Abstract:

The Kepler space telescope has observed hundred of thousands of stars continuously during the four years of the prime mission. It has detected thousands of potential transiting planets up to 1AU and down to the size of the Earth. These detections provide new constraints to the theories of planet formation, migration, and evolution, at a level never reached before. However, transit signals could be mimicked by other, non-planetary scenarios. These other scenarios, the so-called false positives, bias the physical properties of exoplanets derived from the transit detections and thus, they might lead us to wrong conclusions. To secure these planet detections, two main techniques are used: the velocimetric and statistical validation methods. In this seminar, I will first present the astrophysical motivations of finding (transiting) exoplanets and the limitations raised by the presence of false positives. I will then describe the two main solutions I'm using to overcome these limitations. This will be illustrated by the recent results achieved thanks to a 5-year programme with the SOPHIE spectrograph at Observatoire de Haute-Provence (France). This spectroscopic programme allowed us to derive unbiased statistical properties of giant transiting exoplanets within 400 days of period. In this context, I will finally present the on-going observing programmes to extend this work towards the new candidates detected by the K2 space mission.