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a bubble in the Orion Nebula

Editor’s Note: This week we’re at the 233rd AAS Meeting in Seattle, WA. 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 next week.


Plenary Talk: A Color Out of Space: ‘Oumuamua’s Brief and Mysterious Visit to the Solar System (by Stephanie Hamilton)

The first plenary session of #AAS233 kicked off with a presentation by Hawai’i native Ka’iu Kimura describing the work of the ‘Imiloa Astronomy Center, an astronomy and culture education center in Hilo, HI that showcases the role of Hawai’ian culture in astronomy. The long history of tension between Hawai’i natives and astronomers regarding the development of Mauna Kea has made the subsequent development of ‘Imiloa difficult. The Center features exhibits and displays of Hawai’ian culture on one side (the “brown carpet”) and showcases astronomy displays on the other (the “blue carpet”). But the mere presence of the two topics in the same space has opened opportunities for discussions about each in the realm of the other.

‘Imiloa’s role in astronomy reached new heights with the discovery of the first-ever interstellar asteroid, ‘Oumuamua. Kimura recalled her experience with naming ‘Oumuamua — Doug Simons, executive director of the Canada-France-Hawai’i Telescope (with which the object was discovered), contacted her asking for a Hawai’ian name “within the next 48 hours.” Her uncle, an advocate for Hawai’ian culture, suggested the name ‘Oumuamua, which translates to “scout or messenger from the distant past.” At that time, ‘Imiloa had already been developing a process for naming astronomical objects and ‘Oumuamua provided the first test of that process. Now a pilot program called A Hua He Inoa invites a group of 10 students to study and name asteroids. They have already named two: 1) Kamo’oalewa, one member of a dissociated binary object now left to orbit in the solar system on its own, and 2) Ka’epaoka’awela, a retrograde asteroid near Jupiter.

The plenary session continued with Yale’s Dr. Gregory Laughlin’s overview of the discovery and study of ‘Oumuamua. Due to the unfortunate lack of Hawai’ian words in the English language, Laughlin commented on his phone’s habit of autocorrecting ‘Oumuamua, until it eventually started autocorrecting everything else to ‘Oumuamua:

Discovered on 25 October 2017, ‘Oumuamua was visible until just last month, December 2018. It was discovered at a distance of just 60 lunar distances, whizzing by with a velocity of 26 km/s. It reached its closest approach to the Sun of 0.25 astronomical units at 88 km/s before leaving our solar system forever.

Laughlin's 'Oumuamua talk

The properties of ‘Oumuamua. The left plot shows that the object (black circle) resembles bodies in our own solar system. Assuming low albedo (reflectance), astronomers calculate its size to be ~100m.

After the discovery announcement, there was a mad scramble to obtain observations before ‘Oumuamua got too faint, particularly for spectroscopy. The Palomar telescope showed a relatively boring spectrum — red and featureless, similar to many of the bodies in our own solar system. Additional observations of ‘Oumuamua’s light curve suggested a rotation period of ~8 hours. But what was truly remarkable was the variation in the light curve — almost 3 magnitudes from brightest to faintest! No other object that astronomers have studied shows nearly that degree of variation, and it offers clues to ‘Oumuamua’s size and shape. It is not a contact binary since such an object would have been disrupted, and we know that it must be extremely elongated (latest estimates calculate the ratio of the long axis to short axis at ~5:1) due to the extreme light curve variation.

‘Oumuamua’s surprises didn’t stop there: astronomers then found that their observations fit better if the object was accelerating, e.g. due to outgassing. Laughlin and collaborators have developed a model of outgassing on a triaxial cylindrical object (like what ‘Oumuamua is thought to be) that matches the observed variations in the light curve quite well. Look out for that paper coming soon to an arXiv near you!


Press Conference: Stars & Planets from SOFIA, Spitzer & Citizen Scientists (by Susanna Kohler)

As AAS Press Officer Rick Fienberg noted, the first press conference of AAS 233 was a historical event: it marked the very first conference in which the entire press corps donned 3D glasses! Beautiful visuals and exciting discoveries populated this session.

Alexander Tielens (Leiden University) opened the conference by announcing new infrared observations from the GREAT instrument on NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), an infrared telescope that flies in the stratosphere on a modified 747 jetliner. GREAT’s observations were of the center of the Orion nebula, where the massive star θ1 Ori C is gradually blowing a bubble in its surrounding molecular cloud. Astronomers have long suspected that stellar winds from massive stars might be responsible for removing material and halting further star formation. Now SOFIA’s observations have caught θ1 Ori C in the act of destroying its natal environment, lending support to this theory. Press release

Orion's Dragon

A screenshot of Orion’s Dragon, taken from the 3D video of the Orion nebula created from SOFIA infrared data. [NASA/SOFIA]

Joan Schmelz (SOFIA/USRA) followed up with more stunning infrared imagery from GREAT on SOFIA: a 3D data cube (including spectra) of the Orion Nebula, which reveals a spectacular structure the team dubbed “Orion’s Dragon”. Those of us attending the press conference were all provided with a pair of red/blue 3D glasses, through which we could watch a 3D fly-around of the gas dragon that towers in this star-forming region. Got a pair of 3D glasses? You can check it out yourself here! Press release

Next up, Thomas Beatty (University of Arizona) detailed the results of a study of hot Jupiters, large gaseous exoplanets that orbit very close to their host stars and are tidally locked — i.e., the same side of the planet always faces the star. New observations from Spitzer suggest that these planets all have clouds on their night sides (the side facing away from the star) and are all clear on their day sides (the side facing toward the star). Press release

K2-288Bb

Artist’s illustration of newfound planet K2-288Bb, which was discovered by citizen scientists. [NASA’s Goddard SFC/Francis Reddy]

What’s new in the world of transiting exoplanets? Graduate student Adina Feinstein (University of Chicago) detailed the citizen-scientist discovery of a planet signal in Kepler data that was missed by automated pipelines. The citizen scientists of Exoplanet Explorers, a Zooniverse project in which the public searches Kepler’s K2 observations to locate new transiting planets, discovered the signal of K2-288Bb, a planet roughly twice the size of Earth that is located within its star’s habitable zone. Press release

Lastly, Kevin Hardegree-Ullman (California Institute of Technology) rounded out the session by sharing a follow-up discovery in the citizen-scientist-discovered planetary system of K2-138. This star was determined last year to host five planets, and there were tantalizing hints that there may be a sixth lying further out. Using recent Spitzer observations, scientists have now confirmed the presence of that sixth planet, K2-138g. This is the ninth known planetary system with six or more planets — and there may be more planets hiding between K2-138g and the five inner planets, so we should definitely keep looking! Press release


Plenary Talk: The Dawn of Gravitational Wave Astrophysics (by Mike Zevin)

In the second plenary talk of AAS 233, Vicky Kalogera of Northwestern University illuminated the dawn of gravitational-wave astrophysics in her Dannie Heineman Prize Lecture. Kalogera is an astrophysicist in the LIGO Scientific Collaboration, though her group’s research interests span a range of topics in high-energy astrophysics, such as gravitational-wave data analysis, modeling of compact-object populations, the evolution of massive stars in binary systems, X-ray binaries, and supernovae.

LIGO/Virgo compact binaries

Masses of detected LIGO/Virgo compact binaries. [LIGO/VIrgo/Northwestern Univ./Frank Elavsky]

In this talk, Kalogera covered the exciting progressions in the field of gravitational-wave astrophysics over the past few years — from the first observation of a binary black hole merger in September 2015 to the 10 binary black holes discovered to date (and who can forget the infamous binary-neutron star merger detected in gravitational waves as well as across the electromagnetic spectrum). Extracting information about the compact objects that created the signals (such as their masses, spins, and redshift) provides a unique and unprecedented probe into the population of merging compact objects in our universe.

Kalogera stressed how influential these detections have been for confirming predicted rates of compact-object mergers, and in some cases, vastly exceeded predictions. The rates of double neutron star mergers is amazingly spot-on with predictions from almost a decade before the first binary neutron star mergers were observed. Black hole mergers, on the other hand, vastly exceeded expectations — the rate of such mergers were found to be about 10 times higher than theoretical predictions! How the past few years have changed our understanding of black hole merger rates it quite astounding — before the first gravitational-wave detection, the uncertainty of black hole merger rates spanned a few orders of magnitude. After a single detection, the rate uncertainty went down to a factor of 200, and after 10 detections it shrunk to an uncertainty factor of just 4!

Vicky Kalogera

Vicky Kalogera presents the spectrograms and waveforms for LIGO-discovered gravitational-wave transients.

One exciting finding that gravitational-wave observations have already unveiled has to do with the mass spectrum of black holes — that is, the relative rate at which the universe churns out black holes of a given mass compared to other masses. Stellar evolution and supernova theory predicts multiple mass gaps — dearths in the mass spectrum of compact objects. With the 10 binary black hole observations to date, we are beginning to see definitive evidence of an upper mass gap due to a theorized type of supernova known as pulsational pair instability supernovae. 99% of the black hole population detected by LIGO have masses lower ~45 solar masses, right in line with where this predicted ‘gap’ starts. This is an excellent example of the corroboration of theoretical predictions with observational data, and it exemplifies the power that gravitational-wave observations have in deciphering the mysteries of our universe.

Lastly, Kalogera alludes to the upcoming years of operation of gravitational-wave detectors. In the next observing run of the LIGO and Virgo interferometers, which are expected to continue observations in March 2019, we can expect to observe up to a few black hole mergers per week and possibly a neutron star merger as frequently as once per month! Gravitational-wave scientists will certainly have their hands full, and the future of gravitational-wave astronomy will assuredly unveil more secrets about the dark universe.


Special Session: Know Your Power (by Mia de los Reyes)

Astrobites was one of the sponsors of the Know Your Power special session, run by Lauren Chambers, Leah Fulmer, and Dra. Nicole Cabrera Salazar. This special session aimed to address several questions: how do we recognize and leverage our power in academia to effect positive change? How do we collaborate with others, particularly those at different career stages and with different identities? As defined in this session, “power” is “the collection of authority, credibility, and knowledge that allows one to enact their autonomy and influence their environment.”

The session began by acknowledging that the #AAS233 meeting is occupying land traditionally belonging to the Duwamish and Puget Sound Salish peoples. The organizers further recognized the labor of the facilities and cleaning staff who have enabled this conference and all academic work. Finally, the organizers then reviewed some basic guidelines and reminded attendees to keep in mind the concept of “positionality”: the idea that we all have unique perspectives as a result of our unique intersections of identity.

Dra. Cabrera Salazar then moderated a panel discussion among a group of accomplished astronomers from all levels of academia. The panelists gave examples from their own lives and careers of how they’ve used their power to cause positive change, which led to some great discussions on various related topics: how to be a good collaborator when pushing for change (a key point is to listen and learn), how to use available resources (such as networks, opportunities, and awards) to uplift ourselves and others, and how to work together as a collective to amplify our individual power within the system of academia.

The session then broke into small group discussions, where attendees were able to talk among themselves about their own ways to use power to promote change. The discussion questions guided attendees to think about actionable ways to advocate for a more equitable and inclusive environment in academia — and about how to hold ourselves accountable. Several organizations were mentioned for their work in fostering inclusivity, including the Banneker-Aztlán Institute and the National Astronomy Consortium.

Even after the session officially finished, the organizers noted that the work isn’t over. The Know Your Power document is a compilation of suggestions for ways that people at all different academic career stages can use their power. We invite you to contact the organizers if you’re interested in contributing to this living document!


Press Conference: Early Science from the Transiting Exoplanet Survey Satellite (TESS) (by Caitlin Doughty)

The Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey with a 2-year prime mission: to target main-sequence dwarf stars in the ever-expanding search for exoplanets. Having launched in April 2018 and begun science operations the following July once it reached its lunar orbit, the satellite works by using its four cameras to cover what the TESS team calls a sector of the sky, stacking many integrations taken over the course of 30 minutes into one final image. It remains trained on this sector for 27 days, taking images all the while, before re-positioning itself to observe a new field. In total, TESS will observe 26 such sectors, covering more than 85% of the sky. In contrast, the Kepler Space Telescope, reigning king of exoplanet-discoverers, by design was only able to observe 0.25% of the sky. Per the status report given by George Ricker of MIT, TESS has completed observations of its 6th sector and the team put out the first data release in December 2018. Over 1 million files of TESS data have been downloaded, amounting to more than 67 terabytes of information.

Xu Chelsea Huang (MIT) reported on some early science results pertaining to planet discoveries. From preliminary analysis, over 300 exoplanet candidates were found (roughly 42 of which were re-discoveries of previously known exoplanets). Eight of these candidates have been confirmed from follow-up observations. In particular, Huang highlighted three of the eight: Pi Mensae c, LHS 3844 b, and HD21749 b. Pi Mensae c is the first exoplanet discovered by TESS and is a super-Earth with a radius of 57 times that of Earth. LHS 3844 b is a rocky planet only about 30% larger than Earth in diameter, but it is so close to its host star that it is probably a “lava world.” HD21749 b is a sub-Neptune gas giant with about 23 times the mass of Earth that orbits its host star in 36 days. The host star is also believed to possess a 2nd planet, roughly Earth-sized, but this has yet to be confirmed.

Michael Fausnaugh (MIT) reported on some early science results of studying astronomical transients with TESS. One of the interesting capabilities of TESS is that because it is an in-progress survey of a large part of the sky, astronomers can reference images with timestamps coinciding with reported transient events to help determine the cause of the event, or to study the object in the time leading up to its outburst. As proof of concept, Fausnaugh cited a reported event that occurred on August 3, 2018, where an odd brightening was observed in the sky. Since TESS had observed the same patch of sky, TESS data from a few days prior to the event was examined and astronomers were able to identify it as a stellar flare. For such a brief event, there would otherwise have been no other way to determine the cause once it died down, highlighting the utility of the TESS mission. Changing the subject to supernovae, in a single month of observation, TESS was able to capture six supernovae’s light curves. This mission will prove invaluable for studying their early light curves before they’ve achieved their maximum brightness, which can help astronomers distinguish between different progenitor scenarios.

The last of the updates came from Thomas Barclay (Goddard Space Flight Center & University of Maryland, Baltimore County), who was sitting in for Paul Hertz and Patricia Boyd. The Guest Investigator Program with TESS provides funding to science proposals that utilize either the full-frame images or the raw 2-minute cadence data in TESS data releases. This program gives astronomers who are interested in doing science outside of the core goals of the mission the opportunity to receive the funding necessary to focus on this work. For Cycle 1 of this program, more than 140 proposals were received and the Cycle 2 submission deadline is February 28th, 2019.

Press release


Plenary Talk: “Make No Small Plans” (George Ellery Hale, 1868–1938) (by Kerry Hensley)

The first afternoon plenary was given by former AAS Historical Astronomy Division chair Marc Rothenberg, filling in for David DeVorkin (Senior Curator for the Space History Department of the Smithsonian), who was unable to travel to the meeting due to the US government shutdown. Rothenberg introduced the achievements of George Ellery Hale — a prolific solar observer, observatory founder, and visionary in the field of astronomy. As an astronomer, Hale is best known for his discovery of magnetic fields in sunspots, but his legacy extends far beyond the field of solar physics.

Hale Telescope

The 200-inch Hale Telescope at Palomar Observatory is still used for research today. (Palomar/Caltech)

Hale was not only interested in generating scientific results but also in developing the instruments that led to them. He constantly pushed for the construction of larger telescopes, from the 40-inch refracting telescope at the Yerkes Observatory (still the largest refracting telescope ever used for science) to the 200-inch (~5-meter) reflecting telescope at Palomar Observatory. (Built in 1948, the 200-inch telescope at Palomar was the world’s largest telescope until 1976!) This constant drive for progress reflects Hale’s personality as an “impulsive planner” who mapped out his next, larger project as soon as his current one was finished. (Hence his advice to friends and colleagues to “make no small plans.”)

However, not all scientists shared Hale’s enthusiasm for bigger and bigger telescopes: Edward C. Pickering (the director of the Harvard College Observatory) believed that we’d reached the useful limit in terms of telescope size. He thought that advances in astronomy expeditions, education, and prizes would lead to greater improvements in the field than spending more money on large telescopes. While the number of prizes has increased as Pickering hoped, telescopes have certainly continued to grow as well!

Hale’s lasting legacy also encompasses the institutions that he worked to found. He helped found the National Research Council during World War I as well as the Astronomical and Astrophysical Society of America, which later became the American Astronomical Society.


Plenary Talk: The Obscured Early Universe (by Nora Shipp)

In the final plenary of the day, Caitlin Casey gave the Newton Lacy Pierce Prize lecture on unveiling the obscured universe. Casey, a professor at UT Austin, looks back the most massive and luminous galaxies in the early and distant universe, which form stars hundreds of times faster than the Milky Way. These extreme galaxies are essential for our understanding of galaxy formation in early epochs, but they are very difficult to study using usual methods, because their observations are altered by dust. Although dust makes up only a small fraction of the mass in galaxies, it can have a huge effect on the light galaxies produce, since it absorbs starlight and reradiates it at different wavelengths. For this reason, Casey does not use optical, ultraviolet, and infrared wavelengths like many astronomers; instead, she observes these distant galaxies at submillimeter wavelengths using the Atacama Large Millimeter Array (ALMA).

Antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), on the Chajnantor Plateau in the Chilean Andes. [ESO/C. Malin]

Casey explained how ALMA has revolutionized our view of the submm sky by detecting the most distant known galaxy (at a redshift of 9.1!), resolving features like spiral arms and bars in distant galaxies, and revealing many of these dusty star forming galaxies (DSFGs). These galaxies, when observed at submm wavelengths, can answer exciting questions about galaxy formation in the early universe. In particular, Casey highlighted four big questions:

  1. What do these extremely massive galaxies tell us about the most massive halos that could have formed at that point in the evolution of the universe?
  2. Are these unique systems formed through mergers, or via another mechanism?
  3. Are DSFGs the very first metal-enriched galaxies in the universe?
  4. Are they the progenitors of the most massive galaxy clusters that exist today?

Casey described how her research group at UT Austin has sought to answer these questions and produce a unified model of dusty galaxies at high redshifts. They have gathered all the available sub-mm data and compared it to various models embedded in mock observations. Casey suggested that for a more complete characterization, future shallow and wide-area submm surveys would be necessary to observe as many of these rare, massive, high-redshift, dusty galaxies as possible.

In addition to this exciting science, Casey took a few minutes to reflect on her experiences within the astronomy community. She thanked her mentors, colleagues, and friends throughout her career, and she acknowledged both the difficulties she has faced in reaching this point as well as the privileges that have made her path smoother than others. For graduate and undergraduate students in the room, it was encouraging and refreshing to hear that a decade ago this prize-winning researcher sat in this very audience, listening to a AAS prize talk, wondering whether she would ever make it. Prof. Casey’s journey is a reminder that the future of astronomy is bright!


Astrobites at AAS 233

This week, Astrobites is attending the American Astronomical Society (AAS) meeting in Seattle, Washington!

Astrobites at AAS 233

Astrobites authors talk to students at the undergraduate orientation at AAS 233 Sunday night.

We had a great time at the undergrad reception this evening talking to the awesome students here about their past work and their goals for the future. Thanks to all of you for joining us; we hope to see you around at the rest of the meeting!

If you’re at the meeting and missed us at the undergrad reception, please stop by and visit this week! You can find us at the AAS booth in the exhibit hall — we have sunglasses, stickers, and more, so swing by to pick up some swag and say hi.

For anyone who’s missing the meeting, or for those attending who can’t make all the sessions you want to: Astrobites and AAS Nova will be working together to report highlights from each day. We’ll particularly be covering the keynote talks and the press conferences coming out of the meeting. You can follow along here on the site, or at aasnova.org — look for an update after each day of the meeting. If you’d like to see more timely updates during the day, we encourage you to search the #aas233 hashtag on twitter.

Lastly, if you’re interested in reading up on some of the keynote speakers before their talks at the meeting, keep following along at astrobites.com … we’ll be posting interviews with speakers in advance of their keynote talks. Seven of these interviews for AAS 233 have already been published; you can check them all out under the aas233 tag on astrobites.com. This is a great opportunity to learn more about prominent astrophysicists and the path they took to where they are today!

AAS 233

Will you be at the 233rd American Astronomical Society meeting in Seattle, Washington? AAS Publishing looks forward to seeing you there! You can come find us in the exhibit hall at booth #425, and you can check out AAS-Publishing-related endeavors in a number of events throughout the week. Below are just a few.

AAS Publishing, AAS IOP ebooks, and Astrobites Booth

Monday–Thursday | All day | Exhibit Hall Booth 425

Come stop by to visit AAS Publishing (we’ll be well-stocked with corridor pins!) and learn about our journals and our ebooks produced in partnership with IOP. You can also visit with the team of graduate-student Astrobites authors live-blogging the meeting (and pick up some Astrobites swag!).

AAS Publishing Happy Hour

Tuesday | 5:00 PM – 6:15 PM | Exhibit Hall Booth 425

Join us for a happy-hour event at the AAS exhibit hall booth! We’ll be celebrating you — our authors — and a successful past year, as well as the launch of a few new initiatives.

AAS WorldWide Telescope Booth

Monday–Thursday | All day | Exhibit Hall Booth 437

The WWT team will staff a station within the AAS booth in the exhibit hall over the entire conference. See what it’s like to use WWT through an Oculus Rift VR headset or a giant Microsoft Surface Studio touchscreen panel! Or just chat with our developers and expert WWT users about what WWT can do for your research, teaching, and outreach, and where the project is going.

AAS WorldWide Telescope presents: The University of Washington Mobile Planetarium

Monday–Thursday | All day | Exhibit Hall Booth 437

Planetaria aren’t just for slideshows anymore! Just across from the AAS WWT booth, come learn how modern planetarium software and hardware — an inflatable Go-Dome, a hemispherical mirror, and a laptop running WWT — can engage the public, educate students, and dynamically visualize modern research data. The University of Washington Mobile Planetarium is portable and can be set up in under an hour by a small team of people. Besides enjoying this immersive experience on its own terms, at our booth you can also learn how to bring a mobile planetarium to your own institution or astronomy club. The UW Mobile Planetarium team has made its resources freely available online and is happy to offer tips if you’re curious!

Special Session: AAS WorldWide Telescope Presents: Advances in Astronomical Visualization

Monday 1/7 | 10:00 AM – 11:30 AM | Room 214 | Jonathan Fay

This session is aimed to bring the AstroViz 2018 workshop — exploring the many aspects of astronomical visualization for science, informal education, and communication — to the AAS community. There will be a mix of invited speakers and contributed lightning talks showcasing the cutting edge of astronomical visualization.

Special Session: Professional Development with AAS WorldWide Telescope

Tuesday 1/8 | 10:00 AM – 11:30 AM | Room 214 | Peter K. G. Williams

The WWT is a seamless data visualization tool with an engaging learning environment. The WorldWide Telescope project enables terabytes of astronomical images, data, and stories to be viewed and shared among researchers, exhibited in science museums, projected into full-dome immersive planetariums, and taught in classrooms from elementary school to college levels. Learn to spruce up your paper and share your research with WorldWide Telescope! This workshop is aimed at astronomy researchers of all levels. You don’t need to have any previous knowledge of WorldWide Telescope. This is an interactive tutorial: please bring an internet enabled laptop.

Special Session: AAS WorldWide Telescope in Outreach and Education

Tuesday 1/8 | 2:00 PM – 3:30 PM | Room 214 | Patricia Udomprasert

WWT is also a powerful tool for astronomy outreach and education. Its rich visualization environment functions as a virtual telescope, allowing anyone to make use of real astronomical data to explore and understand the cosmos. WWT users navigate through 3-dimensional and 2-dimensional views of planets, stars, and galaxies, giving them a better mental model of our universe. WWT can also be used to create scripted multi-media paths called “Tours,” to share stories about how we came to know what we know in astronomy. Students can make their own tours for astronomy projects, and educators can use tours to design lesson plans about curricular topics. In Part 1 of this session, invited speakers will present brief examples of WWT being used in a variety of educational settings, including Astro 101 classes, K12 science, online courses, and planetaria. Part 2 of the session will be a hands-on WWT tutorial, where we will lead attendees through a variety of activities in the WWT web client. Please bring your own computer. (Windows is not necessary).

Special Session: AAS WorldWide Telescope with Python and Astropy

Wednesday 1/9 | 10:00 AM – 11:30 AM | Room 214 | O. Justin Otor

Join us for a workshop where we will learn how to visualize FITS files and Astropy data sets against imagery from large-scale sky surveys with pyWWT, a Python-driven and Astropy-integrated interface of WorldWide Telescope. pyWWT is an open-source and actively developed Python package designed to offer a more research-focused take on WWT, an interactive, two and three-dimensional astronomical visualization engine powered by imagery from many prominent telescopes and widely used in K-12 education and for planetarium shows. In this tutorial, attendees will be interactively guided through the package on their own laptops to sample features that fill everyday needs in the workflow of the data-savvy astronomer. Attendees will leave with knowledge of how to use pyWWT to plot their own Astropy-compatible tables and personal FITS files on real-data sky backgrounds and, in the future, create their own visualizations for talks, astronomy lectures, and “video abstracts.” We also be encouraging feedback and suggestions on how to make pyWWT more useful to the astronomy community! Please bring your own computer. (Windows is not necessary).

Special Session: AAS WorldWide Telescope Shareathon and Brownbag

Wednesday 1/9 | 12:40 PM – 2:00 PM | Room 214 | Gina Brissenden

Do you use the AAS WorldWide Telescope (WWT) — in your research, publications, teaching, outreach, or elsewhere? Perhaps you’re a WWT Developer — of software, visualizations, curriculum, tours, or something else? Not sure what all of this is about but are curious? Perfect! Grab your lunch, AND a colleague, then come join others in our community for an informal discussion about how we’re all using the AAS WWT, or would like to be, what our development needs are, and about ways in which we can engage with each other — and build community — beyond the length of this session. Presenters from AAS WWT sessions held earlier in the meeting will also be along to contribute to our conversation. Thanks to the AAS WWT, light beverages will be provided, so we strongly encourage preregistration. We very much look forward to seeing you there!

WWT at the Hack Together Day

Thursday 1/10 | All day | Room 4C-2

Last but not least, WWT developers will be attending the now-traditional Hack Together Day on the final day of the meeting. Seek them out if you have project ideas, have any questions about how WWT works under the hood, or want to learn about creating fast and portable web-based 3D visualizations using WebGL!

AAS Publishing

Editor’s Note: There’s a lot of discussion in the scientific community right now about topics like open access, preprint servers, and the role of scientific journals in the evolving academic publishing landscape. The following article, which is reproduced here from the new AAS journals website, explores the AAS journals business model in the context of these conversations.

The American Astronomical Society is a nonprofit professional society for astronomers that is somewhat unusual in owning and having complete editorial control over its own journals. The AAS prides itself on the fact that these journals — The Astronomical Journal, The Astrophysical Journal, The Astrophysical Journal Letters, and The Astrophysical Journal Supplement Series — are run by scientists, for scientists. But in the age of the internet, when anything can be posted online and viewed around the world, what is the value and role of a scientific journal?

We recently sent out a survey asking authors for feedback on the AAS journals. We’re carefully studying the thousands of responses we received with an eye to improving the journal offerings — but in the meantime, we thought this would be a good opportunity to clarify the AAS journals business model.

Our Business Model

Realistically speaking, it’s not possible to publish a journal without money. As the AAS is not a commercial publisher, it has no source of external funding for its journals. Money within the AAS is generally divided into separate pools: dues and meeting fees are fed back into the Society, whereas the journal operating costs and development are supported by journal revenue. As a result, there are only two potential revenue streams that the AAS journals can use to meet operating costs: author fees and subscription fees.

To completely eliminate author fees (free to publish), the entire operating cost must be shouldered by subscribing institutes — which can be a significant hardship, particularly for smaller institutes whose libraries may not have a large budget. Because the AAS is committed to providing broad access to our authors’ work, dramatically increasing subscription fees to eliminate author fees is not currently an option.

Instead, the AAS has had a combination revenue stream for decades, meeting part of the journal operating costs via author fees and the other part through subscription fees. With such a model, the Society is able to adapt to fluctuating economic times both nationally and internationally, adjusting its fee scale as the scientific funding landscape changes.

journal revenue

History of annual institutional subscription rates for AJ and the ApJ family (ApJ, ApJS, and ApJL). The 2017 institutional subscription rate for Monthly Notices of the Royal Astronomical Society, an example of a journal that does not charge author fees, is shown for comparison (source). Bottom: History of author fees per page published in AJ, ApJ, and ApJS.

The Role of Open Access

What does this mean in the age of open-access journals and preprint servers? Again, it comes down to a choice: for a journal to be fully open-access, its revenue can’t come from subscription fees. With no subscription fees, nor author fees, nor external funding (even the arXiv needs nearly $2 million of external funding annually to run!), the journal cannot exist — so a compromise is necessary.

The AAS believes that broad access to astronomical research work is crucial for open scientific dialog and for communication with the larger community that funds the research. Toward this end, the Society has instituted three policies for its journals:

  1. All articles published in AAS journals are made freely available twelve months after publication.
  2. For authors who would like to make their work publicly available immediately upon publication, the AAS journals offer authors the option of Gold Open Access: for a fee (set at a level that offsets the lost subscription revenue), an article can be published under a CC-BY license and will be available for any reader to download or read for free immediately.
  3. Under the AAS journal copyright, authors who publish in AAS journals may also post their preprint to the astronomy preprint server arXiv, to another repository, or even to their own personal website, thus ensuring that a version is immediately available to the public for free.

With this model, the AAS hopes to both support broad access to scientific research while still generating enough revenue to meet journal operating costs.

What the AAS Journals Offer

interactive figure

An example of an interactive figure within an ApJ manuscript. Visit the article, “Evolution of a Pulsar Wind Nebula within a Composite Supernova Remnant” by Kolb et al. 2017, to experience the interactivity yourself.

So why bother having an official journal if everyone can post for free on the arXiv instead?

As scientists ourselves, we at the AAS journals don’t see our role as simply republishing our authors’ work with better typesetting. Instead, we feel that the critical mission of the AAS journals is to increase the scientific integrity of the field. To us, achieving this means not only providing the obvious services — such as acting as gatekeepers for pseudoscience, facilitating peer review for manuscripts, and providing long-term preservation of articles and data — but also the less obvious services that improve the quality and reach of manuscripts published with us.

As astronomy is driven more and more by big data and statistics, ensuring that these aspects are correctly handled in manuscripts will systematically improve the quality of research published in the field. For this reason, the AAS journals employ two full-time data editors, Drs. Greg Schwarz and Gus Muench, who review submitted manuscripts and edit the data, figures, and software citations for those articles that contain significant tabular or other data material. Our data editors provide many forms of author support, including developing and supporting AASTeX and documenting best practices for using online repositories and data linking. They also set up and maintain new initiatives for the journals, such as interactive and animated figures, and they work with in collaboration with community archives and science platforms to improve data linking.

AAS Nova

The homepage of AAS Nova, a website through which summaries of recent AAS journal articles are shared with the community.

Additionally, the AAS journals have a dedicated statistics editor: astrostatistician Dr. Eric Feigelson, professor at Pennsylvania State University. The statistics editor reviews all AAS journal manuscripts that include a significant statistical component, offering authors recommendations on how to strengthen the statistics of their studies in accordance with current best practices in the field.

In the interest of broadening the reach of articles published in our journals, the Society developed AAS Nova, a website designed to help disseminate our authors’ work to the larger astronomical community and the broader public. AAS Nova editor Dr. Susanna Kohler produces and edits summaries of research articles that appear on AAS Nova, ensuring that this work is shared with other astronomy researchers, science journalists, and the general public.

We’re Your Journals

AAS journals are produced by the astronomy community, for the astronomy community — which sets us apart from commercially published journals. We pride ourselves on our work with and support for existing community structures (like databases, repositories, and archives). The development and operations within AAS publishing are all pursued under the oversight of a Publications Committee, which is comprised of astronomers seeking to advance the broader community goals.

The intent of the AAS journals has always been to add value to the astronomy community, and to improve the quality and reach of the research work produced by astronomers. That said, we also acknowledge that there’s always something we can improve — and the fact of the matter is, we’re your journals. Please don’t hesitate to let us know if there’s something we can do to better serve your needs. Our team of more than 30 journal editors — astronomers across a broad range of subfields — would love to chat with you at future scientific meetings. By listening to you, we hope that we can continue to evolve and to play a meaningful part in today’s academic publishing landscape.

RNAAS

Editor’s note: This week, we celebrate one year since we first launched Research Notes of the American Astronomical Society (RNAAS) — a non-peer-reviewed, indexed, and secure record of brief works in astronomy and astrophysics. Editor Chris Lintott shares his thoughts on one year of RNAAS below.

Launched in October 2017, Research Notes of the AAS (RNAAS) has now reached its first birthday. The idea behind RNAAS was to provide a venue for quick and easy publishing of things that otherwise might not enter the formal record, like negative results, one-off observations, or student projects. We knew what the format was — one figure or table, 1,000 words — but the truth is, I don’t think any of us knew quite what to expect.

A year on, it seems evident that RNAAS is an enormous success. 243 notes have been accepted, and the diversity has been astounding. There have been flurries of activity around exciting events, like the passage of ‘Oumuamua through our solar system or the release of Gaia data, but there have also been conference reports, theoretical notes, comments on statistical techniques, reports of observations by students, (polite) quibbles with published results, suggestions for classroom activities, and even people using Research Notes to record predictions. I’m also excited to see people using RNAAS to publicise the release of catalogues and data online, rather than allowing the need for a full paper be a reason to delay or not to document such a release. 

We’ve highlighted just a few of my favourites below, but it’s the variety that strikes me. It turns out that all sorts of people wanted an open, slightly formal (indexed in ADS!), but not peer-reviewed way of recording their thoughts and efforts, and my mornings are enlivened by reading them as part of the moderation process. Another pleasant surprise has been the degree to which RNAAS has entered the mainstream of astronomical work; nearly 70 Notes have already been cited. 

My thanks to the Journals team, and to my fellow editors who help keep an eye on things. We’ve all worked to keep to our goals of being fast and keepingNotes both free to publish and free to read without being too rough around the edges. If you have any suggestions, do get in touch. 

I hope you’ll keep Research Notes in mind for pretty much anything, and drop me an email if you have questions about what might be suitable. The odds are we’d love to publish your thoughts. 

Chris Lintott
Editor, Research Notes of the AAS

 

Highlights from a Year of RNAAS

Want a taste of the research that’s been published in the first year of RNAAS? Check out these ten suggestions from RNAAS Editor Chris Lintott.


'Oumuamua galactic velocity

‘Oumuamua’s galactic velocities don’t match those of any nearby star systems. [Mamajek 2017]

“Kinematics of the Interstellar Vagabond 1I/‘Oumuamua (A/2017 U1),” Eric Mamajek 2017 Res. Notes AAS 1 21. doi:10.3847/2515-5172/aa9bdc

Calculations in this Note support a picture in which the asteroid 1I/’Oumuamua (A/2017 U1) originated from outside of our solar system, but did not come from any of the dozen star systems nearest to us. This is currently the most-cited Research Note and has been downloaded more than 1,300 times.


“The Third Workshop on Extremely Precise Radial Velocities: The New Instruments,” Jason T. Wright and Paul Robertson 2017 Res. Notes AAS 1 51. doi:10.3847/2515-5172/aaa12e

This Note provides a very brief overview of events during the Third Workshop on Extremely Precise Radial Velocities, held in Pennsylvania in August 2016. The Note includes a link to a table produced during the workshop that summarizes nearly all of the next-generation extremely precise Doppler velocimeters being designed, built, or commissioned today.


“Strong Hydrogen Absorption at Cosmic Dawn: The Signature of a Baryonic Universe,” Stacy S. McGaugh 2018 Res. Notes AAS 2 37. doi:10.3847/2515-5172/aab497

After the groundbreaking discovery of the signature of light from the very first stars in the universe, first announced in February 2018, this Note rapidly followed on its heels with a theoretical explanation for the signal’s unexpected strength.


“Another unWISE Update: The Deepest Ever Full-sky Maps at 3-5 μm,” A. M. Meisner et al 2018 Res. Notes AAS 2 1. doi:10.3847/2515-5172/aaa4bc

This Note presents the deepest ever fully-sky maps at 3.4 and 4.6 µm, built by reprocessing ~140 terabytes of infared images from the Wide-field Infrared Survey Explorer (WISE) and Near-Earth Object Wide-field Survey Explorer (NEOWISE) missions.


NGC1052-DF2

The backwards “S” shape faintly visible in the true-color image of NGC1052-DF2 (background) and zoomed insets may be a cold stellar stream. [Abraham et al. 2018]

“The Maybe Stream: A Possible Cold Stellar Stream in the Ultra-diffuse Galaxy NGC1052-DF2,” Roberto Abraham et al 2018 Res. Notes AAS 2 16. doi:10.3847/2515-5172/aac087

Remember the controversial NGC1052-DF2, the ultra-diffuse galaxy reported to be strangely lacking dark matter? This Note reports on the provisional detection of a cold stellar stream within this galaxy, cautiously referred to as “The Maybe Stream”. If confirmed, this would be located 500 times further away than the current most-distant cold stellar stream known.


“No Bursts Detected from FRB121102 in Two 5 hr Observing Campaigns with the Robert C. Byrd Green Bank Telescope,” Danny C. Price et al 2018 Res. Notes AAS 2 30. doi:10.3847/2515-5172/aaaf69

This Note is an excellent example of a helpfully documented null result. The repeating fast radio burst FRB 121102 was observed over two 5-hour observation sessions on the 100-m Green Bank Telescope, and no bursts were detected during that time. These are among the longest published contiguous observations of FRB 121102, and support the notion that FRB 121102 bursts are episodic.


“The Spectroscopic Classification of Seven Cataclysmic Variables with the Liverpool Telescope,” E. W. Upsdell et al 2018 Res. Notes AAS 2 161. doi:10.3847/2515-5172/aadee7

This Note presents a student project in which the spectra of seven cataclysmic variables — observed using the 2-m Liverpool Telescope in the UK — are analyzed. The objects are shown to be consistent with dwarf novae.


“Predicting The Orbit of TRAPPIST-1i,” David Kipping 2018 Res. Notes AAS 2 136. doi:10.3847/2515-5172/aad6e8

What would the period be for a hypothetical eighth planet in TRAPPIST-1, an exoplanetary system currently known to host seven planets that share near mean motion resonances with their neighbors? This Note presents a prediction that we can hope to test, should we discover TRAPPIST-1i in the future.


North Celestial Pole path

Path, in green, of the apparent position of the North Celestial Pole (i.e., the center of star trails) as a function of time. [Wright 2018]

“Proving Heliocentrism and Measuring the Astronomical Unit in a Laboratory Astronomy Class Via the Aberration of Starlight,” Jason T. Wright 2018 Res. Notes AAS 2 119. doi:10.3847/2515-5172/aad0f5

For professors looking for an interesting class project, check out this Note, which describes a student project to measure the aberration of starlight caused by the motion of the Earth. With just a small telescope and camera, students can directly prove that the Earth travels around the Sun.


“Unbiased Inference of the Masses of Transiting Planets from Radial Velocity Follow-up,” Benjamin T. Montet 2018 Res. Notes AAS 2 28. doi:10.3847/2515-5172/aac2c1

This Note reveals an overlooked observational bias toward artificially high mass values estimated for planets discovered via the radial velocity method. The author proposes a means for avoiding this bias in the future.


 

NGC 2623

Editor’s Note: This week we’re at the 232nd AAS Meeting in Denver, CO. 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 next week.



Wednesday, 6 Jun



Plenary Lecture: George Ellery Hale Prize, Amazing Journeys to the Hearts of Stars (by Kerry Hensley)

The first talk of the day was given by Dr. Sarbani Basu (Yale University), who was awarded the George Ellery Hale Prize for “outstanding contributions to the field of solar astronomy.” Dr. Basu is an expert in helioseismology — the study of tremors and vibrations of the Sun. While stars in certain mass ranges undergo huge, regular oscillations (so-called variable stars, like Cepheid or RR Lyrae variables), Sun-like stars experience smaller-amplitude pulsations generated at the top of their convective zones.

These subtle pulsations hold the key to understanding the interior structure of the Sun and other stars — a problem that renowned astronomer Arthur Eddington thought would never be solved, commenting that although telescopes enable us to peer at more and more distant stars, no instrument could help us look into the interiors of stars. Luckily, that’s not the case! The Sun oscillates in millions of different modes, which we can tease apart using helioseismology. Helioseismology can help us determine the true metallicity of the Sun (a long-standing problem that has huge implications for virtually all of astronomy!), how the solar interior rotates, and the degree of diffusion and settling of different elements within the Sun.

One of the huge triumphs of helioseismology came in the midst of the solar neutrino controversy — the realization that the number of solar neutrinos received by Earth-based neutrino detectors was too small by a factor of three. By using the absurdly good helioseismology data (Dr. Basu showed a plot of data where the 1,000-sigma error bars were smaller than the plotting symbols!), solar physicists showed that their models of the solar interior were right and the error must lie in the standard model. As it turns out, they were absolutely right — neutrinos, which were initially thought to be massless, instead possessed a tiny amount of mass, which allowed them to oscillate into any of three “flavors” (only one of which was easily detectable) as they traveled from the Sun to the detector.

red giants

Different types of red giants fall in distinct areas of parameter space. Another win for asteroseismology!

In the case of stars outside our solar system, asteroseismology can help us infer the fundamental properties of stars, since the maximum frequency of stellar oscillations scales with the stellar mass and the square root of the temperature. Also very exciting is the potential to distinguish between red giant branch and red clump stars — two types of stars that fall in the same area of the HR diagram but represent different stages of stellar evolution. Although they have similar temperatures and luminosities, their internal structure is different — and we can probe that structure with asteroseismology. Expect big discoveries from this field in the future!


Press Conference: Erupting Stars & Dissolving Stars (by Gourav Khullar)

corona

Layers of a total solar eclipse. [Inside: SDO/LMSAL/NASA GSFC;
Middle: Jay Pasachoff/Ron Dantowitz/Williams College Solar Eclipse Expedition/NSF/National Geographic;
Outside: LASCO/NRL/SOHO/ESA]

For this morning’s press conference, Kerry Hensley began the proceedings, supported by AAS media officer, Rick Feinberg, and Gourav Khullar.

The conference opened with Jay Pasachoff (Williams College & Carnegie-Hopkins Observatories), who discussed observations of the solar corona during the 2017 total solar eclipse. Salem, Oregon was the observing site for the project, where Pasachoff and collaborators constructed composite images of the eclipse to highlight the corona. Coronal streamers were also studied, along with polar plumes. Pasachoff also showed some observations from the International Space Station, clearly exhibiting a shadow of totality!

This was a great opportunity to study active regions in the Sun, especially from composites from multiple sites around the US. Pasachoff ended with a pitch about future total and annular eclipses across the US in the next 5 years.

This was followed by Thomas Ayres (University of Colorado Boulder), who described his project characterizing the habitability of planets around our nearest interstellar neighbour, the Alpha Centauri star system. Two of the stars have Sun-like environments, but Alpha Cen C is what Ayres likes to call a ‘weather hell’, due to its extreme X-ray flux capable of stripping away atmospheres and frying unprotected life. Ayres and collaborators used the Chandra X-ray Observatory to track the X-ray emission from the Alpha Cen system over the past 13 years. Chandra observations are the only ones capable of resolving stars A and B — B is seen to have stronger X-ray flux than A. According to Ayres, it so happens that Alpha Cen A is great for potential habitability prospects (its X-ray hazard is much lower than that of the Sun). Cen B is not too bad either, whereas Cen C is literal death!

Sofia Moschou (Harvard-Smithsonian Center for Astrophysics) was to follow, with her work on studying coronal mass ejections (CMEs) in the star Algol. Moschou’s recent paper in The Astrophysical Journal described indirect observations of monstrous CMEs in Algol. This work also characterized Algol’s place on the well-known proportionality between CMEs and flare intensities in the Sun (known as the solar CME–flare relation). The objective here, according to Moschou, is to see whether the proportionality of strength of the flares with CME activity continue with more active stars like Algol. The answer? It probably does. Stellar CME observations via Doppler shift measurements and X-ray absorption characterization enabled Moschou and collaborators to demonstrate Algol’s properties in the context of the relation, within the bounds of systematic uncertainties in observations of the Sun and Algol.

The final presentation of the press conference was by Andrea Kunder (Saint Martin’s University), talking about dissolving globular-cluster stars! Globular clusters are the oldest stars in a galaxy, akin to fossils. Kunder and collaborators are interested in seeing the interplay of globular clusters and the Milky Way bulge, especially since the bulge is the site of exciting activities! Kunder studied NGC 6441, the 5th most massive cluster in the Milky Way, which lies in a crowded bulge field with many field stars, and affected by massive amounts of gas and dust. This study used RR Lyrae stars as distance and velocity indicators on a velocity-radius diagram to isolate stars in the globular cluster from RR Lyrae stars outside the cluster. Kunder showed the results, which remarkably point to the idea that there are groups of RR Lyrae stars on the outskirts of the current form of NGC 6441, and the trajectory of the cluster indicates that these are ex-cluster members. In other words, stars in this globular cluster are dissolving away as we write this!


Plenary Lecture: Supermassive Black Hole Fueling and Feedback in Galaxies (by Mia de los Reyes)

Dr. Julie Comerford’s plenary talk at lunch time was — appropriately — on hungry galaxies. Comerford, a professor from University of Colorado Boulder, started by describing how nearly every massive galaxy hosts a supermassive black hole (SMBH). Sometimes, the black hole is actively accreting and spitting out energetic jets; this is called an active galactic nucleus or AGN. (Comerford has a great explanation of supermassive black holes and AGN in this feature by PhD Comics.)

The properties of an AGN are intimately linked with the properties of its host galaxy; the SMBH mass is correlated with the galaxy’s halo mass, and its accretion rate is proportional to the star formation rate of the galaxy. These black holes are truly behemoths, with masses equivalent to millions or billions of suns — but they’re not that big compared to their host galaxies. Yet SMBHs still manage to influence their galaxies on such large scales. As Comerford noted, the scale difference between a galaxy and its SMBH is equivalent to the difference between a grain of rice and the size of the Earth!

Comerford’s talk focused on two major ways that AGN can influence their host galaxy: fueling (the SMBH accretes matter) and feedback (the SMBH launches energetic jets and outflows, which can help turn off star formation in a galaxy). If you want to read more about these, check out my interview with Julie Comerford here!

Both fueling and feedback can be traced using pairs of supermassive black holes. These pairs can either be observed as dual AGN, in which both SMBHs are active, or offset AGN, in which one SMBH is quiescent so the active one looks off-center.

How do we actually find these dual and offset AGN? As Comerford explained, we can search for galaxies with narrow emission lines that have two peaks. These double peaks can be caused either by dual AGN, by disk rotation, or by AGN outflows; spectroscopy and images from radio and X-ray data can then be used to identify the dual AGN. We can also look for offset AGN by carefully comparing the positions of SMBHs (in X-ray images) and galactic centers (in optical images).

Comerford then listed several science questions that we can answer with these AGN:

  • Are the most luminous AGN triggered by galaxy mergers? Simulations have suggested this is the case, but observations were unclear… until now! Using dual AGN, it seems that the major mergers do trigger the most luminous AGN. (Contrast with some earlier Astrobites posts!)
  • Where in a galaxy merger does AGN fueling occur? The fraction of AGN increases as the two SMBHs get closer together, and new observations show that the AGN fraction is highest in the inner ~1 kpc.
  • Can outflows from moderate luminosity AGN contribute to feedback? The most powerful outflows seem to be driven by the most luminous AGN, But it turns out that about 90% of moderate-luminosity AGN outflows that have double-peaked narrow emission lines do have enough energy to turn off star formation in the galaxy!

Finally, Comerford talked about ways to connect fueling and feeding. Her group recently discovered a dual AGN that showed two discrete accretion events — a flickering AGN! Each event caused an outflow event, leading to a signature of asymmetric outflows. In the future, integral field spectroscopy on other interesting systems like this will help us further our understanding of these hungry galaxies.


Press Conference: The Milky Way & Active Galactic Nuclei (by Susanna Kohler)

This afternoon’s press conference explored distant, active galaxies — and also a quieter galaxy much closer to home: our own Milky Way.

William Reach (SOFIA/Universities Space Research Association) opened the conference by presenting work exploring where cosmic rays — highly energetic particles — originate and how they’re accelerated to their incredible speeds. Recent research has localized the source of some energetic cosmic rays and suggested that they may be originating in interactions between supernovae and molecular clouds. At these interaction sites, dense shocks occur, which can accelerate particles to their high speeds.

Ekta Patel (University of Arizona) followed next, presenting her efforts with her advisor, Gurtina Besla, to obtain a precise estimate of the mass of the Milky Way. Finding the mass of our galaxy is tricky, since we’re stuck in the middle of it — values in the literature range from 700 billion to 2 trillion solar masses! Patel has developed a new approach to weighing our galaxy, by comparing observations of nine of the Milky Way’s satellite galaxies’ full three-dimensional motions with the motions of tens of thousands of simulated galaxies. From these comparisons, she estimates the mass of the Milky Way to be 0.96 trillion solar masses. We can look forward to even more precise estimates using this technique in a few years, after simulations increase in resolution and we get Gaia’s measurements for even more of the Milky Way’s satellites! (Press release)

Next up, Randall Campbell (W. M. Keck Observatory) & Anna Ciurlo (University of California, Los Angeles) tag-teamed a presentation on Keck observations of the galactic center over the past 12 years. The center of the Milky Way hosts a supermassive black hole, Sgr A* — and we can learn a lot by watching close-in objects orbit around it! In particular, Campbell and Ciurlo have tracked several G-objects — objects in the same class as the exciting G2 that passed close to Sgr A* in 2014. Observations of these objects suggest that they are likely puffed-up stars shrouded by their thick outer layers of dust and gas. They may have originated from binary mergers, and it’s possible that they’re the progenitors of future S-stars: young, bright and very massive stars.

The press conference rounded out with results for which Julie Comerford had provided us with a quick teaser during her earlier plenary. Scott Barrows (University of Colorado, Boulder) presented efforts to hunt for offset active galactic nuclei (AGN): accreting supermassive black holes that don’t reside at the center of a galaxy. These objects are generally signs of a recent galaxy merger that left an AGN stranded away from the center of the newly formed galaxy, and they often mean that a second AGN that hasn’t yet turned on may be lurking nearby. Barrows found that single offset AGN were most commonly hosted in lopsided mergers — those in which one galaxy was more than four times the size of the other — whereas mergers hosting two active black holes at the center were more commonly equal-mass collisions. (Press release)


Plenary Lecture: Status of the Daniel K. Inouye Solar Telescope: Unraveling the Mysteries of the Sun (by Kerry Hensley)

The final talk of the day was an update on the status of the Daniel K. Inouye Solar Telescope (DKIST) given by Dr. Valentin Martínez Pillet (National Solar Observatory; NSO). DKIST is a 4-meter solar telescope currently under construction at Haleakala Observatory on the island of Maui in Hawai’i. After 8.5 years, DKIST (formerly known as the Advanced Technology Solar Telescope) is 83% complete, with first light planned for 2019 and the beginning of science operations following in 2020. DKIST aims to answer persistent questions about the Sun — in particular understanding the physical driver for coronal mass ejections. The 4-meter aperture translates to a resolution of 25 kilometers and a signal-to-noise ratio of 10,000 — so it’s no surprise that Dr. Martínez Pillet called it “a microscope on the Sun”!

DKIST promises to transform solar physics with its multiwavelength (0.38 – 28 microns) observing capabilities, coronagraph, and polarimetry. Some of the most exciting possibilities for DKIST involve the potential to combine its observations with those from Parker Solar Probe (which will fly to within 9 solar radii of the Sun’s surface and make detailed measurements of plasma properties there), Solar Orbiter (which will orbit the Sun at about the distance of Mercury’s orbit and carry both plasma instruments and a telescope), and the Atacama Large Millimeter/submillimeter Array (ALMA; a ground-based radio telescope array). This signals the beginning of a true multimessenger era for solar physics — get excited for first light in 2019!



Thursday, 7 Jun



Plenary Lecture: Gaia: Mapping the Milky Way: The Scientific Promise of Gaia DR2 (by Gourav Khullar)

The final plenary session of AAS232 is upon us, and what better to talk about than one of the greatest set of observations taken this century — the Gaia Data Release 2 (DR2)! Nicholas Walton (University of Cambridge, and Gaia), began by crediting the European Space Agency, the Gaia Collaboration, the Data Processing and Analysis Consortium (DPAC), and the massive efforts put in by industry and member universities of the collaboration. Read more about Nick Walton here!

This talk was both an overview of the Gaia mission and a brief description of science currently being done with this ginormous new dataset released a month ago! Gaia was launched in December 2013 and traveled all the way up to the 2nd Lagrangian point (L2 orbit) between the Earth and the Moon. Its first data release occurred in September 2016, and DR2 came out last month — with 1.7 billion objects in the catalog, recording photometry, spectrometry, and astrometry. This dataset is being used to characterize dust in the Milky Way, as well as the luminosity, proper motion, position, color, and surface temperature of stars around us!

Gaia maps the sky with a 1-arcsecond resolution, showing the Large and Small Magellanic Clouds, and the Sagittarius stellar stream in all their glory! The talk described the Gaia focal plane (106 CCDs, a billion pixels!), data-processing effort (pan-European, 450 specialists in 24 countries!), and DR1, which did not utilize the entire processing flow that allowed DR2 to obtain its microarcsecond-level astrometry, milli-magnitude level photometry, and 1 km/s-level radial velocities. This blows my mind! Read more Astrobites coverage of this mission here.

This was followed by a discussion of the completeness and sky coverage of the mission, which is significantly better for nearby astrophysical objects than ground-based surveys. While the astrophysical parameters (which we call second-order parameters here, derived from primary observations) need to be interpreted with care, Walton (and we at Astrobites!) would urge you to check out all the 70 arXiv papers in the last month or so based on DR2. These papers characterize the Milky Way disk kinematics, discover new stellar streams, construct magnificent HR diagrams for 4 billion stars, survey asteroids in the solar system, measure dynamics of globular clusters in the Milky Way, and so much more!

Walton also cautioned the audience to treat DR2 and DR1 as independent datasets, since the systematics are different, as well as the photometric processing pipeline. The future is bright, since Gaia is scheduled to make extended observations over the next five years, and release datasets beyond DR4 (Data Release 4)! Accessing DR2 data is as easy as googling the Gaia Collaboration website, which lets you parse any sub-dataset with ease. Log on and get to science, people!

Sculptor dwarf galaxy

Editor’s Note: This week we’re at the 232nd AAS Meeting in Denver, CO. 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 next week.

Plenary Lecture: Small Interstellar Molecules and What They Tell Us (by Kerry Hensley)

The first talk of the day was the Laboratory Astrophysics Division plenary given by Dr. David Neufeld (Johns Hopkins University). While biologists and chemists can poke and prod some of the substances they study, astrophysicists aren’t so lucky. Other than rocks from the Moon and a puff of cometary dust captured in aerogel, we get most of our information about the universe from photons and gravitational waves (other than solar system missions, through which we can directly probe magnetic fields and plasma — but we don’t get to bring those home with us!). Laboratory astrophysics is a powerful tool to help us interpret the messages those photons are sending, giving us a better idea of the physics at work in the universe.

Dr. Neufeld specializes in laboratory studies of small molecules, the kind that might be found in the interstellar medium or the material surrounding young stars. In particular, Dr. Neufeld studies a class of small molecules called hydrides — molecules made up of just one heavy element (typically one that is happy to donate electrons) and any number of hydrogen atoms. So, for example, ammonia is a hydride since it contains only one “heavy” element (nitrogen).

These tiny molecules are particularly helpful in three situations:

  1. Tracing cold molecular hydrogen gas
    Take hydrogen fluoride (HF) as an example. Laboratory studies showed that HF should form readily in cold environments from molecular hydrogen and fluorine, so even though fluorine isn’t extremely abundant in the universe, it should form HF whenever it’s in a cold environment with abundant molecular hydrogen — like the interstellar medium. Observations of diffuse interstellar clouds showed that HF was present — and could be used to trace more diffuse clouds than carbon monoxide could. Just one example of how laboratory astrophysics can guide observational astrophysics!
  2. Tracing gas that has been warmed by shocks or turbulence
    Warm interstellar gas can also be traced by hydrides, in this case SH, SH+, and CH+. These molecules react endothermically with H2, and the amount of heat needed for the reaction differs between the three molecules. Determining the amount of each of the three compounds in an interstellar cloud can help us figure out the temperature of the cloud.
  3. Helping to measure the cosmic ray ionization rate in the galaxy
    Cosmic rays, which aren’t “rays” at all but instead extremely relativistic particles, ionize gas everywhere from Earth’s atmosphere to the most distant interstellar clouds. Dr. Neufeld highlighted two ways in which interstellar molecules can be used to measure cosmic ray ionization rates: observing H3+ ions in diffuse molecular gas and observing ArH+ in diffuse atomic gas.
    In order to use molecules to infer the properties of interstellar gas, we need to know how those molecules behave under different conditions (temperature, density, etc.). That’s where laboratory astrophysics is hugely helpful! In the future, expect to see astronomers pair more laboratory determinations of molecular properties with observations to learn more about the interstellar medium.

Press Conference: Stars that Make You Say “WTF?” (by Mara Zimmerman, Gourav Khullar, and Susanna Kohler)

What’s the latest news regarding the mysterious Boyajian’s star? This strange object and another odd star, Epsilon Aurigae, were the subject of the talks at today’s morning press conference.

The first presentation was given by two high school students, Yao Yin and Alejandro Wilcox of the Thacher School! These intrepid students presented their research monitoring Boyajian’s star since April of 2017 using the Thatcher Observatory. Yin and Wilcox found that Boyajian’s star’s bizarre flux dips have a dependence on the wavelength of light observed, suggesting that the dimming may be due to dust that differs in composition or size distribution.

Boyajian's star

Bizarre recent dips in the light curve of Boyajian’s star. [Boyajian et al. 2018]

Eva Bodman, a postdoc at Arizona State University, backed these findings with the results from a Kickstarter-backed study of Boyajian’s star using LCOGT. An endearing quality of this campaign is that funders get to vote on the names of the weird dips in Boyajian’s star’s light curves! Bodman’s work focused on four dips in particular: Elsie, Celeste, Skara Brae, and Angkor. This study agrees that dust is the most likely conclusion for the dips — and it appears to be an extremely complex dust cloud that is likely clumpy and amorphous, with ephemeral fine grains and longer-lasting large grains. We still have a lot to learn about this strange star!

Switching up the topic, Dr. Robert Stencel from the University of Denver presented work completed with his graduate student Justus Gibson on Epsilon Aurigae, which belongs to a class of ‘disk-eclipsed’ binary stars. This is a very bright star, often associated with a hidden companion that is grabbing material and creating an accretion disk that produces irregular variability in its flux. When given the opportunity to interferometrically image the disk, observers found an opaque accretion disk, with the data characterizing the star as a pre-asymptotic giant branch star that may be obstructed by this disk.

A question raised during the Q&A led to interesting discussions — what can comparing these two stars tell us? The participants felt that any oddities in stellar observations can help provide us with more insight in the science of stars, pushing the limit of what is possible with the observations of stellar-type objects.


The Dynamics of the Local Group in the Era of Precision Astrometry (by Mia de los Reyes)

Dr. Gurtina Besla from the University of Arizona started today’s lunch plenary talk with a reminder: although textbooks might suggest that we’ve known everything about the Local Group for a long time, it’s only over the last decade or so that we’ve gotten precise positions and motions of these nearby systems! This has led to a lot of new and exciting science; as Besla said, “With every measurement, we have challenged conventional wisdom.”

The “Local Group” refers to the Milky Way, M31 (the Andromeda Galaxy), and about 50 nearby dwarf satellites. By studying the kinematics of these satellites, we can better understand all kinds of science. The recent data release from the European Space Agency’s Gaia mission has revolutionized our ability to do this by measuring the proper motions of over a billion stars to incredible precision — the accuracy involved in these measurements is equivalent to measuring the speed of human hair growth at the distance of the moon!

Besla gave us the run-down on several of the exciting results made possible with data from Gaia and the Hubble Space Telescope:

  • The orbits of Milky Way satellites: Besla started by noting the historical importance of the Magellanic Clouds to indigenous cultures around the world (see the figure below). The new Gaia data can tell us about how these galaxies, which are the Milky Way’s nearest satellites, orbit the Milky Way. It suggests that these satellites are “new neighbors” that only recently fell into the Milky Way’s gravitational potential for the first time!

  • The Large Magellanic Cloud (LMC): The LMC seems to be moving much faster and is about 10 times more massive than was previously thought. In fact, the LMC is so massive that it dragged five other satellite galaxies along with it when it fell into the Milky Way. It’s even massive enough to perturb the Milky Way’s halo and change its shape!
  • Andromeda and its satellites: In 2012, the Hubble Space Telescope delivered a (very) early collision warning: in a few billion years, the Andromeda galaxy (M31) will irrevocably change our view of the night sky. It’ll collide with our Milky Way, destroying the galactic disk and leaving us sitting in a giant elliptical galaxy (see the figure below).

Now, with Gaia DR2, we can look directly at internal motions of M31 and its largest satellite M33! We can confirm the earlier result that Andromeda will in fact collide with our galaxy — but beyond that, we can watch how M31 and M33 are rotating and interacting with each other. Besla’s group has found that, like the LMC in our Milky Way, M33 may be on its first infall into Andromeda now! The James Webb Space Telescope will look more at M31’s satellites in the future.

Besla concluded by noting that we still haven’t fully understood the dynamics of the Local Group. She also spoke to the young people in the room, reminding them that the gut reaction to a new and exciting result is often “no.” “But look at what the new data is telling you,” she said, “and continue onwards.”


Talk: Astrobites as a Pedagogical Tool in Classrooms (by Susanna Kohler)

Astrobiter Gourav Khullar presented today in the “College-Level Astronomy Education: Research and Resources” session. At two past AAS meetings (AAS229 and AAS231), Astrobites hosted workshops on how to introduce modern research into undergraduate and graduate classrooms using astrobites.com as a resource. Today, Khullar provided a speed-introduction to the idea for educators and outreach practitioners who may not yet have considered the idea, or who may not know where to start!

astrobites in the classroom talk

Gourav Khullar presents on using Astrobites to bring current astronomy research into the classroom.

Khullar opened his talk with a brief overview of the site. Astrobites recently celebrated publishing its 2,000th article (!), so the site, at this point, provides an extensive archive of brief summaries of astronomy research conducted over the past 7 years. Have a topic in mind that you’d like your students to learn about? We’ve almost certainly covered it!

Khullar then briefly introduced the three full lesson plans that we’ve written up as suggestions of how to use Astrobites in the classroom — which come complete with student handouts, online form templates for collecting student work, grading rubrics, adaptations for different learning levels, and more.

He rounded out the talk by introducing the research study we are currently conducting — with the aid of an AAS Education & Professional Development (EPD) mini-grant — to explore how Astrobites has been used in classes and the impacts that it has had. If you’ve used Astrobites in your class or journal club or plan to in the future, and you’d be interested in being a part of our study, please don’t hesitate to reach out! Email us at astrobites@gmail.com.


Press Conference: Metal-Poor Stars & Dwarf Galaxies (by Susanna Kohler and Mia de los Reyes)

The second press conference of #AAS232 started off with Timothy Beers, a professor from the University of Notre Dame. Beers explained that while we may never directly see the first generation of stars, we can see their “fingerprints.” This is because the first stars distributed their nucleosynthetic products when they died, and these elements were then incorporated into the second generation of stars. These second-gen stars have a characteristic abundance pattern: lots of carbon, and not much of any other heavy elements (“metals”). They probably formed in ultra-faint dwarf galaxies and were then accreted onto the Milky Way halo, so we can actually look for these stars in our own galaxy! (Press release)

galaxy accretion simulation

A simulation showing the process of galaxy accretion. It’s a messy business! [J. Helly, A. Cooper, S. Cole and C. Frenk (ICC)]

Kris Youakim from the Leibniz Institute for Astrophysics in Germany then continued on this theme. He started with some beautiful simulation videos of dwarf galaxies being accreted onto the Milky Way, and then showed that we can actually use stars with very low metal abundances to trace this accretion. In particular, he found that the most metal-poor stars are the most strongly clustered. This implies that not only are there a lot of small metal-poor dwarf galaxies, but also that these satellites haven’t yet been tidally disrupted by the Milky Way.

Next up, Gina Duggan from Caltech spoke about using the metal abundances to track how elements were produced in dwarf galaxies over time. In particular, she uses barium as a proxy for elements that are produced by a nucleosynthetic mechanism called the r-process (see our summary of Enrico Ramirez-Ruiz’s talk yesterday for more details). It’s not clear where the r-process happens; it could occur either in a special class of supernovae or in neutron star mergers. The pattern of barium abundances that Duggan observes suggests that neutron star mergers are the culprit in dwarf galaxies! (Press release)

JWST

One of the goals of the James Webb Space Telescope is to explore the most distant objects in the universe, including the first stars and galaxies. [NASA]

Aparna Venkatesan (University of San Francisco) next discussed how we might be able to use nearby galaxies as a tool to answer questions about much more distant objects, such as the very first stars in the universe. She argues that nearby low-mass, star-forming galaxies are ideal analogs for the first galaxies that formed in the universe. Studying these convenient nearby dwarfs can therefore advance our understanding of early star clusters and the physical conditions of early galaxies, providing context for when we start to get results from JWST’s planned observations of distant galaxies in the universe.

The final presentation of the conference was by Mustapha Ishak-Boushaki (University of Texas, Dallas), who introduced an intriguing prospect: discrepancies between data sets (normal a source of concern for astronomers!) may actually be useful for informing our understanding of the universe. Ishak-Boushaki’s work addresses an age-old problem: what happens when different missions take measurements that imply different values for cosmological parameters — for instance, the age of the universe, or how quickly it’s expanding? There are two possible resolutions: either there are errors in one or more of the data sets, or the models we’re using are missing new physics! Ishak-Boushaki and collaborators developed a new mathematical tool to quantify these inconsistencies between different data sets. The goal of this tool is to help us better explore issues like tensions between local and large-scale measurements, to evaluate whether we need to reconsider our models (Press release)


Plenary Lecture: An Era of Precision Astrophysics for Exoplanets, Stars, and the Milky Way (by Kerry Hensley)

It’s a great time to be an astronomer! In the final plenary session of the day, Dr. Keivan Stassun (Vanderbilt University) highlighted the many (many!) exciting advances in the field of high-precision astrophysics. In this talk, Dr. Stassun focused on the importance of precisely determining the properties of stars. After all, you need to first understand stars in order to understand the planets that orbit them, the galaxies that are composed of them, and how those galaxies have evolved over time.

Dr. Stassun focused on three categories of advances in high-precision astrophysics: astrometry, photometry, and spectroscopy. He covered a lot of cool techniques, but here I’ll summarize just a few.

Astrometry
Astrometry is one of the oldest astronomical techniques, but this simple act of plotting the positions of stars and tracing their motions is still valid today. Highly precise parallaxes (the kind you might get from Gaia or Hubble) enable a technique that Dr. Stassun calls “pseudo-interferometry,” which allow us to make careful measurements of stellar radii. Advances in astrometry may soon allow us to determine stellar radii to within a few percent at a distance of three hundred light-years! Precisely measuring the radii of stars is critical for studying exoplanets (since uncertainty in the radius of the star translates to uncertainty in the radius of the planet… and its density, composition, surface gravity…) and can also help us better understand stellar activity and stellar structure.

Photometry
One of the coolest techniques that Dr. Stassun covered in his talk was the use of highly precise photometry (measuring the light from an object in wide wavelength ranges) to obtain stellar masses. This technique works by analyzing the change in the light emitted by the star due to granulation — the motion of individual convective cells bubbling up to the surface of the star. The amplitude of the modulation tells us about the surface gravity of the star. If you know the radius of the star (say, from some precise astrometry), this gives you the mass. The most exciting part of this technique is that it works for individual isolated stars, which have long been a challenge to weigh! Dr. Stassun estimated that this technique will yield masses to within 10% accuracy for hundreds of thousands of stars.

Spectroscopy
While highly precise spectroscopy is exciting in and of itself, it’s best when paired with machine learning. Using machine learning, we can amass thousands of stellar spectra and extract temperatures, gravities, bulk metallicities, and abundances of individual chemical elements for the individual stars. This means large-scale chemical forensics, allowing us to piece together the formation histories of everything from galaxies to planetary systems and track down the Sun’s long-lost siblings!

While astronomers have already achieved amazing advances with the help of precise astrophysical techniques, more discoveries are headed our way. So sit back, relax, and enjoy the show (or get some data and get crunching!).

Sedna

Editor’s Note: This week we’re at the 232nd AAS Meeting in Denver, CO. 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 next week.


 Sunday, 3 June


Using Python to Search NASA’s Astrophysics Archives (by Gourav Khullar)

The sessions for this AAS meeting began with a workshop on using python to parse NASA data archives, organized by Vandana Desai (IPAC/Caltech) and the team at NASA Astronomical Virtual Observatory (NAVO).

To quote the workshop organizers, “NASA missions have collected a huge amount of data spanning a large range in wavelengths. These data are housed in four different archives: the HEASARC, MAST, IRSA, NED…..The archives have been working together…to assemble the data you need to get your research done. We’ve done this by standardizing the way that programs can access the data we house. Since Python is a very popular programming language, we are going to use it to show you how you can take advantage of this standardization..

The resources are available at the following link: “https://github.com/NASA-NAVO/aas_workshop_2018_summer”. We would like to encourage all our readers to start retrieving multi-wavelength information from these rich exquisite datasets!


Using Anchored Inquiry to Teach Astronomy and Physics (by Gourav Khullar)

This session, organized by Zoe Buck Bracey, PhD (BSCS Science Learning), focused around pedagogical techniques to be used in classrooms about concepts. This 4-hour workshop was full of mini-experiments, tasks and group work (along the ideas of “Think, Pair, Share!”), to encourage instructors towards building classes around concept “anchors”. The example studied throughout this amazing workshop attempted to teach the model of the Earth-Sun system and encourage understanding of seasons on our planet. We used average planetary temperature datasets as anchors, which allowed us participants to put student engagement at the forefront, encouraging students to come up with a model that explains why seasons occur. Throughout the activities, the emphasis was on students bringing prior knowledge into a class and how an instructor can enable them cross the bridge from having a partial idea of concepts to a complete understanding.


Monday, 4 June


poster sessions

Don’t forget to check out poster sessions at AAS 232 and talk with presenters!

Plenary Lecture: Welcome Address (by Susanna Kohler)

AAS President Christine Jones opened the day with a brief session welcoming attendees to this meeting and outlining some of the highlights that we can look forward to at AAS 232 in the coming week. She especially drew attention to the plenary sessions (don’t forget to check out our interviews with keynote speakers!), the town halls, and a few special sessions such as this morning’s AAS Taskforce on Diversity and Inclusion in Astronomy Graduate Education, which Gourav reported on below. She also pointed out the value of visiting posters and talking with presenters — we appreciated the photos of students presenting their work at past meetings!


Kavli Foundation Lecture: From Extrasolar Planets to Exo-Earths (by Susanna Kohler)

Dr. Debra Fischer (Yale University) kicked off the plenary talks of this meeting by giving the Kavli Foundation Plenary Lectureship, an invited talk on “recent research of great importance.” Fischer’s opening comment — “It’s tough to give a lecture on exoplanets these days, because I know there are so many experts in the audience!” — acknowledged the huge boom that exoplanet research has undergone since its inception. Fischer, however, is a highly qualified expert herself: she’s spent more than two decades in the field, developing techniques for detecting exoplanets.

Fischer gave a broad overview of the past and current state of exoplanetary studies, discussing the types of planets we’ve discovered and how we’ve found them. There are several approaches that have been used to discover and characterize the ~4,000 exoplanets known at this time:

  1. Transits, in which a dip in a star’s light reveals the presence of a planet passing in front of its host;
  2. Direct detection, in which exoplanets are actually imaged directly by telescopes;
  3. Gravitational microlensing, in which the planet is never seen, but its gravitational pull bends light from a background star in a telltale way, indicating the planet’s presence;
  4. Astrometry, in which the visible wobbling motion of a star reveals the gravitational tug of an orbiting planet; and
  5. Radial velocity, in which such a stellar wobble is seen in the star’s spectrum, as its spectral lines shift back and forth due to the approaching and receding star.

This last technique, radial velocity, is the approach that Fischer has been working to improve. Thus far, the smallest radial-velocity wobble we’ve been able to detect is around 1–2 m/s, or roughly walking speed; Fischer hopes that in the future we can push this precision down to just 10 cm/s, a signal akin to the wobble that Earth induces in the Sun. This requires remarkable advancements in both technology of spectrographs and modeling of things like contamination of stellar spectra by Earth’s atmosphere — but Fischer and other members of the field are making significant progress in these directions!

Fischer concluded by mentioning the many new and upcoming missions that will advance the field of exoplanet studies — like Gaia, TESS, CHEOPS, JWST, and WFIRST — and she threw in a sales pitch for the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR), a space telescope under consideration as a future NASA project. She also pointed out the broad community and general-public support of exoplanet science. The future of this field is bright!

You can check out Stephanie Hamilton’s interview of Fischer here.

HST vs. LUVOIR

A simulated view of the same part of the sky as observed by Hubble Space Telescope (left) vs. the proposed LUVOIR (right). [G. Snyder, STScI /M. Postman, STScI]


Press Conference: Minor Planets, Dwarf Planets & Exoplanets (by Susanna Kohler)

Sedna

Artist’s rendering of the minor planet Sedna, a distant body in the outer solar system. [NASA/JPL-Caltech]

The first press conference of the meeting kicked off (a little late, due to some technical difficulties) with a presentation by undergrad Jacob Fleisig of University of Colorado Boulder. Fleisig and his advisor, Ann-Marie Madigan, have a proposal that may be disappointing to the many fans of the Planet Nine theory: they argue that the population of detached trans-Neptunian objects (TNOs) — icy bodies like the minor planet Sedna in the outer reaches of our solar system — can be explained by a different theory than Planet Nine, a hypothetical massive planet orbiting beyond Neptune. Fleisig and Madigan instead suggest that the collective gravity of objects like Sedna and other space debris in the outer solar system could explain how the detached TNOs reached their odd orbits. Press release

press conference 1 of aas232

Panelists prepare for the first press conference of AAS 232.

Next up, University of Virginia graduate student Jake Turner presented his and collaborators’ work in the search for exoplanets with magnetic fields. Magnetic fields are of interest in the context of exoplanets and habitability because they can protect their planets from stellar winds and help them to retain their atmospheres. Turner and collaborators hope to be able to use the Low-Frequency Array (LOFAR) to find exoplanet radio signals that would indicate the presence of magnetic fields. To improve their ability to extract such radio signals from background radio noise, the team simulated the expected signals using a real planetary signal — Jupiter’s radio waves, as seen by LOFAR. They hope to soon use these methods to discover magnetic fields of planets beyond our solar system. Press release

Intrigued by Tattooine? In the final presentation of the press conference, graduate student Franco Busetti (University of the Witwatersrand, South Africa) one-ups this sci-fi binary by discussing how planets might orbit around triple star systems. By running a series of orbital integrations — over 45,000 of them! — Busetti and collaborators showed that exoplanets can exist on stable orbits in substantial regions around triple systems. While only 40 or so planets have been found around triple systems thus far, we can hope that the Gaia and TESS missions will find many more.


AAS Taskforce on Diversity and Inclusion in Astronomy Graduate Education (by Gourav Khullar)

This AAS special session aimed to disseminate updates of the AAS Taskforce on Diversity and Inclusion to the membership. Kelle Cruz and Alex Rudolph began the proceedings with a description of the Taskforce, which was empaneled in November 2018, and is in the process of putting together a report on their findings via several of their initiatives.

A description of the Taskforce’s charge is as follows:

  1. To look into retention and recruitment practices along all axes of identity.
  2. To build consensus on evidence-based practices across the community.
  3. To create and collaborate on a statement of best practices.
  4. To develop guidelines that help astro grad programs towards implementation of suggestions coming out of the Taskforce initiatives.
  5. To develop recommendations for ongoing data collection from astro grad programs.

The Taskforce has 3 working groups:

  • Recruiting & Admission
  • Mentoring & Retention
  • Data Collection & Dissemination

Some of the working-group recommendations were discussed, after which we broke out in smaller sessions for direct engagement with the working-group members:

Recruiting and admission

  1. Inclusive Astronomy & Nashville Recommendations were brought up (read more about this here: https://astrobites.org/2017/12/25/building-an-inclusive-astronomy-community/).
  2. Partnering with institutions producing PhD-ready under-represented minorities could go a long way in bringing diversity and representation to departments.
  3. There is a need for implementing evidence-based, holistic approaches to admissions.
  4. Coordinating with campus offices regarding fee waivers, fellowship opportunities, GRE policies, and application contents is a priority.

Mentoring and retention

  1. One of the priorities was facilitating an accessible and welcoming environment, ending harassment in and around astro workplaces, and supporting effective, evidence-based mentorship at all levels of astrophysics research.
  2. The working group is also involved in engaging departments in conversations, conducting assessments in your local environment, incentivizing professional development, taking actions, and monitoring progress on these actions.

Data Collection & Dissemination

  1. This working group’s priorities are built on baselines and progress in demographics and climate, as well as initiatives that provide accountability.
  2. There is a proposal to conduct climate surveys every 2 years, collect and report demographic data, and create a platform to collect data, analysis and decentralize information as soon as is feasible.


Plenary Lecture: Heavy Element Synthesis in the Universe (by Kerry Hensley)

What do gold, krypton, plutonium, and europium have in common? They’re all r-process elements, of course! Elements heavier than iron form through neutron-capture processes; when an atom captures a free-roaming neutron, the neutron will often change into a proton by emitting a beta particle (an electron, in this case). This leads to atoms bulking up into heavier and heavier elements over time. There are two neutron-capture processes: rapid (r-process) and slow (s-process), where the speed refers to the rate of neutron capture compared to the rate of beta decay. While all elements heavier than iron can be formed through both pathways, some elements (like gold and europium) are almost exclusively formed through the r-process.

In today’s lunchtime plenary, Dr. Enrico Ramirez-Ruiz (University of California, Santa Cruz) described the importance of understanding r-process nucleosynthesis in the universe. While the basic understanding of how heavy elements form has long been known, the details are still unclear — especially in terms of what astrophysical objects produce them and in what amounts. In this talk, Dr. Ramirez-Ruiz focused on neutron star mergers as a source of r-process elements. Although neutron star mergers are rare, each collision can produce about a Jupiter-mass worth of gold — equivalent to the gold abundance of a million stars!

R-process enrichment by Type II supernovae (left) and neutron star mergers (right). Cookies are now scientifically relevant! [brandeating.com and handletheheat.com]

Dr. Ramirez-Ruiz used a tasty metaphor to explain the relative contributions of Type II supernovae and neutron star mergers to the cosmic r-process abundance: while Type II supernovae spread a thin layer of r-process elements fairly evenly across a galaxy like a layer of chocolate coating on a cookie, neutron star mergers generate huge amounts of these elements in random locations — like the chocolate chips in a chocolate chip cookie.

This unevenness in heavy-element production helps to explain the huge variation in europium abundance (europium is almost exclusively made through the r-process) relative to iron in old stars. While we still need to know more about how heavy elements get mixed throughout a galaxy, studying and modeling neutron star mergers can help us understand the origins of very heavy elements in the universe.

Be sure to check out Mia de los Reyes’ interview with Dr. Ramirez-Ruiz here!


Plenary Lecture: The Relationship Between Galaxies and the Large-Scale Structure of the Universe (Mia de los Reyes, Mara Zimmerman, and Gourav Khullar)

Dr. Alison Coil (UC San Diego) started off the last plenary lecture of the day with a map of bright galaxies in the sky — a snapshot of the large-scale structure of the universe (see tweet below). This beautiful filamentary structure comes from the evolution of the universe, which is largely driven by what Coil described as a “tug of war between different cosmological parameters.”

These cosmological parameters more or less describe the ingredients that make up our universe:

  • Quantum fluctuations in the early universe produced density perturbations, which collapse into dark matter halos
  • Baryonic matter (that is, “normal” observable matter) then fell into these halos, eventually producing the galaxies we see today
  • At later times in the universe, dark energy became important, pushing apart galaxies and increasing the space between them

This led us to Coil’s main topic: the connection between galaxies and dark-matter halos, and what this can tell us about these cosmological parameters.

The way galaxies cluster can help us do precision cosmology to constrain these parameters. This is because galaxies trace the underlying dark-matter distribution of the universe, sometimes called the “cosmic web” (see tweet below). The challenge is then connecting our observations of galaxies (especially from galaxy surveys like DEEP2, which mapped out the positions of galaxies out to a redshift of z~2) with our theoretical understanding of the cosmic web (particularly cosmological simulations like the Millennium Simulation).

As Coil described, one way we can bridge this theory-observational gap is by using the halo model. This model reasonably assumes that more massive halos host more massive galaxies, so that we can use a technique called abundance matching to match halos with their associated galaxies. “This is a very, very successful model,” Coil pointed out.

We can also figure out what other parameters affect the clustering of galaxies. It turns out that the clustering of galaxies depends on several parameters: more luminous/massive galaxies and redder galaxies are both more strongly clustered than less luminous or bluer galaxies. Also, older halos are more strongly clustered in a phenomenon called assembly bias, which might be required to explain an effect called galactic conformity (how galaxies at the center of a halo appear to influence the star formation rates of galaxies in another halo).

Understanding all of these effects is vital for understanding the close connection between galaxies and halos. Coil concluded that in order to do this, theorists and observers need to work together to do precision cosmology and interpret the results!

aas232

Greetings from the 232nd American Astronomical Society meeting in Denver, Colorado! This week, AAS Media Fellow Kerry Hensley and I will be joined by a team of talented Astrobites authors — Gourav Khullar, Mia de los Reyes, and Mara Zimmerman — writing updates on selected events at the meeting. We’ll post the summary of the day’s events at the end of each day, and you can follow along here or at astrobites.com. The usual posting schedule for AAS Nova will resume next week.

Want to get a head start before the #AAS232 plenaries begin? Astrobites has been conducting brief interviews with the plenary speakers; you can read about them as they come out over at Astrobites.

We hope to see you around at Denver! Drop by to visit AAS, AAS Journals, and Astrobites at the AAS booth in the exhibit hall to learn more about AAS’s new publishing endeavors, pick up some Astrobites swag, or grab a badge pin to represent your AAS journals corridor!

corridors

InSight

Atlas-V

JPL’s Stephanie Smith introduces the InSight prelaunch press briefing next to a model of the Atlas-V rocket. [AAS Nova]

Were you awake at 4 am PDT today? If so, you were in good company — a lot of anxious and excited scientists, engineers, media, and others were wide awake at Vandenberg Air Force Base at 4:05 am PDT, when the NASA InSight spacecraft was lifted on its way to Mars on board an Atlas-V rocket.

A Unique Journey

Today’s launch marked the first interplanetary launch to take off from the west coast. Usually, launches to other planets occur from the east coast; this is because the Earth’s spin gives the rocket an extra boost when it launches east.

But rocket launchpads are crowded, and the wait to get in on the east coast can be extremely inconvenient for an interplanetary mission with a specific timeline for when it needs to launch. InSight had an alternative, however: the Atlas-V rocket was still plenty powerful — even with the southward launch from Vandenberg — to hoist InSight and send it on its way into a parking orbit. After launch, the second stage then boosted InSight out of Earth’s orbit and on its way to Mars.

What Happens Next?

InSight model

The guest of honor at the pre-launch briefing: a model of the InSight lander. [AAS Nova]

205 days from now, in November of this year, InSight will arrive at Mars and proceed to enter the planet’s atmosphere at more than 13,000 mph. A parachute will then slow it to around ~130 mph before the lander separates and lowers itself to Mars’s surface using 12 descent engines.

So once InSight touches down, it can start doing science, right? Not so fast! The placement of the lander’s instruments on the ground will take 10 weeks after it lands; sinking the heat probe will then take another 7 weeks after that. Impatient? Do try to remember that we’re operating a robot on Mars.

Experiencing InSight’s Launch Firsthand

I had the good fortune of being able to catch the InSight launch in person today, as well as the lead-up to it. At Thursday’s press briefing, the media gathered at the NASA building on Vandenberg AFB to hear from people representing multiple facets of the mission — from those who built it, to those who would be launching it, to those who will manage the science that comes from it.

press in the fog

Reporters ready to photograph the InSight launch to Mars, should Vandenberg’s marine layer clear out in time for a view. [AAS Nova]

Seeing the faces behind the mission makes the excitement and tension surrounding launch very real, and occasional comments reminded us that cockiness is never a good attitude for a mission being blasted off into space. Stu Spath, the InSight program manager at Lockheed Martin — a veteran company that has been involved with 20 Mars missions in the past — summed up the sentiment nicely: “There’s nothing ‘routine’ about going to Mars.”

Fortunately, you wouldn’t have known it from the launch itself! Liftoff occurred right on schedule at the start of the first launch window, and the Atlas-V took off without a hitch. For those of us in the press viewing area at Vandenberg, a typical blanket of marine-layer fog enveloped us, hiding the launch from view. But the roar of the engines and tremble of the ground is unmistakable, and we could hear cheers echoing in the distance around us through the fog, alerting us to the success of the first step in InSight’s journey to Mars. Sometimes, being awake at 4 am can be pretty awesome.

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