2015A&A...573L...5C

We report the first disclosure of the planetary nature of Kepler-432b (aka Kepler object of interest KOI-1299.01). 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 simultaneously fitting these new data and Kepler photometry, we found that Kepler-432b is a dense transiting exoplanet with a mass of M_p=4.87±0.48M_Jup and radius of R_p=1.120±0.036R_Jup. The planet revolves every 52.5d around a K giant star that ascends the red giant branch, and it moves on a highly eccentric orbit with e=0.535±0.030. By analysing two near-IR high-resolution images, we found that a star is located at 1.1'' from Kepler-432, but it is too faint to cause significant effects on the transit depth. Together with Kepler-56 and Kepler-91, Kepler-432 occupies an almost-desert region of parameter space, which is important for constraining the evolutionary processes of planetary systems.