Welcome to the summer American Astronomical Society (AAS) meeting, held virtually for the first time! Astrobites is attending the conference as usual, and we will report highlights from each day here. If you’d like to see more timely updates during the day, we encourage you to search the #aas236 hashtag on twitter. We’ll be posting once a day during the meeting, so be sure to visit the site often to catch all the news!

Solar Physics Division (SPD) Hale Prize Lecture: From Jets to Superflares: Extraordinary Activity of Magnetized Plasmas in the Universe (by Abby Waggoner)
The last day of AAS 236 started off with the Solar Physics Division Hale Prize Lecture by Kazunari Shibata from Kyoto University. Dr. Shibata was awarded the Hale prize for his years of research on magnetized solar and astrophysical plasma and the discovery of solar jets. Dr. Shibata is the first scientist from Japan to receive the Hale prize, which is the most prestigious award in solar physics. Dr. Shibata didn’t always study solar physics. During his graduate studies (1973–1977) he sought to solve the “biggest puzzle in astrophysics”: the jets produced by active galactic nuclei (AGN). A series of jets were discovered in the 1960s, but the physics behind them was unknown at the time. AGN are difficult to observe directly, as they are billions of light-years away from Earth, so Dr. Shibata approached the problem from the theory side by studying magnetohydrodynamic (MHD) plasma. When the first protostellar jets were discovered, Dr. Shibata noticed that the morphologies of protostellar jets and AGN jets were similar, thus indicating that the jets were likely driven by the same physics.What are astrophysical jets like? Here's a quick summary: pic.twitter.com/g0s6s889yq
— astrobites (@astrobites) June 3, 2020
The energy of unwinding of field lines can be released into kinetic energy! pic.twitter.com/75GiuvwAS2
— astrobites (@astrobites) June 3, 2020
In the 1960s, the standard flare model was developed. Below the prominence, we have antiparallel lines that release magnetic energy. pic.twitter.com/yx4TbkrM1T
— astrobites (@astrobites) June 3, 2020
(Conclusions continued)
— astrobites (@astrobites) June 3, 2020
-"Extreme activity (such as superflares) on the Sun may have been related to the origin and evolution of life on Earth, whereas it would be extremely dangerous for our civilization in the future."
Press Conference: Mysteries of the Milky Way (by Haley Wahl)
Today’s first press conference follows on the heels of yesterday’s conference on the galactic center, and focuses on the broader picture of things. The first speaker today was Dhanesh Krishnarao, a graduate student at the University of Wisconsin, Madison, speaking on the Fermi bubbles, which are massive lobes that expand out from the center of the galaxy. It’s known that these bubbles absorb light, but Krishnarao and his team discovered that they actually emit light too, and this was all seen by the Wisconsin H-Alpha Mapper, or WHAM! By measuring the optical emission and combining it with the UV absorption data, they were able to conclude that the Fermi bubbles have a high density and pressure. Press releaseFirst discovery of optical light coming from Fermi Bubbles, paper on the ArXiv yesterday (arXiv:2006.00010)! Here's an artist's impression of the bubbles #AAS236 pic.twitter.com/JOZVEwHEe9
— astrobites (@astrobites) June 3, 2020
Plenary Lecture: Our Dynamic Solar Neighborhood (by Luna Zagorac)
Jacqueline Faherty (American Museum of Natural History) studies our solar neighborhood (20–500 pc from the Sun) because it lets us investigate faint sources in more detail, including brown dwarfs. One important question we can begin to answer in the solar neighborhood is where the high-mass limit of planet formation ends and the low-mass limit of star formation begins. To illustrate what the stellar neighborhood looks like, Dr. Faherty took us on a virtual flight using the OpenSpace software, illustrating the advancement in mapping and astrometry from the Hipparcos data set to Gaia DR2, which mapped more than 1.3 billion sources. Gaia is an optical survey and, as such, is not very sensitive to faint, cold sources like brown dwarfs. When Gaia data was combined with ground-based measurements, however, 5,400 sources were extracted from the sample of Gaia objects within 20 parsecs of the Sun. These sources could then be arranged on a color-magnitude diagram (known as an HR diagram), with brown dwarfs clustering in the lower-left part of the diagram.Here's these satellites plotted on a color magnitude diagram (an HR diagram)! White dwarfs in the lower left corner. pic.twitter.com/3snO7H8JNn
— astrobites (@astrobites) June 3, 2020
Citizen scientists have been searching for these objects by eye through @backyardworlds! pic.twitter.com/OhPZHINKTP
— astrobites (@astrobites) June 3, 2020
"These companions are at a temperature that's kind of crazy." Here's an example. They look a lot like Jupiter and have thick clouds. We want to look at how their light is changing. pic.twitter.com/9Oz4W4pLwj
— astrobites (@astrobites) June 3, 2020
OSTP Town Hall with White House Science Advisor Kelvin Droegemeier (by Tarini Konchady)
Note: In the recording of this session, Dr. Droegemeier’s audio for the Q&A was lost. This writeup covers only the topics discussed before the Q&A. The main speaker at the Office of Science and Technology Policy (OSTP) town hall was Director Kelvin Droegemeier. Droegemeier’s scientific background is in meteorology; in 1985 he joined the University of Oklahoma as an assistant professor and has remained at that institution to this day (he has taken a leave of absence to serve as OSTP director). Droegemeier has a long career in federal policy as well, notably serving on the National Science Board from 2004 to 2016. Aside from being OSTP director, Droegemeier is also the Acting Director of the National Science Foundation. He will stay in this role till the Senate confirms the president’s nominee — Sethuraman Panchanathan — for the job.The Office of Science and Technology Policy (OSTP) Town Hall happening now! Today's speaker is Dr. Kelvin Droegemeier, OSTP Director and Acting NSF Director.#aas236
— astrobites (@astrobites) June 3, 2020
National High Performance Computing User Facilities Town Hall (by Sanjana Curtis)
The National High Performance Computing (HPC) User Facilities town hall was kicked off by Dr. Richard Gerber (NERSC) who introduced the goals of the town hall: inform the community about HPC and new directions in HPC, discuss opportunities for using HPC to advance astronomy research, communicate what is available at National HPC centers, and gather feedback from the community about their questions, needs and challenges. He also introduced the other presenters from major HPC facilities around the US: Niall Gaffney (TACC, UT Austin), Michael Norman (SDSC, UCSD), Jini Ramprakash (ALCF, Argonne National Lab), Bronson Messer (OLCF, Oak Ridge National Lab), and Bill Kramer (NCSA/Blue Waters, UIUC). Dr. Gerber defined HPC as computing and analysis for science at a scale beyond what is available locally, for example, at a university. HPC centers have unique resources, including supercomputers, big data systems, wide-area networking for moving data quickly, and ecosystems that are designed for science (for, e.g.: optimized software for simulations, analytics, artificial intelligence and deep learning). These centers also offer lots of support and expertise, since they are staffed by people who are experts in HPC, many of whom have a science background. This helps bridge the gap between the domains of science and computing. The traditional picture of a supercomputer is a system consisting of hundreds of thousands of the world’s fastest processors, coupled together by very high speed custom networks. Typically, they have a large scratch disk (~petabytes) optimized for reading and writing large chunks of data. These machines were originally designed to have all their compute nodes tightly coupled, where each node needs to know what the other nodes are doing, mainly to solve partial differential equations using linear algebra — they are really good at matrix multiplications! Users interact with supercomputers via SSH and command line, and submit their jobs to a scheduler or queue system for execution. However, the HPC landscape is now changing, and rather abruptly! Single-thread processor performance growth that used to be exponential (Moore’s law-like) has stalled. Instead, we have to rely on parallelism and accelerators for increase in performance. Demand for data analysis is expanding, both from experimental and observational facilities, and large collaborative teams have become the norm. We are also witnessing the rise of artificial intelligence (AI), machine learning, and other emerging technologies with new needs. So what’s next for HPC? According to Dr. Gerber, HPC will continue to advance the limits of computation and analysis. We will see data-intensive science and simulation science merging together, and large scale analysis of experimental and observational data moving to HPC. Since AI and deep learning are here to stay, HPC centers will have to accommodate this demand. Finally, supporting large collaborations will require enabling tools, such as tools for user authentication and data management. Dr. Niall Gaffney (TACC) was up next, speaking about Astronomy and Advanced Computing in the 21st Century. He started out by mentioning the three pillars of modern computational science: simulation, analytics and machine learning/AI. Astronomy and computing are old friends and there exists a long list of very impressive simulations, such as the Renaissance Simulation, the SciDAC Terascale Supernova Initiative, black hole merger simulations for LIGO, and more! These large simulations are what people typically associate with supercomputing centers. However, there was a shift in this paradigm when SDSS came online and showed astronomy the power of large-scale data and compute resources. The notion of a data center where you could go to run your analysis, without having to download huge quantities of data, was a big change. Now, there is an explosion of AI and machine learning methods, required by facilities like the Vera Rubin Observatory that will generate large amounts of data at very high rates. Astronomy has always been at the forefront of computational science and will continue to drive the field forward.Not just the three pillars of astronomy, but many observational sciences! Astronomy has been key in pushing this forward. We've always had big data (physics of building a CPU = building a CCD!) #AAS236 pic.twitter.com/EU6t7YG5Ku
— astrobites (@astrobites) June 3, 2020
Soon, will have both Slurm jobs running continuously and Kubernetes jobs running containerized jobs! The divide will be set by user demand #AAS236 pic.twitter.com/IdTt9X0fqN
— astrobites (@astrobites) June 3, 2020
Press Conference: Sweet & Sour on Satellites (by Amber Hornsby)
For the final press conference of the summer AAS meeting, we hear all about satellites — both the good and the bad.First up, @AstroRach tells us about a hunt for the first stars that were born in the universe. Observations from Hubble suggest they may have formed even earlier than we previously thought — within the first 500 million years after the Big Bang! #AAS236 pic.twitter.com/OgHpP11OPz
— astrobites (@astrobites) June 3, 2020
Gone with the Galactic Wind: How Feedback from Massive Stars and Supernovae Shapes Galaxy Evolution (by Haley Wahl)
Our very last plenary of the meeting was given by Dr. Christy Tremonti from the University of Wisconsin, Madison. Tremonti took us on a trip through the process of stellar feedback, showing us what causes it and how it affects star formation. Feedback is the process by which objects return energy and matter into their surroundings (for example, black holes spewing out jets into the surrounding interstellar medium). In the context of galaxies, feedback is very important because it helps slow down star formation. Without feedback, star formation would progress much more quickly, resulting in galaxies today with very different shapes than what we observe. Feedback influences star formation rates, stellar masses, galactic morphology, and the chemistry of the interstellar medium and circumgalactic medium. Galactic feedback comes from five major sources. The first of those is supernovae; when massive stars explode, they release an enormous amount of energy into the surrounding interstellar medium, and they create pressurized bubbles of ejected material that expand and sweep up ambient gas. The second is stellar winds, which contribute as much energy and momentum as supernovae, but begin immediately, whereas supernovae effects are delayed by a few million years. The third is radiation pressure on dust grains. When ultraviolet radiation radiation hits a dust grain, it is reradiated in the infrared; these infrared photons carry momentum and in order to conserve it, the dust grains must move, causing the radiation pressure. This can be a significant contributor to the feedback in the center of very dense, dusty galaxies. Another source is photoionization, a process where ionizing ultraviolet photons heat the surrounding gas. The final source of feedback is cosmic rays. Around 10% of a supernova’s energy is thought to be in cosmic rays, and these rays scatter off magnetic homogeneities in the ISM, transferring the cosmic ray momentum to the gas. All of these processes can contribute to the feedback process on different temporal and spatial scales. The process of feedback creates a cool phenomenon called a “galactic fountain.” Galactic fountains are formed when star formation surface densities are low and isolated superbubbles break out of the disk. When star formation surface densities are high, these superbubbles begin to overlap and they can more efficiently drive centralized outflows. In the local universe, winds are primarily found in starburst galaxies like M82. This galaxy is very close, which allows us to study it in detail.M82 is a good galaxy to study for galactic winds. Starting with x-rays. Hard x-rays show key feedback processes (blue) #aas236 pic.twitter.com/dqtmtZO0Qs
— astrobites (@astrobites) June 3, 2020
It’s a very interesting read!
One minor fact check though: the Tianhe-2, currently ranked 4th fastest supercomputer, is also located in a university campus.