Over the past three and a half days, I joined astronomers from all over the world for the 218th meeting of the American Astronomical Society. This was my second astronomy conference (the first was AAS #217 in Seattle) and was definitely the smaller of the two. There weren’t quite as many overlapping talks – not that I didn’t have schedule conflicts – and the halls where the exhibitors and posters were presented were substantially smaller. Maybe it was the size, maybe it was the fact that the it wasn’t my first meeting or maybe it was actually knowing people, but this conference was definitely less intimidating than the last.
As at the last AAS, I attended a whole slew of talks about exoplanets. This time a larger emphasis was placed on the stars themselves, although Courtney posted about one of the exoplanet discoveries announced in her last astrobites post. There were many exciting talks and posters, from the seriously good precision with which Kaspar von Braun and team can use the CHARA interferometric array to measure the radii of distant stars to the new binaries found by Julian C. Van Eyken (with the Palomar Transient Factory team) and Elisabeth R. Adams (with Andrea Dupree and the Kepler science team). In this astrobite, I’ll talk about just two of the talks I went to.
Stellar astrophysics from the Kepler Mission
One of the topics that stood out to me in this invited talk by Ronald L. Gilliland (STScI) was the photometric variability of an average star in the Kepler field. Our Sun, it turns out, is special: it is quieter than 75% of similar-magnitude stars. This poses a small problem for the Kepler team, whose goal it is to detect an Earth-like planet around a Sun-like star. Since most stars are noisier than the Sun, their light curves will show more variations, making it even more difficult than it already is to detect the tiny dips in the light curve that might signify a transiting planet.
Gilliland also discussed some of the amazing asteroseismology results coming out of Kepler. Asteroseismology is the study of oscillations in a star and is used to learn about its interior, similar to the way terrestrial seismic waves tell us about the structure of the Earth. Two papers on the subject were published recently: Beck et al. (2011) and Bedding et al. (2011). The first reports the detection of modes of oscillation that reaches down to the core of a red giant star in the Kepler field, based on 320 days of observations. In the latter, the authors are able to distinguish between red giant stars in the hydrogen shell burning and helium core burning stages based on asteroseismic observations. The inability to determine which stage a red giant is in has made research on red giant evolution difficult and the new results from Bedding et al. remove this stumbling block.
Exoplanet Characterization with Kepler
Avi Shporer (UCSB) was able to detect transiting exoplanet candidate KOI-13.01… without the transit. The planet is Jupiter-sized and orbits close to its host, a bright A star. Three effects (the most straight-forward of which is reflection of light by or the heating of the planet) result in photometric variability that is directly related to the planet’s orbit. Shporer removed the planet transits and occultations from Kepler’s light curve of KOI-13 and looked for this photometric signal. He reported an unambiguous detection of KOI-13.01. This result means we could detect a non-transiting exoplanet! Shporer calculated that a Jupiter-mass planets could be detected around bright stars by this orbital photometry method.
If you know where to find more information on some of the talks and posters I mentioned (because I don’t!) or if you had any favorite talks at AAS, please share! We’d love to hear from you.