We study the Kepler object Kepler-432, an evolved star ascending the red giant branch. By deriving precise radial velocities from multi-epoch high-resolution spectra of Kepler-432 taken with the CAFE spectrograph at the 2.2m telescope of Calar Alto Observatory and the FIES spectrograph at the Nordic Optical Telescope of Roque de Los Muchachos Observatory, we confirm the planetary nature of the object Kepler-432 b, which has a transit period of 52 days. We find a planetary mass of Mp=5.84 +\- 0.05 Mjup and a high eccentricity of e=0.478 +\- 0.004. With a semi-major axis of a=0.303 +\- 0.007 AU, Kepler-432 b is the first bona fide warm Jupiter detected to transit a giant star. We also find a radial velocity linear trend of 0.44 +\- 0.04 m s−1 d−1, which suggests the presence of a third object in the system. Current models of planetary evolution in the post-main-sequence phase predict that Kepler-432 b will be most likely engulfed by its host star before the latter reaches the tip of the red giant branch.
@article{arxiv.1410.3000,
title = {Kepler-432 b: a massive warm Jupiter in a 52-day eccentric orbit transiting a giant star},
author = {Mauricio Ortiz and Davide Gandolfi and Sabine Reffert and Andreas Quirrenbach and Hans J. Deeg and Raine Karjalainen and Pilar Montañes-Rodríguez and David Nespral and Grzegorz Nowak and Yeisson Osorio and Enric Palle},
journal= {arXiv preprint arXiv:1410.3000},
year = {2014}
}
Comments
5 pages, 3 figures. Accepted for publication in A&A. Updated title and corrected typos. See also paper by Ciceri et al