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.

Return to Table of Contents.

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!

Return to Table of Contents.

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.

Return to Table of Contents.

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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Hubble image of the spiral galaxy Messier 94

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:

Historical Astronomy Divison Doggett Prize: William Donahue (St. John’s College / Green Lion Press) (by Graham Doskoch)

One of the most influential works in the history of astronomy is Johannes Kepler’s Astronomia Nova. Published in 1609, the book presents data and calculations that support Kepler’s theories about the motion of the planets, lending support to the heliocentric model. While nowadays it is widely accepted that planets move in elliptical orbits, Astronomia Nova was the first work to make such a claim.

Like many scientific treatises of the age, Astronomia Nova was written in Latin. Translating the 500-page tome to English is a monumental task — one that Prof. William Donahue, now of St. John’s College, took on four decades ago. His first version was published in 1992, with a revised edition released in 2015, and it has strongly influenced most English-language studies of Kepler’s book. Completing the project required an intimate knowledge of the text and, as Prof. Donahue admits, a love of untangling complicated arguments and figures.

Prof. Donahue gave Tuesday morning’s plenary lecture after being honored with the Doggett Prize as recognition of his lengthy career making the history of astronomy more accessible — including his work on translating Astronomia Nova and Kepler’s treatise on optics, Astronomiae Pars Optica. In this talk, Prof. Donahue chose not to guide us through the book but rather to go through two pages of Kepler’s calculations, imagining we were looking over Kepler’s shoulder as he wrote one April morning.

The pages in question describe Kepler’s work on reconciling observations with two hypotheses: the “vicarious hypothesis,” influenced by Ptolemy and a classical understanding of planetary motion, and the “physical hypothesis,” which is influenced more by Kepler’s perspective, viewing orbits as being governed by physics and gravity, where planets traveled at different speeds at different points in their orbits. Kepler had observational data at his disposal thanks to important observations by Tycho Brahe. His method was to compare the predictions of both hypotheses against Brahe’s observations of Mars, tweaking parameters in the physical hypothesis to match at different points in the orbit.

Kepler — after making several mistakes and typos, some of which were notably crossed out -— came to the conclusion that the two models differ significantly at certain positions in Mars’s orbit, and both failed to adequately reproduce the observations. The vicarious hypothesis, for instance, was off by an angular distance of 9 minutes of arc at one point.

After some thinking, Kepler realized that the physical hypothesis could be saved if he made the assumption that orbits were elliptical. We now know this as Kepler’s First Law, and it forms a key part of orbital dynamics and studies of exoplanets and multiple-star systems. Before this point, however, it hadn’t occurred to him. It took lengthy calculations, not to mention typos, incorrect multiplications, and minus sign errors, but Kepler did arrive at one of the pillars of astronomy. Although it may have taken 500 pages to fully explain and justify, this journey can be traced through merely two sides of what Prof. Donahue simply describes as “the most fascinating piece of paper in the universe.”

See live-tweets of this session here, by Graham Doskoch.

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Imaging X-ray Polarimetry Explorer: Initial Results (by Graham Doskoch and Briley Lewis)

IXPE artist's rendition; long telescope pointing at a colorful swirl on a black background

Artist’s rendition of IXPE in space. [NASA/IXPE]

All the hype lately has been about JWST, but NASA actually launched another revolutionary telescope last December: the Imaging X-ray Polarimetry Explorer, or IXPE for short. It’s the first satellite to take X-ray polarimetry measurements since the Eighth Orbiting Solar Observatory (OSO-8) mission in 1975, and will be 100 times more sensitive!

Launched on December 9th, 2021 on a SpaceX rocket, it has a 2-year baseline mission, with plans for 3 or more years of general observer time and an 18-year orbit lifetime. This mission uses X-ray optics and a gas pixel detector to record the polarization (or orientation) of the high-energy light, while also taking images and doing spectroscopy. After launch, IXPE had to go through rigorous calibration since it uses cutting-edge technology, but now it’s been steadily operating for around six months and it’s returning its first science results. The first speaker, Brian Ramsey (NASA/MSFC), emphasized that this is an exciting time — after 50 years since the first X-ray polarization measurement of the famous Crab Nebula, sensitive X-ray polarimetry capabilities have arrived. And now, we could detect the Crab at an incredible 100 sigma!

Today’s press conference discussed multiple exciting new observations, but many of them are currently under a press embargo, meaning we can’t share them with you today. But believe us — there are some very cool papers coming very soon!

One study we can tell you about is the first X-ray polarization detection of Cassiopeia A, a core collapse supernova that’s about 350 years old. Today, Riccardo Ferrazzoli (INAF-IAPS) recapped this finding, which was just published on the arXiv. Using IXPE, we can probe not only the magnetic field but also the turbulence of this interesting object. They had two goals in the study: (1) to see how the degree of polarization in X-rays from IXPE compares with the degree of polarization in radio observations and (2) to investigate the structure of the magnetic field, asking: is it tangential, radial, random? So far, they have a fairly modest 5-sigma detection — a hint of polarization. The degree of polarization is low as well, only ~2-5% depending on what effects you account for. Yet, they did find evidence that the magnetic field is radial!

Herman Marshall (MIT) concluded by reminding us that this is only one of the many sources IXPE will study, and quite a few other sources are in the planning or exploratory phase right now. They’re looking at a diverse range of objects, and there’s plenty of interesting science ahead for this new mission!

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Imaging the Nearest Supermassive Black Hole, Sgr A*, with the Event Horizon Telescope (by Sabina Sagynbayeva)

the first image of Sgr A*. The image shows a red-yellow ring on a black background.

The first image of Sgr A*. [EHT Collaboration]

Today, we had six speakers talking about their ApJ articles about the recent result from the Event Horizon Telescope (EHT) that revealed the first image of our own Milky Way’s black hole, Sagittarius A*!

The first speaker, Dr. Sera Markoff, gave us an overview of the EHT collaboration. The collaboration has over 300 scientists in over 80 institutions around the globe. Dr. Markoff also reminded us that EHT is not like a usual telescope. In fact, it is not actually a telescope at all  rather it is a collection of different observatories around the world that are all strung together. The next speakers go into more detail about the physics and image processing of the exciting result.

Dr. Daryl Haggard gave us multi-wavelength insights into Sgr A*. Dr. Haggard pointed out that the best data sets came out from observing runs on April 6th and April 7th in 2017, therefore most plots shown today had those two dates on them. The amplitudes of the final data product are well described by a ~50-microarcsecond ring model, which is the angular diameter of the ring! The data also showed a very interesting variability in its light curve. It turns out that Sgr A* is way more variable than M87* (the previously imaged black hole). So, intrinsic source variability is likely present, but they do not conclusively establish variability on resolved scales. To sum up the comparison between M87* and Sgr A* (which are very different!), here’s a great table provided by Dr. Haggard:

a table comparing Sgr A* and M87*.Next speaker, Dr. Kazunori Akiyama, told us about the whole complexity behind the image processing. One of the most important assets to obtain the images was Earth’s rotation! Because of this rotation, you can get data from different angles (sort of like looking at things from different perspectives), but not only that, you can also get more data that samples different size scales to reconstruct an image from the sparse data. They have three complicated and code-heavy techniques for the image processing that consider their Gaussian noises mostly uncorrelated. Different prescriptions have been used to account for scattering effects by the interstellar medium and mitigation of the rapid intra-day variability. They conclude that the EHT Sgr A* data show compelling evidence for an image that is dominated by a bright 50-microarcsecond ring, consistent with the expected “shadow” of the galactic center supermassive black hole!

Dr. Chi-Kwan Chan was talking about the physics behind the image (also on behalf of Dr. Feryal Ozel). In order to address most of the physics, they needed to consider magnetic fields and general relativity (magnetohydrodynamics [MHD] and general relativistic MHD [GRMHD]) in the context of hydrodynamics. In all the artistic renditions of black holes, you will see an accretion disk, but a thin accretion disk is not a good model for Sgr A*. The standard “good” model is an optically thick and geometrically thin disk. The physics analysis shows that the accretion flow is dominated by a magnetic field (magnetically arrested disk, MAD) and that it is possibly prograde. They also compared their image with the Kerr black hole to check general relativity. The key distinguishing characteristic is the size of the ring/shadow. It turns out the size of the imaged black hole is consistent with Kerr predictions to within ~10%!

Last but not the least, Dr. Dominic Pesce talked about morphologies. Their technique, called geometric modeling, provides a useful low-dimensional representation of the Sgr A* image structure: an exploration of simple geometric source models demonstrates that ring-like morphologies provide better fits to the Sgr A* data than other morphologies with comparable complexity. Two schemes have been employed to mitigate the impact of Sgr A* variability during model-fitting: 1) a “snapshot” approach that fits only to individual short segments of data during which Sgr A* can be reasonably approximated as static, then averages the fits to each segment. 2) a “full-track” approach that fits the average structure of the entire data set at once, while also simultaneously characterizing the fluctuations about that average via a parametrized model. Their schemes helped them to calibrate the relationship between measured diameter and gravitational radius using GRMHD simulations.

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

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Press Conference: Nearby Disks, Faraway Galaxies & a Record-Breaking Star (by Briley Lewis)

5 people behind a long table, all wearing masks, surrounded by screens and a formal AAS backdrop

Panelists lined up before the press conference begins. [Briley Lewis]

Graph showing debris disks at low luminosity over many ages, with a much higher luminosity outlier labeled "extreme debris disk"

A chart showing that the “extreme” debris disk discovered is an outlier with higher luminosity. Click to enlarge. [Marc Kuchner]

Tuesday’s first press conference brought together three quite different themes: planet forming disks, the earliest galaxies, and the fastest nova yet observed. First up: Marc Kuchner (NASA/GSFC) discussed findings from the Disk Detectives citizen science project, using data from the Wide-field Infrared Survey Explorer (WISE) and Gaia. The big question is “how old are the disks?” so that we can use them to figure out the steps of planet formation. We figure out ages by looking for moving groups — associations of stars that formed together. They actually used virtual reality as a sort of “time machine” to help researchers find these groups. Kuchner said, “Using their velocities, we can go back in time to see how the stars are associated.” From this work, they found 10 new disks, an extreme debris disk (J0925), and even a new moving group (Smethells 165). This “extreme” debris disk was much brighter than other disks, indicating that its dust may have been freshly replenished by a large collisional cascade of colliding protoplanets. WISE is still collecting data, too, which means the Disk Detectives are still at it looking for even more new discoveries. Kuchner encourages you to join in the fun!

Image of disk with pericenter, apocenters, star and disk center labeled

A diagram of the debris disk, illustrating the disk offset from the star (which indicates eccentricity) and the brighter apocenter. [Meredith MacGregor]

Next up, Meredith MacGregor (University of Colorado, Boulder) introduced another new debris disk (sometimes called an “Exo-Kuiper Belt”) around the star HD 53143, observed by the Atacama Large Millimeter/submillimeter Array (ALMA). It’s a star very much like a younger version of our Sun, so this system is like a glimpse into our own past. This disk was first resolved by Hubble, but now we have a clearer view — and, wow, do we see some interesting things! The disk is eccentric (i.e., not circular) and is brighter at apocenter, the farthest point from the star. Simple models don’t fit the data, though, indicating that there’s something more complicated going on. MacGregor and collaborators found that there’s an inner disk — like an analog to our asteroid belt — that’s not in the same plane. This is quite strange, and points to some dramatic planetary migration or shaping that tweaked the disk to where it is now.

Changing gears a bit to galaxies, Chris Conselice (Univ. of Manchester) showed new data that probes galaxy formation at high redshifts, z > 6. A big question in galactic astronomy is how the galaxies we see grew out of the early universe. We have an idea on the when, but the how still escapes us. To investigate this question, Conselice and collaborators wanted to ask a related question: Do galaxy mergers happen in the past as well? Is this how galaxies grow? Through their REFINE survey (Redshift Evolution and Formation in Extragalactic Systems), they looked for pairs of galaxies across distance/time to see if there were more mergers in the past. They also considered star formation in order to see which builds galaxies — star formation, or mergers. The result? Mergers dominate in the early universe, and star formation comes later! JWST will soon help us explore this further, so lots to look forward to.

Black background with many specks, some of which are larger and look like galaxies

Slide from Xin Wang’s talk showing a deep field photo containing more than 5,000 galaxies. [Xin Wang/NASA/Hubble]

Fourth on the roster for this press conference: Xin Wang (Caltech/IPAC), discussing the UVCANDELS survey. This survey revisits the classic Hubble Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) fields, the telescope’s largest survey of distant galaxies, but now in ultraviolet (UV) and blue light! This data set covers over 140,000 galaxies, in an area on the sky equal to 60% of the size of the full Moon, taking over 10 days of Hubble observations. You may be wondering — why UV light? Well, UV comes from the most massive, youngest, and hottest stars, and therefore provides insight into star formation. This new data set enables a wide range of science explorations, such as the mystery of reionization (“how the first galaxies ended the dark age”). Wang and collaborators looked at 90 galaxies over 11 billion years old, which should be analogous to the first galaxies in the universe, and found a hint of extreme UV radiation that supports the idea that massive stars had a starring role (hah, get it, starring?) in causing reionization. This incredible data set is now available at the Mikulski Archive for Space Telescopes (MAST), starting today!

Last, but certainly not least, Sumner Starrfield (ASU) presented on V1674 Her — the fastest nova ever seen! Novae are particularly important, since they make all sorts of important things in the universe, like cosmic rays and lithium (which is incredibly important for our smartphones and tech here on Earth!). So, what makes a nova fast? How quickly its light dims after the initial burst. This can be an indication of a particularly massive white dwarf in the binary system that causes the nova outburst. V1674 Her broke the speed record, but that record has been broken many times — and the Vera Rubin Observatory is likely to break it again soon, as we become able to see even shorter transients with this incredible new telescope.

See live-tweets of this session here, by Briley Lewis.

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Plenary Lecture: Thomas Zurbuchen (Associate Administrator, NASA Science Mission Directorate) (by Yoni Brande)

The second plenary of the day was presented by Dr. Thomas Zurbuchen, Associate Administrator for NASA’s Science Mission Directorate. Dr. Zurbuchen highlighted some of the recommendations of the recent Astro2020 Decadal Survey and argued that NASA needs to succeed in five domains in order to build effective teams and truly lead the way into the future of astrophysics.

Astrophysics as a field is at a crucial moment. The recent launch of JWST and the upcoming launch of the Roman Space Telescope are examples of the forefront of our current capabilities. The Astro2020 Great Observatories have the potential to revolutionize astrophysics, and we have to build up our communities to ensure that such missions succeed.


Zurbuchen pointed out the Decadal’s equity, diversity, and inclusion recommendations, noting that some of the NASA leaders now recognized for their pivotal contributions were fighting uphill battles when they started out decades ago. Failing to address bigotry like racism and sexism hurts people, and it also affects scientific progress. Following this, NASA recently implemented dual-anonymous peer review across its proposal streams, which has already made a significant impact in reducing gender and racial bias in awards, as well as increasing the number of awards made to early career scientists.


Zurbuchen said that NASA also needs to continue to focus on the future, even if it means ending well-loved missions. The Spitzer Space Telescope, which stuck around for years after its active coolant ran out, ended its mission in 2020, and NASA is ending the Stratospheric Observatory for Infrared Astronomy (SOFIA) in order to apply some of these resources to future projects.


By prioritizing strategic mission goals, Zurbuchen said that NASA can make sure ambitious projects like Mars Sample Return succeed.


NASA has only been able to do its work because of significant technological innovation. Lessons learned from previous missions will inform future projects. If JWST was mostly purpose-built, and needed nearly a year of continuous system modeling to succeed, can NASA leverage new launch technologies and economies of scale to build cheaper, more robust observatories? Zurbuchen says yes, pointing to the massive increase in launch capability in the market now, as well as budding human serviceability and on-orbit assembly capabilities and improvements in sensor technology.


Zurbuchen outlined the partnerships NASA has made both with industry partners and international partners, both critical to current missions and future missions. Next gen telescopes will be more like JWST, with private, academic, and international stakeholders providing engineering and scientific expertise. NASA can both continue to be a leader in the field as well as a partner to help other institutions succeed. The future of astrophysics lies in collaborative science and open data.


He ended his talk with a quote from Maya Angelou: “In diversity there is beauty and there is strength.”

See live-tweets of this session here, by Yoni Brande.

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Press Conference: Galactic Neighbors & Insights from ALMA (by Yoni Brande)

The last press conference for today focused on galaxies and observations with the Atacama Large Millimeter/submillimeter Array (ALMA), featuring Astrobiter Katya Gozman (University of Michigan), Eric Bell (University of Michigan), Janvi Madhani and Charlotte Welker (The Johns Hopkins University), Hollis Akins (Grinnell College), and Ambesh Singh (University of Arizona).

Katya Gozman started us off with some exciting results and a presentation titled “An Extragalactic Fossil Record: M94’s Merger History through its Stellar Halo.” M94 is a nearby spiral galaxy with a very large stellar halo, which may have evidence of past galactic mergers. In order to identify M94’s merger history, Katya and her team used the Subaru Observatory’s Hyper Suprime-Cam instrument to observe the stars in M94’s halo as well as the galaxy’s internal structure. M94 has a particularly large pseudobulge, which makes up about about half of its total mass, and its stellar halo is fairly low mass and low metallicity. If M94 had been through some energetic mergers in the past, its halo should be a lot more massive and metal rich. However, it’s not just the halos that are related to mergers, but also the galaxy’s internal structure. The team also compared M94 to another galaxy, M101. These have similar halo masses, but vastly different bulge masses, implying that M94’s significant internal structure must have been built by some other process than mergers!

Next up was Eric Bell presenting new results with a presentation titled “Building Out the Census of Faint and Ultra-Faint Satellites of Milky Way-Mass Galaxies: New Satellites-of-Satellites in the M81 Group.” His group also used the Subaru/Hyper Suprime-Cam, but studied the M81 galaxy group. M81 has several large satellite galaxies, but Eric used Subaru’s sensitivity to find lots of small, faint, unresolved galaxies in the same field. By cleverly identifying those at the same distance as M81, the team found one new dwarf satellite and several candidate dwarf satellites. These small faint galaxies will need space-based imaging from Hubble or JWST to resolve their stars and confirm their nature, but if confirmed would be among the least luminous galaxies yet found outside our own Local Group! In addition, the distribution of the dwarf satellites is notably asymmetric, centered on one of the larger satellites. Perhaps M81 tends to destroy its own satellites over time and these are more recent additions to the group.

Third in this session were Janvi Madhani and Charlotte Welker with their talk, “Are Planes of Satellite Galaxies as Elusive in Simulations as Previously Thought?” Satellite galaxies are often observed in thin coplanar streams, coherently orbiting their host galaxies. Previous simulations have struggled to reproduce these at their observed fractions. Janvi and Charlotte conducted new, higher resolution surveys to try and fix this. With the same cosmology and gravity models as previous studies and only higher resolution simulations, they were able to finally create these observed streams consistent with observations.

The last in-person presentation was from Hollis Akins and was titled “ALMA Reveals Extended Cool Gas and Hot Ionized Outflows in a Distant Star-Forming Galaxy.” Galaxies aren’t just made up of stars, but also significant amounts of interstellar gas. This gas in the interstellar medium (ISM) is constantly reprocessed into stars and replenished by supernovae, and it is also continually exchanged with the circumgalactic medium. Hollis and his team used ALMA to observe the distant galaxy A1689-zD1, which is 13 billion light-years away, in order to study its gas content. The team found very different distributions of hot/ionized and cold/neutral ISM gas in the galaxy, with compact hot gas and much more extended cold gas. This could be an effect of previous mergers, or it could be driven by gas outflows from processes in the galaxy itself. ALMA spectroscopy showed that the hot gas in the core of the center of the galaxy was being blown outward, implying that as the gas flows, it cools to form the unexpected extended neutral gas feature!

The final talk of the day was online from Ambesh Singh, titled “ALMA Reveals the Molecular Outflows in the Ejecta of VY Canis Majoris.” VY Canis Majoris is a hypergiant star with a mass greater than 20 solar masses, and it is subject to intense sporadic mass-loss events. The team searched the gaseous envelope of the star for evidence of particular molecules that may be able to trace some of these mass-loss events. Using ALMA, they were able to identify particular molecules (such as lots of carbon-bearing species, water, salt, etc.), including some that are biologically important (like phosphorus monoxide)! By taking different images at different frequencies, the team found that each molecule was associated with different expanding gaseous shells, implying they came from different mass-loss events!

See live-tweets of this session here, by Yoni Brande.

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Henry Norris Russell Lecture: Nicholas Scoville (Caltech) (by Graham Doskoch)

If you look around the universe, you can tell that galaxies are an incredibly diverse bunch. There are spirals and irregular galaxies, giant ellipticals and dwarf spheroidals, green peas and luminous red galaxies. Yet in this wild and wonderful zoo, patterns emerge: trends across cosmic time. In one of this afternoon’s plenary lectures, Prof. Nicholas Scoville presented results that show how galaxy populations changed as the universe grew and evolved, viewed through the lens of a simple but ubiquitous tool: gas!

Molecular gas is extremely important. Much of it exists in the interstellar medium, with some of it lying in the form of giant molecular clouds, or GMCs. These massive structures can weigh in at hundreds of thousands of solar masses. They’re well known among astronomers for forming stars, as well as for blocking many observations within the galactic plane; the dust within GMCs causes enormous amounts of interstellar extinction. To illustrate this, Prof. Scoville pointed out that if the solar system lay inside a large molecular cloud, Earthbound astronomers wouldn’t be able to see any stars.

GMCs — or, more precisely, the gas they contain — are useful tools for extragalactic astronomers. It turns out that the mass of gas in a galaxy is related to some of its other properties. By searching for spectral line emission from GMCs, such as carbon monoxide (CO), astronomers can measure a galaxy’s gas mass and uncover these relationships. Unfortunately, at high redshifts, only certain parts of this CO emission are visible, corresponding to only the hotter gas. In his plenary talk, Prof. Scoville presented an alternative: looking for the long-wavelength spectral “tail” produced by dust within GMCs and other gas reservoirs, allowing him to trace gas in a broader range of temperatures.

By doing so, he uncovered several trends. For example, galaxies in the early universe had more gas than the Milky Way — often by factors of 10 or 100! They also had higher star formation efficiencies. This led to high star formation rates — at least until gas reservoirs were depleted; it’s a well-known trend that star formation peaked when the universe was a few billion years old, a time known as “cosmic noon.” Prof. Scoville also found that some galaxies with high star formation efficiencies were starburst galaxies, likely resulting from galactic mergers. As he pointed out, it’s possible that this is because the collisions compressed gas clouds, making it easier for them to fragment and form even more stars.

Prof. Scoville finished by acknowledging the astronomers who played a role in these studies and related projects over the years, from the team at the Cosmic Evolution Survey (COSMOS) he founded to the scientists and engineers who designed, built and operate the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, which has been instrumental to this work.

See live-tweets of this session here, by Graham Doskoch.

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Laboratory Astrophysics Division Plenary Speaker: Dennis Bodewits (Auburn University) (by Pratik Gandhi)

The final plenary talk for the day featured Prof. Dennis Bodewits, who talked about “Comets as Natural Laboratories” for this year’s annual Laboratory Astrophysics Division (LAD) plenary talk. Dr. Bodewits is a professor at Auburn University originally from the Netherlands, with an asteroid (Asteroid 10033 ‘Bodewits’) named after him by the International Astronomical Union!

Right from the very beginning, Dr. Bodewits emphasised that understanding the formation, composition, and evolution of comets is crucial to a variety of endeavours, including solar system formation, planetary science, astrochemistry, geophysics, and more. Since comets are leftover building blocks from the solar system’s early days, they often encode information that can shed light on how the solar system formed in the first place. Two key questions are: (a) what are their primordial properties, and (b) how do comets evolve over billions of years?

Through observations, the community has been able to identify ~50 different atoms/molecules in and around comets, which are often extremely useful for probing the properties of the comets themselves. Dr. Bodewits then pulled out the main idea behind the talk: over scales ranging from the comet’s nucleus to its outer atmosphere, there are a few main kinds of reactions that are useful to study.

The first is resonant fluorescent emission (RFE) where “parent molecules” like H2O and CO2 come out of the nucleus, are excited by sunlight, and re-emit the light that we can then detect — this tells us how many molecules there might be. RFE can also occur from “fragment species” that occur when H2O or CO2 break up into smaller atoms/molecules. The second reaction is prompt emissive photodissociation (EP), where H2O and CO2 coming off the nucleus can get hit by sunlight immediately and split up, resulting in different energy states and spectra than from RFE. Some gases like CO2 and O2 can be studied using observations of atomic oxygen that arises from emissive photodissociation in the presence of sunlight — an example of the utility of this type of reaction. Third, we have dissociative electron impact excitation (DEIE): when H2O and CO2 coming off the nucleus get illuminated, they can emit electrons (photoelectric effect), which in turn can excite molecules and lead to very different excited states and radiation than the previous reactions.

Throughout all this, Dr. Bodewits emphasised that observing each of these reactions/effects/processes tells us different information about the chemical composition of the comet, which is why he and his group study all of them together! The final reaction he highlighted is charge exchange, where an ion encountering an electron in an atom/molecule can emit radiation in certain special cases, and often the emission can be in the X-ray regime! Dr. Bodewits explained that X-rays are usually associated with very high temperature sources, while comets are fairly cold — yet this is a case of comets showing up in X-ray emission! Charge exchange often occurs because of charged particles from the solar wind hitting the comet.

In conclusion, Dr. Bodewits re-emphasised how comets are excellent labs that allow us to study planetary science, geophysics, plasma science, chemistry, and so much more!

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

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spitzer space telescope infrared image of the DR22 cloud in the Cygnus X star-forming region

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:

Fred Kavli Plenary Lecture: Phosphine in the Atmosphere of Venus, Jane Greaves (by Briley Lewis)

AAS 240 started off today with a hot topic: possible detections of alien life. (More specifically, phosphine in Venus’s atmosphere!)

the rocky dry surface of venus with a bit of the venera lander at the bottom of the image

Venera’s view of the Venusian surface. [NASA/Russian Academy of Sciences/Venera 14]

In 2020, Professor Jane Greaves and collaborators released a paper that became headline news and claimed a detection of phosphine on Venus, which could be a possible sign of extraterrestrial life. Venus, though, has long been thought of as quite an inhospitable place. Early missions like Mariner 2 and Venera 14 revealed a dried-out surface with a sweltering temperature of 900°F, the result of a “runaway greenhouse effect.” Yet, some scientists think that microorganisms from a previously lush surface could have taken refuge in Venus’s thick clouds, where they may still reside today.

These microbes, if they existed, probably wouldn’t use oxygen since there’s little of it in the Venusian atmosphere, and we know that anaerobic (not using oxygen) microbes on Earth can produce phosphine (PH3). Phosphine is also produced by industrial processes on Earth and even in the guts of penguins! But we don’t know of a way to make lots of phosphine just through photochemistry in an atmosphere. This means that if we were to observe phosphine on Venus, it could be taken as a likely sign of anaerobic life.

Greaves had the idea to investigate this in what she calls a “blue skies” project — something that was a bit of a long shot and would only take a few hours of observing time, but could be revolutionary if it worked. She used the James Clerk Maxwell Telescope (JCMT) on Mauna Kea to observe Venus at millimeter wavelengths, peering into a “temperate” layer of clouds on Venus to search for spectral signatures of phosphine’s J=1-0 line. Much to her surprise, the spectra showed a detection! To be sure of what she was seeing, Greaves spent nearly three years looking at the data set and analyzing it before publishing her landmark research. Now, there are three epochs of data — two from JCMT and one from the Atacama Large Millimeter/submillimeter Array (ALMA) — showing a detection of this phosphine spectral line.

three plots of spectra, all showing the phosphine line. JCMT 2017, ALMA 2019, JCMT 2020

Greaves’ three observations of the phosphine line on Venus from JCMT and ALMA. [Jane Greaves]

The article prompted significant discussion and debate, as any potential detection of life should. In her talk today, she explored the question of why there was so much debate and why this is such a hard detection to make. The answer is actually pretty simple: interferometry is hard! ALMA’s phase errors are symmetric, which leads to ripples in the spectra that need to be removed. For JCMT, signals that are delayed by bouncing off the parts of the radio antenna can be misinterpreted as different frequencies, again leading to ripples. These ripples are usually removed by fitting a polynomial and subtracting it away. Some have pushed back on this method, saying you could create a false signal with that method, but Greaves assured people today that this is a very standard practice in radio astronomy and, if done carefully and properly, cannot produce false signals as claimed. She has also recently reduced data from JCMT with an alternate method, removing the ripples in Fourier space, to reduce any bias in the reduction — and the signal is still present!

Greaves addressed a few other criticisms as well. First, some have suggested that the phosphine line is actually just a line of sulfur dioxide that’s been shifted over. According to her model fits to the data, it’s a low probability that could be the case. Plus, sulfur dioxide could only mimic phosphine if its abundance had increased by a factor of 10 within a week — something that’s never been seen in millimeter monitoring of Venus! Others have speculated that volcanoes could explain the presence of phosphine, but today Greaves made “a case against volcanism.” The idea is that phosphides from deep in the mantle could explosively erupt into the atmosphere and then react to create phosphine. After talks with geochemists, Greaves determined that’s an unlikely scenario. Plus, explosive eruptions need water — something Venus is notoriously lacking!

Despite this, Greaves isn’t wholly convinced it’s life, either. The clouds are acidic and lacking in water, making it hard even for something microscopic to live there. But the conditions in the clouds aren’t uniform, and they’re always changing — so maybe “microhabitats” of habitable conditions could exist!

Now, Greaves and her collaborators are following up, looking for ways to make this detection clearer and understand what exactly is going on in Venus’s clouds. Using data from JCMT, they’re looking for phosphine, semi-heavy water (HDO), sulfur dioxide (SO2), and sulfuric acid (H2SO4) all at the same time to see how they vary together. They also want to see if these lines shift with Venus’s velocity, which would confirm they’re not just artifacts in the data. Plus, Greaves’ collaborators have used data from the Stratospheric Observatory for Infrared Astronomy (SOFIA) to search for phosphine lines, and found a hint that there’s something there! Further observations could be useful, and Greaves gave “a plea from me to keep this wonderful observatory [SOFIA] flying” despite its planned cancellation at the end of the summer.

Greaves' slide showing the tentative SOFIA detection of phosphine

Greaves’ AAS slide on SOFIA observations, showing the spectrum of a different PH3 line (4-3) and her plea to keep the observatory running. [Jane Greaves/NASA/Cordiner et al.]

The debate about life on Venus is nowhere near settled, but we can thank Jane Greaves for starting this incredible discussion. There’s much to look forward to, especially as new missions like DAVINCI+, VERITAS, EnVision, and more launch to our neighboring planet in the coming decade!

See live-tweets of this session here, by Briley Lewis.

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Press Conference: Deciphering Dust, Analyzing Andromeda & Evolving/Ending Exoplanets (by Pratik Gandhi)

The first press conference of AAS240 was also the first-ever attempt at a fully hybrid one! We had three in-person presenters (Dr. Angela Speck, Dr. Jeonghee Rho, and Dr. Ivanna Escala) and two joining remotely (graduate students Jacob Hamer and Ricardo Yarza).

Dr. Speck (University of Texas San Antonio) kicked us off with her talk “Spontaneous Reheating during Crystallization of Stardust: Resolution of an ISM Paradox”: “there is dust in space everywhere — it’s important for how stars form and die, and for molecule formation and dynamics. So understanding dust is really important!” The key question is whether dust is usually amorphous or crystalline, and using lab techniques, Dr. Speck’s group found that during crystallization by cooling, the material can often spontaneously heat up for a short period of time, which means that crystallizing dust can briefly glow really bright, while amorphous dust won’t glow as brightly. They also found that dust forming around stars will show crystalline structure, but cool dust in the interstellar medium is usually amorphous.

Second, Dr. Rho (SETI Institute), talked about the polarization and dust properties of the supernova remnant Cassiopeia A. Since one of the theoretical pathways for dust formation is via supernovae, supernova remnants are great places in which to study dust. The polarization of light coming from the remnant can give us a wealth of information about the dust grain sizes, dust composition, and magnetic fields. Dr. Rho’s team discovered high polarization in the Cass A remnant, which could mean that the dust present is composed of large grains and mostly made of silicates, rather than carbon. Their work also indicates that supernovae are one of the main sources of dust in the early universe!

Next, Dr. Ivanna Escala (Carnegie Observatories) discussed the chemistry and dynamics of ‘tidal shells’ in the Andromeda galaxy. Tidal shells are thought to form by the destruction of low-mass satellite galaxies falling into a more massive host galaxy on highly radial orbits, resulting in stars getting stripped from the satellite due to tidal forces. Studying tidal shells can tell you about both the properties of the original satellite galaxies that merged in, as well as the dark matter in the massive host galaxy. Dr. Escala reported spectroscopic confirmation of a tidal shell system in Andromeda, which is also the first-ever observation of a multi-shell system! Andromeda is great for studying such features because it’s the closest Milky Way-like galaxy, allowing for exquisite observations. The simplest explanation for the multiple-shell system is that all of the shells have a common origin and resulted from a single merger, because they have very similar chemical compositions.

The first of the remote presenters, PhD student Jacob Hamer (Johns Hopkins University) talked about his use of data from the Gaia mission to study Hot Jupiter exoplanets. However, many exoplanets we observe are nothing like the ones in our solar system, because they are massive yet orbit really close to their stars; these are called Hot Jupiters! One of the key questions about their origin is: do Hot Jupiters form with their orbits misaligned with the star and then align over time? Using Gaia data, they found that aligned Hot Jupiters arrived at their current orbits early on, while mis-aligned ones arrive at their current orbits late, after the protoplanetary disk would have dissipated.

Finally, we had PhD student Ricardo Yarza (UC Santa Cruz), who works on the fluid dynamics of planetary engulfment, which is the process by which old stars engulf planets into their outer layers when they expand into giants. Yarza’s group uses simulations to study planetary engulfment, but this is difficult because giant stars and planets have very different radii, and the simulations cannot resolve such different scales simultaneously. Their group’s solution was to simulate just the zoomed-in region of the planet and its immediate surroundings within the stars as it gets engulfed; they found that engulfment could significantly boost the star’s brightness over short periods of time!

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

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Royal Astronomical Society Gold Medal Lecturer: Jocelyn Bell Burnell (University of Oxford) (by Katya Gozman)

This morning’s plenary session was probably one that many people have been waiting for, since the speaker was none other than Dame Jocelyn Bell Burnell, one of the most well-known women of astrophysics in the last century. Dr. Bell Burnell is the recipient of the Royal Astronomical Society’s (RAS) Gold Medal, which is the highest honor awarded by the society. A winner of multiple prestigious awards over her distinguished career, Bell Burnell is also a big advocate for budding astronomers and donated most of the prize money she received from the Special Breakthrough Prize to fund underrepresented minorities and refugees. While Dr. Bell Burnell is most well known for her groundbreaking discovery of radio pulsars in 1967, her talk was on the more human side of science — today she discussed women in astrophysics.

The main focus of her talk was her exploration of membership data for the International Astronomical Union (IAU). The IAU is the “king” of all astronomical societies, and many regional groups such as the American Astronomical Society fall under the umbrella of the IAU. The IAU is unique in that unlike other professional societies in STEM fields, such as math or physics, it offers memberships to both organizations such as AAS as well as individual memberships, making it a unique treasure trove of demographic data. This data set is also freely available online, and the IAU has published membership data segregated by gender since the late 1990s. Dr. Bell Burnell has taken this opportunity to print out the membership statistics over the last few years to examine the trends in women’s membership across different countries over time.

The statistics paint a picture of a slow rise in women’s membership over the last 15 years. In 2005, 12.8% of the IAU’s total members identified as female. In 2020, this rose to a slightly higher 18.3%. But Dr. Bell Burnell wondered what the statistics would look like if she split these numbers up by country — is there a trend to which countries have the highest or lowest percentage of women’s membership? Looking only at countries that had 100 or more total IAU members, the top three countries with the most female members in 2005 were Argentina, France, and Italy, with Argentina’s membership being 35% women! The IAU average for all countries was 13%, and countries like the US and UK fell below that average at 11% and 10%, respectively. Japan had the least number of women in the IAU — only 4%! In 2010, Argentina still held the #1 position at 37%, with Ukraine coming in 2nd and the US and UK still below average. Burnell noted that this trend continued on until 2020, with southern European and South American countries taking the lead while northern European and English-speaking countries fell consistently below average.

Two countries in particular caught Dr. Bell Burnell’s eye: the Netherlands and Russia. In 2005, the Netherlands was one of the countries with the lowest percentages of women in the IAU — 9%. But in 2020, that statistic rose to 19% — on par with the average world percentage that year. What did they do to drastically increase women’s representation? Dr. Bell Burnell found out that for a few years, the Dutch had certain positions such as professorships that were only open to female applicants, which boosted their IAU membership. Meanwhile Russia’s percentage has always stayed above average, from 18% in 2005 to 21% in 2020. Russia’s success story is attributed to a darker reason — the Soviet Union tragically had a lot of casualties during World War I along with a flu epidemic, and because the state provided nursing and childcare facilities, women in the USSR and Russia have taken on jobs historically reserved for men, leading to a more consistent number of women astronomers.

With all of these numbers swimming around our heads, Dr. Bell Burnell ended her talk by musing on why these participation disparities between countries might exist. She posited a list of possible cultural factors that might influence these statistics, such as men taking on jobs in other subjects that are seen as more prestigious than astronomy or other cultures having a stronger family network to raise children together. She also considered large wealth and class disparities that may make it more common for less wealthy women to work in childcare or housekeeping, leaving more well-off women with time for doing astronomy.

When asked what advice she would give to senior people in positions of power in hopes of increasing representation in astronomy, Dr. Bell Burnell urged them to look at their application and admissions data and look for biases in their hiring. In her words, “data speaks to scientists, so gather the data.” What about people at the opposite end — what should early career women that want success in astronomy do? To this question, Dr. Bell Burnell’s answer was short: “Hang in there!”

If you want to find more information on women who are currently trailblazing in astronomy, check out the Astrobites interview series for Women in Astronomy and other articles related to this topic!

See live-tweets of this session here, by Briley Lewis.

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Addressing the Impact of Satellite Constellations on Astronomy: The Pathway Forward (by Isabella Trierweiler)

At this splinter meeting, a panel of astronomers outlined current efforts for mitigating the effects of satellite constellations in telescope observations. The appeal of using constellations of many small satellites for communication has led to thousands of these satellites being deployed in orbit, with thousands more on their way. These small satellites already show up in astronomical images as long streaks, so the goal of the AAS Committee on Light Pollution, Radio Interference and Space Debris is to figure out how to minimize their impact on current and upcoming telescopes. In addition to visible trails in images, which are a big worry for upcoming survey telescopes such as the Vera Rubin Observatory, the transmissions from satellites may overflow into radio bands used by astronomers.  

To address all of these issues, the International Astronomical Union formed the Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS), a joint program with the Square Kilometre Array (SKA) Observatory and the National Optical-Infrared Astronomy Research Laboratory (NOIRLab). The idea is that the Centre would bring together everyone who has a stake in keeping skies dark, and tackle the mitigation of satellite constellations simultaneously through multiple avenues. Their plans include developing a worldwide network to carefully track the satellites that are already in orbit, creating the software and hardware needed to remove satellite signals from data, and working with policy makers and satellite companies to make future constellations as astro-friendly as possible. 

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

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Press Conference: Magnetic Fields & Galaxies (by Katya Gozman)

One of the quintessential questions that gets thrown in after a discussion in astronomy is “What about magnetic fields?” This afternoon’s press conference speakers dared to address this question while also making us hungry for Italian food, letting the (magnetic) force be with us on Tatooine, and talking about (mind) bending jets in galaxies.

Our first speaker was Dan Clemens from Boston University, who introduced us to a region called Cygnus-X, a radio source in its namesake constellation. This region has a long history of star formation and one of the big questions that astronomers have asked is whether magnetic fields are a “friend or foe” for star formation — do they let dense gas condense further and start star formation, or do they hinder gas flow and quench it? Cygnus-X also has an interesting structure: with its massive star forming zones, it has multiple individual clouds we can see — but are these filaments of star formation tangled up like a bowl of spaghetti or arranged in flat, uniform layers like lasagna?

In order to answer this question, Dan looked at the structure of gas velocity using observations of 13CO gas and made maps color-coded by velocity. Then they identified zones that had only a single velocity component and used data from Gaia to determine distances to these single velocity clouds. Combining this with polarization and stellar color data, Dan was able to determine that Cygnus-X is a delicious lasagna — they found that these different star forming zones were well separated at different distances and likely did not collide to trigger star formation. These results forge the path for using Stratospheric Observatory for Infrared Astronomy (SOFIA) High-resolution Airborne Wideband Camera Plus (HAWC+) data to look closer at the magnetic fields of these single velocity clouds and interpret polarization maps across the entire Cygnus-X field.

Our second speaker was Erin Cox from Northwestern University. While Dan told us about larger scale structures, Erin zoomed in to studying systems that are just beginning star formation — molecular clouds at the point of collapse with two stars orbiting each other that we call protobinary systems. If you’ve ever seen Star Wars, you might recognize the planet Tatooine, which orbits around a binary star system. When molecular clouds accumulate material, this creates a disk around the protostar system, as well as outflows that we can observe. Binaries come in two different flavors — close binaries (<500 au separation) and wide binaries.

But simulations throw us a curveball: they show us that some binaries can actually be born as wide binaries and then migrate inward to transform into a close binary. Since planets and stars form at the same time, understanding how binaries form and evolve сan also teach us about these “Tatooine” planets that orbit binaries. This is also an asset for learning about stars in general, since over half of stars are in binary pairs. Erin looked at the magnetic fields of a nearby star called L483 using three telescopes: Pico Dos Días, SOFIA, and the Atacama Large Millimeter/submillimeter Array (ALMA). They found that its protostellar envelope actually hosts twisted magnetic fields, with a close binary whose stars orbit at the distance between the Sun and Neptune. They believe that L483 is an example of a star that formed as a wide binary whose stars have migrated inward and changed their dynamics, causing the system’s magnetic fields to twist around.

The last speaker, Melissa Morris of the University of Wisconsin-Madison, looked at magnetic fields in a different light by studying the environments of radio galaxies that host bent jets. Lots of radio galaxies we also call active galactic nuclei (AGN) have very straight, collimated jets like Cygnus A, but many galaxies aren’t straight: their jets are bent like an antennae on the top of a fast-moving car. Melissa used a catalog of 175 bent and 187 straight jet galaxies and used a friends of friends algorithm with DECaLS data to find other members of the galaxy group or cluster they are part of in order to study the environments these two kinds of AGN are found.

They found that AGN with bent jets occur more often in larger and denser environments than straight jet galaxies. They also looked at the magnitude gap in these different galaxy groups and clusters — basically the difference in brightness between the brightest and second brightness galaxy. The reason this metric is useful is from the way galaxies evolve: in a galaxy cluster, two biggest galaxies will merge and consume other galaxies, getting brighter and brighter. So if the magnitude gap is small, that means the group is dynamically young — it didn’t have as much time to have many mergers and grow much brighter than other galaxies. Melissa found that AGN with bent jets are also more likely to occur in these dynamically young environments that didn’t have time to grow one enormously bright galaxy. From these findings she infers that it’s possible all the intracluster gas and dust that are dispersed within galaxy groups and clusters act as a medium to bend AGN jets as they move through space. Armed with this information, she can now use these bent jet AGNs as tracers of dense environments, measure that density, and study how galaxies in such environments evolve over time.

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Plenary Lecture: Héctor Arce (Yale University) (by Mike Foley)

An aerial image of the large primary dish for Arecibo Observatory

Arecibo Observatory [University of Central Florida]

Proceeding the afternoon talks, we turned to a simultaneously heartbreaking and empowering topic: Arecibo Observatory. For nearly 70 years, Arecibo served as one of the foremost radio observatories in the world until it collapsed in December of 2020. Dr. Héctor Arce was born and raised in Puerto Rico, and he was inspired to pursue astronomy by both his grandfather and Arecibo. Now a professor of astronomy at Yale University, he charted out the history of this great observatory and prospects for rebuilding.

Arecibo Observatory was originally conceived in the late 1950s. Since then, it has remained a fixture in public perception of astronomy, immortalized in pop culture through scenes in movies like “Contact” and “GoldenEye”. Until 2020, Arecibo was making groundbreaking discoveries across all areas of astronomy, including the discoveries of the first binary pulsar, the first exoplanet and exoplanetary system, and the first fast radio burst. One of the major surveys conducted at Arecibo — the Galactic Arecibo L-Band Feed Array HI Survey (GALFA-HI) — was instrumental in mapping our interstellar medium and studying star formation in the Milky Way. 

Furthermore, the observatory was key for planetary science, making the first maps of the surface of Venus and discovering its retrograde rotation, suggesting ice poles on Mercury, and identifying near-earth asteroids. The number of near-earth asteroids discovered is projected to advance drastically beyond existing planetary radars in the next decade, so Arecibo and other radio observatories will be crucial to keeping tabs on these interstellar neighbors! 

The observatory went through two major upgrades, the most recent of which happened in the 1990s. However, the 2020 Decadal Survey identified Arecibo as a critical avenue for future radio science. At the time of collapse, a number of improvements were already planned and funded for the observatory. Indeed, the observatory grew to represent more than just astronomical research interests. “Arecibo is more than an icon in Puerto Rico, it is a part of our culture… A symbol of inspiration,” writes Dr. Ed Rivera-Valentín in Physics World. It is so beloved that, a year after the collapse, a US Senate resolution passed unanimously in support of Arecibo that encouraged the National Science Foundation and other federal agencies to study the ways that the observatory might be rebuilt. Next-generation ideas are already rolling in, from an improved dish design to the introduction of a robotic collimator that can drive around the primary dish. In these new designs, it will be important to keep alive the universal legacy of Arecibo — the observatory worked for all astronomical fields of research, and the rebuilt observatory should strive to do the same. Arce closes with a firm call to action: “Congress and federal agencies, let’s find the money to make this a reality!”

See live-tweets of this session here, by Mike Foley.

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Heineman Prize Talk: Robert Lupton (Princeton University) & David Weinberg Ohio State University (by Mike Foley)

While the next few decades will feature incredible advancements in survey astronomy, astronomers are still actively using data from many surveys that began back in the late 20th century. The Sloan Digital Sky Survey (SDSS) was one of the most significant of these surveys, and it is still going strong over 20 years later with SDSS-V! Robert Lupton and David Weinberg have been key players in SDSS, and they told us all about the significant successes of the survey and what may come next.

One of the main early goals of SDSS was conducting a redshift survey to chart the 3D structure of the universe. With the most recent data release from SDSS-V in 2020, astronomers were able to produce the largest 3D map of the universe to date, covering nearly 11 billion years of expansion history. They have also produced large databases of stellar spectra, mapped out baryon acoustic oscillations, and explored the internal structure of thousands of galaxies. 

With all of this success, it was surprising to hear that there was a lot of early skepticism surrounding SDSS. However, SDSS broke the redshift detection record in 1999, observing the farthest object ever discovered at the time. This convinced the astronomical community that SDSS could be a major player. The speakers noted that CCDs — charged coupled devices, which are essentially cameras for a telescope — were what set SDSS apart. The survey uses a telescope with 2.4-meter mirrors, 120 Megapixel cameras, and exposures that last for 54 seconds. Many new telescopes and upcoming surveys will beat that, so we can only imagine what the generation of survey astronomy will look like! 

In closing, Lupton and Weinberg offer advice for running a successful survey:

  1. Design for big technical advantage on one or more axes.
  2. Don’t fret too much about competition.
  3. Think deeply about the data. Maximize quality and usefulness.
  4. Value technical contributors!
  5. Recruit and value good leadership.
  6. Create coherent data sets that support a wide range of science.
  7. Make data public.
  8. Foster collaboration, diverse science, individual initiative, and creativity.
  9. Build and sustain a multi-generational collaboration.
  10. Have fun!

See live-tweets of this session here, by Mike Foley.

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Committee for the Status of Women in Astronomy Activities in the Context of the Astro2020 Decadal (by Isabella Trierweiler)

The evening splinter meeting was hosted by the Committee on the Status of Women in Astronomy (CSWA) to present their strategic plan and its importance to the Astro2020 Decadal Survey. Their plan has four main focus-points, including addressing harassment and bullying, creating inclusive and ethical workspaces, and interactions with AAS. Much of the work includes collaboration with other AAS committees, including demographics, employment, and minority identity committees. A full list of their plans can be found here. After introducing the committee, the session then broke out into small groups to brainstorm additional ideas. Check out their website for advice and a database of their previous departmental surveys!

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

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After the 2020 World-Wide Protests: Progress and Failures of Implementing Substantial Change in Astronomy (by Sabina Sagynbayeva)

The panel for this town hall was moderated by Howard University graduate student and #BlackInAstro founder Ashley Walker and Vanderbilt University graduate student KeShawn Ivory. The panel included Dr. Nicole Cabrera Salazar, Dr. Ron Gamble, Pratik Gandhi, Yoni Brande, and three “ghost” panelists who couldn’t be present but answered the questions: Dr. Mia de los Reyes, Dr. Gourav Khullar, and Huei Sears. 

First, Ashley Walker explained to the audience the context for the town halls like this: social unrest during Summer 2020 led to the #Strike4BlackLives and #BlackInAstro. After the protests in support of the Black Lives Matter movement, major institutions like the AAS and the National Society of Black Physicists (NSBP) created letters of support for #BlackInAstro. There were also some concrete institutional changes like removing Physics GRE requirements and sending out climate surveys to help students from marginalized groups. Other than that, however, Ashley acknowledges that almost nothing has changed.

Astrobites’ posts about these issues served as additional inspiration behind this panel. Therefore, the first part of the discussion was about these posts. Dr. Mia de los Reyes shared how she got the idea to write those posts: Kate Storey-Fisher pointed out to her that astro departments had made a lot of statements in support of Black scientists in 2020, but it hadn’t been clear what actions had actually been taken.

The next part of the discussion was about structural committees that a lot of institutions created after the 2020 protests. Dr. Gamble and Dr. Cabrera Salazar pointed out the main problem with these committees: not enough people who do actual work. The departments create different Diversity, Equity, and Inclusion (DEI) committees, but the members either have no expertise in the subject of matter or do not care about the issues. As a result, most of the work falls onto junior scientists’ shoulders, but junior scientists often don’t have the institutional power or emotional bandwidth to deal with the systemic problems. “It is like you need tragedy to have triumph,” says Dr. Gamble, emphasizing the fact that people tend to start caring about these issues in the wake of a tragedy. In order to make DEI committees function successfully, Dr. Cabrera Salazar says that we need to learn to ask Black people what they actually need. 

Another important issue that was discussed was the system that hires faculty or accepts applicants, and what needs to be done to make the system more inclusive and equitable. The whole problem is with people in power. People in positions of power in an academic department need to be mindful of the struggles Black students face prior to entering the department. However, once Black folks are accepted to the department, they should feel that they’re valued, like any other student, so they won’t leave the field due to toxic environments or a lack of support.

Though everyone pointed out that even in two years after the George Floyd protests not a lot has been done, Dr. Cabrera Salazar acknowledges that there’s still hope because “she has seen the willingness to do the emotional work to help them, but it is a collective work, not something done by individuals only.”

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

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graphic with photos of astrobites authors announcing the astrobites-related events at AAS 240

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

AAS Nova Editors Kerry Hensley and Susanna Kohler and AAS Media Fellow Haley Wahl will join Astrobites Media Intern Briley Lewis and Astrobiters Sabina Sagynbayeva, Macy Huston, Katya Gozman, Graham Doskoch, Yoni Brande, Pratik Gandhi, Luna Zagorac, Mike Foley, Abby Lee, Isabella Trierweiler, and Sumeet Kulkarni 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 Susanna, Haley, Kerry, and Briley at the press conferences all week.

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

Astrobiters Pratik Gandhi and Yoni Brande will be joining the panel “Progress and Failures of Implementing Substantial Change in Astronomy” at 6 pm PT on Monday, 13 June, hosted by the Committee on the Status of Minorities in Astronomy (CSMA) and BlackInAstro, to discuss what astronomy institutions have done well versus should have done better since the world-wide protests and #Strike4BlackLives in Summer 2020.

Wednesday, 15 June, at 9:30 am PT, Astrobites Media Intern Briley Lewis will be giving an Exhibit Hall Theater presentation titled “Astrobites: A Tool for Scientists, Educators, Journalists, Students, and More” — this presentation will give an overview of the different ways Astrobites can help you, whether you’re a teacher, a student, a scientist, a journalist, or just someone interested in space.

In the Wednesday evening poster session (5:30–6:30 pm PT), Astrobites Media Intern Briley Lewis will be available to chat at our poster about Astrobites’ numerous “Beyond” initatives, from our climate change advocacy to diversity, equity, and inclusion efforts and beyond. Visit us at iPoster 345.09, “Expanding Astrobites to Cover Climate Change, DEI, Astronomy Education, and More.”

For anyone interested in using Astrobites in their classroom, on Thursday from 10:00 to 11:30 am PT in the Sheraton Justine’s Ballroom, we’re hosting a special session titled “Introducing Current Research Into Your Classroom With Astrobites” to introduce educators to Astrobites lesson plans and connect them with other instructors to discuss best practices and different ways to use Astrobites in formal education. In this workshop, we’ll explore how you can use Astrobites to enhance your students’ experience — and if you’ve already used Astrobites in the classroom, we’d love for you to come share your experiences and learn from fellow educators! Whether you’re currently teaching, interested in applying this someday, or just curious what we have to offer, you are welcome to attend!

Lastly, if you’re interested in reading up on some of the keynote speakers before their talks at the meeting, be sure to check out the interviews conducted by Astrobites authors! They’ll be published throughout this week, and they provide a great opportunity to discover more about these prominent astrophysicists and learn about the paths they took to where they are today.

You can read the currently published AAS 240 keynote speaker interviews here. Be sure to check back all week as the remainder are released!

GIF cycling through photos of the AAS 240 plenary speakers

AAS 240 banner

AAS 240 is nearly here! The AAS Publishing team looks forward to reconnecting with meeting attendees in Pasadena and online, and we’re excited to share a preview of upcoming publishing-related sessions. 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), Janice Sexton (AAS Editorial Operations Manager), and Frank Timmes (AAS Lead Editor of the High-Energy Phenomena and Fundamental Physics corridor). AAS Nova Editors Kerry Hensley and Susanna Kohler, AAS Media Fellow Haley Wahl, Astrobites Media Intern Briley Lewis, and the rest of the Astrobites team will also be available at the Astrobites booth in the Exhibit Hall.

Making the Most of AAS WorldWide Telescope

Sunday, June 12, 11:00 am PT – 12:30 pm PT | Convention Center Conference Room 204 and online

AAS WorldWide Telescope (WWT) is a tool for showcasing astronomical data and knowledge. The new “2022 edition” of the free and open-source WWT visualization software can power a wide range of initiatives like interactive “live” images in journal articles, exploratory data visualizations in Jupyter notebooks, immersive custom websites, and professional-grade planetariums. This interactive tutorial will introduce attendees to the WWT software ecosystem in the context of its applications to research, education, and public outreach. Participants should bring a laptop with battery charger and a modern web browser installed.

Make Your Research More Discoverable with a Community Supported Vocabulary: Applications of the Unified Astronomy Thesaurus

Monday, June 13, 11:00 – 11:30 am PT, Exhibit Hall Theater A/B (in person only)

screen capture of the unified astronomy thesaurus website

An example of the interconnected concepts captured by the UAT. Click to enlarge. [Unified Astronomy Thesaurus/AAS]

Do you struggle to find archival data that could be useful to your research? Would you like to make your data and publications more visible in data archives and the astrophysics data system (ADS)? Find out how data archives, publishers, and libraries are leveraging a new community-supported vocabulary, the Unified Astronomy Thesaurus (UAT), to improve discovery of data and scientific literature with keyword tagging. The UAT is an open, interoperable, and community-supported thesaurus that formalizes astronomical concepts and the relationships between them. It is managed under the auspices of the AAS. The UAT contains more than 2,000 unique concepts, organized into 11 categories and arranged in a deep hierarchy. It is expanded annually through community feedback. As a living resource enabling multiple opportunities for integration and metadata enrichment in systems like ADS and data archives, the UAT will continue to benefit astronomical systems and researchers well into the future. We share the latest UAT integrations with AAS participants and engage in a discussion on how we can work together to continue to build and leverage the UAT as a community to aid in research and discovery.

Sky & Telescope Astronomy 101 Ambassadors

Monday, June 13, 1:30 – 2:00 pm PT, Exhibit Hall Theater A/B (in person only)

Join Peter Tyson, editor in chief of Sky & Telescope, and Tom Rice, the AAS education and mentoring specialist, to learn more about the AAS Sky & Telescope initiative to support Astro 101 courses and the Sky & Telescope Ambassadors program. During this presentation, you will learn about free resources to use in your classroom this year and more about a community of sharing resources related to teaching Astro 101.

Introducing WWT 2022: The Next Generation of AAS WorldWide Telescope

Monday, June 13, 5:30 – 6:00 pm PT, Exhibit Hall Theater A/B (in person only)

WWT New Horizons Pluto

Screenshot of the WWT web interface displaying the New Horizons Pluto data. [WWT]

AAS WorldWide Telescope is a free and open-source software tool for astronomical data visualization. Its slick, interactive interface allows you to explore all sorts of astronomy data in context and overlay images, all-sky surveys, and catalogs from across the electromagnetic spectrum. Earlier this year, the WWT team released “WWT 2022,” the latest version of the WorldWide Telescope system, which is jam-packed with new features and data sets. In this presentation, you’ll learn about what WWT can do and see some of the exciting new capabilities of WWT 2022, including a new application custom-built for use in JupyterLab. Learn more about WWT 2022 at https://worldwidetelescope.github.io/editions/2022/.

AAS Journals Peer Review Process with AAS Editor Brian Jackson

Tuesday, June 14, 5:30 – 6:00 pm PT, Exhibit Hall Theater A/B (in person only)

You’ve toiled for months over your LaTeX editor, cajoled your co-authors for figures, begged your advisor to give you feedback, and finally, you’re ready to submit your masterpiece to ApJ. You upload all your source files to the eJournal Press website and click the submit button.

What happens next? In this presentation, AAS science editor Brian Jackson will discuss the peer review process for the AAS Journals (ApJ, ApJS, ApJL, AJ, PSJ, and RNAAS) and answer your questions: How are referees chosen to review articles? If I’m chosen to review, what kind of feedback is the most useful? If I’m supposed to receive my referee report in three weeks, why did it take six weeks? What is “double-anonymous review,” and how does it work?

Supercharging Your Science with Software: The Asclepias Project

Wednesday, June 15, 2:00 – 3:00 pm PT | Convention Center Conference Room 204 and online

screen capture of the asclepias user interface

Screen capture of the Asclepias user interface. Click to enlarge. [The Asclepias Project/AAS]

Discovery in astronomy is being driven by the development of new software tools within every aspect of our science. Be it capturing and collecting data to extracting the most science out of our ever-growing datasets to simulating the physics underlying our understanding of the universe, the development of code and software is growing as a part of how we do science and how we communicate it.

The Asclepias project was born out of scientists’ need to distribute, discover, and track software as it is used in science. This tool allows you to connect the software tools and the scientific results, making your progress faster, more open, and reproducible.

In this session, we will have a demonstration of the Asclepias tools to track software and articles that use it, a panel discussion of how to supercharge your own science by finding the software tools to help you or distributing the code that you’ve written to increase its impact, and we’ll open the floor to the community to discuss the future of these efforts.

screenshot of seven presenters in a Zoom room

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

Then the AAS Media Fellowship might be for you! This position was developed in 2017 by the American Astronomical Society to provide training and experience for a graduate student in the astronomical sciences interested in science communication. The fellowship is a remote, quarter-time, one year (with the possibility of extension to two years) position intended to be filled by a current graduate student at a US institution. The new AAS Media Fellowship term will begin in Fall 2022.

If this sounds like a good fit for you, you can get more information below or at the job register posting. Apply by 6 July 2022 by submitting your contact information, advisor approval, a cover letter, and a short CV to personnel@aas.org. See the job register posting for the full application details.

Essential Duties & Responsibilities

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

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


The Fellow must:

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


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

Artist's impression of an exoplanet

Editor’s Note: This week we’re reporting on the virtual programming related to the canceled 239th AAS Meeting. 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. The usual posting schedule for AAS Nova will resume on January 18.

Welcome to the Astrobites coverage of virtual events based around the canceled American Astronomical Society (AAS) meeting! We will report on highlights from each day here, from AAS Press Conferences to grassroots astronomy community meet-ups. If you’d like to see more timely updates during the day, we encourage you to search the #aas239 hashtag on twitter. We’ll be posting once a day during the week, so be sure the visit the site often to catch all the news!

Press Conference: Exoplanets & Their Atmospheres (by Lili Alderson) 

Cold and Distant: Meet the Newest Brown Dwarf

This artist’s rendering of a brown dwarf shows bands of clouds in its atmosphere. [NASA/ESA/JPL]

Thursday morning’s press conference focused on brown dwarfs, exoplanets, and their atmospheres. Kicking off the session was Johanna Vos (American Museum of Natural History), who discussed recent work on the weather of young brown dwarfs. Brown dwarfs, which are often called “failed stars,” aren’t massive enough to burn hydrogen, but have similar masses, temperatures, and compositions to large exoplanets. Young brown dwarfs are often very similar to directly imaged exoplanets, and so make great analogs. Using over 590 hours of Spitzer Space Telescope observations, Johanna and collaborators watched brown dwarfs rotate to look for variations in their brightness indicative of the presence of clouds like Jupiter’s Great Red Spot that reflect or absorb light. They found that younger brown dwarfs were more likely to show variations than older brown dwarfs, and that the variations were more extreme, possibly due to the fact that brown dwarfs become more compact as they get older, changing the atmosphere. These observations will help improve models of the atmospheres of directly imaged planets, which will be important when JWST observes these planets. Press Release

An artists impression of XO-3b

Artists’s impression of the internal heating of XO-3b, along with its elliptical orbit. [NASA/JPL-Caltech/R. Hurt (IPAC)]

Next, graduate student Lisa Dang (McGill University) presented results from a study of XO-3b, a hot Jupiter exoplanet in an eccentric orbit, which is in the process of migrating towards a more circular one! The eccentric orbit means XO-3b has very strong seasonal variations, with its “winter” lasting twice as long as its “summer.” Using Spitzer to observe the planet as it traveled around its star, Lisa and her team measured XO-3b’s phase curve, which allows the wind speeds and temperature variations to be studied throughout the seasons. The team found that XO-3b has excess heat that cannot be explained by seasonal changes alone, and, using Gaia data, found that the planet was puffier than expected. Both of these findings indicate that the planet is experiencing internal heating, which could be due to tidal heating from the forces the XO-3b experiences as it migrates to a circular orbit. NASA JPL Press Release | McGill U. Press Release | U. Montreal Press Release

Illustration of the TESS satellite in front of the distant Sun.

With the Transiting Exoplanet Survey Satellite (TESS), we can explore not only distant planetary systems, but also our own. [NASA’s Goddard Space Flight Center/CI Lab]

Up next with the discovery of three new exoplanets was Samuel Grunblatt (American Museum of Natural History and the Flatiron Institute). All of the Transiting Exoplanet Survey Satellite (TESS) planets in this presentation are orbiting evolved stars (those which have moved away from the main sequence and are giants or sub-giants) and, given their short orbits, are some of the hottest planets known to exist around evolved stars! The first planet, TOI-2669b, could potentially be in an eccentric orbit, which would be unusual for its short period, while the second, TOI-2337b, has an extremely high density and will likely be consumed by its host star sooner than any other known planet. Perhaps the most interesting, TOI-4329b, is the best planet orbiting an evolved star for atmospheric characterization, and it would be a great target for JWST to help understand how exoplanets can end up in orbits like these. Keck Observatory Press Release | U. Hawaiʻi Press Release

Illustration of the “super Neptune” TOI-674 b.

Illustration of the “super Neptune” TOI-674 b. [NASA/JPL-Caltech]

Graduate student Yoni Brande (University of Kansas) then presented the tentative detection of water vapor in the atmosphere of a super-Neptune exoplanet, TOI-674b. With a mass 23x that of Earth and an orbital period of less than 2 days, TOI-674b lies in the Neptune Desert, making it one of few known Neptunian planets orbiting close to their stars. Yoni and collaborators made use of Hubble’s Wide Field Camera 3 to look at the planet as it transited its star in the infrared and search for wavelength-dependent changes in the planet’s apparent size caused by its atmosphere. They found that the atmospheric transmission spectrum can be best explained by the presence of water vapor, making TOI-674b one of a very small number of Neptune-like planets to have evidence of water! Press Release

The night sky from a rocky planet is shown, with a large streak of white light reaching up into the sky from the horizon

An artist’s impression of the detected zodiacal light on Kepler-69c. [SHAO/Yue Xu]

Finally, Jian Ge (Shanghai Astronomical Observatory) discussed the detection of zodiacal dust in three Kepler systems. Joined in the press conference by high school students and collaborators Amanda Hao and Justin Hou, Jian explained how his team wanted to look for light scattered by dust from asteroids and comets around systems with potentially habitable exoplanets, like the solar system’s zodiacal dust cloud as seen from Earth. Using data from a host of all-sky surveys, they found an excess of infrared radiation around Kepler-69, Kepler-1229, and Kepler-395, all of which host planets in the habitable zone. They also found that the dust had temperatures around 400K, hotter than in the solar system, suggesting that the dust is likely located closer to the stars of these systems than in our own solar system. Press Release
YouTube recording

Press Conference: Intriguing Stars & Citizen Discoveries (by Graham Doskoch)


Artist’s impression of the roiling surface and strong stellar winds of Betelgeuse, a red supergiant star. [ESO/L. Calçada]

The final press conference of the week combined unconventional techniques with unusual objects. The first speaker was Andrea Dupree (Center for Astrophysics | Harvard & Smithsonian), who summarized our understanding of the Great Dimming exhibited by Betelgeuse between December 2019 and February 2020. The red supergiant interrupted its normal 400-day cycle of minor dimming and brightening by dropping roughly one magnitude in optical light. Archival observations taken earlier in 2019 by the Hubble Space Telescope, coupled with later measurements, indicate that this was the result of a large mass ejection and dramatic outflow in the star’s atmosphere. The resulting dust scattered and absorbed Betelgeuse’s light, making it appear dimmer. It’s quite possible that Betelgeuse and other massive stars near the end of their lives have previously undergone similar episodes.

flaring star

A flare erupts from a young red dwarf star in this artist’s illustration. [David A. Aguilar (CfA)]

The next presentation pivoted from one of the brightest stars in the sky to some of the dimmest: red dwarfs. Scott Engle (Villanova University) presented the results of a long study of M-type dwarf stars aimed at improving our understanding of their evolution and characteristics. Since red dwarfs are dim and age slowly, this has historically been a challenge — and an important problem for astronomers testing evolutionary codes. Using years of data on red dwarfs in binary systems from the 1.3-meter robotic telescope at Kitt Peak National Observatory, the team found that the stars fell into two groups: the more massive “early” red dwarfs of spectral types M0 to M2, and the less massive “late” red dwarfs of spectral types M2.5 to M6. The groups exhibited different starspot patterns and obeyed different sets of changes in X-ray and ultraviolet activity with age.

Artist's impression of an exoplanet

An artist’s impression of the Jovian exoplanet TOI-2180 b. This planet has the longest orbit of any planet discovered by the Transiting Exoplanet Survey Satellite (TESS) so far — and it’s a “cool” 170℉. [NASA/JPL-Caltech/R. Hurt]

The second half of the session was dedicated to discoveries made or enabled by citizen astronomers. Paul Dalba (University of California, Riverside) announced the detection of a Jupiter-mass giant planet, TIO-2180b, which has a wide orbit around a bright star. It was first discovered as a single, long transit in data from TESS by the Visual Survey Group, an organization of citizen scientists who search for exoplanet candidates that might be missed by algorithms. Follow-up observations by Dalba and colleagues using the Lick Observatory provided more information on its properties. While a massive effort by the team and citizen astronomers at 14 sites over three continents was unable to detect the second predicted transit, they plan to try again in February when TIO-2180b is next expected to transit. UC Riverside Press Release | NASA Press Release | U. New Mexico Press Release

images of the brown dwarf binary pair

WISE (left) and Dark Energy Survey (right) images of the binary system. [WISE/DES/Softich et al.]

Undergraduate Emma Softich (Arizona State University) presented a truly unique find. Using data from NASA’s Wide-field Infrared Survey Explorer (WISE) and working in conjunction with the Backyard Worlds citizen science program, she discovered a binary brown dwarf with the largest known separation of its kind. CWISE J014611.20-050850.0AB consists of an L4-type brown dwarf 72 times the mass of Jupiter and an L8-type brown dwarf 66 times the mass of Jupiter, orbiting each other at around 129 astronomical units. Although the system is expected to stay bound for several billion years, it’s surprising that it survived efforts to tear it apart by neighboring stars near its birthplace. Lying only 135 light-years from Earth, CWISE J014611.20 raises an interesting question: how many systems like it are out there? Press Release

A selection of 24 galaxies analyzed by the Galaxy Zoo project to search for blue star-forming clumps

A selection of 24 star-forming galaxies analyzed by volunteers from the Galaxy Zoo: Clump Scout project. Some blue star-forming clumps are quite bright, while others are harder to detect. Click to enlarge. [Nico Adams]

The session concluded with a trip through cosmic time guided by graduate student Nico Adams (University of Minnesota, Twin Cities). Adams presented the results of the Galaxy Zoo: Clump Scout project, which gathered information on blue “giant star-forming clumps” in galaxies in the modern universe. There are two proposed methods for their formation: the in situ model, where turbulence within the galaxy governs their formation and evolution, and the ex situ model, where they form externally via galaxy mergers. While these clumps have been studied in distant galaxies in the early universe, their properties later on were not well-known. High-redshift galaxies show “clumpy fractions” — the fraction of galaxies with clumps — around 60%. The Galaxy Zoo: Clump Scout project enlisted volunteers to identify clumps in tens of thousands of modern-day galaxies and used the resulting 7,000 clumps in 10,000 of those galaxies to find that the modern-day clumpy fraction is only 2-3%. This provides evidence that clumps form in situ, from clouds of gas within a galaxy, since turbulence has gone down throughout cosmic time but merger rates have stayed flatter. If the ex situ model was correct, merger rates would have needed to drop to explain the relative lack of clumps in the local universe. Press Release

Live-tweeting by Graham Doskoch
YouTube recording

CHAMPs Early Career Researcher Highlight Seminar (by Macy Huston)

When the AAS 239 meeting was canceled, many were disappointed to lose the opportunity to present their research. Immediately, astronomers began planning events to try to fill that void. Not long after, the CHAMPs (Consortium on Habitability and Atmospheres of M-dwarf Planets) collaboration announced their Exoplanet Early Career Highlight Seminar, a two-day event where those with canceled talks could gather and discuss their work.

champs logoDr. Erin May, the postdoc who leads the organization of the new CHAMPs seminar series, emphasized the importance of focusing on early career researchers for whom conferences and networking are especially important. She tweeted, “While this can’t fully replicate the lost networking, we hope it takes some of the pain away.” The idea for this event had been in Erin and others’ minds before the AAS 239 cancellation as an alternative for those who didn’t feel comfortable making the trip in person. When COVID spiked and AAS 239 cancellation became a likely scenario, the planning process launched. Despite only having a couple weeks over the holidays to put it together, the organizers hit only a few technical snags along the way.

Almost 60 abstracts were submitted for the seminar, and the organizers were able to accept 47, 10 of which were dissertation talks, where soon-to-be PhD recipients were given a bit more time to present a fuller story of their work. Three of these non-dissertation talks were from current Astrobites authors: Ali Crisp, Macy Huston, and Yoni Brande!

The event was held January 13-14, 2022 and consisted of four sessions:

  1. Transits, Radial Velocities, and Direct Imaging
  2. Interstellar Objects, Terrestrial Planets, Biosignatures and Habitability
  3. Atmospheres (Exoplanets and Brown Dwarfs)
  4. Disks, Planet Formation, and Star-Planet Interactions

Subsections of these sessions were each moderated by an early career researcher who spoke at the event. Recordings of Day 1 are available here, and Day 2’s will be posted on the same YouTube channel shortly.

In addition to the talks and Q&A sessions held on Zoom, a Slack workspace was created for the event for extending discussions and networking. The #random channel provided entertainment and social interaction during the event, primarily being devoted to pet photos, including some friendly competition between dog and cat people, as well as some unique pets like frogs, hedgehogs, and even donkeys!

Overall, over 200 astronomers registered for the event, and at the point of peak attendance, over 100 people were present! The organizers were thrilled with the positive response to the event and hopeful that speakers were able to reach even more people than they would have at in-person AAS 239.

illustration of local bubble

Editor’s Note: This week we’re reporting on the virtual programming related to the canceled 239th AAS Meeting. 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. The usual posting schedule for AAS Nova will resume on January 18.

Welcome to the Astrobites coverage of virtual events based around the cancelled American Astronomical Society (AAS) meeting! We will report on highlights from each day here, from AAS Press Conferences to grassroots astronomy community meet-ups. If you’d like to see more timely updates during the day, we encourage you to search the #aas239 hashtag on twitter. We’ll be posting once a day during the week, so be sure the visit the site often to catch all the news! 

NSF/AST Community Webinar (by Catherine Manea)

The first event of the day was the National Science Foundation’s Division of Astronomical Sciences (NSF/AST) Community Webinar, a town hall-style event led and moderated by Prof. Debra Fischer, Prof. James Neff, Dr. Ashley VanderLey, and Donna O’Malley. The focus of this webinar was to provide updates on the NSF/AST’s existing and upcoming programs, grants, and fellowships, with particular focus on the recommendations of the Astro2020 Decadal Survey.

Fischer began the webinar by introducing the organization and highlighting its original guiding mission: “to advance the understanding of the universe, to promote US scientific leadership, to build a diverse workforce of scientists and engineers, and to enhance the lives of our citizens.” She highlighted some relevant and important recommendations from the Decadal Survey, namely to:

  • “augment and protect individual investigator grants”
  • “build opportunities for diversity in the workforce”
  • “increase transparency [in budgets and proposal statistics]”
  • “reduce the carbon footprint associated with research.”

In summary, “fund people and develop the workforce,” remarked Fischer, a principle that aligns with many of the existing NSF/AST initiatives supporting students, post-docs, and early-career faculty from under-represented and minoritized groups. In addition, Fischer highlights that it is important to ensure that the astronomy community is developing astronomers with flexible, adaptable skills that they can take outside of academia, should they so choose. Fischer next summarized and provided updates on the various ongoing NSF/AST-funded programs and facilities (such as CAREER, REU, PAARE, Mid-Scale Innovations Program, the Atacama Large Millimeter Array, Green Bank Observatory, and Arecibo, among many others).

Some updates included that construction on the Daniel K. Inouye Solar Telescope (DKIST) on Haleakalā Crater, in Maui, HI is complete, and DKIST is now in operation. Fischer emphasized that DKIST is “the largest and most powerful solar observatory on our planet” and will transform the field of multi-messenger astrophysics. DKIST will provide astronomers with the first in-depth, high-resolution look at the Sun’s magnetic fields, opening the door to a better understanding of the effects of magnetism on both the structure of the Sun’s surface and life on Earth.

Fischer also updated attendees on the current status of the decommissioned and dearly missed Arecibo Observatory in Puerto Rico. After two breaks in the cables stabilizing the radio receiver, the NSF decided to decommission the instrument in 2020 and began the process of demolishing it. Fischer announced that the emergency cleanup team has now “safely removed approximately 14,000 damaged panels, or 35% of the reflector area” of the instrument. In addition, the team repaired several hundreds of feet of concrete rim wall, installing organic erosion control measures (coconut fiber matting and seeding) that encourage native vegetation growth.

Neff followed with an update on recent and upcoming NSF/AST-funded programs, including various fellowships for astronomers at all career stages. Neff highlighted that Partnerships in Astronomy & Astrophysics Research and Education (PAARE) in particular is looking for applications, with a proposal deadline of February 7th. PAARE is a program that seeks to form partnerships between the NSF and various institutions to foster a diverse, equitable, and inclusive environment in astronomy research and education.

Artist's impression of Earth surrounded by a swarm of satellites. In the bottom left corner of this image, there is an example of a satellite-streaked CCD optical image.

A satellite-streaked optical CCD image, an example of the negative effect that the growing population of low-Earth-orbit satellites have on astronomical science, against a background of an artist’s impression of a satellite-swarmed Earth, something that is a growing reality. [NSF/Ashley VanderLey; ESA]

VanderLey finished off the presentation portion of the webinar with a summary of the NSF’s recent activities related to new satellites. The growing number of satellites in low-Earth orbits is a major concern for astronomers worldwide. Current projections suggest that the number of satellites circling Earth will exceed 50,000 by 2028!  VanderLay emphasizes that building telescopes in remote locations is no longer sufficient to prevent interference. The NSF is thus advocating for international recommendations and regulations on satellite design to minimize interference with astronomical observing. Many satellite-producing companies, such as SpaceX and Amazon, are beginning to take into account the concerns of the astronomy community. For example, Amazon’s Kuiper satellite will be designed with a dimming visor to minimize its intensity. Vanderlay notes that she is “very excited to see the movement” of these companies in alignment with the needs of the astronomical community and hopes that more companies will sign on to work with the astronomical community to mitigate satellite interference.

The event ended with questions from the audience. One question arose highlighting concerns for the high NSF budget dedicated to upcoming facilities, something that could risk funding for individual grants. Fischer assured attendees that the NSF/AST’s top priority will be individual grants and increasing the availability of individual funding gradually, in line with the recommendations of the Decadal Survey. To round off the event, Neff emphasized that “everything will be guided by Astro2020 Decadal Survey.”

Live-tweeting by Catherine Manea

Press Conference: Evolving Stars & Their Activity (by Macy Huston and Huei Sears)

photograph of an open star cluster

The star cluster Messier 67. [Jim Mazur]

Today’s first press conference focused on post-main sequence stars. First, graduate student Andrew Nine (University of Wisconsin-Madison) discussed blue lurkers in M67 and their white-dwarf companions. Classic blue stragglers are bluer and brighter than the main-sequence turnoff of a cluster, thought to form when stars merge or transfer mass. Blue lurkers, on the other hand, are stars on the main sequence that rotate at anomalously fast rates, corresponding to very young gyrochronological ages. Eleven of these were discovered on the main sequence of M67 as part of the ongoing WIYN Open Cluster Study (WOCS), eight of them residing in binary systems. Andrew’s team observed these eight binary blue lurkers with the Hubble Space Telescope. The team detected two white dwarf companions based on their far-ultraviolet flux out of a sample of eight blue lurkers, or 25%, which fits expectations from simulations. It is plausible that the blue lurkers are the products of mass transfer and are low-luminosity analogues to the classical blue stragglers. Press Release

photograph of the SOAR telescope

The Southern Astrophysical Research (SOAR) Telescope was used to determine some of the properties of this strange object. [CTIO/NOIRLab/NSF/AURA/J. Fuentes]

Next, Samuel Swihart (Naval Research Laboratory) presented a unique binary system containing a gamma-ray-bright neutron star and a very low-mass proto-white dwarf. Most stars are born in binary systems. The more massive star eventually goes supernova and sometimes leaves behind a spinning neutron star (pulsar), which gradually loses energy over time. A millisecond pulsar can form through a “recycling” process, where the companion star expands and its material accretes onto the neutron star, speeding up its rotation. Most binary milisecond pulsars have distant white-dwarf companions, while some have short periods where the companion is being consumed. Millisecond pulsar 4FGL J1 120.0-2204 (shortened to J1120) is a gamma-ray source that has an X-ray and optical counterpart. So, what is it? Spectroscopy with the NOIRLab SOAR telescope reveals a slowly contracting hot object, the precursor to an extremely low-mass white dwarf, orbiting an unseen companion. J1120 is the first system ever discovered in the penultimate phase of the millisecond pulsar recycling process. Press Release

Kepler K2 Light Curve of V2487 Oph, showing dramatic brief increases in brightness, with consistent lengths of about an hour and roughly a day between them and varying brightnesses

Kepler K2 light curve of V2487 Oph. [Bradley Shaefer]

The final presentation today came from Bradley Schaefer (Louisiana State University, Baton Rouge), who discussed the recurrent nova V2487 Ophiuchi’s extreme superflares. V2487 Oph, which erupted in 1900 and 1998, is one of just 10 recurrent novae known in the Milky Way. The Kepler Space Telescope revealed that this source has extreme superflares roughly once per day lasting for about an hour, with very high energy levels of 20 Mega-Carringtons per flare. (A “Carrington” is equal to the amount of energy released in the Carrington event, the largest coronal mass ejection  in recorded history.)  In 1989, Brad discovered and named superflares — stellar flares with energy greater than 100 Carringtons and durations on the order of hours. These events are caused by the reconnection of twisted magnetic field lines and occur in all types of normal stars, including those like the Sun. The radiation from superflares can kill all unprotected life and destroy ozone layers, allowing in sterilizing ultraviolet light, meaning that they make planets around stars extremely uninhabitable. V2487 Oph is the most extreme superflare star, with the most frequent flares, >10x more energy per flare than any other superflare star, and >100,000x the yearly energy budget. How these flares can be so powerful poses an interesting challenge for theorists. Press Release

Live-tweeting by Huei Sears
YouTube recording

Press Conference: Mapping Local Structure & More Evolving Stars (by Zili Shen)

illustration of the local bubble

The Local Bubble, with the Sun near the center, and the Ophiuchis, Pipe, Lupus, Corona Australis, Musca, and Chamaeleon, and Taurus star-forming regions shown. Click to enlarge. [Catherine Zucker]

The second press conference today is about Mapping Local Structure & More Evolving Stars. We start with Catherine Zucker (Space Telescope Science Institute and Center for Astrophysics | Harvard & Smithsonian). She tells us the ultimate origin story by explaining how all nearby star formation (within ~500 light-years of our Sun) began. Her team uses Gaia data to retrace the star formation history around the solar neighborhood. Here’s how it happened: around 14 million years ago, a chain of supernovae blew out the 1,000-light-year-wide Local Bubble. The shockwaves from the supernovae piled up ambient gas into an extended shell and triggered star formation. Nearby stars were born on the surface of the Local Bubble, riding outward as it expanded. Our Sun was 1,000 light-years away when the bubble first started forming. But about 5 million years ago, the Sun’s path through the galaxy took it into the bubble and now we happen to be near the bubble’s center. The next step is to search for more supernovae-driven bubbles and study how they interact in the Milky Way. CfA Press Release | Hubble Press Release | Project Website


Artist’s conception of the heliosphere with the important structures and boundaries labeled. [NASA/Goddard/Walt Feimer]

Zooming back one million years in the history of our Sun, Seth Redfield (Wesleyan University) presents a project led by Hunter Vannier, who is now a graduate student at Purdue University. They are particularly interested in the interstellar medium, the stuff between stars inside a galaxy. All stars expel particles into the interstellar medium, and in the case of our Sun, the particle stream carves out our little region in the interstellar medium called the heliosphere. Since the Earth sits inside the heliosphere, the cosmic rays we receive depend on the conditions of the interstellar medium outside. Seth pointed the Hubble Space Telescope in the direction that the Sun came from, using it as a rear-view mirror. Since the interstellar medium is too diffuse to be directly imaged, they use absorption spectroscopy to locate the gas clouds that the Sun traveled through in the last one million years. They reconstructed the Sun’s path through these clouds and found that we are currently departing the Local Interstellar Cloud. This technique can help scientists look in our future direction and generate a space weather forecast. Press Release

Our next topic is Wolf-Rayet stars. Avishay Gal-Yam (Weizmann Institute of Science) was the first to observe a new class of supernovae from exploding Wolf-Rayet stars. Wolf-Rayet stars are the most massive stars we know of, and the nuclear fusion that goes on in their core produces layers of successively heavier elements. The outer layers get blown out by intense radiation pressure and this gives Wolf-Rayet stars a distinctive signature in their spectra. Although these stars are predicted to explode at the end of their lives, no carbon-oxygen Wolf-Rayet SN had been observed. Avishay’s team took a spectrum of a supernova on the Gemini telescope three days after it was discovered by the Zwicky Transient Facility survey, and they discovered spectral lines that match what you expect for an exploding Wolf-Rayet star! The newly discovered supernova type Icn is illustrated below. Weizmann Inst. Press Release | ZTF Press Release

Newly discovered supernova type Icn compared to known types.

Illustration of the composition of a Wolf-Rayet star as a supernova progenitor. Right panel: The newly discovered type Icn supernovae from carbon and oxygen rich Wolf-Rayet stars. Bottom: spectra of the supernova remnants. [Avishay Gal-Yam]

Continuing with the exciting discovery of Wolf-Rayet supernova, Daniel Perley (Liverpool John Moores University) found a Wolf-Rayet star that exploded and likely became a black hole. His team found another supernova of a Wolf-Rayet star and obtained both the distance and a spectrum using the Liverpool Telescope. In this field, speed is key because the supernova remnants expand and fade quickly. Daniel’s team managed to get the Hubble Space Telescope to observe this source. They followed the explosion site for months, and saw that it eventually faded beyond detection. The initial glow was from shockwave-compressed gas, but once the shockwave passed, the star collapsed into a black hole and there was no more radiation to be observed. Daniel says that this type of supernova could be very common, but they have not been observed until now because they only glow for a very short time. Press Release

Live-tweeting by Zili Shen
YouTube recording

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