Kepler-432 b: a massive planet in a highly eccentric orbit transiting a red giant

Abstract

We report the first disclosure of the planetary nature of Kepler-432 b (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-432 b is a dense transiting exoplanet with a mass of Mp = 4.87 +/- 0.48 MJup and radius of Rp = 1.120 +/- 0.036 RJup. The planet revolves every 52.5 d 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 NIR 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.

4 pages, 5 figures, accepted for publication in A&A Letters. Also see the companion paper by Ortiz et al

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• The Densities of Planets in Multiple Stellar Systems
• The Orbit and Mass of the Third Planet in the Kepler-56 System
• The Pan-Pacific Planet Search. II. Confirmation of a two-planet system around HD 121056
• Moderately Eccentric Warm Jupiters from Secular Interactions with Exterior Companions
• A planetary system and a highly eccentric brown dwarf around the giant stars HIP67851 and HIP97233
• The Curious Case of KOI 4: Confirming Kepler's First Exoplanet
• Kepler-432 b: a massive warm Jupiter in a 52-day eccentric orbit transiting a giant star
• Kepler-447b: a hot-Jupiter with an extremely grazing transit
• Eclipsing binaries and fast rotators in the Kepler sample. Characterization via radial velocity analysis from Calar Alto
• The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370
• Follow-up of non-transiting planets detected by Kepler. Confirmation of three hot-Jupiters and validation of three other planets
• A simple model to describe intrinsic stellar noise for exoplanet detection around red giants
• Companions to Kepler giant stars: A long-period eccentric substellar companion to KIC 3526061 and a stellar companion to HD 187878
• Observational studies of transiting extrasolar planets (invited review)