Protostars and Planets VI, Heidelberg, July 15-20, 2013
Inferring the Rate of Planet Occurrence by Injecting and Detecting Transits in the Kepler Light Curves of M Dwarfs
Dressing, Courtney (Harvard University)
Charbonneau, David (Harvard University)
The Kepler mission has discovered thousands of planet candidates, but some transiting planets may evade detection by the Kepler pipeline. Specifically, transiting planets might be missed around stars exhibiting large brightness variations due to starspots. Knowledge of the detection efficiency is therefore required in order to accurately estimate the fraction of stars that host planets. In a recent paper, we revised the stellar parameters of the smallest Kepler target stars and determined that the occurrence rate of 0.5-4 Earth radius planets with periods <50 days is 0.90 (+0.04/-0.03) planets per small star. We also found that there are at least 0.04 Earth-size (0.5-1.4 Earth radius) planets within the habitable zones of small stars, implying that the nearest transiting Earth-size planet is within 21 pc with 95% confidence. Our previous estimates of the occurrence rate assumed 100% detection efficiency at SNR=7.1 sigma; the occurrence rate would have been underestimated if the actual detection efficiency is lower. We will present the results of an ongoing project to improve our estimate of the occurrence rate by developing a customized pipeline to detect transiting planets around Kepler M dwarfs. We will directly measure the pipeline detection efficiency by injecting transits into the light curves of Kepler M dwarfs and attempting to recover the injected signals. These stars are fainter than the majority of Kepler targets and frequently demonstrate considerable brightness variations due to spot activity. Our pipeline is designed to remove this stellar variability while preserving the signatures of planetary transits. We will compare the list of candidates identified by our pipeline to the list released by the Kepler team and discuss any new candidates. We will then combine our completeness calculations, the resulting list of planet candidates, and our revised stellar properties to refine our estimate of the planet occurrence rate around M dwarfs.
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