In section 10. Planets and planetary systems
SOPHIE velocimetry of Kepler transit candidates VII. A false positive rate of 35% for Kepler close-in giant candidates
The Kepler mission had announced the discovery of more than two thousand planet candidates seen in transit and ranging from Earth-size to Jupiter-size. The vast majority of these candidates are unconfirmed by other techniques. This means that stellar eclipsing binaries hidden behind the target stars may mimic a planetary transit signal. Based on statistical arguments it was thought that this would rarely occur, i.e., less than 10% of the time. Santerne et al. directly tested this for the first time for the giant planets. Using the SOPHIE spectrograph at the Observatoire de Haute-Provence, they surveyed 46 Kepler candidates identified in the giant planet range and found that about 35% of these are in fact not planets. Although most of the candidates are genuine planets, this shows that follow-up studies are crucial for the validation of planetary candidates and that statistical studies based on photometric surveys alone have to carefully account for the possibility of false positives.