Radial velocity data of Kepler-432

We accurately constrained its mass and eccentricity by high-precision radial velocity measurements obtained with the CAFE spectrograph at the CAHA 2.2-m telescope. By a simultaneous fit of these new data and Kepler photometry, we found that KOI-1299 b is a dense transiting exoplanet, having a mass of Mp=4.87+/-0.48M_Jup_ and radius of Rp=1.120+/-0.036R_Jup_.

The planet revolves around a K giant star, ascending the red giant branch, every 52.5d, moving on a highly eccentric orbit with e=0.535+/-0.030. By analysing two NIR high-resolution images, we found that a star occurs at 1:100 from Kepler-432, but it is too faint to cause significant effects on the transit depth. Together with Kepler-56 and Kepler-91, KOI-1299 occupies an almost-desert region of parameter space, which is important to constrain the evolutionary processes of planetary systems.