changing look quasar

Editor’s Note: This week we’re at the 227th AAS Meeting in Kissimmee, FL. Along with several fellow authors from astrobites.com, I will be writing updates on selected events at the meeting and posting at the end of each day. Follow along here or at astrobites.com, or catch our live-tweeted updates from the @astrobites Twitter account. The usual posting schedule for AAS Nova will resume next week.

Welcome to Day 4 of the winter American Astronomical Society (AAS) meeting in Kissimmee! Several of us are attending the conference this year, and we will report highlights from each day here on astrobites. If you’d like to see more timely updates during the day, we encourage you to follow @astrobites on twitter or search the #aas227 hashtag.

Helen B. Warner Prize: Origins of Structure in Planetary Systems (by Erika Nesvold)

Another excellent prize lecture started off today’s sessions. The Helen B. Warner Prize is awarded for achievement in observational or theoretical astrophysics by a young researcher (no more than eight years after their Ph.D.). This year’s Warner Prize was presented to Ruth Murray-Clay of UC Santa Barbara. For her award lecture, Murray-Clay told us all about planetary system architecture: the number, masses, and orbits of planets in a given system.


Ruth Murray-Clay [photo from http://web.physics.ucsb.edu/ ~murray/biocv.html]

The underlying question motivating this type of research is: How rare is the Solar System? In other words, how likely is it that a given planetary system will have rocky planets close to their star, gas giants farther out, and ice giants at the outer reaches of the system? Answering this question will help us solve the physics problem of how and where planets form, and will also help us on our search for other planets like Earth.

The data on exoplanet population from transit and radial velocity observations and from direct imaging tell us that our Solar System is not “common” (many systems we observe have much more eccentric gas giants), but that doesn’t mean it’s not typical. While we wait for more and better observations of exoplanet systems, theory can help us understand why the Solar System formed the way it did, and where to look for systems that formed the same way. For example, some of Murray-Clay’s previous work has shown that metal-rich stars tend to host more hot Jupiters and eccentric giant planets (very different from Solar System architecture). So if we want to find more systems like our own, we need to search around stars with low-to-moderate metallicity.

Extrasolar Planets: Hosts, Interactions, Formation, and Interiors (by Caroline Morley)

This session was a mashup of a variety of planetary topics ranging from solar flares to interiors to habitability.

Leslie Rogers kicked off the session by presenting work done in collaboration with her student Ellen Price to constrain the composition of the ultra-short period (4 hours!?!) planet candidate KOI 1843.03 using models of the object’s interior. Since it’s so close to the star, it can only exist without being torn apart if it’s very dense, which allows them to calculate that it must be iron-rich like Mercury!

Next Kevin Thielen, an undergrad at Eckerd College, presented results from a summer project to apply a variable polytrope index to planet models. Tom Barclay then showed models that demonstrate the huge effect that having giant planets in the outer solar system has on the formation of terrestrial planets. He finds that without Jupiter and Saturn, more planets would form (8 instead of 3-4!) and giant impacts (like the moon-forming impact) would be more frequent but less energetic.

Aomawa Shields shifted to discuss her 3D GCM models to determine the orbital configurations that would lead to liquid water on the surface of the planet Kepler-62f. She determines the effect of eccentricity, axis tilt (obliquity), and rotation rate on habitability. Edward Guinan brought us closer to home discussing the potential for “superflares” — solar flares up to hundreds of times more energetic than normal—in our solar system. Analyses of Kepler data suggest that these flares likely happen every 300-500 years in Sunlike stars (way more often than previously thought!), and would devastate communications systems on Earth (and hurt astronauts in space).

Peter Buhler and Taisiya Kopytova finished up the session. Peter showed how he used Spitzer secondary eclipses and MESA models to determine the tidal love number and core mass of HAT-P-13b. Taisiya presented her thesis work on observations of brown dwarfs and low-mass stars. She shows that in many cases, particularly for young objects and cold objects, the models for these objects do not fit the data very well!

Press Conference: Sloan Digital Sky Survey (SDSS) IV (by Susanna Kohler)

The final press conference of the meeting was all about the fourth generation of the Sloan Digital Sky Survey.

In the opening talk, Michael Blanton (New York University) presented some early results from SDSS-IV, which is slated to run from 2014 to 2020. The major components to SDSS-IV are extended Baryon Oscillation Spectroscopic Survey (eBOSS), a cosmological survey of quasars and galaxies; APO Galactic Evolution Experiment (APOGEE-2), a stellar survey of the Milky Way; and Mapping Nearby Galaxies at APO (MaNGA), a survey that will map the detailed internal structure of nearly 10,000 nearby galaxies.

Next up was Melissa Ness (Max Planck Institute for Astronomy), speaking about APOGEE’s creation of the first global age map of the Milky Way. APOGEE obtained the spectra for 70,000 red giant stars. These spectra, combined with the stars’ light curves, allowed the team to infer the ages of these stars distributed across the Milky Way galaxy. The resulting map is shown in the video below. From this map, Ness says it’s pretty clear: the Milky Way started as a small disk, and it’s expanded out from there, since. “Our galaxy grew, and it grew up by growing out.” Here’s the press release.

Francesco Belfiore (University of Cambridge) gave the next talk, cleverly titled “Proof That Some Galaxies Are LIERs.” The title is a play on the astrophysical source known as a LINER, or Low-Ionization Nuclear Emission-line Region — an area within a galactic center that displays line emission from weakly ionized or neutral atoms. These have commonly been interpreted as being a wimpy active galactic nucleus (AGN). But a closer look with MaNGA, which is able to take spectroscopic data for the whole galaxy at once, has revealed that these sources are actually distributed throughout the galaxy, rather than being nuclear — hence, no N: these galaxies are LIERs. Instead of AGN, the sources may be newly born white dwarfs. Here’s the press release.

Artist's conception of the changing look quasar as it appeared in early 2015. [Dana Berry / SkyWorks Digital, Inc.; SDSS collaboration]

Artist’s conception of the changing look quasar as it appeared in early 2015. [Dana Berry / SkyWorks Digital, Inc.; SDSS collaboration]

The final speaker was Jessie Runnoe (Pennsylvania State University), who captured everyone’s attention with the topic of “changing look quasars.” We know that quasars can transition from a bright state, where active accretion onto the galaxy’s central supermassive black hole is visible in their emission spectrum, to a dim state, where they look like a normal galaxy. But SDSS has just observed the quasar SDSS J1011+5442 turn off within the span of just 10 years. Based on the data, the team concludes that this quasar exhausted the supply of gas in its immediate vicinity, turning off when there was no longer anything available to accrete. Runnoe showed an awesome animation of this process, which you can check out here. Here’s the press release.

Coffee, Black Holes, Editors and Beer: The Science-Writing Life (by Susanna Kohler)

This talk was a part of the series “Beyond the Academy: Showcasing Astronomy Alumni in Non-Academic Careers.” Matthew Francis is a former academic scientist (with a PhD in physics and astronomy) who transitioned to being a freelance science writer. Wearing a distinctive bowler hat, Francis talked to a room full of students (and some non-students!) about what it’s like to be a science writer. Here are some highlights from among his recommendations and comments.

A day in the life of a science writer.

A day in the life of a science writer.

About the mechanics of freelancing:

  • Some sample numbers: he wrote 73 articles in 2015, for 12 different publications. These vary in length and time invested. He supports himself fully by freelancing.
  • The time between pitching a story and getting it published can vary between a few hours for online news stories to months for feature articles.
  • The answer to the question, “What do science writers do all day?” (see photo)

About transitioning into science writing:

  • If you’re interested in a science writing career, start blogging now to build up a portfolio.
  • Use your training! As a researcher, you can read plots, understand scientific articles, and talk to scientists as colleagues. These are great strengths.

About writing for the public:

  • There’s a difference in writing for academics and the public: when writing for academics, you’re trying to bring them up to your level. When writing for the public, that’s probably not the goal.
  • That said, on the subject of “dumbing down”: “If you think your audience is somehow deficient, you’ve already failed.”

At the end of the session, Francis told us what he considers to be the best part of being a science writer: getting to tell people something that they’ve never heard before. “Getting it right is communicating a mundane fact to you that is an astounding surprise to your audience.”

Plenary Talk: News on the Search for Milky Way Satellite Galaxies (by Susanna Kohler)

The second-to-last plenary talk of the meeting was given by Keith Bechtol, John Bahcall fellow at University of Wisconsin-Madison. Bechtol spoke about the recent discovery of new satellite galaxies of the Milky Way. Dwarf galaxies orbiting the Milky Way are often hard to spot because they are so faint — while globular clusters have mass-to-light ratios of around 1, the ultra-faint satellites around the Milky Way can have mass-to-light ratios of hundreds or thousands! A combination of better facilities and improved analysis techniques has been lengthening the list of known Milky Way satellites, however: SDSS took us from ~10 to ~30 in the last ten years, and facilities like the Dark Energy Survey Camera (DES), Pan-STARRS 1, SkyMapper, and Hyper Suprime-Cam pushed that number to ~50 in 2015.

The new candidates discovered with DES are all less luminous and more distant than previous satellites found. One interesting aspect of this sample is that 15/17 of the candidates fall in the southern half of the DES footprint, and are located near the Large and Small Magellanic Clouds. This anisotropy is not thought to be a selection effect — so is it coincidence, or could they possibly be satellites of satellites? We’re not sure yet!

Why do we care about finding Milky Way satellites? There are lots of reasons, but one of the biggest is that they may help us to unravel some of the mysteries of dark matter. These faint-but-massive galaxies were probably born in the Milky Way’s dark-matter halo, and they could be great places to indirectly detect dark matter. In addition, there’s the “missing satellite problem” — the phenomenon wherein the cold-dark-matter model predicts there should be hundreds of satellites around the Milky Way, yet we’ve only found a few dozen. Finding more of these galaxies would help clear up whether it’s the theory or the observations that are wrong.

Overall, Bechtol declares, it’s been an exciting year for the discovery of new Milky Way satellites, and with new surveys and facilities still in development, the future looks promising as well!

Hack Day (by Meredith Rawls)

A large contingent of astronomers spent our Friday working on small projects or chunks of larger projects that could be accomplished in a day. Astrobites has written about hack days before. Look for a dedicated recap post with all the great projects later in January!


Editor’s Note: This week we’re at the 227th AAS Meeting in Kissimmee, FL. Along with several fellow authors from astrobites.com, I will be writing updates on selected events at the meeting and posting at the end of each day. Follow along here or at astrobites.com, or catch our live-tweeted updates from the @astrobites Twitter account. The usual posting schedule for AAS Nova will resume next week.


Welcome to Day 3 of the winter American Astronomical Society (AAS) meeting in Kissimmee! Several of us are attending the conference this year, and we will report highlights from each day here on astrobites. If you’d like to see more timely updates during the day, we encourage you to follow @astrobites on twitter or search the #aas227 hashtag.

Henry Norris Russell Lecture: Viewing the Universe with Infrared Eyes: The Spitzer Space Telescope (by Erika Nesvold)

The Henry Norris Russell Award is the highest honor given by the AAS, for a lifetime of eminence in astronomy research. This year’s award went to Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics. Fazio became a leader in gamma ray astronomy before switching mid-career to the study of infrared astronomy, and he gave his award lecture on the latter subject, specifically on the Spitzer Space Telescope, one of the most successful infrared telescopes of all time.


Artist’s rendering of the Spitzer space telescope. [NASA/JPL-Caltech]

Spitzer has been operating for more than twelve years, and has resulted in over six thousand papers in refereed journals in that time. The telescope sits in an Earth-trailing orbit around the Sun, and is now farther from the Earth (1.4 AU) than the Earth is from the Sun. Fazio gave the audience a fascinating overview of the science done by Spitzer over more than a decade. One of the most productive areas of research for Spitzer is the study of exoplanets, which hadn’t even been discovered when the Spitzer Telescope was first conceived. Spitzer’s high sensitivity and ability to observe exoplanets over many orbits has made it a powerhouse for learning about the temperatures, atmospheres, and orbits of exoplanets. The list of examples that Fazio provided included the first global temperature map of an exoplanet (HD 189733b), the detection of the closest transiting exoplanet (HD 219134b), and the measurement of thermal emission from a super-Earth (55 Cnc e). Spitzer’s large distance from the Earth (specifically, the ground-based telescopes on Earth) even allowed astronomers to observe an exoplanet via gravitational microlensing using a special technique called space-based parallax.

Spitzer has also been extremely useful for observing everything from Solar System scales (such as the enormous infrared dust ring around Saturn) to galactic structures. Comparing images of galaxies observed at visible wavelengths with Spitzer images of the same galaxies at infrared wavelengths has allowed us to probe the structure and composition of galaxies at a new level.

Astronomers have also used Spitzer to explore the evolution of stars. Thanks to its infrared detectors, Spitzer can look through large clouds of dust that are opaque at visible wavelengths, and observe young stellar objects in their birth environments. Cosmologists can use Spitzer to study the early universe and the formation of galaxies over twelve billion years ago. Fazio used all of these examples and more to demonstrate that Spitzer has truly changed our understanding of the universe.

Climate Change for Astronomers (Meredith Rawls)

The second half of the session was a presentation by Doug Duncan featuring an activity from his 101-level college course. He uses climate change as a way to teach critical thinking and scientific reasoning. Members of the audience were walked through an exercise that included interpreting plots of changing surface temperatures, think-pair-share style “clicker” questions, and comparing excerpts from scientific articles and the media. Eventually, students discover that the Earth’s overall temperature is going up, but observations can vary from year to year because heat is moving between the atmosphere and the oceans.

Press Conference: Fermi’s Vision, First Stars, Massive Galaxy Cluster, and Dark Energy (by Susanna Kohler)

Today’s afternoon press conference was an exciting assortment of results, difficult to categorize under a single umbrella.

First up was Marco Ajello (Clemson University), who spoke about 2FHL, the second Fermi-LAT catalog of high-energy sources. LAT stands for Large Area Telescope, an instrument on board the Fermi gamma-ray space observatory that scans the entire sky every three hours. Ajello described the contents of the 2FHL catalog: 360 gamma-ray sources, of which 75% are blazars (distant galactic nuclei with jets pointed toward us), 11% are sources within the galaxy, and the remaining 14% are unknown. With this catalog, Fermi has expanded into higher energies than ever before, providing the first map of the 50 GeV – 2 TeV sky. Here’s the press release.

Next to speak, John O’Meara (St. Michael’s College) told us about the discovery of a gas cloud that may be a remnant from the first population of stars. O’Meara showed us the emission spectrum from a distant quasar, which displays abrupt absorption by a cloud of gas located at a redshift of z~3.5. Absorption by gas clouds is not unusual — but what is unusual is that this cloud is extremely metal-poor, with only 1/2500th solar metallicity. This is the lowest heavy-element content ever measured, and a sign that the cloud might have been enriched by Population III stars — the theoretical first population of stars, which were born when gas in the universe was still pristine. Here’s the press release.


Cluster IDCS J1426.5+3508. [NASA, European Space Agency, University of Florida, University of Missouri, and University of California]

Mark Brodwin (University of Missouri, Kansas City) was up next, discussing the most distant massive galaxy cluster that has ever been discovered. The cluster IDCS J1426.5+3508, weighing in at several trillion solar masses (as measured by three independent techniques!), is located at a redshift of z=1.75. Since clusters take several billion years to form, and its redshift corresponds to a time when the universe was only 3.8 billion years old, we’re probably seeing it at a very early age. This combination of mass and youth is unique! Brodwin also pointed out another interesting feature: the cluster’s core isn’t centered, which means it probably underwent a major merger with another cluster within the last 500 million years. Here’s the press release.

The final speaker was Sukanya Chakrabarti (Rochester Institute of Technology), who gave a very interesting talk about a topic I’d never heard of: “galactoseismology.” Galactoseismology involves observing waves in the disk of a galaxy to learn about the properties of dwarf galaxies that caused the perturbations. In this case, Chakrabarti evaluated ripples in the outer disk of our galaxy, and used these to predict the location of a dwarf galaxy that must have skimmed the outskirts of our galaxy a few hundred million years ago, causing the waves. This is a cool technique for learning about dwarf galaxies whether or not they’re visible, since they’ll cause ripples even if they’re dominated by dark matter. Chakrabarti showed an awesome simulation of this dwarf’s interaction with the Milky Way, which you can check out on her website. Here’s the press release.


Editor’s Note: This week we’re at the 227th AAS Meeting in Kissimmee, FL. Along with several fellow authors from astrobites.com, I will be writing updates on selected events at the meeting and posting at the end of each day. Follow along here or at astrobites.com, or catch our live-tweeted updates from the @astrobites Twitter account. The usual posting schedule for AAS Nova will resume next week.


Welcome to Day 2 of the winter American Astronomical Society (AAS) meeting in Kissimmee! Several of us are attending the conference this year, and we will report highlights from each day here on astrobites. If you’d like to see more timely updates during the day, we encourage you to follow @astrobites on twitter or search the #aas227 hashtag.

Plenary Session: Black Hole Physics with the Event Horizon Telescope (by Susanna Kohler)

If anyone needed motivation to wake up early this morning, they got it — in the form of Feryal Ozel (University of Arizona) enthralling us all with exciting pictures, videos, and words about black holes and the Event Horizon Telescope. Ozel spoke to a packed room (at 8:30am!) about where the project currently stands, and where it’s heading in the future.

The EHT has pretty much the coolest goal ever: actually image the event horizons of black holes in our universe. The problem is that the largest black hole we can look at (Sgr A*, in the center of our galaxy) has an event horizon size of 50 µas. For this kind of resolution — roughly equivalent to trying to image a DVD on the Moon! — we’d need an Earth-sized telescope. EHT has solved this problem by linking telescopes around the world, creating one giant, mm-wavelength effective telescope with a baseline the size of Earth.

Besides producing awesome images, the EHT will be able to test properties of black-hole spacetime, the no-hair theorem, and general relativity (GR) in new regimes.

Ozel walked us through some of the theory prep work we need to do now in order to get the most science out of the EHT, including devising new tests of GR, and performing predictive GRMHD simulations — hydrodynamics simulations that include magnetic fields and full GR treatment. Ozel pointed out that one of the recent theoretical advancements in GRMHD simulations is harnessing the power of GPUs to render images in simulations; check out the tweet below for the awesome video she showed us!

Deployment of the full EHT array is planned for early 2017, and they’ve already got 10 targets selected — black holes that are near enough and large enough that the EHT should be able to image their shadows. I, for one, can’t wait to see the first results!

Grad School and Postdocs as a Means to a Job (by Meredith Rawls)

This morning session was presented by Karen Kelsky of The Professor Is In. She presented a very practical overview of the advice in her book (which this job-searching Astrobiter highly recommends). Her target audience is postdocs and graduate students who are finishing their PhDs and applying for tenure-track jobs. Karen’s background is in the social sciences, but she has worked with many scientists and her expertise easily transferred. Much of her writing advice also applies for undergraduates who are writing research statements and proposals to apply to graduate school. For example:

One of Karen’s main takeaways is that academia is not automatically good preparation for a job search. Writing documents like cover letters, resumes, and research statements will be harder and take more time than you think, and it is important to make them top-notch. Karen was also surprised that the majority of professional astronomers at the AAS meeting carry backpacks, because she typically advises against bringing a backpack to a job interview or campus visit. She conceded that astronomy is an exception to this rule!

Brown Dwarfs and Exoplanets (by Caroline Morley)

I started my morning in a session near and dear to my heart on brown dwarfs. The session had four dissertation talks, showcasing each student’s (impressive!) work over the last 4+ years.

Astrobites alumnus Ben Montet kicked off the session to talk about his recent work to study the eclipsing brown dwarf LHS 6343, discovered in Kepler data. This brown dwarf is one of the best so-called benchmark brown dwarfs that we have discovered. Unlike almost every other object, we can measure LHS 6343’s mass, radius, luminosity, and metallicity. Ben’s Spitzer observations reveal that it’s a ~1100 K T dwarf.

Joe Filippazzo spoke next about his work to put together a large and impressive database of 300 brown dwarfs ranging in spectral type from M to Y, stitching together literature photometry, parallaxes, and both low and high resolution spectra. He studies the effect of age on the fundamental properties of these objects, empirically without needing models! You can download the database at BDNYC.org and use Joe’s open-source Python package astrokit which includes the SQL management tools to use the database.

Jonathan Gagné presented results from his survey to find young free-floating objects in young moving groups. These objects are really interesting because they have the masses of planets but are easier to observe since they don’t have nearby stars. He is currently extending his survey from his PhD thesis to be able to find even cooler objects (literally and figuratively) in these groups.

Sebastian Pineda gave a very interesting talk about his thesis work to understand auroral emission from brown dwarfs. Brown dwarfs with a range of temperatures have been observed to have both radio activity and H-alpha emission, despite their neutral atmospheres. These properties are believed to be generated by auroral emission — just like aurorae on Jupiter! One of many interesting results is that cooler objects have rare and weak aurorae. Sebastian postulates that these brown dwarfs may have aurorae that are modulated by the presence of satellites (brown dwarf moons?!). Very cool idea that needs more study!

The last speaker of the session was the only non-dissertation talk of the session. Nolan Grieves presented results from his statistical survey of brown dwarf companions using the MARVELS radial velocity survey and finds a brown dwarf companion occurrence rate around 0.7%.

Science to Action: Thoughts on Convincing a Skeptical Public (by Meredith Rawls)

This year’s Public Policy plenary talk was delivered by William Press from UT Austin. Many scientific stories follow a familiar narrative, and too often, scientific consensus about a hazard has been accepted by the public only after some catalyzing event like a catastrophic fire or a spike in deaths linked to smoking. Press suggested that climate change may be at the tipping point of mainstream acceptance. He also discussed how a definition of “science” can encompass two distinct ideas: a series of fact-based conclusions and a value judgment based on rational thinking. To illustrate this dichotomy, he posed a question to the audience:

Press stated that he strongly supports the top view, but it was eye-opening to see a nearly even split of raised hands. His point was that GMO labeling ultimately boils down to a value judgement, not a scientific one, and we should be careful to understand the difference. Science communicators certainly have our work cut out for us! In the broadest sense, Press’ takeaway for effective science communication is a two-step approach: (1) communicate the value of a rationalist approach to decision making, and (2) communicate well-established scientific results.

AAS Journals Workshop for Authors & Referees

First half (by Susanna Kohler)

Disclaimer: I’m an employee of the AAS, as editor of AAS Nova.

This 2-hour-long author & referee workshop was intended partially as an overview of what it means to be an author or a referee (in any journal), and partly as a reveal of some of the new features that are now being implemented within the AAS publishing program. Many of the presentations have been uploaded here. A few highlights from the first half:

  • Talks about authoring articles by Ethan Vishniac, and refereeing articles by Butler Burton
  • Intro to AAS Nova — the AAS’s means of sharing its authors’ results with the broader community — by me!
  • Discussion of the AAS’s new policy for software citation by Chris Lintott

Second half (by Becky Nevin)

In between hopping between all the amazing science sessions today I made it to the last half of a very interesting Author & Referee Workshop run by AAS journals. Even with missing the first half, I can still tell that there’s a lot of changes coming to AAS journals (which include ApJ, AJ, ApJS, ApJL), in particular in the way that your research will be published. All good from what I saw — in particular they’ve addressed the long-standing problem of how to cite astronomical software (usually produced for free by a keen member of the community). Now they give guidelines for how to do this and have even appointed a new lead editor for instrumentation & software.

What got me most excited though was the demonstration by Greg Schwarz of AASTex v6.0 — a markup package to assist authors in preparing manuscripts intended for submission to AAS-affiliated journals — i.e. super cool amazing new LaTeX commands to satisfy even the most obsessive LaTeX-er! Check it out, because it will definitely ease the pain of writing and responding to referees. In the final talk (before free lunch, score!) Gus Muench showcased the new ways that authors will be able to include interactive JavaScript figures into articles in AAS journals. You can check out some of the amazing integrations in this nifty tutorial.

A Report on the Inclusive Astronomy 2015 Meeting: Community Recommendations for Diversity and Inclusion in Astronomy


This very well-attended session recapped the Inclusive Astronomy 2015 meeting (see this link for a summary!)

The IA2015 meeting results can be found here.

A draft of the recommendations from IA2015 is here. Note that this document, termed the “Nashville Recommendations,” is a living document that isn’t yet finalized, and feedback is welcome.

Dannie Heineman Prize: From “~” to Precision Science: Cosmology from 1995 to 2025 (by Erika Nesvold)

Marc Kamionkowski of Johns Hopkins University and David Spergel of Princeton University shared this year’s Heineman Prize for outstanding work in astronomy, and gave an impressive tag-team overview of the progress in the field of cosmology over the past 20 years.

Spergel pointed out that in 1995, cosmologists were still debating over the value of the Hubble constant, and whether or not the universe is flat. Kamionkowski pointed out that back then, cosmology was an “order of magnitude game” where observations lagged far behind theory. He noted that in general, theorists tend to “sit around predicting things,” and not much progress is made in testing those predictions, at least not within the lifetime of an individual theorist. In cosmology, however, the measurements and observations made since 1995 have been more successful and precise than anyone could have anticipated.

This is thanks in part to the WMAP mission and later the Planck satellite, which measured the cosmic microwave background and collected an amazing set of data. There is excellent agreement between the data from WMAP and Planck, a triumph for observational cosmologists. Much to the surprise of Spergel and other cosmologists, a simple model of only five fundamental parameters fits these data extremely well. Twenty years later, thanks to the hard work of cosmologists, we now know that the age of the universe is 13.8 billion years, and that it is composed of roughly 4% atoms, 23% dark matter, and 73% dark energy.

Spergel and Kamionkowski then pointed towards the future, predicting even more spectacular results to come over the next decade or so. Our current model of the universe predicts gravitational waves, which we haven’t observed so far, but the search is heating up. Kamionkowski called this potentially the most important new physics result of this century! He also explained that we can now do neutrino physics using the cosmic microwave background, which already provides the strongest constraint on the sum of neutrinon masses. In the next decade, we should be able to further determine the neutrino mass hierarchy. The coming years in cosmology could be even more exciting than the past twenty!

HEAD Rossi Prize talk: A New View of the High Energy Universe with NuSTAR (by Susanna Kohler)

This year’s Rossi Prize winner Fiona Harrison capped off the main part of the day with a plenary talk about some of the highlights from the first two years of the NuSTAR mission, NASA’s space-based, high-energy X-ray telescope.


Additional science results from the past two years with NuSTAR.

Harrison began by telling us about NuSTAR’s launch in 2012, in which a Pegasus rocket — with NuSTAR as its payload — was launched from a L-1011 ‘Stargazer’ aircraft. She claims to have been unconcerned about this part: “The payload would go up or it would go down, there wasn’t anything I could do about it.” The real terror for the NuSTAR team came 9 days later when the telescope slowly unfolded itself over the span of 24 minutes, snapping components into place. All went well, however, and NuSTAR has since been forging exciting new territory in the high-energy X-ray regime!

Harrison discussed science highlights from the last two years of NuSTAR, like the discovery of a population of dead stars in the inner parsecs of the galaxy, the identification of the mechanism that most likely re-energizes stalled shocks in supernovae and launches the explosion (in case you’re keeping track, it’s because the star sloshes around. Seriously.), or the evidence that supernova 1987A exploded asymmetrically.

NuSTAR is funded through the end of 2016 and is now in its extended mission, so we can expect to see more exciting science coming from it in the future!


Editor’s Note: This week we’re at the 227th AAS Meeting in Kissimmee, FL. Along with several fellow authors from astrobites.com, I will be writing updates on selected events at the meeting and posting at the end of each day. Follow along here or at astrobites.com, or catch our live-tweeted updates from the @astrobites Twitter account. The usual posting schedule for AAS Nova will resume next week.


aas 227 astrobites booth

Things kicked off last night at our undergraduate reception booth. Thanks to all of you who stopped by — we were delighted to have so many people tell us that they already know about and use astrobites, and we were excited to introduce a new cohort of students at AAS to astrobites for the first time.

Tuesday morning was the official start of the meeting. Here are just a few of the talks and workshops astrobiters attended today.

Opening Address (by Becky Smethurst)

The President of the AAS, aka our fearless leader Meg Urry kicked off the meeting this morning at the purely coffee powered hour of 8am this morning. She spoke about the importance of young astronomers at the meeting (here’s looking at you reader!) and also the importance of the new Working Group for Accessibility and Disabilities (aka WGAD pronounced like wicked) at the AAS. The Society has made extra effort this year to make the conference accessible to all, a message which was very well received by everyone in attendance.

Kavli Lecture: New Horizons – Alan Stern (by Becky Smethurst)

We were definitely spoilt with the first Plenary lecture at this year’s conference – Alan Stern gave us a a review of the New Horizons mission of the Pluto Fly By (astrobites covered the mission back in July with this post). We were treated to beautiful images, wonderful results and a foray into geology. 

Some awesome facts from the lecture that blew my mind:

  • New Horizons is now 2AU (!) beyond Pluto
  • The mission was featured on the front pages of 450 newspapers worldwide on every single continent (including Antartica!)
  • New Horizons reached the Moon in 9 HOURS after launch (compared to the ~3 days it took the Apollo missions)
  • The mission controllers were aiming for a 100km window of space all the way from Earth
  • There was a window of ~400seconds which the probe had to arrive within – the probe arrived 90 seconds early! Putting tardy astronomers everywhere to shame.
  • Charon was the only satellite of Pluto known at the time of the mission proposal
  • The canyon found on Charon is not only bigger than the Grand Canyon but bigger than Mariner Valley on Mars which is already 4000 km (2500 mi) long and reaches depths of up to 7 km (4 mi)!

  • The mountains ringing the Sputnik Planum (aka the heart of Pluto) are over 4km high and are snow capped with methane ice

  • Pluto’s atmosphere has a dozen distinct haze layers – but how they are created is a mystery

Alan also spoke about the future of New Horizons – there is a new mission proposal for a fly by of a Kuiper Belt object 2014MU69  in Jan 2019 which should give us a better understanding of this icy frontier at the edge of the Solar System. As a parting gift Alan played the most gorgeously detailed fly over video of Pluto’s surface that had all in the room melting into their flip flops. It’s safe to say that the whole room is now Pluto-curious and wondering whether a change of discipline is in order!

Press Conference: Black Holes and Exoplanets (by Susanna Kohler)

This morning marked the first press conference of the meeting, covering some hot topics in black holes and exoplanets.

Hubble (background) and Chandra (purple) image of SDSS J1126+2944. The arrow marks the second black hole. (From http://casa.colorado.edu/~comerford/press)

Hubble (background) and Chandra (purple) image of SDSS J1126+2944. The arrow marks the second black hole. (From http://casa.colorado.edu/~comerford/press)

The first speaker was Julie Comerford (University of Colorado Boulder), who told us about SDSS J1126+2944, a galaxy that was shown by Chandra X-ray detections to contain not just one, but two supermassive black holes. This is a sign of a recent merger between two galaxies, which can result in one new, larger galaxy with two nuclei for a while. The second black hole is surrounded by only a small sphere of stars. This may be because the rest have been stripped away in the process of the merger — but it’s also possible that the second black hole is an elusive “intermediate mass black hole” of only 100-1,000,000 solar masses! Here’s the press release.

The second speaker was Eric Schlegel (University of Texas, San Antonio), who spoke about the galaxy NGC 5195. Eric discussed an interesting problem: we know that star formation ends in galaxies after a time, but the gas must be cleared out of the galaxy for the star formation to halt. What process does this? Schlegel’s collaboration found evidence in NGC 5195 for a “burping” supermassive black hole — the shock from the black hole’s outflow sweeps up the hydrogen gas and blows it out of the galactic center. Here’s the press release.

NuSTAR image of Andromeda, inset on a UV image by NASA's Galaxy Evolution Explorer. Click for a better look! [NASA/JPL-Caltech/GSFC]

NuSTAR image of Andromeda, inset on a UV image by NASA’s Galaxy Evolution Explorer. Click for a better look! [NASA/JPL-Caltech/GSFC]

Next up was Daniel Wik (NASA/Goddard SFC), who discussed recent high-energy X-ray observations of Andromeda galaxy with NASA’s NuSTAR. As Wik described it, NuSTAR is like a CSI detective, working to identify what fraction of the compact remnants in X-ray binaries of Andromeda are neutron stars, and what fraction are black holes. Since X-ray binaries play a crucial role in heating gas in protogalaxies, shaping galaxy formation, it’s important that we learn more about this population and how it evolves over time. Here’s the press release.

The final speaker was grad student Samuel Grunblatt (University of Hawaii Institute for Astronomy), who spoke about measuring the mass of exoplanets around active stars. In radial velocity studies of exoplanets, a planet orbiting its star causes the star to “wobble”. This signal for an Earth-like planet is as tiny as 9 cm/s! Unfortunately, activity of the star can cause radial velocity noise of 1-10 m/s — so to detect Earth-like planets, we need to find a way of subtracting off the noise. Grunblatt talked about an intriguing new method for determining planet masses that controls for the signature of their host’s activity. Here’s his paper.

Annie Jump Cannon Award Lecture: On the Dynamics of Planets, Stars and Black Holes (by Erika Nesvold)

This year, the Annie Jump Cannon Award was given to Smadar Naoz, an assistant professor at UCLA. The Cannon Award is given every year to a young (less than 5 years since PhD), female astronomer for outstanding work in her field. Traditionally, the Cannon Award recipient delivers a lecture on her research, so this year we were lucky to see a dynamic and engaging talk by Smadar Naoz about her research in dynamical theory.

You may have heard the common career advice that you should focus on becoming “the” expert on one particular facet of astronomy: a particular type of object, an observational technique, a type of instrument, etc. Naoz has managed to follow that advice while still managing to study a huge range of astronomical topics, from exoplanets to cosmology. She studies hierarchical triples, systems of three gravitational bodies in which two of the bodies orbit one another very closely, while the third orbits the other two from a much greater distance. For example, a planet in a tight orbit around a star, with a brown dwarf orbiting hundreds of AU away, make up a hierarchical triple system. So does a system in which two black holes orbit each other closely, with a third black hole orbiting farther away. The physics of these systems are all the same, so by studying the equations that govern a hierarchical triple system, Naoz can study a huge variety of astronomical objects.

In particular, Naoz studies a mechanism called the Kozai-Lidov mechanism, named after the two researchers who discovered it independently. If the outer body in a hierarchical triple orbits at a high enough inclination to the inner body (> 40 degrees), the Kozai-Lidov mechanism will excite the inclination and eccentricity of the inner body. In fact, the inclination and eccentricity will oscillate opposite one another: as the inclination increases, the eccentricity will decrease, and vice versa. In the course of her research, Naoz discovered a flaw in Kozai’s original derivations of this mechanism, and derived a more accurate, general set of equations describing the Kozai-Lidov mechanism. These new equations indicate that the eccentricity of the inner object can become extremely high, and that the inclination can become so high that the object’s orbit can flip from prograde to retrograde! In other words, the object can start orbiting in the opposite direction around the central body.

This work has applications in many different types of systems. For example, over the past decade, observers have discovered a large number of retrograde hot Jupiters, gas giant planets orbiting very close to their star, in the opposite direction from the star’s spin. Naoz showed that the new, correct Kozai-Lidov mechanism can explain the orbits of these exoplanets, because it increases the planet’s eccentricity until its orbit approaches very close to the star, and it flips the inclination into a retrograde orbit.

Naoz also showed applications of the Kozai-Lidov mechanisms to dark matter halos around black holes, triple black hole systems, and so-called “blue stragglers”: main-sequence stars in clusters that are brighter and bluer than they should be. Her body of work is an excellent example of how theorists can adapt general physics theories to a wonderful variety of astronomical problems.

Harassment in the Astronomical Sciences Town Hall (by Caroline Morley)

The Town Hall on Harassment in the Astronomical Sciences involved a sobering panel discussion on the current state on workplace climate in astronomy and the current steps that the AAS and federal agencies are taking to improve it. Christina Richey kicked it off by presenting preliminary results from the CSWA Survey on workplace climate. This survey involved 426 participants, and reveals that many people, especially junior members of the field, experience harassment including both verbal and physical harassment. These results will be published this year. Next up, Dara Norman, a Councilor of the AAS and a member of the AAS Ethics Task Force, spoke about the proposed changes to the current AAS Ethics Statement. These changes will focus on corrective policies to improve the state of the field; they will solicit community feedback this Spring and vote on the changes at the Summer AAS meeting. Last, Jim Ulvestad, representing the federal agencies including NSF, NASA, and the DOE, spoke about the current policies for reporting to federal funding agencies. He reminds us that if an institution accepts money from the federal government, they are required by law to follow laws such as Title VI (covering racial harassment) and Title IX (covering sexual harassment), and that breaches can be reported to the funding agency.

Tools and Tips for Better Software (aka Pain Reduction for Code Authors) (by Caroline Morley)

This afternoon breakout session included a drinking-from-the-firehose set of short talks that covered everything from source-code management and software testing to building communities that create sustainable code. First, Kenza Arraki discussed software such as Git to do version control to keep track of code changes. (Version Control is my (science) New Years Resolution, so I was happy to learn that there is a CodeAcademy tutorial for Git!). Next up, Adrian Price-Whelan described the merits of software testing and suggests that we actually do “Test-driven development” where we write tests for the code first, then write code, run tests and debug until tests all pass. Erik Tollerud spoke on “Why Document code and how you might convince yourself to do so” (documenting code is another good science New Years Resolution!) The most important rule is to always document as you code because you won’t ever go back! Bruce Berriman described the best practices for code release, including, importantly, licensing it and describing it well (with tutorials, examples). Matthew Turk reminded us the importance of building community around code development. Robert Nemiroff ended the talks with a discussion of what to do with “dead” codes. The lowest bar? Put it in your Dropbox and share it with your collaborators and students!

For more info on all of these topics and more, consider attending a Software Carpentry workshop.


AAS 227

Greetings from the 227th American Astronomical Society meeting in Kissimmee, Florida! This week, along with several fellow authors from astrobites, I will be writing updates on selected events at the meeting and posting at the end of each day. You can follow along here or at astrobites.com, or catch our live-tweeted updates from the @astrobites Twitter account. The usual posting schedule for AAS Nova will resume next week.

AAS Journals

If you’re an author or referee (or plan to be!) and you’re here at the meeting, consider joining us at our Author and Referee Workshop on Wednesday in the Tallahassee room, where we’ll be sharing some of the exciting new features of the AAS journals. You can drop into either of the two-hour sessions (10 AM – 12 PM or 1 PM – 3 PM), and there will be a free buffet lunch at noon. Here’s the agenda:

Morning Session Topic & Speaker
10:00 am – 10:05 am Introductions
Julie Steffen
10:05 am – 10:35 am Changes at AAS Journals; How to Be a Successful AAS Author
Ethan Vishniac
10:35 am – 11:00 am The Peer Review Process
Butler Burton
11:00 am – 11:15 am AAS Nova: Sharing AAS Authors’ Research with the Broader Community
Susanna Kohler
11:15 am – 11:30 am Fixing Software and Instrumentation Publishing: New Paper Styles in AAS Journals
Chris Lintott
11:30 am – 11:45 am Making Article Writing Easier with the New AASTeX v6.0
Greg Schwarz
11:45 am – 12:00 pm Bringing JavaScript and Interactivity to Your AAS Journal Figures
Gus Muench
Lunch Session Topic & Speaker
12:00 pm – 12:15 pm Unified Astronomy Thesaurus
Katie Frey
12:15 pm – 12:30 pm AAS/ADS ORCID Integration Tool
Alberto Accomazzi
12:30 pm – 12:45 pm WorldWide Telescope and Video Abstracts
Josh Peek
12:45 pm – 01:00 pm Arizona Astronomical Data Hub (AADH)
Bryan Heidorn
Afternoon Session Topic & Speaker
01:00 pm – 01:05 pm Introductions
Julie Steffen
01:05 pm – 01:35 pm Changes at AAS Journals; How to Be a Successful AAS Author
Ethan Vishniac
01:35 pm – 02:00 pm The Peer Review Process
Butler Burton
02:00 pm – 02:15 pm AAS Nova: Sharing AAS Authors’ Research with the Broader Community
Susanna Kohler
02:15 pm – 02:30 pm Fixing Software and Instrumentation Publishing: New Paper Styles in AAS Journals
Chris Lintott
02:30 pm – 02:45 pm Making Article Writing Easier with the New AASTeX v6.0
Greg Schwarz
02:45 pm – 03:00 pm Bringing JavaScript and Interactivity to Your AAS Journal Figures
Gus Muench


If you’re at the meeting but can’t make the workshop, stop by the IOP booth in the Exhibit Hall (Booth #223) to learn more about the new corridors for AAS Journals and to pick up a badge pin to represent your corridor!



AAS Publishing News

Do you write code for your research? Use astronomical software? Do you wish there were a better way of citing, sharing, archiving, or discovering software for astronomy research?

You’re not alone! In April 2015, AAS’s publishing team joined other leaders in the astronomical software community in a meeting funded by the Sloan Foundation, with the purpose of discussing these issues and potential solutions. In attendance were representatives from academic astronomy, publishing, libraries, for-profit software sharing platforms, telescope facilities, and grantmaking institutions.

The goal of the group was to establish “protocols, policies, and platforms for astronomical software citation, sharing, and archiving,” in the hopes of encouraging a set of normalized standards across the field.

The AAS is now collaborating with leaders at GitHub to write grant proposals for a project to develop strategies for software discoverability and citation, in astronomy and beyond.

If this topic interests you, you can find more details in this document released by the group after the meeting: http://astronomy-software-index.github.io/2015-workshop/

The group hopes to move this project forward with input and support from the broader community. Please share the above document, comment on it, discuss it on social media using the hashtag #astroware (so that your conversations can be found!), or send private comments to julie.steffen@aas.org.

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