Astrobites@Long Beach: Wednesday Morning Sessions

Astrobites is again 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 Wednesday morning!

-The Astrobites Team

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Image courtesy of NASA Goddard Space Flight Center

8:30am Plenary Session – Heineman Prize: Extreme Transients in the High Energy Universe

This year’s Heineman Prize was awarded to Dr. Chryssa Louveliotou of NASA’s Marshall Space Flight Center.  The award, given jointly by the American Astronomical Society and the American Institute of Physics, recognizes outstanding work in astrophysics. Dr. Kouveliotou was cited for “her extensive accomplishments and discoveries in the areas of gamma ray bursts and their afterglows, soft gamma repeaters, and magnetars.” She is the second female recipient of the award since it was founded in 1980. Her accomplishments include being a member of the team that identified the first optical counterpart associated with a gamma-ray burst (GRB).  Until that discovery, and the ability to directly measure the distance to GRBs that came with it, it was still an open question whether GRBs took place within the Milky Way itself or at cosmological distances.

In her talk Dr. Kouveliotou discussed several aspects of what we have learned about both GRBs and magnetars since she joined the field in 1978.   Although there are always caveats and uncertainties, we have advanced from a point where only a handful of GRBs had been detected (and only in the gamma-rays) to a point where we have two classes of GRBs (long and short) with working theories for both (collapsing massive stars, and merging neutron stars).  In that time astronomers also recognized that magnetars were a separate class of object, likely due to highly magnetized neutron stars, and have even measured the size of the footprint of the magnetic field on the neutron star surface.  Finally, Dr. Kouveliotou mentioned that she was also awarded the Heineman for her, “abilities to create collaborations”.  She cited a recent study by MEJ Newman titled “The structure of scientific collaboration networks”, in which she ranked first for her level of “ in-between-ness.”

10:00am – Astrophysics with Kepler’s High Precision Photometry
This session was devoted to all of the wonderful contributions that the Kepler data has made to stellar astrophysics. In the first talk, Daniel Huber (NASA Ames) gave an overview of the stellar astrophysics enabled by asteroseismology of 14,000 Kepler target stars. Huber highlighted distance measurements showing excellent agreement with Hipparcos parallaxes, measurements of the internal rotation of giant stars, and studies distinguishing between red giants burning helium in their cores and those burning hydrogen in their cores. In the second talk, Travis Metcalfe (Space Science Institute) discussed asteroseismology of Kepler host stars and reminded the audience that our knowledge of the radii of Kepler planets and planet candidates is only as reliable as our knowledge of the radii of the host stars. Metcalfe highlighted the Kepler-21, Kepler-22, and Kepler-36 systems as examples of cases where asteroseismology played a key role in understanding Kepler planets. In the third talk, Lucianne Walkowicz (Princeton) discussed rotation period estimates for a sample of Kepler exoplanet host stars. Walkowicz also presented evidence for star-planet misalignment and possible indications of tidal interactions between stars and planets in close-in systems.

In the fourth talk, Jerome Orosz (San Diego State) introduced the audience to the triple star system KIC 6543674. The triple system consists of an inner binary of Sun-like stars orbited by an 0.5 solar mass star in a more distant 3.1 year orbit. Using Kepler data and ground-based observations, Orosz and his team have accurately measured the radii and masses of all three stars in the system. In the fifth talk, Savita Mathur (High Altitude Observatory) presented measurements of the surface rotation of Sun-like stars. Her team has already measured surface rotation rates for 88 stars and the sample of stars with measured surface rotation rate will expand as more stars are observed at short-cadence (using 1-minute integration times instead of the standard 30-minute “long-cadence” Kepler integration time). Finally, in the last talk of the session, Jennifer van Saders (The Ohio State University) discussed her work modeling the surface rotation rates of stars at a variety of evolutionary stages and masses. In the future, her work will allow astronomers to estimate the ages of stars based on measurements of their surface rotation rates.

10:30am Press Release: Exploding Stars and Dark Energy

Jon Mauerhan (University of Arizona) got things started by discussing the very unusual supernovae SN2009ip.  As you can tell from its name, astronomers’ attention was first draw to this object in 2009 when it underwent an outburst and was incorrectly classified as a supernova.  Since that time the star has undergone several outbursts which may be analogs to the Luminous Blue Variable (LBV) Eta Carinae.  Earlier this year the object brightened significantly and astronomers believe it has finally exploded as a bona-fide supernova.  This is in intriguing because many models of stellar evolution predict that stars should not explode in the LBV phase.  The remaining two speakers discussed topics relating to dark energy.  David Rubin (University of California, Berkeley) presented a measurement of the most distant spectroscopically confirmed Type Ia supernova at a redshift of 1.7.  In order to determine whether dark energy can be described by Einstein’s cosmological constant, it will be necessary to combine many more supernovae at these distances with information from other techniques.  Joshua Frieman (Fermi National Accelerator Laboratory) gave an overview of the Dark Energy Survey (DES), whose goal is to accomplish just that.  DES will examine the nature of dark energy through four techniques: counts of galaxy clusters, large scale structure, weak gravitational lensing, and Type Ia supernovae.  DES took its first light images earlier this fall.  In his commentary Nobel laureate Saul Perlmutter (Univ. of California, Berkeley) drew our attention to a philosophical point. He reminded us that, because of light travel time, when we observe supernovae we are examining in great detail events which took place millions to billions of years ago, but the events themselves last only a matter of weeks.  That is truly extraordinary.

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