels located a foot away from the XTI box), this is not a problem for NICER, which is constantly slewing and bouncing back-and-forth between targets to minimize obscuration. In a fun turn of fate, NICER was sent up to the ISS on the 100th rocket to be launched from Pad 39A at the Kennedy Space Center, the same pad that launched the first humans to the moon.

After reviewing NICER’s key capabilities, Dr. Gendreau passed the mic to Dr. Arzoumanian to talk about NICER’s science results. The initial goal of NICER was to probe the structure, dynamics, and energetics of neutron stars — “the most outrageous objects most people have never heard of.” We currently don’t have a clear picture of what goes on within a neutron star, since the extremely high densities (twice the density of an atomic nucleus) yield matter with exotic properties. However, by measuring the masses and radii of neutron stars (which turns out to be a formidable challenge), one can make inferences regarding the interior composition — stiff cores generally result in larger stars, while fluid cores give smaller stars. By carefully analyzing the X-ray pulses emitted by the millisecond pulsars PSR J0030+0451 and PSR J0740+6620, the NICER team was able to obtain reliable masses and radii for these two neutron stars, thus placing unprecedented constraints on neutron star interiors — favoring a stiff core. Upon the release of NICER’s data on PSR J0030+0451, Nature published an article declaring that “the golden age of neutron-star physics [had]arrived”; with more neutron star measurements on the horizon, NICER should continue to revolutionize our understanding of these compact objects.

A cartoon infographic showing the structure of a neutron star

A cartoon infographic showing the structure of a neutron star. [NASA’s Goddard Space Flight Center Conceptual Image Lab]

Dr. Arzoumanian went on to detail how NICER’s science output has spread far beyond the instrument’s original mission of studying neutron star interiors; through NICER’s vibrant Guest Observer program, the broader astrophysics community has steered NICER towards a wide array of other exotic objects and phenomena. NICER data has “rewritten” the textbook picture of pulsar magnetic fields, definitively illustrating that these fields are more complex than simple dipoles. Additionally, NICER has discovered a new accreting millisecond pulsar in an ultracompact binary system, has traced continuous gravitational wave emission back to rotation-powered and accreting neutron stars, and has placed constraints on the geometry of disks around neutron stars. NICER has also significantly contributed to black hole science: NICER is particularly effective at reverberation mapping — which provides information on black hole structure and mass and illuminates the connection between accretion disks, black hole coronae, and jets — and has solved the mystery behind “changing-look” AGN, accreting black holes with highly variable fluxes. Much of this new science is due to NICER’s scheduling agility and dense monitoring, with NICER carrying out multiple coordinated observations in each ISS orbit.

Dr. Gendreau closed the talk with a brief discussion of NICER’s OHMAN (“On-orbit Hookup of MAXI and NICER”) program. As the name suggests, OHMAN couples NICER to JAXA’s MAXI instrument, another payload on the ISS that’s capable of scanning a huge portion of the sky for X-rays; when MAXI picks up a signal, OHMAN tells NICER to slew immediately towards the source, enabling high-resolution detections of fast transient events. Recently, OHMAN proved invaluable in the study of GRB221009A, the most energetic gamma-ray burst ever detected. Dr. Gendreau concluded by remarking that, with the implementation of OHMAN, NICER has become a dynamic partner in our multi-wavelength and multi-messenger exploration of the universe, well in line with the priorities of the Astro2020 decadal survey.

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Illustration of two bright blue bodies colliding and emitting jets of matter in the process.

Editor’s Note: This week we’re at the 241st AAS meeting in Seattle, WA, 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 on Twitter for live coverage. The usual posting schedule for AAS Nova will resume on January 18th.

Table of Contents:

Fred Kavli Plenary Lecture: Jane Rigby (NASA Goddard Space Flight Center) (by Graham Doskoch)

AAS 241 kicked off with one of the most anticipated plenary talks of the week. Dr. Jane Rigby, the Project Scientist for Operations for JWST, has helped shepherd the telescope through many of its crucial milestones, from the tests upon tests upon tests before it even left the ground to the agonizing hours of launch day to the long, arduous process of scientific commissioning. She was chosen to give the Fred Kavli Plenary Lecture in recognition of her work to build and operate what might be the most important telescope of this decade and the next.

Dr. Rigby began by reflecting on the early days of gravitational lensing surveys, and the wealth of information that can be obtained from this phenomenon, including spectra and possibly details on individual stars within lensed galaxies. JWST was expected to significantly improve on previous observations — and it hasn’t stopped there. Its scientific performance has exceeded expectations across the board, from its point spread function, to its guiding and pointing accuracy, to its sensitivity to background light and stray photons. Over 20,000 people were involved in the telescope’s design, construction, deployment or operation in some way, their work has paid off.

As a brief interlude, Dr. Rigby talked about the human side of this endeavor. She discussed the tense days during and after JWST’s launch, saying, “It’s a lot like having a newborn at home… We didn’t know if the mission was going to be a total failure or if it was going to work.” So many things could have failed, like the unfolding of the solar panels or the deployment of the sunshield.

Fortunately, nothing major failed, and JWST has already produced prodigious amounts of scientific results. Dr. Rigby noted that astronomers have already published 163 papers based on JWST observations — on galaxies alone! In the spectroscopic realm, the telescope has targeted exoplanets, stars and galaxies, probing the cosmos back to a redshift of 13.17 — in other words, when the universe was only a few hundred million years old. The images, too, are phenomenal; she shows a picture of a Wolf-Rayet star in a binary system, which forms concentric circles of dust every eight years.

Before wrapping up her talk, Dr. Rigby took a moment to acknowledge that JWST is “the telescope that 20,000 people built.” That’s what it takes to peer so deep into the cosmos — and the JWST team pulled it off.

View live tweets of this session by Graham Doskoch here.

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#AbolishQuals: Barriers to Success for Graduate Students of Color in Astronomy (by Pratik Gandhi)

One of the first special sessions of this year’s AAS was the panel discussion on qualifying exams organized by the Committee on the Status of Minorities in Astronomy (CSMA). Moderated by Dra. Nicole Cabrera Salazar, co-chair of the CSMA, the panel featured PhD students Erin Flowers (Princeton), Caprice Phillips (Ohio State), and Keshawn Ivory (Vanderbilt), along with professors Enrico Ramirez-Ruiz (UCSC) and David Helfand (Columbia).

Quals, or qualifying exams, are a staple in most US-based astronomy PhD programs, and often consist of a written and/or oral exam used to try and predict which students are most likely to complete their PhDs and succeed. The panel’s focus was addressing the following questions:

  • What is the purpose of quals in astronomy?
  • What is the effect of quals on marginalized students?
  • Have the existence, structure, and validity of quals been properly examined?
  • What are community sentiments about quals?
  • How do we move forward?

AAS CSMA conducted an informal survey on twitter, with 62 respondents, to gauge people’s thoughts on and experiences with qualifying exams. There was a decent variety of respondents, from professors to students to university staff, and while most of them identified as White, there was representation from a variety of backgrounds/races as well. About half were Cis women, a quarter Cis men, and 16% under the Trans umbrella.

pie chart of survey respondents' attitudes toward qualifying exams

Survey results on PhD qualifying exam. [Slide by Nicole Cabrera Salazar]

As highlighted in the image above, the main survey results showed that the majority of respondents did not have positive attitudes towards quals, with 45.0% indicating a negative attitude and 33.3% neutral. Answers to what respondents perceived as the purpose of quals included “gatekeeping,” “illusion of rigor,” “weeding out,” and “negative perpetuation of tradition.” Since there is no standard way of doing qualifying exams and almost every single department does it differently, there is large inconsistency in student experiences, grades, and outcomes across departments and institutions.

After this initial presentation, the panelists answered questions. The first one was about the structure of the qual at their institution, and these were their responses.

  1. Erin Flowers (Princeton): the qualifying exam was based on the 4 subject courses; panel of 4 faculty members who ask you questions on those courses, with optional additional “fun time” for extra questions.
  2. Caprice Phillips (OSU) ​​took two qualifying exams. At the first one in Texas, Caprice could choose three classes for an oral exam after presenting on research. The second exam at the OSU was more research-focused, with a presentation followed by questions.
  3. Keshawn Ivory (Vanderbilt) will be taking the qual in May! It’s research-based with feedback from a committee on the students’ research proposal, with possible general astrophysics questions related to the research.
  4. Enrico Ramirez-Ruiz (UCSC): three requirements — submit a first-author paper by the end of 2nd year, give a talk to the entire department, and a written exam about core and elective classes. The third requirement was abolished after realizing that it didn’t have the intended learning outcomes.
  5. David Helfand (Columbia): abolished exams a while ago! In their first year, students pick a project, regularly present it to a faculty committee for feedback, and in September of the second year they start a different project and repeat the process. Then they segue into their PhD dissertation.

Next question: how much informed consent is there for the quals in your department? Do students go in knowing what to expect? How transparent is it?

  1. Erin noted that learning about the exam going in happens from older grad students. Once they take their exams, they immediately write down questions to act as a study guide for future students. Faculty did not provide explicit guidelines for the exams during classes!
  2. Caprice said that at OSU there’s a level of transparency, with the professors often indicating potential questions, and you’re allowed to discuss and clarify with faculty.
  3. Keshawn noted that at Vanderbilt, the grad students learnt from more senior grads. This is also common at many other institutions! One hidden component, however, relates to the purpose of the test — to determine whether the student possesses the ability to succeed.
  4. Prof. Ramirez-Ruiz said that UCSC did not have a very transparent exam in the past, but is getting better now. In the past, the written exam did not correlate with metrics for success, and it took a couple of faculty doing that analysis to motivate abolishing it.

Dra. Salazar raised the important point that departments have a responsibility to their students; not just the other way around. Fewer than 1 of 5 PhDs are going to become faculty, so why is there so much of an onus on students to replicate the standardized way of doing academia, instead of training them for a variety of research and other careers? Dra. Salazar also mentioned inertia in psychosocial situations: the idea of abolishing something seems like it’ll never happen because of institutional resistance, so we might never try to actually do it. However, there are institutions that ARE and HAVE BEEN doing it successfully!!!

Audience question: how does your institution treat disabled students going through quals?

  1. Prof. Ramirez-Ruiz said that a lot of the UCSC discussions were triggered because a disabled student had difficulties with the test, which prompted re-evaluation of the exam’s purpose as well as eradicating barriers for students across many dimensions of marginalization/oppression.
  2. Caprice noted that often disability accommodations aren’t genuine, because departments use the extra time students are given to ask them extra questions instead of giving the students more time to think!!! Super important when considering the needs of disabled students.

The conversation started wrapping up with Dra. Salazar highlighted the collective power that graduate students have, pointing to the recent UC-wide strikes as an example. However, the problem is that the onus is usually on the students currently in the program and not on the system!

View live tweets of this session by Pratik Gandhi here.

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Press Conference: Eyes on Galaxies with JWST (by Mark Popinchalk)

The first of eight press conferences for AAS 241, which are an opportunity for exciting results to have some additional fan fare. And there is nothing more exciting right now than JWST. The panel of five scientists included Dr. Jeyhan Kartaltepe, Dr. James Rhoads, Dr. Philip Appleton, Dr. Haojing Yan, and Dr. Vivian U, all showing off fascinating new science results using JWST to study galaxies.

What was striking was the diversity of results, thanks to JWST’s wavelength range being in the infrared. This means the observatory is well suited to look at distant high redshift galaxies, which Dr. Kartaltepe used to describe the shape of 850 galaxies at z > 3, Dr. Rhoads used to link modern “green pea” galaxies to ancient young galaxies, and Dr. Yan used to identify 87 candidate galaxies at z > 11. It can also be used to look at incredible structure in nearby modern galaxies, where Dr. Appleton described new theories for the radiation in a shockwave in Stephan’s Quintet, and Dr. U probed the interior structure of NGC 7469, creating the maps of different gas species around the super massive blackhole.

Also worth pointing out that running the press conferences this week are Dr. Kerry Hensley, Ben Cassese, and Zili Shen — all current or past astrobiters being the voice of the society!

You can view live tweets of this session by Mark Popinchalk here.

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Plenary Lecture: Jessie Christiansen (Caltech/IPAC-NASA Exoplanet Science Institute) (by Macy Huston)

For the second plenary lecture of the week, Dr. Jessie Christiansen presented “Towards an Exoplanet Demographics Ladder: The Emerging Picture of Planet Populations!” Astrobites interviewed her in this article, and Macy Huston wrote our Twitter thread of this plenary talk.

Dr. Christiansen is the Project Scientist for the NASA Exoplanet Archive. She started with an intro to IPAC, the Science & Data Center for Astrophysics & Planetary Sciences at Caltech. IPAC hosts the NASA Exoplanet Archive, which reached the amazing milestone of 5,000 confirmed exoplanets last year!

The next portion of the lecture covered the populations of known exoplanets discovered with each of the four main methods (from most to fewest found): transits, radial velocity, microlensing, and direct imaging. The transit method is great for finding planets on close-in (<1 au) orbits, and we see an interesting split into two populations, with a gap near ~30 Earth masses. The radial velocity method primarily finds planets that are relatively high-mass and on short to intermediate orbits. Microlensing can detect planets across the planetary mass range and within a ~1–10-au orbital range. Direct imaging is only possible for very high-mass and wide-orbit planets. So, how do we bring these all together to get a full picture of exoplanet demographics?

A plot of masses, orbital semimajor axis, and discovery method for known exoplanets

A plot of mass, orbital semimajor axis, and discovery method for known exoplanets. [Slide by Jessie Christiansen]

Dr. Christiansen discussed the prevalence of Earth-like planets, quantified as η. Based on the Kepler planet sample, initial estimates of η varied by orders of magnitude. With more recent analysis, η is thought to be in the 10-50% range, but the current estimates are consistent with anything from 1 to 100%. Ongoing refinements of Kepler occurrence rates may help narrow this estimate. Additionally, new exoplanet discoveries from the upcoming Roman Space Telescope and the proposed EarthFinder and Earth 2.0 missions can provide new data sets for this type of analysis.

There are many different types of stars and planetary systems in the Galaxy, so the conditions for planet formation and evolution could impact planetary demographics. Some evidence suggests that Earth-like planets might be more likely to exist in systems that have inner rocky planets and/or outer Jupiter-like planets. Already-discovered systems with planets like these may make good targets for future habitable planet searches. M dwarfs, the most common type of star, may also be potentially habitable host stars.

K2 and TESS are currently enabling the study of small, short-period exoplanets. Dr. Christiansen’s group recently cataloged ~750 K2 planet candidates ready for demographic study, and validated 60. Kepler and K2 populations both show a bimodality in the size distribution of small planets at short periods. Recent M-dwarf studies suggest the existence of a density bimodality dividing rocky planets and water-dominated planets.

A number of other factors could impact the occurrence rates of planets around certain stellar types and regions. Kepler and K2 suggest that small, short-period planets are more common among stars that stay closer to the Galactic plane (i.e., in the thin disk, not the thick disk). Stellar properties like metallicity and age may also affect formation, as protoplanetary disks require planet-building material and dissipate over time.

To wrap up the lecture, we return to the plot of known exoplanets discovered via the four main methods, plotted by orbital semi-major axis and mass (or mass*sin[i]). But, these masses are indirect estimates for all methods. Additionally, different methods focus on different types of host stars. So, combining the data sets is complicated, but not hopeless! There is overlap between the parameter spaces covered. Dr Christiansen proposes the “planet demographics ladder,” as an analogy to the cosmological distance ladder, to bring the methods together where they overlap. Roman’s survey of the Galactic bulge will greatly extend our coverage of planets on orbits around and beyond an astronomical unit, which will work together with Kepler data to establish occurrence rates including η.

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Press Conference: Mergers, Bursts & Jets (by Ryan Golant)

The second press conference of AAS241 featured four speakers: Dr. Michael Koss of Eureka Scientific, Inc., Professor Vikram Ravi of the California Institute of Technology, Professor Cecilia Chirenti of the University of Maryland, and Sirina Prasad of the Harvard/Smithsonian Center for Astrophysics. The four talks covered a range of exotic high-energy phenomena, from merging black holes and neutron stars to fast radio bursts to radio emission around massive stars.

Dr. Koss spoke about the detection of two extremely close active galactic nuclei (AGN) in the galaxy UGC 4211; with a separation of only 750 light-years, these two AGN form the closest dual AGN system yet detected. This discovery was made possible by the combination of data across multiple regions of the electromagnetic spectrum: the bright nuclei were first identified in the near-infrared (using Keck’s impressive adaptive optics), then followed-up by millimeter observations from ALMA and optical observations from MUSE. UGC 4211 is thought to be the intermediate result of two merging galaxies and could thus serve as a valuable prototype for similar mergers of distant active galaxies; currently, the behavior of close-in merging supermassive black holes is poorly understood, but UGC 4211 should provide useful constraints on this process.

Illustration of dual active galactic nuclei

Illustration of dual active galactic nuclei. [ALMA (ESO/NAOJ/NRAO); M. Weiss (NRAO/AUI/NSF); CC BY 3.0]

Professor Ravi presented the first results from the Deep Synoptic Array (DSA), a new radio telescope at Caltech designed to simultaneously discover and precisely localize fast radio bursts (FRBs). In 2022, DSA discovered 30 FRBs, more than doubling the yield from all other FRB observatories. Furthermore, DSA’s impressive field of view, time resolution, and angular resolution allow it to localize FRBs to one-millionth of square degree on the sky — a localization accuracy roughly 600 times better than that of CHIME, another leading FRB instrument. With its remarkable specs, DSA is seeking both to better understand the origins of FRBs and to use FRBs to study the unseen hot luminous matter around and between galaxies; over 80% of the luminous matter in the nearby Universe is unseen, but the dispersion of radio pulses from FRBs can reveal the spatial distribution of this matter. The first results from DSA have already placed new constraints on the mass of the Milky Way’s circumgalactic medium — these results only used data from one DSA-detected FRB, leaving 29 more FRBs to analyze.

illustration of two neutron stars approaching a merger.

An illustration of two neutron stars approaching a merger. [ESO/L. Calçada]

Professor Chirenti described the discovery of two hypermassive neutron stars in archival gamma-ray burst (GRB) data. As two neutron stars merge, the system first emits a gravitational wave signal and then launches a short, violent GRB. Detailed computer simulations incorporating general relativity suggest that, in the time between the gravitational wave emission and the GRB, a single extreme neutron star can form; this hypermassive neutron star (HMNS) is short-lived, however, collapsing into a black hole in less than a second. Prof. Chirenti and her collaborators looked through data on 700 short GRBs from the BATSE instrument and identified two bursts (GRB 931101B and GRB 910711) that exhibited the quasi-periodic gamma-ray signal indicative of HMNS formation. These HMNSs demonstrate record-breaking characteristics for neutron stars, rotating twice as fast as the fastest pulsars and possessing 20% more mass than the most massive neutron stars. While we can currently only see these HMNSs via gamma rays, the next generation of gravitational wave observatories will be able to detect them via their high-frequency gravitational wave emission. (Side note: huge props to Prof. Chirenti who, in the face of computer audio issues during her talk, sang the gravitational wave and GRB frequency signals of a binary neutron star merger herself!)

Finally, Sirina Prasad discussed how recent ALMA observations have shed new light on the peculiar binary star system MWC 349. MWC 349a is a massive evolved star surrounded by regions of hydrogen recombination line maser emission; recombination line maser emission — which presents strongly at radio wavelengths — occurs when the capture of free electrons by free protons triggers stimulated emission. Previously, the Submillimeter Array (SMA) had observed maser emission in MWC 349’s circumbinary disk and in an hourglass-shaped region around MWC 349a caused by an ionized wind; while these SMA observations provided useful information on the dynamics of the disk and of the rotating and expanding wind, the precision of the study was limited by SMA’s angular resolution. ALMA’s superior angular resolution provided a much clearer picture of MWC 349’s maser emission regions, both confirming the disk dynamics and revealing a previously unobserved jet emerging from MWC 349a; this is the first time a collimated jet has been detected around a massive evolved star, thus raising new questions about the process of jet formation and the degree to which jets can impact binary star systems.

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Plenary Lecture: Rich Matsuda (California Association for Research in Astronomy) (by Briley Lewis)

photograph of Mauna Kea stewardship panelists

The panelists from the plenary on Mauna Kea stewardship. From left to right: Rich Matsuda, Dr. Noe Noe Wong-Wilson, John Komeiji. [Screenshot of AAS 241 livestream.]

(Note: If you are unfamiliar with the context of observatories on Mauna Kea, we highly recommend reading/skimming these bites on the history of astronomy on Mauna Kea, the 2019 TMT-related protests, and recent developments with the MKSOA before diving into this session!)

In the wake of the 2019 demonstrations on Mauna Kea and other movements towards social justice, the Astro2020 Decadal Survey recommended that astronomy should engage in sustained conversation and collaboration with local indigenous communities. One outcome of this recommendation is the creation of the Mauna Kea Stewardship and Oversight Authority (MKSOA), a governing body to collaboratively manage the care of the mountain and the future of astronomy on Mauna Kea. This afternoon’s plenary was a discussion, moderated by Ka’iu Kimura, with multiple members of the MKSOA: Rich Matsuda, former director of Maunakea Observatories, Dr. Noe Noe Wong-Wilson, a Hawaiian elder (kūpuna) who participated in the blocking of the summit access road, and John Komeiji, chair of the MKSOA.

“To do the best Earth-based astronomy requires access to places unpopulated by city lights… in many cases, those places also happen to be the ancestral lands of people who connect their lineage and heritage back to the beginning of their universe there as well,” said Kimura. “That is certainly the case for Mauna Kea.”

The road to the recent climactic conflict surrounding the Thirty Meter Telescope was long, as Wong-Wilson described in the session. At the time of the first telescopes in Hawai’i, local communities were overwhelmed by other changes brought about by colonization, but as early as the 1980s Native Hawaiians began to speak up in dissent. Despite “following the rules” and attending community meetings, filing public comments, and opening court cases, their voices went unheard, leading to the more severe actions of physical roadblocks in 2019.

Eventually, a working group was formed to determine a path forward and bring together the various voices in the debate around Mauna Kea. Although it was received initially with great skepticism, the working group produced useful recommendations that then became law, creating the MKSOA. Matsuda credits four ingredients to the success of the working group: relationship-building between the group members, creating a safe and equitable space for all to share opinions, gaining a deeper understanding of Hawaiian culture, and centering the one thing they all had in common — the Mauna itself.

The MKSOA is still in its early formative stages, and (as any government entity does) it will take time to fully develop. Around 14 billion dollars have been allocated to the MKSOA, and they will take the next five years to hire staff and get up and running. After that, it is their responsibility to create plans for the future of astronomy on Mauna Kea, for environmental conservation efforts on the mountain, and more. “Our overall purpose is to manage the mountain and try to understand how mutual stewardship actually happens,” said Komeiji.

All three panelists agreed on the deep importance of the task of caring for Mauna Kea, which is not only important for astronomy but also for defining the culture of Hawai’i in future years. “We are going to be the generation that could finally come together and figure out how to take care of our Mauna,” said Wong-Wilson.

“I hope all of you didn’t see this as only a Hawai’i issue, or only an astronomy issue,” added Matsuda. He emphasized that it is a time to think about systems and whether they’re inclusive, equitable, and allowing everyone’s voices to be heard. The working group and subsequent creation of the MKSOA is truly a testament to the power of community-building when the right relations are prioritized, such as the spirit of the Hawaiian Kapu Aloha. Although Matsuda and Wong-Wilson were once seen as polarized opposition in a false dichotomy between science and culture, they have “been able to forge an unbelievable relationship” according to Kimura, praising how the two have come together to create a better future for Hawai’i.

“Out of extreme challenges come opportunities for new ways forward and new relationships,” said Kimura. In the spirit of the MKSOA, she ended the session by encouraging everyone to build relationships with those who have differing opinions — and with the land they are on.

You can view live tweets of this session by Briley Lewis here.

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Newton Lacey Pierce Prize Lecture: Erin Kara (MIT) (by Graham Doskoch)

How do you study the environment around supermassive black holes (SMBHs for short)? These gargantuan beasties may be massive, but when viewed from millions of light-years away, they look small and dim. Fortunately, there’s a way around this — and that was the focus of the plenary talk given by Prof. Erin Kara, the recipient of the Newton Lacey Pierce Prize.

Prof. Kara took us through two intertwined journeys: one personal, one scientific, with valuable lessons from both. Her path through astronomy began as an undergraduate at Barnard College, where she took a physics class taught by Prof. Reshmi Mukherjee and fell in love with the cosmos. She also learned a valuable lesson: always find a good mentor. Prof. Mukherjee certainly was, and Kara soon found herself entering graduate school.

Around the same time, astronomers were making big strides in the study of a subset of supermassive black holes called active galactic nuclei, or AGN. These are SMBHs which are accreting matter; as that matter falls into the black hole, its gravitational potential energy is used to power relativistic jets or is transformed into high-energy X-rays. AGN are more luminous than quiescent SMBHs and can be detected at a variety of wavelengths, but traditional methods couldn’t reach the minute scales needed to probe their inner depths.

Fortunately, astronomers developed a way around this problem with a technique called reverberation mapping. Some of the x-rays created by infalling matter will be “echoed” off the accretion disk, which gives us information about the disk’s structure. Prof. Kara used a more down-to-Earth analogy: audience members could hear sound waves traveling directly from her mouth to their ears, but they could also hear echoes from her as other sound waves bounced off the walls. If someone precisely measured the arrival times of these echoes and calculated the speed of sound, they could determine the shape and size of the room they were in.

Reverberation mapping isn’t quite that simple — but then again, research rarely is. This was the second lesson Prof. Kara shared, the one she learned as a graduate student: every research project ebbs and flows, with periods of stagnation and periods of productivity. The secret to success is having people around you who will support you when you hit those walls.

Taking advantage of the information gathered by reverberation mapping requires adjustments and corrections. For example, AGN exhibit random, stochastic variability, which can drown out the light echoes. Astronomers can get around this by Fourier transforming the data and searching for signals that travel on different timescales than the stochastic variations; these are signals of the echoes. They also have to take into account relativistic effects, from both the intense gravitational pull of the black hole and the fast-moving matter in the accretion disk.

AGN aren’t the only objects that can be studied using reverberation mapping. Other promising targets include tidal disruption events and even stellar-mass black holes in binary systems. The latter group of objects can emit X-rays if their companion is a normal star; astronomers refer to these systems as X-ray binaries. They’re interesting because they undergo outbursts, but on timescales of only months to a year. This makes them potential analogs for AGN, which can evolve similarly but on much longer timescales.

As another interlude, Prof. Kara discussed a third lesson, from her time as a postdoc: branch out in your research, and work with new collaborators. Reverberation mapping is being applied to new types of objects and is yielding exciting new results; the same can be true for any astronomer poking their nose into a new subfield.

The study of X-ray binaries has been aided by NICER, on the International Space Station. Prof. Kara described some work that has been enabled by NICER, led by Kingyi Wang, a PhD student at MIT. Wang created a pipeline to study X-ray binaries and track them over the course of an outburst. Her results show that as the emission changes throughout an outburst, the lag times of light echoes can increase by an entire order of magnitude — so something in the X-ray binary is physically changing size by quite a lot! One possible culprit could be the relativistic jets given off by the accreting black hole.

Prof. Kara gave one final bit of advice, this time from her years as a professor: “Don’t forget about your hobbies!” Astronomers are human beings, not machines; we need rest and relaxation and time away from our work.

Prof. Kara closed the talk by showing some examples of sonification applied to AGN. Sonification is a method of turning images into sounds, making them accessible to visually impaired folks without losing any of the information. She showed several model AGN echoes and their sonified counterparts, joking, “You can hear the general relativity in these simulations!” She was right — and it was spectacular.

Prof. Kara spoke to Astrobites about her experience and you can read the post here.

You can view live tweets of this session by Graham Doskoch here.

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JWST Town Hall (by Graham Doskoch)

Judging by the hundreds of papers about data from its first months of observations, astronomers can’t get enough of JWST. Appropriately enough, then, we both began and ended the day with sessions about the telescope and its results. To complement the morning’s plenary lecture by Dr. Jane Rigby, the evening brought us the JWST Town Hall, a set of short talks describing the mission, the telescope’s performance so far, and the resources available to astronomers using it.

Bridget Samuelson, of Northrop Grumman, opened the session with a brief welcome and a reminder of the public recognition JWST has already achieved. Northrop Grumman is one of the leading contractors on the telescope’s design and fabrication, and Samuelson has played several roles during the odyssey to send it to space. She noted that excitement about JWST hasn’t worn off — in fact, the team was just awarded the Goddard Memorial Trophy.

Next to take the podium was Dr. Nancy A. Levenson, who is currently serving as the Interim Director of the Space Telescope Science Institute (STScI). She showed some of the most famous early images from JWST: iridescent nebulae, mind boggling spectra, and deep galaxy fields. Dr. Levenson gave a brief overview of the role STScI plays for JWST. It’s the Missions Operations Center for the telescope, and handles proposals, data collection, communication with observers, and much more. She also drew attention to the JWST Users Committee (JSTUC), which provides a voice for the astronomers using the telescope.

Dr. Levenson was followed by Dr. Jonathan Gardner, of Goddard Space Flight Center, who gave updates on improvements since the telescope’s launch. After a notable micrometeoroid impact in May 2022, the team decided to implement a micrometeoroid avoidance zone in the next observing cycle. In August, an increase in friction was noticed in one of the grating wheels of the Mid-Infrared Instrument (MIRI), leading the team to pause one particular MIRI observing mode until November while the cause was investigated. Dr. Gardner also noted that the telescope briefly went into safe mode in December after a software problem hit the attitude control system, but was brought back online within a couple days, with minimal disruption to science operations.

Dr. Gardner finished by walking through some of the science highlights since observing began last year, including the highest-redshift images taken to date, wonderful exoplanet spectra, and observations of barred spiral galaxies only a few billion years after the Big Bang. Judging by JWST’s images showing up everywhere from Times Square to a Coldplay concert, the public might be almost as excited by the results as the astronomers who found them.

The next speaker was Dr. Jane Rigby, the Project Scientist for Operations for JWST, who had given the Fred Kavli Plenary Lecture that morning on the telescope’s science performance. In her Town Hall segment, she shared similar information, noting that JWST has exceeded expectations in many of its performance metrics. She highlighted how the smooth mirrors have enabled exceptional sensitivity, and the telescope’s pointing and guiding abilities have far exceeded what was required. The micrometeoroid impact was worrisome, but as Dr. Gardner mentioned, measures are being taken to avoid repeat events. Dr. Rigby noted that with two decades worth of fuel, nobody knows what will eventually limit JWST’s operating lifetime — but it will be sticking around for a while.

Dr. Rigby was followed by Dr. Klaus Pontoppidan, who described the work of the Science and Operations Center during Cycle 1 observations. The Center performs a variety of tasks, including coordinating observations, supporting proposal calls for Cycle 2, public outreach, and more. It also continues to improve the automatic calibration pipeline that processes the data, as well as the many tools available to astronomers using JWST or working on proposals.

To give a view of the mission timeline, the next speaker was Dr. Christine Chen, representing the JWST Science Policy Group at STScI. She reminded everyone that the call for Cycle 2 proposals is out, with the submission deadline of January 27 approaching. Over 5,000 hours will be available for General Observer Programs, with additional time set aside for parallel, survey or archive programs and JWST Joint Programs with other telescopes, like ALMA or the Hubble Space Telescope. PIs will be notified of decisions in May, and Cycle 2 itself will start in July. Looking further ahead, the call for Cycle 3 proposals will be officially made on August 15, with a deadline of October 27, and Cycle 3 will begin in July of 2024.

As if to inspire the audience to finish any proposals by January 27, Dr. Chen was followed by Dr. Amaya Moro-Martín, who described some of the science highlights from the Early Release Science (ERS) programs. These teams were responsible for some of the first JWST results this past summer, and include the CEERS, TEMPLATE and Q3D groups. Over 175 papers have appeared on arXiv in the 6 months since science observations began, and ERS programs deserve a lot of credit for these early strides.

The session finished with a brief overview of how JWST press releases work. Teams using JWST data who believe they have a significant result can submit their results to STScI, which will make a determination. If the research seems to warrant a press release, STScI will create text and visuals, which will then be reviewed by the team and by NASA. The overarching lesson is to talk to the STScI team sooner rather than later, to give them adequate time to work on a release before a paper is published.

You can view live tweets of this session by Graham Doskoch here.

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Banner announcing astrobites's coverage of the 241st AAS meeting

This week, AAS Nova and Astrobites are attending the American Astronomical Society (AAS) winter meeting in Seattle, WA, and online.

AAS Nova Editor Kerry Hensley and AAS Media Fellow Ben Cassese will join Astrobites Media Intern Zili Shen and Astrobiters Macy Huston, Briley Lewis, Yoni Brande, Pratik Gandhi, Graham Doskoch, Mark Popinchalk, Ali Crisp, Isabella Trierweiler, and Ryan Golant to live-blog the meeting for all those who aren’t attending or can’t make all the sessions they’d like. We plan to cover all of the plenaries and press conferences, so follow along here on aasnova.org or on astrobites.org! You can also follow @astrobites on Twitter for the latest updates.

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! In addition, you can catch Kerry, Ben, and Zili at the press conferences all week.

You can also catch us at several sessions throughout the meeting:

Astrobiter Briley Lewis will give a talk during the Resources and Education Research for Introductory Astronomy Courses session titled “Effects of Popular Science Writing Instruction on General Education Student Attitudes Towards Science: A Case Study in Astronomy” on Monday, January 9, from 10:20 to 10:30 am PT (program number 115.03). Briley will also speak during the ExoExplorers special session titled “Early-Career Perspectives on the Intersection of Exoplanet Science and DEIA in Astronomy” on Tuesday, January 10, from 2:45 to 3:00 pm PT (program number 255.04).  Briley’s talk, “Considering Disability and Accessibility in Astronomy,” will describe “challenges faced specifically by disabled astronomers in our field, share personal experiences with accessibility and creating accessible events (e.g., planetarium shows accessible to blind and d/Deaf audiences), highlight the work of leaders in accessibility in astronomy, and make recommendations for how you can contribute to accessibility.”

Astrobiter Ryan Golant is co-leading the AAS National Osterbrock Leadership Program (NOLP) splinter session from 2:00 to 3:30 pm PT on Tuesday, January 10. You can also read the astrobite Ryan wrote about the program last month.

You can read the currently published AAS 241 keynote speaker interviews here. Be sure to check back all week as the remainder are released!

banner announcing the 241st meeting of the American Astronomical Society

AAS 241 is nearly here! The AAS Publishing team looks forward to connecting with meeting attendees in Seattle, WA, and online, and we’re excited to share a preview of upcoming publishing-related events. Also, be sure to stop by the AAS booth in the Exhibit Hall, which will be staffed by several members of the publishing team, including Julie Steffen (AAS Chief Publishing Officer), Ethan Vishniac (AAS Journals Editor in Chief), Frank Timmes (AAS Journals Associate Editor in Chief), and AAS Journals Data Editors Greg Schwarz and Gus Muench. At the booth, you can test drive the augmented reality experience newly added to the AAS journals (and get your very own augmented reality Merge Cube!) and learn more about the upcoming AAS journals peer review workshop, which will take place in February.

AAS Nova Editor Kerry Hensley, AAS Media Fellow Ben Cassese, Astrobites Media Intern Zili Shen, and the rest of the Astrobites team will also be available at the Astrobites booth in the Exhibit Hall.

AAS Production at IOPP: Workflow, Language Editing, and the AAS Style Guide

Tuesday, January 10, 10:00 am PT | iPoster Theater

Concision and clarity are essential to ensuring that your research is meaningful and understandable to the American Astronomical Society (AAS) community. Senior members of the AAS production team explain in this session how Institute of Physics Publishing (IOPP) assists in that mission with publishing and editing expertise. We will focus on the centrality of the AAS Style Guide in achieving that clarity required in your scientific discipline and on how the Language Edit team at IOPP helps you apply the principles of AAS style most effectively.

Keywords and Descriptive Metadata in Astronomy

Over the years, there have been many efforts to codify and create lists of relevant keywords for the astronomy community. In the early days, these vocabulary lists were just that, alphabetical lists of astronomy terms, sometimes arranged into a shallow hierarchy. The most recent effort along these lines is the Unified Astronomy Thesaurus (UAT), which adds a deep hierarchy to organize and define relationships between astronomical concepts, as well as being built using modern technology standards that allow it to integrate with online platforms and services.

The real strength of the UAT is its open call for community feedback. Like all scientific fields, the astronomy community is made up of a diverse group of experts, including both researchers who specialize in narrow fields and those who have a broad understanding of general astronomy. Drawing upon those experts to influence the content and direction of the UAT is what keeps the project relevant and useful as it sees wider adoption.

Stop by the American Astronomical Society (AAS) booth during the morning coffee breaks to catch up with Katie Frey, Curator of the Unified Astronomy Thesaurus. Learn about how the UAT has been implemented by institutions such as the AAS, the Publications of the Astronomical Society of the Pacific, and the Space Telescope Science Institute. Explore the concepts, structure, and hierarchy of the UAT. Do you have any feedback about the UAT? Katie would love to hear it!

Where to find the UAT at AAS 241:

Monday, January 9th Tuesday, January 10th
AAS booth (#627) 9:00 – 10:30 am AAS booth (#627) 9:00 – 10:30 am
CfA booth (#431) 1:30 – 6:30 pm CfA booth (#431) 10:30 am – 1:30 pm
AAS booth (#627) 5:30 – 6:30 pm
Wednesday, January 11th Thursday, January 12th
AAS booth (#627) 9:00 – 10:30 am AAS booth (#627) 9:00 – 10:30 am
CfA booth (#431) 12:00 – 2:00 pm AAS booth (#627) 5:30 – 6:30 pm
AAS booth (#627) 5:30 – 6:30 pm

NOIRLab Legacy Mosaic Data Rescue Project

Sunday, January 8, 4:15–4:30 pm PT | Seattle Convention Center, Room 614

AAS Archive Fellow Nick Foo and AAS Chief Publishing Officer Julie Steffen will present on a collaborative project being carried out by the AAS and NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab) to conduct a rescue project on the legacy mosaic data archived by the National Optical Astronomy Observatory (NOAO; National Optical Astronomy Observatories pre-FY2000). In the mid-1990s, telescopes at Kitt Peak National Observatory (KPNO) and Cerro Tololo Inter-American Observatory (CTIO) made the significant transition to archiving digital observational data stored on magnetic exabyte tapes. From 1993 until 2004 5+ million raw data files on 9,000+ unique data magnetic tapes were collected in the NOAO Science Archive. In the present day, the 8-mm tape format is obsolete, and the data have been offline for the past 20–30 years despite numerous possibilities for archival research. Eventually, they will not be recoverable because the tapes will degrade over time, and the hardware that is required will no longer be available. Using a bank of 8-mm tape readers, the recovery project team has managed to extract and catalog the data. So far, nearly all Mosaic-1 wide-field images have been recovered. Currently, existing pipeline software is being developed to perform calibration and basic analysis to produce science-ready images. All observations recovered from the project will be publicly accessible via the Astro Data Archive ingest. Hopefully, the unveiling of previously dark data will initiate and inspire numerous archival research investigations in the future.

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