Topic: Cool Stars as Exoplanet Hosts
CoRoT is a successfull satellite misison on a low-Earth orbit. It already discovered more than 25 exoplanets, including the first rocky planet with measured radius (CoRoT-7b), the first Jupiter-sized planets with moderate temperature and measured radius (P=95 days, CoRoT-9b), several Neptune- and subsaturn-sized exoplanets and many hot Jupiters. Among the host stars we can find several cool K type stars, too. We re-analyzed the transit events of all CoRoT transiting exoplanets in a homogeneous way, using several improvements: (i) the latest version of the data reduction pipeline, that includes several improvements (ii) a newly developed method to determine the so-called contamination, caused by the large (20x80 arcseconds) PSF of CoRot, (iii) new limb darkening treatment, that means improvement because limb darkening tables were not available for the CoRot passpands at the beginning of the mission, (iv) new orbital treatment because the eccentricities were not well constrained by the radial velocity measurements in some cases, (v) usage of the unbinned light curves instead of the binned one to avoid problems related to binning. As a result, we have a comprehensive table of all the relevant parameters for all the CoRoT planets, and our catalogue contains refined and updated physical and geometrical elements. We also studied the effect of the poorly known limb darkening, and how the stellar spots affect the results, especially the precision of the planet radius determination. In this talk we concentrate on the coolest host stars of the CoRoT exoplanets, which are mostly K dwarfs: how good is the agreement between the observed and theoretically predicted limb darkening coefficients, and what can we learn from such observational tests?