Astrobites@Austin: Tuesday Afternoon Sessions

This year, Astrobites will be liveblogging AAS. In order to avoid inundating our readers’ RSS feeds, we’ll be updating this post with short paragraphs about the talks we’ve heard and posters we’ve seen. So keep checking back throughout Tuesday afternoon! If you missed them, here are the Monday morning sessions, the Monday afternoon sessions, and the Tuesday morning sessions.

3:30 pm — Pierce Prize: Who is Under the HAT? Small Telescopes Yield Big Science
Gaspar Bakos (Harvard-Smithsonian Center for Astrophysics)

Note: The Pierce Prize is awarded by the AAS annually to a young (less than age 36) astronomer for outstanding achievement in observational astronomical research.

This year’s Pierce Prize goes to Dr. Bakos, who observes transiting exo-planets. He opened his talk with a beautiful photograph of the sunset, taken in Chile, and posed the question: what if, at the moment he was taking the picture of the sunset, there was someone behind his back on a planet far away currently observing the earth as a transiting exoplanet around our Sun. Just a thought…

Dr. Bakos was an engaging presenter with interesting anecdotes to explain his project. He had an innovative diagram of planetary mass vs. radius of known exoplanets, including an audio representation of the periods and masses of the exoplanets which have been discovered each year. As more exoplanets populate the plot, the “beeping” increases, with the tone of each “beep” related to the mass of the exoplanet and the cadence related to the period.

More specifically, Dr. Bakos developed the HATNet project, a survey of exoplanets using a network of one-meter class telescopes around the world. This gives extended phase coverage of planet transits, and gathers more observing time independent of weather and conditions at an individual site.

3:00 pm – Session 228: Giant planet companions to T Tauri stars – Christopher Crocket

It’s hard to look for planets around T Tauri stars because their massive spots cause radial velocity modulation that can mimic planetary signals. But young interesting because planet formation is full of open questions. Christopher Crockett is looking for wavelength dependence in radial velocity (RV) amplitudes: if yes, the RV modulation is probably spot induced if no, it could be a planet. The team has observed 150 T Tauri stars (which are young) using a neat technique to use radial velocities: they use atmospheric (telluric) lines as a radial velocity zero point. They can get great precision using this technique. Most of their objects are consistent with spot-induced RV modulation. There is one target that shows little variation in amplitude with wavelength and so could be a planet, but the data is on the confusing side and they don’t know what’s going on. But, Christopher thinks they’re close.

2:30 pm – Session 228: A young exoplanet caught in formation – Adam L. Kraus

Adam Kraus is looking for newly formed planets. They should be brighter (and therefore easier to see) and lie in gaps in protoplanetary disks (so you know where to look). But, these young systems are really far from us and it is very difficult to directly image a planet orbiting so closet its star. Using something called aperture masking interferometry, their collaboration looked at LkCa 15, a disk with a confirmed gap. They found something they think is a protoplanet: it appears as a point source in the blue but extended in red: a planet still accreting material. Just last week, they observed it in a third band and confirm their detection; the three measurements are consistent with a 1 Myr old, 6 Jupiter mass L dwarf.

2:30 PM – Press Release: AN INFRARED EXTRAVAGANZA

Wondering about the latest in NASA projects? This press release extravaganza presented several results from the NASA projects Herschel, Spitzer, WISE, and SOFIA.

Herschel and Spitzer observations show the dust of the interstellar medium. New images show the location of current and potential sites of star formation in the LMC and SMC, two nearby dwarf galaxies (about 200,000 light years away). Margaret Meixner (Space Telescope Science Institute) showed some new images of the nearby galaxies’ stardust, specifically mentioning the temperature of the dust in the regions.

Next, looking closer to home. Joseph Hora (Harvard-Smithsonian CFA) presented a large-scale survey of Cynus-X using Spitzer, unique observations for their size (25 square degrees) and proximity (4600 light years). Cygnus-X is a region of star-formation within our Galaxy, containing thousands of young stellar objects.

Xavier Koenig (NASA Goddard Space Flight Center) explained how massive star formation works, by two models called “collect and collapse” and “chain reaction”. The IR lights up where massive star formation is doing its work, and many young stars are obvious in the newly released image by NASAs Wide-Field Infrared Survey Explorer (WISE) that Koenig presented.

SOFIA (the Stratospheric Observatory For IR Astronomy) is a 747 aircraft with a telescope on board. Erick T. Young (Universities Space Research Association) presented SOFIA observations of W3, which is a star formation region at a distance of about 6500 light years. Several wavelengths were observed, with the warm dust showing a shell around one of the stars as it forms.

The reporters at the press conference especially enjoyed the opportunity to photograph the stunning images of observations released here and displayed on posters around the room.

12:45pm – Press Release: The Universe at Very High Energies

Caught in the Act: A Black-Hole Outburst — Gregory R Sivakoff (University of Alberta)
Dr. Sivakoff discussed the recent observation of a jetted outburst from the stellar-mass black hole H1743-322, located ~28,000 ly away, near the galactic center. This black hole is being fed by the stellar envelope of a binary companion, and it exhibits an X-ray outburst roughly every 8 months. The event was observed both in radio with the VLBA and in X-ray using the Rossi X-ray Timing Explorer (RXTE). Dr. Sivakoff reported that quasi-periodic oscillations were detected from the accretion disk for several days, before abruptly cutting off just before the jet was launched. This suggests a definite link between accretion-disk activity and the launching of this jet, something which has been theorized but not yet verified.

Sources Above 10 GeV in the Fermi Sky — David J. Thompson (NASA Goddard)
Dr. Thompson gave an overview similar to this morning’s Rossi lecture, but focusing specifically on the Fermi gamma-ray sources >10 GeV. This is a unique energy range that hasn’t really been reached before Fermi, and while Fermi has already detected more than 500 sources in this range, it’s anticipated that it will find more than double that before the 10-year mission ends.

NuSTAR: Unveiling the Hard X-ray Universe — Daniel Stern (JPL/Caltech)
Dr. Stern discussed NuStar, NASA’s next astrophysics mission to launch. Launching in 63 days, NuStar will examine the high-energy X-ray regime between Chandra and Fermi. Its science topics are very broad, and include determining what heats the solar corona, examining sources near the galactic center, and studying black holes that aren’t detectable in lower-energy bands due to obscuration by dusty toruses.

2:00 pm – Session 228: Heterogeneous Giant Planet Thermal Evolution with MESA –  Niel Miller

In his thesis talk, Neil Miller talked about the MESA stellar evolution code (it’s written by a software engineer, so it’s “actually good code”, says Neil). It’s open source and reportedly easy to use so anyone can use it. He talked about the ingredients in the code, such as the equation of state (they’ve had to add in water) and planetary atmosphere opacity. One thing they are interested in applying the code to is the interior structure of giant planets. The application that caught my interest was modeling ohmic heating, a mechanism proposed by Batygin & others to explain the inflated hot radii seen in some hot Jupiters (the subject of this astrobite).

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