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.

composite optical and X-ray image of Uranus

Editor’s Note: This week we’ll be writing updates on selected events at the 54th Division for Planetary Sciences meeting in London, Ontario, and online. This post covers the last three days of the meeting. The usual posting schedule for AAS Nova will resume on October 10th.

Table of Contents:

Bold Ideas Plenary Session

Planetary Atmospheres and the Search for Signs of Life Beyond Earth (Sara Seager)

Just 30 years ago, exoplanets were a wild and unpromising idea. Even when the first transiting exoplanet was discovered in 1999, many researchers thought the field wouldn’t go anywhere; sure, exoplanets exist, but the measurements are just too hard to make. In the first of today’s plenary talks, Sara Seager (Massachusetts Institute of Technology) reminded the audience that the line between what is accepted and what is dismissed is constantly changing, and ideas that seem outlandish may someday advance our understanding.

Seager’s talk focused on the search for life on worlds outside our solar system, especially the concept of biosignatures: chemical compounds in the atmosphere of a planet that indicate that life is present. While detecting life in this way sounds simple, Seager delineated the many reasons that it’s not. Part of the issue is our observational constraints, which push us to search for life-bearing planets around the smallest stars, M dwarfs, in search of a strong signal. M dwarfs are far more active and variable than the Sun, which spells trouble for the observational side of the issue (variability can drown out subtle atmospheric signals) as well as the biological side — during an M dwarf’s lengthy “teenage” phase, its extreme thermal output might doom any life that arises on nearby planets.

presentation slide explaining the objections to the discovery of phosphine in the atmosphere of venus

An explanation of the main objections to the discovery of phosphine in Venus’s atmosphere. Click to enlarge. [Slide by Sara Seager]

And claiming detection of a biosignature gas is just the beginning: in 2020, a team led by Jane Greaves announced the detection of a radio transition of phosphine, a gas produced by life on Earth, and controversy ensued. Some research groups cast doubt on the presence of the phosphine line, and others acknowledged its presence but attributed it to a less exciting gas, sulfur dioxide. The question of whether phosphine is an indisputable biosignature at all loomed over the technical debate. While further work by Greaves and collaborators, including Seager, presented new corroborating observations from the James Clerk Maxwell Telescope and archival observations from the Pioneer Venus mission, investigated the sulfur dioxide possibility and found it unlikely, and presented evidence against non-biological origins for phosphine on Venus, the debate continues.

This process shows that science is working, Seager notes, and the back and forth incited by the potential discovery of a biosignature gas in our planetary backyard will likely play out for years to come. And we know far more about Venus than we do about any exoplanet — imagine the debate that would follow the first detection of phosphine on an exoplanet! (As an aside, Seager noted that phosphine is hardly the most outlandish Venus-related proposal — major depletion of sulfur dioxide in Venus’s atmosphere could be explained by ammonia-producing life that partially neutralizes the sulfuric acid within the clouds. A tidy explanation, or optimistic humans connecting unrelated data points? It’s up for debate!)

Seager concluded with a bevvy of tantalizing (or unpromising, depending on your opinion!) possibilities: Breakthrough Starshot would send thousands of miniature spacecraft on a life-finding mission; a solar gravitational lens telescope would boost our technological capabilities; and an Earth-like planet orbiting a white dwarf would give us a chance to detect gases associated with technological processes, like sulfur hexafluoride. The possibilities are wild and endless — buckle up for a decades-long search for life beyond Earth!

Return to Table of Contents.

A Unique Origins Survey: Gaia-Enabled Occultation Measurements of Small Bodies in the Outer Solar System (Marc Buie)

In order to understand the origins of our solar system, we need to understand the small bodies of the outer solar system. So says Marc Buie (Southwest Research Institute), who chases outer solar system bodies from Earth by watching them block the light from distant stars. Part of the challenge of studying these far-flung objects is that you need to study a lot of them to make firm conclusions, so chasing down individual objects with an expensive spacecraft, à la New Horizons’s pursuit of Pluto and Kuiper belt object Arrokoth, is infeasible. Instead, ground-based efforts with telescopes of modest size can play an important role.

color image of Arrokoth

A composite image of the Kuiper belt object Arrokoth, which is a contact binary. [NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Roman Tkachenko]

The New Horizons mission is a source of inspiration for Buie; tracking down Arrokoth prompted scientists to devise new analysis techniques and ways of processing data, and observations of the curious contact binary forced researchers to rethink theories of how objects in the outer solar system formed. Since researchers observed Arrokoth from the ground via a stellar occultation — watching as it blocked the light from a star — before New Horizons encountered it, Buie hopes that linking the ground-based observations to the space-based observations will help us draw better conclusions from ground-based observations of other outer solar system objects.

Using data from the Gaia spacecraft, which has made exceptionally precise measurements of the positions and motions of stars in the Milky Way, Buie anticipates being able to study large numbers of outer solar system objects using stellar occultations. This technique has already allowed us to detect 10-km-scale surface features on the five asteroid targets of the Lucy mission, and it should allow us to constrain collisional processing and cratering of outer solar system objects without sending a spacecraft to them. Multiple possibilities exist for implementing this kind of program, including a fixed robotic array of thirty 28-cm telescopes or a mobile array of small telescopes transported worldwide by trained observers.

While the price tag for implementation might seem large — Buie estimates that observing ten 20-km Kuiper belt objects would require $7 million to cover equipment, travel, and personnel costs — it’s far cheaper than a spacecraft mission. Buie points out that rather than a scientific or technological stumbling block, the issue is a programmatic one; while funding exists for small, speculative projects and massive, spaceflight-ready endeavors, there is something of a funding desert in between these two extremes, making what Buie calls “team science” difficult to get started. In the future, Buie hopes that the planetary science community will consider the kinds of team science it wants to pursue in addition to the kinds of spacecraft missions it hopes to launch.

Return to Table of Contents.

Astrobiology in the Era of Big Data: Leveraging Chemometrics for Prebiotic Chemistry and Planetary Exploration (Laura Rodriguez)
diagram showing the relationships between multiple data science and artificial intelligence themes

An explanation of where chemometrics fits in relative to other data science and artificial intelligence concepts. Click to enlarge. [Slide by Laura Rodriguez]

Laura Rodriguez (NASA’s Jet Propulsion Laboratory, soon to be at the Lunar and Planetary Institute) puts computers to work to help us find the best places to search for life beyond Earth. Using chemometrics — an umbrella term that encompasses a variety of computing techniques applied to chemical data — Rodriguez studies prebiotic chemistry, or the formation of organic compounds that may lead to the formation of life.

Prebiotic chemistry is often studied as a way to probe the origins of life on Earth, but it’s also important for predicting where else in the solar system we might find life. By delving into the formation of molecules in different sites around the solar system, we can start to understand the conditions necessary for life to evolve as well as evaluate compounds proposed as biosignatures — even large molecules like ATP (an important organic molecule in the human body that helps deliver energy to our cells) can form without life being present.

Planetary science missions, especially those tasked with searching for life, represent the intersection of the study of prebiotic chemistry and machine learning. Spacecraft missions have reached the point where the instruments are able to collect a massive amount of complex data. While it’s possible for a spacecraft to dutifully beam these data back to Earth to be pored over by scientists, this process is slow and energy consuming, especially for spacecraft exploring the icy worlds of the outer solar system. Instead, Rodriguez proposes that spacecraft be given the tools to make the first analysis pass themselves, engaging in preprocessing steps that help them decide what to do next, without human intervention.

mass spectrum of the plumes of enceladus

A simplified mass spectrum showing the types of compounds detected in the plumes of Enceladus by the Cassini spacecraft. Click to enlarge. [NASA/JPL/SwRI]

As examples of how this might work, Rodriguez introduced three common techniques for studying chemical compounds on other planets: mass spectrometry (an excellent way to search for biosignature gases; the Dragonfly mission to Titan will carry a mass spectrometer), laser-induced breakdown spectroscopy (used by the Mars rovers to analyze soil samples), and Raman spectroscopy. Rodriguez introduced a rapid and flexible algorithm that could be used by spacecraft to preprocess spectroscopic observations. The process starts with slicing a spectrum into small windows without cutting into important features, allowing the algorithm to fit functions to individual windows separately, increasing the chances of a successful fit. This would allow the spacecraft to deconvolve overlapping spectral lines and rapidly analyze a complex spectrum. Rodriguez also developed a way for spacecraft to predict the chemical formulae corresponding to the peaks in a mass spectrum.

Ultimately, chemometrics will benefit many planned and proposed missions such as the Mars Sample Return program, a Europa lander, and a Ceres sample return mission, allowing spacecraft to make the decisions necessary to optimize limited time, energy, and resources.

Return to Table of Contents.

Workforce Plenary Session

Behind the Myth of Meritocracy: How STEM Fields Perpetuate Racial and Gender Disparities (Adia Harvey Wingfield)

Adia Wingfield, a professor of sociology from Washington University in St. Louis, described the current state of racial and gender diversity in science, technology, engineering, and math (STEM) fields in the United States, the issues facing scientists and engineers belonging to underrepresented groups, and how organizations can work to improve the representation of these groups.

pie charts comparing the demographics of the STEM workforce with the demographics of the United States population overall

Comparison of the demographics of the STEM workforce (top) to the demographics of the US population (bottom). Click to enlarge. [Adapted from slides by Adia Wingfield]

First, the current status: in STEM fields, white men are overrepresented, making up 49% of STEM professionals but just 27% of the US population, as are Asian American men and women, making up 14% and 7% of the STEM workforce and 2.6% and 2.9% of the US population, respectively. All other groups are underrepresented to varying degrees. (See the figure to the right for a full breakdown.)

What’s the cause of this disparity? There are several common — and incorrect — assumptions about the causes of workplace disparities: women tend to prioritize family over work; Black and Latino workers aren’t as qualified; it’s hard to recruit these workers, and once they’re recruited they leave for other opportunities; and STEM is a meritocracy where everything is fair and equal, so these disparities are really out of our control.

In reality, there are biases in the hiring process that disproportionately impact workers belonging to underrepresented groups; unspoken norms and organizational culture can create a “chilly” environment for many employees; harassment is pervasive; and tokenism remains an issue. These issues are wide ranging, and some issues affect people belonging to certain groups more than others (e.g., gender and sexual minorities are more likely to face issues with sexual harassment; tokenism is a complex issue, especially for people who are in the majority with respect to gender but in the minority with respect to race).

As academics, we can learn from the techniques used in corporate settings. Targeted recruitment — turning to historically Black colleges and universities and predominantly Latino-serving institutions rather than solely leveraging existing networks — can open up organizations to job candidates who would otherwise not be part of the applicant pool; formal mentoring programs help connect new hires belonging to underrepresented groups to the rest of the organization, and these programs are especially successful when mentors are incentivized to be invested in the success of their mentees; sexual harassment training with a helpful, rather than punitive, focus (e.g., focusing on bystander intervention rather than the legal consequences of harassment) can improve the organizational climate; and diversity task forces that are given the power to enact change and involve people from all levels of an organization can increase the proportion of historically excluded groups at the managerial level. These techniques, which in a five-year survey were shown to increase recruitment and retention of minoritized individuals, are likely applicable to academic institutions as well.

Return to Table of Contents.

Press Conference

graph of survey results about participation in mission proposals

Survey results regarding participation in mission proposals as principal investigator and co-investigator. [From slide by Julie Rathbun]

Julie Rathbun (Planetary Science Institute) introduced the results of a survey regarding diversity, equity, inclusion, and accessibility in planetary science. The survey, which was funded by the Division for Planetary Sciences, was the result of the latest National Academies of Science Planetary Decadal Survey, which was released earlier this year. For the first time ever, the Decadal Survey included a call to assess the state of the planetary science workforce. The survey results showed that women, disabled scientists, and scientists belonging to the LGBTQ+ community were statistically less likely to be involved in planetary science missions. These results indicate that even after navigating the barriers to entering the field — which are higher for members of historically excluded groups — there are further barriers once you get through the door. Press release

model of the asteroid Phaethon's shape

A shape model of asteroid 3200 Phaethon derived from stellar occultation observations. [From slide by Sean Marshall]

Sean Marshall (Arecibo Observatory and University of Central Florida) reported on the unusual rotation of the asteroid 3200 Phaethon. Phaethon is the first asteroid to have been discovered in spacecraft data, it’s one of the largest potentially hazardous asteroids (Marshall emphasized that its orbit is well known and it’s not a threat to Earth), and it’s also the parent body that provides the dust for the Geminid meteor shower. Phaethon is also the target of the Japanese Space Agency’s DESTINY+ mission, which is scheduled to launch in 2024 and fly by the asteroid in 2028. Over the course of repeated observations, researchers realized that Phaethon’s rotation rate wasn’t matching up with predictions, suggesting that its rotation rate has changed. Thanks to 32 years of observations, Marshall and collaborators were able to discern a slight increase in the asteroid’s spin rate — equivalent to a 4 millisecond decrease in its rotation period each year — making Phaethon the largest asteroid known to have a changing rotation period. The cause of this change is unknown, and the leading hypotheses (solar radiation, asteroidal activity) have major issues. Hopefully, DESTINY+ will provide some answers!

You can watch a recording of this press conference on the AAS Press YouTube channel.

Return to Table of Contents.

Looking Forward/Looking Back Plenary Session

Questions Convey Us: Our Human Exploration of the Solar System, 1962 to Now (and After) (Emily Lakdawalla)

Freelance science writer and planetary scientist Emily Lakdawalla kicked off the final plenary of DPS 54 with a perspective on the history and future of planetary science. Planetary science was born of the merger of two scientific endeavors: astronomy and geography. Astronomy began with humans peering at the night sky, trying to understand what importance the stars held for us, and asking questions about our origins. Initially a solitary endeavor, early astronomy was limited to those with the money to build expensive telescopes. And while early astronomers sometimes guarded their data jealously, astronomy has evolved into one of the most open of the scientific fields.

Geography, on the other hand, began with large surveys funded by the reigning governments of newly conquered territories. These surveys thus involved large numbers of people working together, and they evolved to incorporate information about natural hazards such as flood or earthquake risks, which was shared publicly in accessible databases. It’s impossible to ignore the checkered history of geography, which played an important role in assessing the value of lands acquired forcefully in the colonial era.

map of the moon made by USGS

The first map of the Moon created by the US Geological Survey. [USGS]

Astronomy and geography came together in the form of planetary science when the US entered the space race during the Cold War, promising to reach the Moon. The US Geological Survey created the first map of the Moon and participated in training the Apollo astronauts in geological field techniques. Evidence of planetary science as a tool for international relations came in the form of the many Moon rock samples gifted to other countries. But when the Apollo program concluded, the field of planetary science nearly vanished. Luckily, the Voyager and Viking spacecraft had already been launched, and the iconic images returned by these missions bolstered public opinion and revitalized the field.

Lakdawalla commented on the traditions — both positive and negative — that planetary science retains from its forebears, astronomy and geography. The secretive guarding of data remains an issue (Lakdawalla recounted the case of a spacecraft instrument whose calibration method was never written down in order to maintain the relevance of the sole expert who knew the method; those data are now nearly useless), but planetary science has evolved into an incredibly open field; the existence of the arXiv and the Planetary Data System are proof of that fact.

Lakdawalla closed with some notes of caution for our field: as our exploration of the solar system continues, we must be mindful not to follow the exploitative origins of geography as we consider how best to study these worlds without contaminating them; we must be patient when planning ambitious, decades-spanning missions, and be mindful that these missions may not be for us, but for others who will benefit from them in the future; we’ll need to work hard to convey the importance of the moons and small bodies in our solar system now that all of the planets have been visited by at least one spacecraft; and we should seek to combat the colonialistic tendencies of private space exploration by being sure to include everyone in space exploration, especially those who have been traditionally excluded.

Return to Table of Contents.

The James Webb Space Telescope: A New Era of Science for All (Eric Smith)
an image of JWST fully assembled

JWST, fully assembled for the first time. [NASA/Chris Gunn]

It’s not just for astronomy: JWST has already proven its immense worth to the field of planetary science, and more discoveries are sure to come. Eric Smith (NASA Headquarters) gave an overview of the technical challenges of building JWST and how it will impact the field of planetary science. JWST, as most readers likely know, is a feat of engineering, designed to overcome stringent technical challenges imposed by observational goals. The design and construction of the telescope spanned the tenures of six NASA administrators, and JWST benefited greatly from public support during rough patches in the process.

Smith noted that planetary science proposals during Cycle 1 were particularly successful, with the proportion of selected planetary science proposals being larger than the proportion of submitted proposals. Solar system science will use 7% of the observing time during Cycle 1, amounting to 607.5 hours, 25% of which has already been completed. More than a third of the Cycle 1 planetary science proposals have no exclusive use period, which means the data will become publicly available immediately. Exoplanet science makes up 29% of Cycle 1, requiring 2,516.7 observing hours for 96 programs. Smith commented that several of the Cycle 1 proposals were actually archival proposals, perhaps making this the first mission for which archival proposals were selected for data that hadn’t yet been taken!

illstration of JWST's location at L2

Illustration of JWST’s berth at L2. [STScI]

In the time since JWST settled into its orbit at L2, it’s become clear that the telescope’s performance will exceed expectations. Thanks to an exceptional launch, it didn’t have to spend fuel getting into position and can instead put that fuel toward extending its lifetime — it’s expected to last twice as long as the initial goal. Its sensitivity, pointing stability, moving target tracking, and other factors are also far better than anticipated. And while a strike from a larger than anticipated micrometeroid prompted some panicked headlines, the team is ready to handle those as well; by rearranging the observing programs that do not require the telescope mirror to be pointing in the telescope’s direction of motion, we can limit the impact of these events. JWST has spurred a flurry of scientific activity; Smith estimated that an average of 3–4 JWST-related science papers are published on the arXiv every day — and the mission is just getting started!

Return to Table of Contents.

A Future Mission to Uranus: Exploration of Five Possible Ocean Worlds and a Bevy of Small Icy Moons (Richard Cartwright)
Voyager 2 image of Uranus

A classic Voyager 2 photo of Uranus, taken in 1986. [NASA/JPL-Caltech]

Richard Cartwright (SETI Institute) delved into the icy moons orbiting one of the least explored planets in our solar system: Uranus. While the moons of Jupiter and Saturn were illuminated by the Galileo, Juno, and Cassini missions, Uranus’s 27 moons had only the briefest moment in the limelight following a flyby by Voyager 2. Uranus’s moons fall into three categories: ring moons, classical moons, and irregular moons. Voyager 2 gave us a glimpse of the southern hemispheres of Uranus’s five classical moons (Miranda, Ariel, Umbriel, Titania, and Oberon) and the largest of the ring moons, Puck, in addition to revealing 11 new moons. But these Voyager observations prompted far more questions about Uranus’s collection of moons than they answered: How did the moons form? What do their northern hemispheres look like? Do they have residual oceans? What is the charged particle and dust environment around the moons?

Luckily, the most recent Planetary Decadal Survey prioritized an orbiter and probe to Uranus, opening an avenue for us to answer these questions. Cartwright gave an overview of what we know about Uranus’s moons, what we don’t, and how we might design a spacecraft to the Uranian system to get answers.

Uranus’s 13 ring moons form the most compact group of satellites in our solar system. Only Puck has been spatially resolved in previous observations, and we don’t know the ages of these objects or what their surfaces are like. Perhaps most intriguing of the ring moons is the outermost, Mab, which is likely only 6–12 km in diameter and is probably associated with the dusty μ ring. Given the compactness of the system, it’s likely that the moons share material in an interesting way.

voyager 2 image of Miranda

A detailed view of the surface of Uranus’s moon Miranda. [JPL]

Of the 5 classical moons, Ariel has the best evidence for cryovolcanism, showing a long groove reminiscent of fissure-style volcanism on Earth. Umbriel has the oldest and darkest surface but sports a bright region that may also be related to cryovolcanic activity. Miranda also has the potential to be active, since some craters look like they’ve been filled in with some material — although other craters, even nearby ones, have not. Miranda also lacks the hemispheric asymmetry in water ice and reddish surface material that the other large moons have. It’s possible that Miranda formed at a different time from the other classical moons. As Cartwright points out, there’s simply so much we don’t know about these moons!

In terms of a potential future mission to the Uranian system, Cartwright recommends an orbiter, which offers the best chance of studying internal oceans and geologic processes on the moons. An ideal suite of instruments would include a magnetometer, cameras (optical and mid-infrared), a near-infrared mapping spectrometer, particle and dust detectors, and an ultraviolet spectrograph. Timing is important, too — launching the mission in time to catch the Jupiter gravity assist window in 2030–2034 would get us to Uranus faster and get this long-awaited science started!

Return to Table of Contents.

photograph of a hill in Mars's Jezero Crater

Editor’s Note: This week we’ll be writing updates on selected events at the 54th Division for Planetary Sciences meeting in London, Ontario, and online. This post covers the first two days of the meeting, and a second post on Friday will cover the remainder of the meeting. The usual posting schedule for AAS Nova will resume on October 10th.

Table of Contents:

Astromaterials Plenary Session

Collecting Samples of Mars: The NASA Perseverance Rover’s Role in Mars Sample Return (Chris Herd)

Chris Herd (University of Alberta) kicked off the first plenary session of DPS 54 with an introduction to how the Perseverance rover will contribute to the goals of the Mars Sample Return program, which plans to deliver samples of the Martian surface to Earth in 2033.

Perseverance rover's travel path

Illustration of the path Perseverance has traveled. Click for high-resolution version. [Slide by Chris Herd]

Herd described Perseverance’s journey from its landing site in Jezero Crater to the edge of the Séítah region, which contains impassible rocks and sand dunes. En route, Perseverance made its first attempt at collecting a sample of rock, but the water-weathered rock disintegrated during the coring process, leaving only atmospheric gases inside the sample tube. After collecting a few more samples, the rover backtracked to the landing site and continued onward to an ancient river delta, a region containing sedimentary rocks formed from silt deposited 3.5–4.0 billion years ago. These sandstone samples, Herd noted, should be especially interesting to analyze when returned to Earth.

So far, 14 of Perseverance’s 38 sample tubes have been filled, containing rocks from a wide variety of geologic regions as well as one sample of Mars’s atmosphere. In addition to the sample tubes, the rover carries five “witness tubes” that will allow researchers to assess the amount of contamination within the rover.

Conceptual illustration demonstrating the stages of the Mars Sample Return program.

Conceptual illustration demonstrating the stages of the Mars Sample Return program. [NASA/JPL-Caltech]

Perseverance will soon journey to a new region to cache the samples it has collected so far before departing the delta region and Jezero Crater entirely. In the next stage of the Mars sample return program, a lander will touch down, collect the cached samples into a small rocket, and launch them into orbit. From there, another spacecraft will capture the samples and send them Earthward.

Return to Table of Contents.

Understand Space Weathering of Carbonaceous Asteroids Through the Analysis of Hayabusa2 Samples and Experimental Analogs (Michelle Thompson)
Illustration of the main types and effects of space weathering

Illustration of the main types and effects of space weathering. [Slide by Michelle Thompson]

Michelle Thompson (Purdue University) described how laboratory experiments can help us understand the effects of space weathering — changes to the surface of an airless solar system body by impacts from micrometeorites and solar wind particles. Space weathering typically affects the top few millimeters of a body’s surface, but the effects are far reaching, changing the spectra of these bodies in a way that laboratory experiments can help probe.

Demonstration of how space weathering changes the spectral properties of lunar materials

Demonstration of how space weathering changes the spectral properties of lunar materials. [Slide by Michelle Thompson]

To demonstrate the effects of space weathering, Thompson compared a spectrum of lunar soil, which is subjected to space weather effects, to one of ground-up lunar rock, which is protected from these effects. The weather-beaten lunar soil is darker, has weaker absorption features, and is more reflective at reddish wavelengths than bluish wavelengths.

By approximating micrometeorite impacts and buffeting by the solar wind in a laboratory context, researchers determined that the two processes can have competing effects; while both processes weaken absorption features, solar wind weathering makes surfaces redder and brighter while micrometeorite impacts make them bluer and darker. Through these laboratory experiments, researchers hope to be able to separate primary effects — those that are due to inherent properties of the sample — from secondary effects, which are due to space weathering.

side-by-side comparison of a particle collected from the surface of the asteroid Ryugu and a sample of a meteorite analyzed in a lab

Photographs of a particle from Ryugu (left) and a section of the Murchison meteorite that has been treated in a lab to approximate the effects of micrometeorite impacts. [Slide by Michelle Thompson]

In December 2020, a capsule containing more than 5 grams of material collected from the surface of the asteroid Ryugu crashed down in Australia. An analysis of just one particle from this sample revealed a surface pitted and melted by micrometeorite impacts and never-before-seen teardrop- and lentil-shaped nanoparticles, which indicated a flow in the melted region. The next major sample-return event will be the arrival of a sample of asteroid Bennu’s surface in 2023.

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From Apollo to Artemis and Beyond: How the Apollo Next Generation Sample Analysis (ANGSA) Program Helps to Prepare for Future Sample Missions to the Moon and Beyond (Juliane Gross)
cartoon showing the relationship between the Apollo lunar samples and other facets of planetary science

The Apollo samples underpin much of our knowledge of the Moon as well as other solar system bodies. Click to enlarge. [Slide by Juliane Gross]

Juliane Gross (Rutgers University) described the decades-spanning effort to study samples returned during the Apollo missions. These samples underpin much of our understanding of the Moon as well as other objects in the solar system; researchers use Apollo samples to calibrate remote-sensing data, calibrate the crater-counting curve used for nearly all planetary bodies, identify lunar meteorites that fall to Earth, and understand the space environment surrounding the Moon throughout different periods in solar system history.

Most of the 2,196 Apollo samples were examined decades ago, but a few were set aside for the future; recognizing that our instruments and analysis techniques would improve over time, NASA developed the Apollo Next Generation Sample Analyses (ANGSA) program to connect the Apollo generation of researchers to future generations. Gross and collaborators analyzed one of these samples, 73001/2, which was collected in an interesting region at the intersection of a light-colored mantle deposit and a fault scarp (a region where part of the surface is offset vertically from surrounding areas).

photograph of the lunar surface with the paths taken by astronauts marked in white

Location of the 73001/2 sample collection site (labeled “3”) with respect to the lunar module (LM). [Slide by Juliane Gross]

Gross’s team extracted a precious sample of lunar gas from the outer sample tube before discovering that the inner sample tube hadn’t been closed properly; during the sample collection, the astronauts had overfilled the tube, preventing the locking mechanism from closing completely. Using modern X-ray capabilities and a little creative problem solving, Gross and collaborators were able to collect the sample without contaminating it, paving the way to assessing its properties and cataloging its contents to be shared with other scientists.

With the planned Artemis lunar missions approaching, Gross notes that there is much to relearn that may have been forgotten in the half century since the Apollo missions — and since Artemis will touch down in an entirely different region from Apollo, there will be plenty of new things to learn as well.

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Press Conference

plot of co to co2 ratio as a function of distance from the Sun

Relationship between CO/CO2 ratio and distance from the Sun for various comets. [From slide by Olga Harrington Pinto]

The first of two DPS press conferences (recording available here) brought us updates on comet and asteroid research. The first speaker, University of Central Florida graduate student Olga Harrington Pinto, described a project to determine the rates at which comets produce gases like carbon monoxide (CO), carbon dioxide (CO2), and water (H2O). Pinto found that beyond 3.5 au, where heating from the Sun is minimal, comets produce more CO than CO2, while eight out of nine Jupiter family comets orbiting within 3.5 au are CO2 dominated. Intriguingly, Oort cloud comets orbiting within 3.5 au show a variety of behaviors, with the CO/CO2 ratio increasing with dynamical age. This goes against expectations, and it may indicate that galactic cosmic rays process the outer layers of these comets as they make their first foray into the inner solar system. Finally, Pinto reports that the median C/O ratio is 13%, which is consistent with comets forming within the CO snow line.

plot of the shape of the asteroid Leucus derived from stellar occultation observations

Demonstration of the irregular shape of the Lucy mission target Leucus as determined through stellar occultations. [From slide by Marc Buie]

Next, Marc Buie (Southwest Research Institute) introduced a worldwide citizen science effort to observe the five targets of NASA’s Lucy mission as they pass in front of background stars. These stellar occultations provide a way for researchers to determine the size and shape of distant asteroids, as well as whether they have any moons, rings, or dust. The occultation-observation project, which started in 2018, has taken Buie across the world and involved 500 observers. A major finding from the project is that all of the Lucy mission targets have significant topography (i.e., landforms and surface features), regardless of the size of the object. The project also discovered that one of the targets, Polymele, isn’t flying solo — it’s accompanied by a small moon nicknamed Shaun. Given Polymele’s shape and size, Buie speculated that the Polymele–Shaun system may be similar to the New Horizon’s target Arrokoth, except the two bodies never merged.

animated GIF showing an asteroid's rotation

Animation of asteroid (52768) 1998 OR2’s rotation. [Arecibo Observatory/NASA/NSF]

Finally, University of Arizona graduate student Adam Battle introduced the curious asteroid (52768) 1998 OR2, which has been designated potentially hazardous due to its size (2.2 km) and orbit. In order to constrain the asteroid’s rotation period and composition, Battle used data from a variety of sources, including visible spectroscopy, archival infrared spectroscopy, photometry, and observations from Arecibo and the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE). These data sources painted a conflicting picture of the asteroid’s nature, with evidence for the asteroid being either a carbonaceous chondrite — containing unaltered, primitive material — or an ordinary chondrite. Battle explored several causes for this discrepancy, landing on shock darkening and impact melting as the most likely causes. These processes, which don’t alter an asteroid’s composition but do affect its spectrum, can lead to a misunderstanding of the asteroid’s properties. This discovery adds to the surprisingly small sample of asteroids with known evidence of shock darkening. Press release

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Prize Talks Plenary Session

Understanding Titan’s Weather, Climate, and Paleoclimate (Juan Lora)
Cassini photograph of clouds on titan

Cassini photograph of streaky bands of clouds on Titan. [NASA/JPL-Caltech/Space Science Institute]

Juan Lora (Yale University), who was awarded this year’s Harold C. Urey Prize, described how our understanding of Titan’s surface and atmosphere has evolved. Titan, the largest moon of Saturn, has a massive, extended atmosphere mainly composed of nitrogen, which drives an active methanological cycle similar to the water cycle on Earth. And while some of Titan’s features are similar to Earth — it’s tilted by 26.7 degrees on its axis, giving it Earth-like seasons, and it’s the only other solar system body that hosts standing surface liquid — others are decidedly alien: its year lasts 29.5 Earth years, its day lasts 16 Earth days, and its abundant clouds are mostly methane (but a few are made of deadly hydrogen cyanide!). These similarities and differences make Titan an excellent candidate for comparative planetology: the study of how physical and chemical processes affect different worlds.

Lora notes that our knowledge of Titan has come a long way, both in terms of what we’re able to observe as well as what we’re able to model. Early models were able to approximate the current distribution of surface liquid, but these models required certain characteristics to be imposed to begin with to achieve that outcome. Today, self-similar models reproduce the north polar methane seas without these restrictions. Models also give us a way to explore Titan’s past climate, or paleoclimate; while the north pole is dotted with seas, the south pole contains dry seabeds, indicating that the southern hemisphere likely hosted seas in the past. While researchers have suggested that Saturn’s eccentric orbit drives Milankovitch cycles on Titan, resulting in a net northward movement of methane, there are still plenty of questions to be answered.

Luckily, the next decade will bring us a means of answering them: the Dragonfly mission. Among the mission’s many objectives is to understand how the surface and atmosphere interact, which will help scientists understand Titan’s past and present climate. Looking ahead, the Titan Orbiter recently endorsed by the Planetary Decadal Survey would provide long-term monitoring of Titan’s atmosphere.

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Current Constraints on Ancient Venus (Martha Gilmore)

Martha Gilmore (Wesleyan University) was awarded this year’s Claudia J. Alexander Prize. Gilmore delved into the uncertain history of our neighboring planet, Venus. Today, Venus’s surface is a scorching 450°C, its atmosphere presses down with a crushing force more than 90 times stronger than Earth’s atmosphere, and all but 4% of its air is carbon dioxide. That’s Venus as we know it — but could it have been a more hospitable place billions of years ago?

view of tessera region on Venus

Perspective view of Venus’s Fortuna Tessera constructed from NASA Magellan data. The color scale shows the emissivity of the region. [NASA/JPL/USGS]

The answer might lie in Venus’s unusual tesserae: rough, deformed, high-altitude regions of Venus’s surface. The average age of Venus’s 900 craters is somewhere between 300 million and 1 billion years (Gilmore uses 500 million years as a rough estimate), indicating that the plains regions were resurfaced around that time ago, and the tesserae are likely older. But just how old the tesserae are is up for debate — they could be 500 million +1 years old or 4 billion years old. Gilmore notes that the tesserae witnessed the creation of the plains, which means they were subjected to the chemical and thermal conditions that existed on Venus during that period of extensive volcanism.

More information about the tesserae came from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard the Venus Express orbiter. VIRTIS observations at a wavelength of 1 micron — a wavelength sensitive to changes in iron content in minerals — supported the idea that the tesserae contain felsic igneous rocks, which require water and plate recycling to form. This contrasts with present-day Venus, which is devoid of both water and plate tectonics. Given that Venus’s tesserae potentially overlapped with the presence of water, Gilmore encouraged the audience to consider how rocks on Venus would react not just to present-day runaway greenhouse conditions, but how they would react to water and then the greenhouse.

Future missions and laboratory work will further our understanding of Venus’s history (a Venus sample return mission isn’t impossible!), and, as Gilmore notes, finding a Venusian meteorite would go a long way!

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From Pinpoints of Light to Geologic Worlds: The Magic of Photometry (Bonnie Buratti)
zoomed-in image of europa's surface

Photometry of Europa’s surface hints at a mystery yet to be solved. [NASA/JPL-Caltech/ SETI Institute]

This year’s Kuiper Prize goes to Bonnie Buratti (NASA’s Jet Propulsion Laboratory), who introduced the many instances of photometry being ahead of its time, hinting at discoveries that didn’t follow until much later. Buratti began by describing how researchers can use photometry to assess the roughness of surfaces in the solar system, noting that this technique gives us access to particles far below the resolution limit of our cameras.

There are many examples of photometry giving us the first hint at a significant discovery (too many to detail in this short summary!). Using photometric tools, researchers correctly predicted the presence of carbon dioxide on Saturn’s moon Iapetus, the methane-soaked surface of Saturn’s moon Titan, the plumes of icy Enceladus, and a population of retrograde moons around Uranus.

While photometry has been a major player in many discoveries, it may yet play a role in several unsolved mysteries as well. One example is the surface of Jupiter’s moon Europa. Europa exhibits limb darkening (it’s brighter at the center of its disk than at the edges), but it should be the same brightness across the disk, and it’s very forward scattering (i.e., photons striking particles on its surface are scattered roughly in the direction of the incident light rather than being reflected back). Buratti speculated on what the upcoming Europa Clipper mission might discover to explain these observations. Could icy slurries seeping up from below be compacting the moon’s surface? Or could particles from plumes be filling in cracks in the surface? Time will tell exactly how the mystery posed by these photometric observations is solved!

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banner announcing the 54th annual Division for Planetary Sciences meeting, happening 2–7 October 2022 in London, Ontario, and virtually anywhere

Hello from the 54th annual meeting of the AAS Division for Planetary Sciences (DPS), happening in London, Ontario, and virtually anywhere! This week, we’ll be bringing you updates on selected sessions from the meeting and other great planetary science coverage. Meeting updates will be posted Wednesday and Friday of this week, and the regular AAS Nova posting schedule will resume on Monday, October 10.

In the meantime, if you’re attending DPS, here are some events that might interest you:

  • Planetary Allyship Meeting
    Monday (10/3), 7:00 – 8:00 pm ET, Salon EF
  • Women in Planetary Science Discussion Hour
    Tuesday (10/4), 12:00 – 1:00 pm ET, Salon HJ
  • Planetary Scientists of Color Networking Event
    Tuesday (10/4), 5:30 – 6:30 pm ET, Salon DD1
  • Press Conferences
    Tuesday (10/4) and Thursday (10/6), 12:15 – 1:15 pm ET, Zoom webinar
  • Reception for the Planetary Science Journal (cupcakes for all!)
    Tuesday (10/4), 4:00 – 5:00 pm ET, Exhibit Hall Booth 112
  • JWST Townhall
    Wednesday (10/5), 12:00 – 1:00 pm ET, Salon EF
  • DPS/Federal Relations Subcommittee Space Policy Town Hall
    Thursday (10/6), 12:00 – 1:00 pm ET, Salon BB1

If you’re attending DPS in person, be sure to pop by the AAS Publishing booth (112) to speak to our publishing representatives and to pick up some journal swag. We hope to see you there!


headshot of Ben Cassese

Ben Cassese (Columbia University) has been selected as the 2022–2023 AAS Media Fellow.

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

We are pleased to announce that Ben Cassese, an astronomy graduate student at Columbia University, has been selected as our AAS Media Fellow for 2022–2023.

Before beginning his graduate studies, Ben majored in planetary science and history at the California Institute of Technology. Now a second-year graduate student in the astronomy department at Columbia, Ben works with David Kipping to search for moons orbiting planets outside our solar system and understand how the properties of exoplanetary systems can be inferred from subtle clues in transit light curves.

In addition to research, Ben writes for the graduate-student collaboration Astrobites, acts as a research mentor, and has explored his interest in science policy as a Lloyd V. Berkner Space Policy Intern. Between college and graduate school, he also successfully thru-hiked the 2,190-mile Appalachian Trail.

photograph of astronomers standing outside a telescope dome at night with the Milky Way in the background

An image of Ben and collaborators during an observing run at Palomar. [Ben Cassese]

As the AAS Media Fellow, Ben will regularly write and publish summaries of the latest astronomy research on AAS Nova, assist in managing the distribution of press releases as part of the the AAS Press Office, and gain a broad understanding of the worlds of scientific publishing, communications, and policy. Ben will also be assisting with the press conferences at the upcoming 241st meeting of the AAS, so please say hello if you’re attending the meeting in Seattle, Washington, next January!

photograph of a golden retriever puppy playing with a stuffed animal

Jocelyn Belle is engaged in important duck-matter research. [Haley Wahl]

As we welcome Ben to the team, we’ll also soon bid farewell to Haley Wahl, our 2021–2022 AAS Media Fellow. Haley completed her graduate research on pulsars and defended her dissertation in August 2022. She currently lives in the Washington, DC, area with her new puppy, Jocelyn Belle, and works remotely as a science writer and content creator for the Massachusetts Institute of Technology Lincoln Laboratory.

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

composite representative color image of the andromeda galaxy

Editor’s Note: This week we’re at the 240th AAS meeting in Pasadena, CA, 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 21st.

Table of Contents:

George Ellery Hale Prize: Sami Solanki (Max Planck Institute for Solar System Research) (by Abby Lee)

Solanki began his talk by apologizing for not being at AAS 240 in person. But he had a very good excuse — he and the Sunrise team are preparing to launch their stratospheric solar observatory in Sweden any day now — as soon as weather permits! The goal of the Sunrise mission is to resolve the fine structure and dynamics of the Sun’s magnetic fields. They chose to build a balloon-borne observatory (as opposed to a space-based observatory) with a 1-meter telescope because it’s much cheaper. The Sunrise mission will also be the largest telescope studying the Sun to ever leave the ground. The balloon will depart in Sweden and traverse over Greenland.

Solanki listed some of the many reasons why studying the Sun is important: (1) The Sun supplies Earth with 99.96% of its energy, (2) it produces space weather that can negatively impact technical systems, (3) it is the only star we can resolve and study in detail, (4) it is a gigantic plasma physics laboratory, where you can reach parameter regimes you cannot recreate on Earth, (4) it affects our climate, and (5) it’s fun!

This third run of Sunrise includes a new gondola and three ambitious new instruments. It will probe a much larger height range of the Sun than previous Sunrise runs by studying the chromosphere, the middle layer of the Sun’s atmosphere and the most poorly understood. Whereas previous runs of Sunrise have only been able to probe the photosphere, the lowest layer. Observing the chromosphere with such high resolution will be helpful in modeling sunspots and interactions between the Sun’s magnetic fields.

The second half of Solanki’s talk focused on the question of whether the Sun’s variability could cause climate change. The Sun is variable mostly due to its sunspots, and since 1610, there have been two documented events where low numbers of sunspots coincided with mini ice ages. However, only two documented events are not enough to draw strong conclusions. Furthermore, by measuring the relation between the Sun’s flux and number of sunspots, astronomers discovered that the Sun is actually brightest at times of high solar activity, i.e., when the number of dark sunspots is largest. So the Sun’s variability cannot have caused climate change. Another piece of evidence is that the Sun’s flux has been uncorrelated with temperature since ~1970. Before then, the Sun’s flux actually did correlate to a certain extent with Earth’s temperature, but it is clear now that we cannot blame the Sun for climate change.

In the last 10 minutes of Solanki’s talk, he emphasized that the Sun is not an outlier. They compared stars with similar temperatures, rotation periods, surface gravities, etc., and found that the Sun is typical in its variability to other Sun-like stars. There’s still much to learn about the Sun and its variability, and we are all looking forward to the new data from the Sunrise telescope!

See live-tweets of this session here, by Luna Zagorac.

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Introducing Current Research Into Your Classroom With Astrobites (by Briley Lewis)

6 people sitting in a circle in a conference hall talking

Astrobiters Sabina Sagynbayeva and Graham Doskoch discussing lesson plans with participants. [Briley Lewis]

Astrobites was everywhere at AAS 240, and this morning we hosted a splinter session about how to use Astrobites lesson plans! If you haven’t heard, Astrobites works with educators to develop lesson plans and refine ways to use our content in the classroom. We love feedback from educators, and want to support anyone who wants to use our content.

This session was the work of many Astrobiters: Briley Lewis led the session proposal and logistics, Graham Doskoch and Pratik Gandhi designed the workshop slides and plan, and Katya Gozman, Ryan Golant, Sabina Sagynbayeva, Macy Huston, and Isabella Trierweiler helped facilitate the workshop.

The workshop began with a brief intro on Astrobites and what we do, and went on to describe our three lesson plans, providing examples of possible usage for each. The first lesson plan uses Astrobites articles as reading assignments, with comprehension questions to accompany the readings. Optionally, if the paper has an associated press release, students can read the original paper and press release as well to compare the different genres/styles. The second lesson plan has students pick a topic they’re interested in and do an Astrobites “literature review” to learn more. They complete this mini-research project by giving a small presentation on what they found. Lastly, the third lesson plan actually has students write their own Astrobite on a new paper — Michael Hammer recently wrote a bite about this process, and if you’re interested in publishing some of your class’s bites, email us at education@astrobites.org!

Most of the workshop focused on discussion between the educators in attendance, facilitated by Astrobites authors. They discussed the various lesson plans, how they would use them in their own classes, and any changes they would make. One participant commented that having resources like these pre-made lesson plans could lower the threshold to using Astrobites in their classroom, and another mentioned that the fact we have Astrobites in several languages (especially Spanish) is very helpful. Some of the ways people think of using Astrobites surprised us as well, from using it in undergrad mentorship to introduce students to a project to using Astrobites as preparation reading for colloquia to help undergrads understand the talks.

We also sought feedback from educators on how to improve Astrobites’ education offerings, and the participants had great ideas! Multiple people asked for a platform to share their lesson plans and what they’ve done with Astrobites, and we’re excited to say that’s something we’ve been thinking about too — so keep an eye out for that! Others suggested showing the editing process for a few cases to help students understand how articles are shaped into their final form, and adding some key takeaways at the bottom of bites to help instructors quickly see what’s relevant to their courses. If you have suggestions or want to second any of these ideas, feel free to email us — we focus our efforts based on interest from the community!

Also, if you’re interested in what education work we’re doing here at Astrobites, make sure to sign up for our mailing list here to stay in the loop. You can also check out the slides from the workshop, and our “Teaching with Astrobites” page on our website for more info!

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Press Conference: Dusty Environments Near and Far (by Kerry Hensley)

The final press conference of AAS 240 was all about dust. Love it or loathe it, dust is everywhere in our universe, from the surfaces of planets to the space between stars.

First, Christopher Clark (Space Telescope Science Institute) discussed the dynamic life cycle of dust in the interstellar medium. Dust makes up just 1% of the material in the interstellar medium, but half of all starlight in the universe has been absorbed by dust grains! Clark’s team combined data from multiple infrared telescopes, giving us a new look at emissions from both gas and dust in four nearby galaxies: Andromeda, the Small Magellanic Cloud, the Large Magellanic Cloud, and the Triangulum Galaxy. Intriguingly, the dust-to-gas ratio varies dramatically within these galaxies (up to a factor of ~20) as well as between them; though the Large Magellanic Cloud and the Triangulum Galaxy are similar in many ways, they have very different dust-to-gas ratios. The varying ratios suggest that some regions within these galaxies experience rapid dust growth, while in other regions dust is speedily destroyed. Press release

Pressure measurement across the shock wave detected in Abell 98. The inset image marks the axial shock with a white curve

Pressure measurement across the shock wave detected in Abell 98. The inset image marks the axial shock with a white curve. [Arnab Sarkar]

Next, Arnab Sarkar (University of Kentucky) presented evidence for the first detection of a shock wave generated in the early stages of a galaxy cluster merger. The mergers of galaxy clusters, which contain hundreds to thousands of galaxies, are the most energetic events in the universe since the Big Bang. Sarkar’s team investigated the galaxy cluster Abell 98, the components of which are just beginning the 2-billion-year process of merging. Images reveal an arc of hot gas between the clusters, which is 1) hotter than the gas within the clusters, 2) coincides with a sharp change in X-ray emission, and 3) marks a change in gas pressure consistent with a shock wave. This discovery provides evidence for a previously missing link in the process of large-scale structure evolution in the universe. Press release

Astrophotograph of Barnard's Loop

Astrophotograph of Barnard’s Loop, which appears as a red semicircle in this image. [Wikipedia user Hewholooks; CC BY-SA 3.0]

Mike Foley (Center for Astrophysics | Harvard & Smithsonian [and Astrobites!]) presented a three-dimensional view of the Orion star-forming region. The 3D structure, which you can explore for yourself in an interactive figure, consists of a spherical dust shell bounded by several sinuous molecular clouds. These structures are huge — the famous Orion Nebula, which is about as big on the sky as the full Moon, is just a small component. The placement of the molecular clouds suggests that the star formation within them has been triggered by a central process. The entire Orion region is suffused with emission from a radioactive form of aluminum used to trace supernovae, which suggests that quite a lot of explosive events have occurred in the area. Specifically, emission from hot gas suggests that supernovae from the young star cluster at the center of the dust shell could have played an important role in the creation of Barnard’s Loop, a prominent, curved emission nebula in the region. Overall, the new 3D map of the region allows us to probe new features, like the dragging of stars by expanding shells of dust and gas and the spatially varying gravitational pull of dense gas clouds. Press release

schematic of the nanotube formation process

Schematic of the formation process. Silicon atoms (green) leave the grain, leaving carbon atoms (black) to form sheets of graphene and then nanotubes. [Jacob Bernal/University of Arizona]

Jacob Bernal (University of Arizona) brought us back down to Earth — literally! — with a discussion of new results in laboratory astrophysics. Bernal uses laboratory techniques to study the formation of the largest known molecules in space: fullerenes. Bernal’s team found that when silicon carbide grains — a common component of gaseous envelopes around young stars — in a vacuum are heated to 1000℃, the silicon atoms flee the silicon carbide crystal, leaving behind sheets of graphene that rearrange into spherical fullerenes. When the grains were heated to 1050℃ for a few minutes, though, the grains instead formed multi-walled carbon nanotubes several times larger than the spherical fullerenes! These nanotubes are tough to break apart with radiation, which suggests that they are likely present in the surroundings of stars. If so, this would be a huge leap in the chemical complexity of known molecules in space, with wide-reaching implications. Press release

Aerial view of a dust devil on Mars

Aerial view of a dust devil on Mars. [NASA/JPL-Caltech/Univ. of Arizona]

Finally, Brian Jackson (Boise State University) described his team’s work to understand the impact of dust devils on Mars. Jackson’s team studies dust devils on Mars by analyzing meteorological data from the Perseverance Mars rover and by measuring dust devils on Earth. In an effort “inspired by the movie Twister,” the team duct taped instruments to drones that they flew through dust devils (not as easy as it sounds!). As a dust devil travels across a sensor, the air pressure drops and the wind changes direction and speeds up. We see the same behavior on Mars, but up until the Perseverance rover began taking data, Mars rovers could only tell that air was swirling above them, but not whether or not it carried dust. A new sensor on Perseverance, which detects changes in the amount of sunlight, allowed the team to discern that dust devils on Mars range from nearly transparent to as dust-laden and dark as Los Angeles smog. Press materials (including videos of dust devil encounters on Earth and an incredible time series of dust devils scooting across the Martian surface!)

See live-tweets of the session here, by Luna Zagorac.

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Plenary Lecture: Charting the Chemistry of Galaxies across Cosmic Time, Allison Strom (Princeton University) (by Sabina Sagynbayeva)

Dr. Allison Strom is a postdoctoral fellow at Princeton University, soon to be a faculty member at Northwestern University in the fall. She started off her plenary lecture with a message: she wanted the talk to be useful to everyone, independent of research field, because chemistry is everywhere. To expand this point further, she reminded the audience that large structure formation (like galaxies!) is dominated by dark matter. However, there is still gas everywhere in and around galaxies, which affects smaller structure formation (like stars and supernovae), and this becomes as important as dark matter when we study larger scales.

We know that galaxies are not similar to each other — we observe a huge diversity of them. Despite the fact that we now can observe different kinds of galaxies, we still want to understand the individual members of those types. Studying chemistry is key to this. Dr. Strom calls chemistry the DNA of the galaxies, because it can essentially help us study their evolution. In the figure below, Dr. Strom showed the diversity of known galaxies at different redshifts.

A slide from Dr. Strom's talk showing the diversity of known galaxies on different redshifts.

The diversity of known galaxies at different redshifts. [From Dr. Strom’s presentation slides]

Now, the smaller objects (smaller than galaxies, like stars and star clusters) become important. By looking at stellar metallicity in a galaxy, we can track a galaxy’s mass and growth. This is called the mass–metallicity relation. Mostly these relations for different galaxies show that a galaxy’s mass is bigger if it has more metal-rich stars. But, some other features can be observed as well. For example, results from a study in 2002 shows that galaxies are losing heavy elements through outflows.

Hubble Deep Field: an image of a lot of galaxies.

The Hubble Deep Field. [NASA]

Galaxies are far away and challenging to observe, but the Hubble Deep Field changed extragalactic astronomy. Spectra of HII regions reveal detailed astrophysics at all redshifts. They show electron temperature, and by measuring electron temperature, we can measure metallicities. But, by redshift z~2, the entire rest-optical spectrum shifts to the near-infrared (we don’t see features in optical)! Therefore, better instruments had to be built — the past 10 years were crucial in this field, and we now have a lot of data for high-redshift galaxies. Changes in the mass-metallicity relation reflect the evolving impact of galaxy outflows. A recent study found that high-z galaxies have higher gas fractions and more efficient outflows. It turns out that redshift z=2 galaxies are very alpha-enhanced (higher O/Fe — oxygen/iron abundance). The main takeaway from this: high O/Fe has now been repeatedly confirmed at high redshifts!

Dr. Strom created the package GalDNA (Galaxy DNA!) to measure the physical conditions in high-redshift star-forming galaxies. Chemical analyses are important not only from the perspective of star formation and their evolution, but also the end stages of stellar lifetimes. When stars explode, they eject a lot of chemical elements into space. Type Ia supernovae create a lot of iron and you can measure the oxygen to iron abundance and link the abundance patterns with galaxies across cosmic time.

Dr. Strom is also excited about the launch of JWST. JWST carries a diverse suite of powerful new near- and mid-infrared spectrographs. One of the principal use cases is ultra-deep spectroscopy of high-redshift galaxies. Differences in abundance ratios can introduce systematic biases: most of the methods are for low-shift galaxies, but JWST can help us with this by building more accurate abundance diagnostics. CECILIA is an observing program led by Dr. Strom that will unlock the power of JWST galaxy spectra, and it was inspired by Cecilia Payne-Gaposhkin.

Another important instrument for high-redshift galaxies is the Subaru Prime Focus Spectrograph (PFS) which will obtain spectra of hundreds of thousands galaxies. If we combine observations from the  Subaru Prime Focus Spectrograph and the Nancy Grace Roman Space Telescope, they would follow the transition of the galaxy population from star-forming to quiescent.

Dr. Strom concluded by saying that the field needs all of us. Meaning that there are so many questions that are yet to be answered, and she encourages students to join the field.

You can read Sabina’s interview with Dr. Strom here.

See live-tweets of this session here, by Sabina Sagynbayeva.

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Planetary Decadal Survey Town Hall (by Sabina Sagynbayeva)

The town hall was led by David H. Smith, Robin Canup, and Philip Christansen. They start with comparisons to the prior Decadal survey like identification of top-level science questions and research activities and prioritization of large/medium space missions. The key distinctions of this report include consideration of the state of the profession and actions for enhancing diversity, equity, inclusion, and accessibility (DEIA); organization by significant, overarching scientific questions rather than by destinations; greater emphasis on astrobiology; inclusion of planetary defense; and awareness of human exploration plans and identification of cooperation opportunities.

Planetary decadal survey and report organization.

Planetary decadal survey and report organization. [From slides by Robin Canup]

The prioritized themes of this decadal survey are Origins, Worlds & Processes, Life & Habitability, and Exoplanets.

They launched a new State of Profession writing group. The core principles of it are:

  • Broad access and participation essential to maximizing excellence
  • Substantial evidence shows that implicit biases affect judgements, even among those sincerely committed to equal opportunity and treatment
  • Structures and processes designed to address implicit biases also address explicit biases
  • Implementing objective measures of self-examination and evidence gathering supports DEIA improvement and builds community trust
  • Strong system of equity and accountability needed to recruit, retain, and nurture the best talent

The other priority is increasing investment in Research & Analysis (an intellectual foundation that ensures NASA’s activities maximize the expansion of knowledge) to achieve a minimum annual funding level of 10% of the Planetary Science Divison annual budget by mid-decade, via a progressive ramp-up in funding allocated to the openly completed Research & Analysis programs. Progress in achieving this goal should be evaluated mid-decade.

The National Science Foundation (NSF) should continue (and if possible, expand) support of existing and future observatories important for solar system studies (e.g., NOIRLab, ALMA, Rubin, TMT, GMT, ngVLA) and related PI-led and guest observer programs, and involve planetary astronomers in future observatory plans and development. NASA and NSF would realize greater return on Research & Analysis investments by streamlining mechanisms to support science of benefit to both agencies. NASA and NSF should develop a plan to replace ground-based radar capabilities lost with Arecibo, which are crucial for planetary defense and near-Earth object studies.

Astrobiology also plays a central role in Decadal research strategy (3 of 12 priority science questions) and in many current and planned missions. Dynamic habitability and the co-evolution of planets and life are key concepts that require mechanisms to support interdisciplinary and cross-divisional collaboration. Dedicated focus on research related to subsurface life is warranted given advances in understanding the diversity of terrestrial life, and known subsurface fluids on Mars and icy ocean worlds NASA should accelerate development and validation of mission-ready life detection technologies.

Returning new samples from Mars is a priority because diverse, sophisticated lab instruments on Earth can precisely measure key isotopes, trace elements, and detailed petrologic structures.

Another exciting priority is the first priority flagship goes to Uranus! The Uranus Orbiter and Probe will deploy an atmospheric probe to characterize Uranus’s atmosphere, and will be sent for the mission in 2032!

The second priority new flagship is Enceladus Orbilander! Enceladus is an optimal locale to sample extant subsurface ocean through study of freshly ejected plume material. Study of habitability and life detection at Enceladus is such a high priority that it is included in both New Frontiers and Flagship class missions to provide alternative approaches to pursue this critical science.

To know more about the survey and its prioritized missions and budget allocations, you can read the report!

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Roman Town Hall (by Macy Huston)

Artist's rendition of the Roman telescope with an artistic space background

Artist’s rendition of the Roman telescope. [GSFC/SVS]

The Roman Town Hall began with a brief overview of the mission. The Nancy Grace Roman Space Telescope is the next upcoming flagship NASA space telescope, following the recent launch of JWST. It will have similar sensitivity and resolution to the Hubble Space Telescope and a field-of-view ~100x the size of Hubble’s. It will study exoplanets, dark energy, and galaxies through wide-field infrared surveys. The 2.4 meter telescope will host two instruments: the Wide Field Instrument (WFI) and Coronagraph Instrument (CGI). It will reside in the Sun-Earth L2 Lagrange point and produce an astounding 11 terabytes of data per day!

Roman’s current launch date is scheduled for October 2026. In addition to its large field-of-view, the telescope boasts a rapid slew and settle rate, allowing for the maximum amount of time spent on-sky, gathering data. The telescope will not have to deal with the Earth getting in the way or with  the South Atlantic Anomaly. In addition, its point spread function and flux calibration are precisely characterized. Data will be processed at the Space Telescope Science Institute (STScI) and Science & Data Center for Astrophysics & Planetary Sciences at Caltech (IPAC), with a public archive based on STScI cloud servers.

The WFI will have a 0.281 square degree field-of-view, capable of photometry and spectroscopy in the 0.48-2.3 micron wavelength range. Many individual parts are already completely built and tested, and the instrument will be ready for full system integration and testing in 2023. The CGI will be a technology demonstration for space-based direct imaging and spectroscopy of planets, blocking the overwhelming light from their host stars. The first of its kind in space, the CGI will perform ~100-1,000x better than current ground-based facilities and is a critical stepping stone on the path toward characterizing exo-Earths.

The Roman team prioritizes community engagement in the mission, developing community definitions and ownership for the core surveys: the High Latitude Wide Area Survey, the High Latitude Time Domain Survey, and the Galactic Bulge Time Domain Survey. The core surveys will address many priority areas from the Astro2020 decadal survey: exoplanet demographics, stellar astrophysics, habitable worlds, multi-messenger astronomy, new physics, the dynamic universe, and galaxy growth.

The Roman mission also aims to be very inclusive, involving many different institutions and career stages. Be on the lookout for a couple of upcoming ways to get involved: a call for white papers and a NASA Research Opportunities in Space and Earth Science (ROSES) solicitation. ROSES will provide funding opportunities to work on preparation for WFI science, the creation of infrastructure teams for long-term support for WFI, and a coalition to conduct the CGI technology demonstration. More information and technical specs about Roman are available on the IPAC and NASA Goddard websites.

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Plenary Lecture: Gail Zasowski (University of Utah) (by Pratik Gandhi)

Dr. Gail Zasowski, Assistant Professor at University of Utah, presented the penultimate plenary lecture of AAS 240. Focusing on our own galaxy, she opened with the statement “The Milky Way is a Galaxy: a Deceptively Simple Assertion.” Although it’s obvious that the Milky Way is indeed a galaxy, Dr. Zasowski was trying to discuss the idea that the Milky Way might be an outlier compared to other similar galaxies.

The talk started with a big-picture discussion of the two primary ways that we study galaxies: through theoretical simulations and via observations. Simulations have the advantage of letting us study the full time evolution of galaxies, while observations include both large-scale galaxy surveys and more focused follow-ups of individual galaxies.

mosaic of a galaxy image on the left and spectroscopic studies on the right

[Gail Zasowski and also Roberts-Borsani et al. 2010]

The primary difference between studying other galaxies and studying the Milky Way is that for our galaxy, we’re observing it from within. So how do we study the Milky Way? The key idea here is that we can resolve and observe individual Milky Way stars, small pockets of gas and dust — which we cannot do for most other galaxies! This allows us to study star-by-star dynamics as well as obtain detailed elemental abundance distributions and patterns. However, we don’t have a bird’s-eye view of our galaxy, which makes it harder to study its overall structure and integrated light flux. An analogy Dr. Zasowski provided was looking at a map of Salt Lake City from far above versus standing on a street corner in downtown Salt Lake City and looking in individual shop windows, as shown in Figure 2. She emphasized that both perspectives are crucial for getting a full picture of how galaxies form and evolve!

on the left, an external perspective of the map of Salt Lake City from above, versus on the right, a photo of a street corner in downtown Salt Lake City

[Google Maps, modified by Gail Zasowski]

Next, the big question: is the Milky Way really unusual? Dr. Zasowski provided the important reminder that what’s considered “typical” for galaxies depends on the property being considered. However, two areas in which the Milky Way seems unusual is that it formed fewer stars in its star formation history than expected (more “quiescent”), and that its outskirts are more metal-poor than expected. A couple of other interesting and potentially unique features are that the Milky Way has a number of massive satellite galaxies around it, which is relatively rare, and that the Milky Way’s spatial extent is smaller than expected given its mass. There are two main approaches to answering the question of the uniqueness of our galaxy — looking inwards at its constituents, and looking outwards to compare the Milky Way to other galaxies; Figure 3 shows all of the different techniques/surveys.

on the left, the text 'looking inward' with examples of resolved Milky Way surveys, versus on the right the text 'looking outward' and larger surveys of nearby galaxies

Examples of resolved Milky Way survey and larger surveys of nearby galaxies. [Gail Zasowski]

Dr. Zasowski reminded us that we often try to study “Milky Way analogs”: other galaxies that we think might be similar to ours, in order to predict or compare to Milky Way properties. However, it’s complicated to figure out which galaxies are good analogs, and as Figure 4 shows, if we try to find another galaxy exactly like ours, we are probably not going to!

Venn diagram of 3036 nearby galaxies, some similar to the Milky Way in star formation rate, some in spatial size, some in bulge ratios, but none that match all properties

Venn diagram of 3,036 nearby galaxies, some similar to the Milky Way in star formation rate, some in spatial size, some in bulge ratios, but none that match all properties. [Boardman, G. Z. et al. 2020]

Finally, the talk focused on the detailed elemental abundance distribution of stars in the Milky Way. If we consider the radial distribution of metallicity in the galaxy, it’s a broken profile. The extreme inner and outer parts of the galaxy are metal-poor, while the middle is more metal-rich. If you split the stars into different age bins though, the profiles look straightforward. It’s because stars of different ages give off different amounts of light and are more or less easily observable that the total metal profile appears broken!

Looking ahead to upcoming studies, Dr. Zasowski points out that we need to observe a huge number of stars across the entire galaxy of all the different types — which is what surveys like SDSS-V will help us with. Right now is a really exciting time to be studying the Milky Way and figuring out whether we really are unique!

See live-tweets of this session here, by Sabina Sagynbayeva.

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Lancelot M. Berkeley Prize: Paul Scholz (University of Toronto) (by Isabella Trierweiler)

In the last plenary talk, Dr. Victoria Kaspi and Dr. Paul Scholz shared discoveries from the CHIME and Fast Radio Burst collaboration. About the size of five hockey arenas, CHIME (the Canadian Hydrogen Intensity Mapping Experiment) is a radio telescope which was originally meant to build a 3D map of hydrogen in the Milky Way. However, it turned out to be a really good tool for finding fast radio bursts (FRBs), which are sudden strong pulses of radio waves. The telescope is made up of four half cylinders, each of which houses many smaller antennae. As a whole, it functions like a collection of multiple small telescopes, creating 1,024 beams on the sky!

The CHIME Experiment

The CHIME Experiment. [CHIME Collaboration]

CHIME is great at finding FRBs because it can cover large swaths of sky, waiting for the radio pulses to arrive. In the first year of the search, CHIME found 500 FRBs! These bursts come from all over the sky, last up to a few milliseconds, and arrive at a rate of about 1,000 per day.

A particularly useful type of FRB is one that repeats, with several pulses clustered together in time. The repetition helps pinpoint the location of the FRB source, because it allows other telescopes to make follow up observations. So far, the majority of FRBs come from the outskirts of massive galaxies — usually galaxies that have ongoing star formation. Dr. Kaspi and Dr. Scholz do point out an interesting outlier however, which originates in a dwarf galaxy.

An FRB signal

An FRB signal. [Vicky Kaspi, Paul Scholz]

Addressing the question of what the sources of FRBs are, Dr. Scholz shows an FRB that he found to be a magnetar, or a highly magnetic, rotating neutron star. The energy of the FRB is consistent with a magnetar, and the location identified for the FRB source is a reasonable place for a magnetar to form. Motivated by this discovery, Dr. Scholz and Dr. Kaspi wanted to figure out whether all FRBs are magnetars, or if their observed magnetar is an unusual case. So far, the magnetar they found lives in a different environment than most other repeating FRBs, so it looks like magnetars are not a universal source of FRBs. The search for FRB sources continues!

See live-tweets of this session here, by Isabella Trierweiler.

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artist's impression of a supernova remnant

Editor’s Note: This week we’re at the 240th AAS meeting in Pasadena, CA, 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 21st.

Table of Contents:

High Energy Astrophysics Division Bruno Rossi Prize: Francis Halzen (University of Wisconsin-Madison) (by Luna Zagorac)

Artist depiction of IceCube

Artist’s depiction of IceCube. [IceCube/NSF; slide by Francis Halzen]

Deep in the Antarctic ice, 86 columns of photomultiplier tubes are buried like strings of fairy lights. These strings don’t produce light, but instead capture the smallest numbers of photons produced by passing particles called muons and neutrinos. Of these events, there are about 1011 muons per year, close to 105 atmospheric neutrinos, and only about 200 cosmic neutrinos.

Together, this kilometer cube of ice and electronics make up the Ice Cube Neutrino Observatory. Consisting of more than 300 people from 14 countries, the IceCube collaboration is helmed by Professor Francis Halzen and is the 2020 recipient of the HEAD Bruno Rossi Prize. The prize comes on the heels of the discovery of the 200-odd cosmic neutrinos — neutrinos produced outside our own galaxy! — which may hold the key to revealing the origins of cosmic rays.

A slide titled "The IceCube Collaboration" with the IceCube logo in the bottom, and an elliptical image of 100s of people sitting or standing on grass in front of a building. They are smiling at the camera which is set high up, and are laughing and waving.

The IceCube collaboration. [IceCube/NSF; slide by Francis Halzen]

Indeed, 10 years of IceCube data show a non-uniform sky map, with four main sources of cosmic neutrinos: NGC 1068, OKS 1424+240, TXS 0506, & GB9. Most of these sources are active galactic nuclei, with cores and jets energetic enough to accelerate cosmic neutrinos sufficiently that they eventually reach Earth and IceCube. Furthermore, some of these sources also show optical flares (such as that of TXS 0506 in 2014) corresponding to their neutrino flares. This is particularly exciting since the Universe outside of our own galaxy is opaque to the most energetic photons, or gamma rays. Thus, neutrino astronomy opens new avenues for doing multi-messenger astronomy at different energies when studying sources like these.

The most recent IceCube analyses of these sources are still embargoed, so we were not able to learn whether these four objects are sources of cosmic rays or weird statistical fluctuations in neutrino numbers. However, Professor Halzen noted with a smirk that we would not be discussing them if they weren’t interesting. The most important take-away from the plenary, then, is that neutrino astronomy exists and that multi-messenger astronomy is closing in on cosmic ray sources. We should all stay tuned!

See live-tweets of this session here, by Luna Zagorac.

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Stars, Their Environments & Their Planets (by Macy Huston)

hubble image of a cluster of blue stars

Hubble image of a “blue blob” star system. [Michael Jones]

The first presentation of this session was “Young, Blue, and Isolated Stellar Systems in the Virgo Cluster” from Michael Jones of the University of Arizona. The Virgo galaxy cluster is a hostile environment full of hot intra-cluster medium gas, not thought to be a good environment for star formation. However, the team found five irregular, blue, isolated stellar systems in the Virgo cluster. So, how did these young systems form in this environment? There are two mechanisms which pull gas from galaxies: tidal and ram pressure stripping. Tidal stripping happens when an interaction between two galaxies causes gas and stars to be gravitationally pulled away. On the other hand, ram pressure stripping can force gas out of a galaxy as it falls into a galaxy cluster; the ejected gas can then collapse and begin forming stars. Ram pressure stripping can occur at much higher velocities, so this mechanism better explains the isolation of these 5 clusters. In summary, this new class of stellar system, “blue blobs,” resides in isolated regions of galaxy clusters, where young stars with high metallicities have formed, likely from ram pressure stripped gas. Press release

Next up is “A Survey of Pre-Main-Sequence Stars and Massive T Tauri Protoplanetary Disks with the Gemini Planet Imager” from Evan Rich of the University of Michigan. We know that planets form around young stars in disks, which are composed of gas, small dust, and large dust. This process is difficult to study though, as it is difficult to image planets in the formation process with current technology. This team is working to indirectly trace planet formation through its effect on small dust grains. Radiation from small dust in disks is polarized, while starlight is not, so the overwhelmingly bright starlight can be filtered out of these observations. The Gemini LIGHTS project is uniquely observing stars more massive than our Sun. Stars three times the mass of the Sun do not show any apparent ring structures, which are typically indicative of planet formation. There are a few possible causes for this: the effects of binary companions, higher temperatures, observational bias, or the systems being too young to form rings. This leaves us with an interesting open question: Does stellar mass play an important role in the planet formation process? Press release (University of Michigan) | Press release (NOIRLab)

composite image of the star-forming region 30 Doradus

Composite infrared and radio image of the star-forming region 30 Doradus, also known as the Tarantula Nebula. [ESO, ALMA (ESO/NAOJ/NRAO)/Wong et al., ESO/M.-R. Cioni/VISTA Magellanic Cloud survey. Acknowledgment: Cambridge Astronomical Survey Unit]

The session’s third presentation was “Unraveling a Star Formation Standoff in the Tarantula’s Gaseous Web” from Tony Wong of the University of Illinois Urbana–Champaign. This work explores how gravity and stellar feedback regulate star formation. Can molecular clouds still collapse to form stars in the presence of strong feedback? This study used Atacama Large Millimeter/submillimeter Array (ALMA) imaging of 30 Doradus (the Tarantula Nebula) in the Large Magellanic Cloud, the nearest star-forming galaxy, and one much more active than ours. The team studied the structure of the region’s molecular clouds, with dense clumps embedded in lower-density envelopes. Though feedback is very powerful in certain regions, particularly dominating in thinner parts of the cloud, star formation continues in the thickest parts, along the main filaments. Press release (NRAO) | Press release (ESO)

The fourth presentation of the session was “Far-Ultraviolet Flares on AU Mic and the Implications for Its Planets” from Adina Feinstein of the University of Chicago. Thousands of exoplanets have been discovered to date, but most of these planets are very old. The 12 known planets that are less than 100 million years old have sizes in the range from Neptune to Jupiter, while most known transiting planets are between Earth and Neptune’s sizes. Young planets live in highly irradiated environments, subject to flares from their young stellar hosts. The team acquired Hubble observations of AU Mic, a roughly 22 million year old system with 2 close-in transiting exoplanets. The Hubble light curve shows 13 flares, or 2.5 flares per hour, an extremely high rate! These powerful flares can rip material away from their planets. Interestingly, the flares show a surprising increase in far-UV flux, compared to longer wavelengths. So, young stars show powerful flares which can cause high mass-loss rates in their planets, but the extent of this contribution is still an open question. Atmospheric characterization of planets undergoing mass loss is hard due to stellar activity, but the field is making progress toward making this possible.

Illustration of two rocky planets orbiting an M dwarf.

Illustration of two rocky planets orbiting an M dwarf. [NASA/JPL/Caltech]

The final presentation of this session was “The HD 260655 System: Two Rocky Worlds Transiting a Bright M Dwarf at Just 32 Light-Years” from Rafael Luque of the University of Chicago. HD 260655 is an M-dwarf in the solar neighborhood, which hosts two known planets. These planets went unnoticed by previous radial velocity monitoring but were recently found via transits with the Transiting Exoplanet Survey Satellite (TESS). Looking back, some small radial velocity signals were found in old HIRES and CARMENES observations. This combination of data allowed for mass and radius measurements of both planets! So, why are these planets so interesting? Because of their proximity to the Sun, they are some of the best potential targets for JWST atmospheric characterization. If the planets do have atmospheres, JWST may be able to detect components like water, methane, and hydrogen. This result also demonstrates the value of archival data. Press release (NASA) | Press release (IAC) | Press release (MIT) | Press release (ORIGINS) | Additional multimedia materials

See live-tweets of this session here, by Macy Huston.

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Helen B. Warner Prize: Rebekah Dawson (Pennsylvania State University) (by Macy Huston)

The 2021 Helen B. Warner Prize recipient is Professor Rebekah Dawson from Penn State University. Today, she presented a talk titled “Multifaceted Views of Planetary Systems.” The textbook version of planet formation proposes that rocky planets form close in, while gas giants form further out, based on the structure of our solar system, where planets are on circular and aligned orbits. However, even in the solar system, this formation theory isn’t the complete picture.

Early exoplanet discoveries revealed systems very different from our own, like hot Jupiters and planets on highly elliptical and misaligned orbits. Three different theories have been proposed as a formation mechanism of close-in giant planets: in situ formation, disk migration, and tidal migration. Astronomers have found hundreds of these planets now, so these theories can be tested.

illustration of the three phases of planet formation

Stages of planet formation: collapsing cloud, then gas disk, then planetary system [Image from Rebekah Dawson’s slides]

One interesting property to test these theories is eccentricity. We have discovered exoplanets consistent with the tidal migration mechanism, as evidenced by their semi-major axis and eccentricity, but is this the whole story? Host star metallicity may be able to teach us about the contents of the star’s disk during planet formation. These tidal migration planets tend to be metal-rich but some close-in planets are around metal-poor stars, so in situ formation or disk migration may play a role. The high eccentricity tidal migration mechanism would not allow for nearby planetary companions. Only a handful of hot Jupiters have been observed to have nearby companions. No singular channel for hot Jupiter formation/migration is fully consistent with observed systems. In addition to examining large statistical samples, detailed views of individual systems can be great case studies for giant planet formation.

Evidence shows that, contrary to the textbook version of planetary system origins, gas giants may form or migrate closer-in to their stars. Additionally, planets interact with gas, solids, and each other. Transit studies have shown that super-Earth-sized planets are common. Planets from the size of Earth to Neptune show a wide range of different compositions. Multi-transiting planet systems are typically “dynamically cold,” perhaps even more flat and circular in orbit than we might expect. These systems can be surprisingly tightly packed and similar (in mass, size, spacing), as well as in resonant chain orbits.

Just like close-in giant planets, there are many theories for the formation of close-in super-Earths/mini-Neptunes. Today, Prof. Dawson focused on the in situ formation mechanism. Terrestrial planets are thought to form in the inner disk once gas has mostly cleared out of the system. However, gas has been detected in some disk “cavities.” Perhaps an intermediate era where some gas is still present is when super-Earths form. In situ formation of super-Earth/mini-Neptune planets requires more solids in inner disks than initially expected. The diversity of planet compositions may be due to variations in disk solids in different systems.

We see two different modes of formation for these planetary systems: dynamically cold (low density planets, tight/uniform systems, formed with residual gas) and dynamically hot (rocky planets, more spacing and orbital variation, formed after the gas stage). Resonant chain systems can form three different ways: long scale migration, short scale migration, and eccentricity damping. And this brings us to a summary of the multi-faceted properties of close-in super Earths. Overall, the origins of planetary systems are much more complicated than we may have thought before discovering a large number of exoplanets. Current and upcoming missions are closing the gaps between the sensitivity ranges of different exoplanet detection methods. Prof. Dawson wrapped up her talk with a vision of the future, and how current and upcoming missions will enable multi-faceted views of more systems.

See live-tweets of this session here, by Macy Huston.

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Preparing for the North American Solar Eclipses of 2023 and 2024 (by Abby Lee)

Image of the solar corona as seen during a solar eclipse

The solar corona as seen during a solar eclipse. [NASA/Aubrey Gemignani]

The main thrust of this session was the preparation for the two upcoming solar eclipses. The first upcoming eclipse will occur on October 14, 2023, and is an annular solar eclipse, which is when the Moon does not completely cover the Sun and you can see the classic “ring of fire” (which is actually the Sun’s photosphere). The second is happening on April 8, 2024, and will be a total solar eclipse, which is when the Moon completely obscures the Sun (you may remember the last total solar eclipse that happened in North America in 2017!). The speaker (Rick Fienberg, former AAS press officer and member of the AAS Solar Eclipse Task Force) emphasized that everyone should try to see a total solar eclipse at least once in their lifetime because it is “completely life-changing.” Eclipses are incredible coincidences because the Sun is the same angular size as the Moon — in 500 million years, we will no longer see total eclipses because the Moon is drifting away from Earth by about 4 cm per year!

In 2014, AAS created a task force to engage as many Americans as possible with solar eclipses. Their main working groups focus on organizing outreach and education events with local communities, working with local press, doing museum work, and communicating with local transportation officials (because traffic can get really bad during eclipses!). All of the information for this task force can be found at their website.

The task force’s number one priority is safety and the distribution of glasses. Looking at an annular solar eclipse or partial solar eclipse can physically or chemically burn your retinas permanently, so you need glasses made of special material in order to protect them. Though over 300 million Americans viewed the solar eclipse in 2017, only a couple dozen people suffered (temporary) retina damage due to looking at the Sun. This was due in large part to the hard work of the AAS Solar Eclipse Task Force, who worked diligently to educating the public on eye safety during the eclipse and with glasses distributors to make sure they were compliant with safety regulations. There are non-reputable sellers on Amazon, so make sure you buy from a trusted source. The task force recommends visiting their website for a list of reputable eyewear vendors.

If you are interested in getting involved with the AAS Solar Eclipse Task Force, visit their website! There are many opportunities for outreach including formal K-12 education groups, informal social media groups, and helping to prepare communities in the path of totality.

See live-tweets of this session here, by Abby Lee.

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The Arecibo Observatory, An Engine For Science and Scientists In Puerto Rico And Beyond (by Graham Doskoch)

Photograph of a radio telescope dish set into the landscape, surrounded by towers that support suspended cables across its face.

Photograph of the Arecibo Telescope prior to its collapse. [NAIC Arecibo Observatory]

The collapse of the 305-meter dish at the Arecibo Observatory on December 1, 2020, was a huge tragedy for scientists around the world. Completed in 1963, the enormous structure was the largest single-dish telescope in the world for over half a century. Over 57 years, it made groundbreaking contributions in three primary fields: planetary science, radio astronomy, and atmospheric science. In the aftermath of its loss, both the scientific and Puerto Rican communities have reflected on its legacy and worked to preserve the observatory’s future. Today’s splinter session served as both an emotional, personal eulogy to the telescope and a reflection on the work that lies ahead to maintain the world-class science still being done at the Arecibo Observatory.

After an introduction by Dr. Nicole Lloyd-Ronning, the first portion of the session was led by Dr. Francisco Córdova, director of the observatory since 2018, who first provided a summary of the 305-meter dish’s significant accomplishments. Arecibo played an instrumental role in the measurement of the rotation rate of Mercury, the detection of the first exoplanets, and the observation of the first repeating fast radio bursts. Additionally, the observatory has — and continues — numerous outreach programs, including an REU (Research Experiences for Undergraduates), AOSA (Arecibo Observatory Space Academy), and the STAR Academy.

After listing the telescope’s major contributions, Dr. Córdova gave a detailed update on the work being done at Arecibo in the wake of the collapse. He announced that the majority of the cleanup efforts have been completed. A second forensic report on the collapse will be released by the end of the third quarter of 2022. While the dish may be gone, plenty of cutting-edge science is still being done, including ongoing observations with the 12-meter dish and work in the observatory’s lidar (light detection and ranging system) and optical labs. The visitor’s center, a major scientific attraction in Puerto Rico, has also been reopened. In conjunction with this, outreach efforts have been continued, and the staff are investigating potential new capabilities for the observatory to explore, including a possible replacement for the 305-meter dish.

The remainder of the session was devoted to a panel discussion, mediated by Prof. Marcel Agüeros of Columbia University. The four panelists were Viviana Vélez, an undergraduate who participated in the STAR Academy, Dr. Thankful Cromartie, a postdoc at Cornell University who was an REU student at Arecibo, Dr. Carlos Padín, of the Universidad Ada G. Méndez, and Dr. Allison Smith, a postdoc at Arecibo. Vélez and Cromartie both spoke about their experiences as student participants in Arecibo’s outreach programs; Vélez noted that the STAR Academy “inspires students to keep on dreaming.” Cromatie revealed that her summer at Arecibo “shaped everything I’ve done in science since then,” as it stimulated her love of pulsars and led to her meeting her future PhD advisor.

Smith and Padín both spoke at length about their involvement in education and public outreach (EPO) at the observatory. Padín demonstrated the popularity and reach of Arecibo outreach efforts by providing statistics about the numerous applicants to the observatory’s various programs. The major programs include the REU, the STAR Academy, and AOSA but in addition, Arecibo has observatory nights, the Girls Educating Girls mentorship programs, and of course the ever-popular visitor’s center, which has welcomed hundreds of thousands of visitors, many of them schoolchildren from around Puerto Rico. The experience of visiting Arecibo stays with people; Padín mentioned that “a person stopped by our [AAS] booth and said, ‘I was there when I was 9 years old.’” When people first see the dish, he says, “There’s always that ‘Woooow!’”

Smith related how she became acquainted with Arecibo firsthand not as a postdoc but as a graduate student, attending the single-dish summer school the observatory runs jointly with the Green Bank Observatory in West Virginia. Unlike the observatory’s other programs, it’s more technical, aimed at graduate students performing research in radio astronomy. Smith is now involved with the coordination of the program — a challenge now that the pandemic has forced the summer school to go online and hybrid.

All four panelists were asked about their thoughts on the observatory’s future. Vélez said she hopes the observatory keeps going with its EPO efforts and eventually builds a replacement for the 305-meter dish. Cromartie echoed the sentiment, and also advocated for additional use of the other on-site facilities. Padín described plans to integrate the arts into future EPO projects, and noted that Arecibo will need more funding to keep its programs going. “The future is bright,” Smith said when describing a proposal for an “advanced REU program,” wherein undergraduate students would do additional work on research projects throughout the academic year, culminating in summer work on-site at the observatory. “Arecibo has been a model for EPO programs,” she said. “There’s nothing more exciting than coming to a place like the Arecibo Observatory when you’re a student.” Agüeros finished the discussion by mentioning how the Puerto Rican community has gained a sense of ownership of the observatory over the past two decades, given its importance to the community.

Prof. Héctor Arce of Yale University, who gave a plenary lecture on Arecibo on Monday, concluded the session by noting that the observatory practices “outreach inspiring outreach.” The world-class research performed at a world-class facility strengthened the impact of the site’s EPO programs. At the same time, he said, “The observatory is made by the people.” As long as Arecibo’s scientists continue to make groundbreaking contributions to science — particularly if a replacement for the 305-meter dish is built — Arecibo’s legacy will endure.

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Press Conference: Extragalactic Investigations & Evolved Stars (by Sabina Sagynbayeva)

The first speaker was Dr. Valeria Olivares from the University of Kentucky with a presentation titled “Black hole activity is not evolving in central cluster galaxies.” Galaxy clusters are the most massive systems of the universe. In a galaxy cluster, a massive central elliptical galaxy sits at the center, which generally hosts an active black hole. Some of these clusters are rapidly cooling, with strong X-ray emissions at the center. So, Dr. Olivares and collaborators looked at the evolution of black holes in a sample of 164 galaxy clusters from the Planck telescope. The interaction between a supermassive black hole and its host galaxy in clusters has been in place since 8 billion years ago, and since then has evolved mildly. However, future high resolution X-ray observations can find more cavities in the faintest clusters and confirm their findings in high redshift clusters. Press release

The next speaker was Dillon Dong from Caltech presenting the Discovery of an Extremely Luminous, Decades-Old Pulsar Wind Nebula in the Very Large Array Sky Survey. The story begins with a galaxy far away… a star collapsed and became a magnetically active neutron star! Another star also blew up in a supernova around the neutron star, launching its guts outwards and creating a supernova remnant. Using the Very Large Array Sky Survey, Dong and his team discovered this emerging wind nebula as a radio transient. Explosive radio transients have never before been observed with such flat spectra. They noticed two clues: the transient is located in the central star cluster of a dwarf starburst galaxy, and it is almost as luminous as fast radio bursts. This transient turned out to be potentially the youngest known pulsar (or magnetar) wind nebula! As the remnant material expanded, it eventually became transparent to radio waves only a few decades ago. Press release

An image of a radio transient discovered by Dong et al.

Observations of a radio transient. [Dong et al.]

Thirdly, Dr. Curtis McCully (Las Cumbres Observatory) presented some Models for the Late-Time Excess Flux of a Peculiar Supernova! Dr. McCully and collaborators were looking at the supernova 2012Z (SN 2012Z) in the galaxy NGC 1309 and were surprised to find that the star that exploded was not destroyed. It survived and became brighter! NASA’s Hubble Space Telescope observed NGC 1309 — SN 2012Z’s host galaxy — in 2005, 2006, and 2010, before the supernova outburst. The group reprocessed the pre-explosion images to make them sharper and noticed an object at the supernova’s position. The source in the pre-explosion image was likely a combination of the companion star that was donating mass to a white dwarf and the disk of material around the white dwarf. The best explanation for why the supernova has not faded as expected is that we are seeing a combination of the shell of material that was ejected from the white dwarf and a heated remnant of the white dwarf that did not fully explode. Press release

Different images of SN2012Z

Observations of SN2012Z. [McCully et al.]

The next talk was about The Proper Motion of a Pulsar in a Galactic Supernova Remnant by Dr. Xi Long and Dr. Paul Plucinsky (Center for Astrophysics | Harvard & Smithsonian). The group measured the first direct proper motion of a pulsar: 612 km/s (1.4 million miles per hour)! The pulsar’s location is G292.0+1.8, an oxygen rich galactic supernova remnant about 2,000 years old. The kick direction is ~126° and the jet direction is nearly north-south aligned, which is consistent with random spin-kick alignment from simulations and is also consistent with the neutrino driven explosion mechanism for core collapse supernovae from simulations. Press release

The last speaker was Ted Johnson (University of California, Los Angeles) describing some Strange Abundances in a White Dwarf: Evidence for Simultaneous Accretion of Rocky and Icy Bodies. Ted’s team found the first evidence for a white dwarf star consuming two distinct objects! Roughly 30% of white dwarfs are “polluted” by planetary material. Hence, they become a great planetary laboratory — you can learn about planetary composition and formation from a white dwarf’s lunch. They looked at the white dwarf’s composition and noticed something interesting: it mostly has a mix of icy and rocky-metallic material. Their interpretation of this result was that the white dwarf might be accreting an icy Kuiper belt object body and a Mercury-like asteroid. Press release (UCLA) | Press release (STScI)

See live-tweets of this session here, by Sabina Sagynbayeva.

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Annie Jump Cannon Award Lecture: Laura Kreidberg (Max Planck Institute for Astronomy) (by Pratik Gandhi)

This year’s Annie Jump Cannon Award was given to Dr. Laura Kreidberg for her seminal work on characterizing exoplanet atmospheres. In her plenary lecture titled “Planets are places: characterization of other worlds in the 2020s and beyond,” Dr. Kreidberg discussed the contributions of Annie Jump Cannon to the field of astronomy, the importance of studying exoplanet atmospheres, and the main frontiers remaining to be addressed in this field. Dr. Kreidberg is the Director of the Atmospheric Physics of Exoplanets (APEx) Department at the Max Planck Institute for Astronomy in Heidelberg, Germany.

To begin, Dr. Kreidberg drew the audience’s attention to the legacy of Annie Jump Cannon, a pioneer in stellar classification. Her OBAFGKM scheme for classifying stellar spectral types remains in use to this day! “She was also profoundly hard of hearing, and experienced enormous discrimination,” said Dr. Kreidberg.

Of the 5,000+ known exoplanets, many can be assigned to two populations that we don’t see in our solar system. We call these planets Hot Jupiters and super-Earths/sub-Neptunes, although Dr. Kreidberg also suggests the term “Neptini”! Dr. Kreidberg adds that now is a great time to be working on exoplanet atmospheres and characterization, and that studying their atmospheres can inform our knowledge of the exoplanets’ formation and prospects for life elsewhere in the universe!

As far as exoplanet atmospheres are concerned, we can often characterize them using a basic technique called “Transmission/Emission Spectroscopy”. This is possible whenever the planet passes in front of or behind the star — starlight gets filtered through the planet’s atmosphere, leaving an imprint of the chemical composition of the atmosphere on the star’s spectrum. Moving on, she talks about the four main frontiers in this field:

Frontier #1: what can we learn about planet formation from planetary atmospheres? Gas giant planets in particular retain a fairly pristine atmosphere that reflects the conditions of when the planet first started forming. Dr. Kreidberg adds that over the past few years, the Hubble Space Telescope has really transformed the study of water and oxygen abundances in planetary atmospheres, especially in Hot Jupiters! There are some interesting outliers though — KELT-11b is a planet with 100 times less atmospheric water than expected from compositions in the solar system. This kind of low water content could point to planet formation by pebbles and not planetesimals, because gas is wet and pebbles are dry.

Frontiers #2-#3: what can we learn about Earth from its cousins? Studying sub-Neptunes could allow us to study volatile element delivery to small rocky bodies, as might have happened with the proto-Earth. Dr. Kreidberg then pointed to a result from 2014 of a warm “Neptino” with a spectrum so featureless that there must have been clouds or haze in the planet’s atmosphere, which is extremely cool!

Note that one “shortcut” to determining whether a small rocky planet has an atmosphere is thermal phase curve observations — presence of an atmosphere tends to even out temperatures between the day and night sides of the planet, which can be a useful probe! Dr.Kreidberg added that JWST observations will be extremely exciting for exploring the diversity of rocky exoplanet atmospheres around M-dwarf stars! More than 10 rocky exoplanets are scheduled to undergo JWST observations, and chemical features could be detectable!

Finally, the plenary wrapped up with Dr. Kreidberg speculating on Frontier #4: when will we detect biosignatures? She encouraged a little caution — even with JWST etc, we may not have the capacity currently to detect biosignatures in exoplanet atmospheres. A next generation space telescope is needed, which is a priority for the 2020 Decadal Review!

See live-tweets of this session here, by Pratik Gandhi.

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Newton Lacy Pierce Prize: Courtney Dressing (University of California at Berkeley) (by Isabella Trierweiler)


Artist’s impression of TESS observing planets orbiting a dwarf star. [NASA Goddard SFC]

In her plenary talk, Dr. Courtney Dressing (an Astrobites founder!) took us on a tour through three exoplanets, each in a multiplanet system. One of the most common ways to detect exoplanets is the transit method, which searches for the dip in starlight that occurs when a planet passes in front of its host star. NASA’s Transiting Exoplanet Survey Satellite (TESS) uses the transit method to search for planets all over the sky, and has found over 5000 new candidates. Since the last in-person AAS meeting (in 2020), the number of exoplanets discovered has increased by a whopping 20%! Dr. Dressing emphasizes that in addition to simply detecting more planets, we need to build a sample set of well-studied planets with data applicable to multiple scientific disciplines. This is the goal of the TESS-Keck Survey (TKS), which will build a database of exoplanets including bulk compositions, atmospheric masses and compositions, planetary architectures, and systems around evolved stars.

We start the tour at K2-136c, which is unique as it is one of the few young planets with a density estimate. It’s about twice as dense as Neptune, and a little less dense than Earth. While we can’t get an exact composition with just bulk density measurements, one possible composition for this planet is a rocky core with a hydrogen/helium atmosphere.

Up next is HIP 41378f, part of a five-planet system. This planet is remarkable for having very low density. It’s a little unclear what makes the density so low — the planet might have a ring system, or it could be a super-puff planet, or have an atmosphere. There actually are several planets with similar low densities. Taken as a group, rings are not able to explain all of these planets, but hazes in the atmosphere could be the solution, and Dr. Dressing hopes to use upcoming JWST observations to confirm this.

The last stop on the tour is TOI-1246, a system that has extensive data from adaptive optics imaging, radial velocity, and transit detection. With all this data, Dr. Dressing’s team found a surprise — an extra planet hidden in the radial velocity signals! While the mass of this extra planet is not well known, it is accompanied by four sub-Neptunes in the system. The architecture of this system is somewhat unusual, in that it does not follow the “peas-in-a-pod” arrangement of most exoplanet systems, and instead shows a gap between the inner and outer planets.

In the last bit of her talk, Dr. Dressing discussed future efforts towards understanding habitability, a topic that was named as a focus point for the next decade by both the Astro 2020 Decadal Survey and the Planetary Decadal Survey. These surveys recommend that NASA aim to launch a telescope capable of searching for biosignatures by the 2040s. Dr. Dressing further argued that even if such a habitability mission doesn’t find habitable planets, it will definitely find hundreds more exoplanets, of all types, so there’s really nothing to lose but everything to gain from a biosignature search!

table showing the number of exoplanets detected that fall into various categories

Searching for habitable planets = finding all kinds of planets! [Aki Roberge (NASA/GSFC), Courtney Dressing]

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SOFIA Town Hall (by Briley Lewis)

Town halls are a place to get updates on the big missions and happenings in astronomy — and the Stratospheric Observatory for Infrared Astronomy, SOFIA, the famous flying observatory, had a big update to discuss today: its upcoming cancellation. Before diving into that controversial topic, though, the team wanted to provide some positive news on what the observatory has been up to in 2022.

First up, Robert Minchin, Instrument Scientist at the SOFIA Science Center, told us about SOFIA’s latest deployments: a recent trip to Santiago, Chile in March 2022, and an upcoming visit to Christchurch, New Zealand in the next month. While in Chile, SOFIA completed a significant portion of one of its “legacy surveys” — observation programs meant to create rich data sets for future use. They’re planning to do more of these legacy observations with the infrared polarimeter, HAWC+, and the German instrument GREAT while in New Zealand, probing magnetic fields in star forming regions and characterizing the interstellar medium with detailed spectral line measurements. He emphasized that these current deployments are doing science that SOFIA wasn’t capable of two years ago. Plus, you can follow along and track the upcoming flights with apps like FlightAware by searching for the callsign (NASA747) or the tail number (N747NA) since flights in New Zealand happen during the daytime in the US! “Watch us go out there and get that science!” said Minchin.

Next, Arielle Moullet, SOFIA Scientist and Outreach Team Manager, publicized a new call for proposals for using archival data from the mission. The data has a long path from the telescope to the scientist, passing through processing by the SOFIA Science Center and cataloging in the IRSA archive. Currently, there’s around one million dollars to be distributed over a series of projects using old SOFIA data, and Moullet emphasizes how rich the archived data sets are. They’ve even sorted things into categories, including “high-potential” data sets. Plus, there are 100 data sets on sources with either existing ALMA data or expected JWST data, and the nine legacy programs.

Speaking of legacy programs, Margaret Meixner, Director of SOFIA Science Mission Operations, took a moment to spotlight the various legacy programs that are being completed. This really is a high point for SOFIA — annual publication rates have doubled over the past 3 years! The legacy programs are part of this success, and are intended to be a resource for the community. Along those lines, they’re available to the community immediately, too! One exciting example of a legacy program is Lunar: Water on the Moon, a follow-up to the first direct detection of molecular water on the sunlit lunar surface. They’re hoping to use it to study the distribution of water on the moon across the surface and across time, helping to probe key questions about planetary habitability!

For the rest of SOFIA’s operating lifetime — until September 30, 2022 — they’re prioritizing these legacy programs and high priority proposals from the ongoing general observer cycle. But, they can’t complete all of this by the end of the mission. It’s expected that only around 74% of the high priority and legacy programs will be fully finished. The next proposal cycle had also already commenced, and many hopeful observers turned in their proposals for Cycle 10, only to find out that the mission was canceled — and even if selected, their observations won’t be happening, with the exception of a few extra exciting programs that have been wedged into the current cycle.

Meixner really stressed the incredibly high caliber of SOFIA’s science, calling it “the far-IR observatory for this decade.” Its observations address half of the decadal survey’s science priorities, and the mission is ending at “peak performance” and leaving an archive for the community to use for years to come.

Lastly, Naseem Rangwala, SOFIA Project Scientist, addressed the elephant in the room: how exactly is the end of SOFIA going to happen? Slowly, or all at once? The answer: slowly and methodically. They are currently focusing on science flight operations and will do so until September 30th, and then an orderly close-out process will begin October 1st. Close-out planning is already underway, and they’re working out the details. Rangwala said, “Our goal is to provide the SOFIA mission and the SOFIA team a very strong finish!”

SOFIA has certainly had quite a legacy — 702 science missions have been flown since its first light in 2010, and they’ve had science results featured in AAS press conferences and the cover of journals like Nature Astronomy. Rangwala expects its legacy to continue, and many more papers to be published during the closeout phase and from archival data for years to come.

Naturally, the Q&A featured many inquisitive questions about the future of the mission, some from supporters who are sad to see the beloved and unique observatory’s demise. There is hope the aircraft will become part of a museum, but no details are set yet. Some attendees probed for more information on why this cancellation is even happening, and NASA Astrophysics Division Director Paul Hertz stepped up to answer. He reminded everyone again about the findings of the decadal survey: that they found SOFIA had a particularly high cost for only a modest science output, and should be scrapped to make way for other upcoming missions in need of funding. Attendees also worried about the huge gap SOFIA will leave in mid- to far-infrared astronomy, and Hertz seemed unfazed, saying “We all wish that we could have capabilities at all wavelengths at all the time, but that’s just never been the case.”

Despite the clear and in-motion plans to conclude SOFIA operations, some, like German SOFIA Institute Deputy Director Bernhard Schulz, are vehemently and vocally opposed to the situation. The session ended on a somber note, after Schulz gave an impassioned plea for American astronomers to call their congresspeople and convey the importance of funding this mission — or else, deal a grave blow to science by losing this incredible observatory. At this point, only time will reveal exactly how the end of the mission will play out for SOFIA, or even if there really is going to be an end after all.

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