SOPHIE velocimetry of Kepler transit candidates II. KOI-428b: a hot Jupiter transiting a subgiant F-star

TL;DR

This paper reports the discovery and characterization of KOI-428b, a hot Jupiter transiting a subgiant F-star, using Kepler photometry and SOPHIE radial velocity data, highlighting its significance as the largest evolved star with a transiting planet.

Contribution

First detection of a hot Jupiter transiting a subgiant F-star using combined Kepler and SOPHIE data, providing detailed stellar and planetary parameters.

Findings

KOI-428b has a radius of 1.17 RJup and a mass of 2.2 MJup.

The host star is a large, evolved F5IV star with R* = 2.13 Rsun and M* = 1.48 Msun.

The planet orbits its star every 6.87 days.

Abstract

We report the discovery of a hot Jupiter transiting a subgiant star with an orbital period of 6.87 days thanks to public photometric data from the Kepler space mission and new radial velocity observations obtained by the SOPHIE spectrograph. The planet KOI-428b with a radius of 1.17 +/- 0.04 RJup and a mass of 2.2 +/- 0.4MJup, orbits around a F5IV star with R* = 2.13 +/- 0.06Rsun, M* = 1.48 +/- 0.06 Msun and Teff = 6510 +/- 100 K. The star KOI-428 is the largest and the most evolved star discovered so far with a transiting planet.