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IPAC Astronomy Lunch Seminar

Friday, December 2, 2011
12:00pm to 1:00pm
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IPAC 102 (Large Conference Room)
Validating and Characterizing Transiting Exoplanets from Space with EPOXI, Kepler, and Warm Spitzer
Sarah Ballard, CfA,
I will present analyses of transiting exoplanets, ranging from hot Jupiters to habitable-zone super-Earth candidates, with observations from three space-based instruments. The Extrasolar Planet Observation and Characterization (EPOCh) component of the EPOXI mission repurposed the Deep Impact Spacecraft to gather photometry of six known transiting exoplanet systems in 2008. I conducted an investigation of the EPOXI light curves for additional transiting planets. One such investigation led to the identification of an additional candidate transiting planet in the exoplanet system GJ 436. We gathered Warm Spitzer light curves of GJ 436 during a predicted transit of this putative planet: while we ruled out the presence of the hypothesized planet, we developed a novel reduction technique for Warm Spitzer observations and demonstrated the sensitivity of that instrument to sub-Earth-sized transiting planets. I next applied these techniques on a sample of planetary candidates identified by the Kepler mission. To date, Kepler has found hundreds of transiting planetary candidates smaller than twice the radius of the Earth. In the absence of radial velocity confirmation (challenging for such small planets), it is still possible to make a statistical argument for the planetary nature of the candidate, if the combined likelihood of all false positive scenarios is sufficiently smaller than the planet scenario. An authentic planet will exhibit an achromatic transit depth, as measured in the optical with Kepler and near-infrared with Warm Spitzer. The transit of a stellar blend, in contrast, is likely to vary with wavelength. Kepler-19b, a 2.2 R_Earth planet in a 10 day orbit, is a recent example of a planet we validated using this methodology, combined with other false-positive identification tools. The Kepler-19 system also exhibits the first robust transit timing variation signal attributable to an additional, non-transiting planet: Kepler-19c.
For more information, please contact Luisa Rebull by phone at x4565 or by email at [email protected] or visit