SOPHIE velocimetry of Kepler transit candidates. IV. KOI-196b: a non-inflated hot Jupiter with a high albedo

We report the discovery of a new hot-Jupiter, KOI-196b, transiting a solar-type star with an orbital period of 1.855558 days ± 0.6 s thanks to public photometric data from the Kepler space mission and new radial velocity observations obtained by the SOPHIE spectrograph mounted on the 1.93-m telescope at the Observatoire de Haute-Provence, France. The planet KOI-196b, with a radius of 0.89 ± 0.05 R_Jup and a mass of 0.55 ± 0.09 M_Jup, orbits a G6V star with R_⋆ = 1.02 ± 0.03 R_⊙, M_⋆ = 1.12 ± 0.07 M_⊙, [Fe/H] = 0.29 ± 0.16 dex, T_eff = 5620 ± 140 K, and an age of 650 ⁺²⁵⁰⁰_-300} Myr. KOI-196b is one of the rare close-in hot Jupiters with a radius smaller than Jupiter suggesting that it is a non-inflated planet. The high precision of the Kepler photometry permits us to detect the secondary transit with a depth of 64 ⁺¹⁰_-12} ppm as well as the optical phase variation. We find a geometric albedo of A_g = 0.30 ± 0.08, which is higher than most of the transiting hot Jupiters with a measured A_g. Assuming no heat recirculation, we find a day-side temperature of T_day = 1730 ± 400 K. The planet KOI-196b seems to be one of the rare hot Jupiters located in the short-period hot-Jupiter desert.

Based on observations made with SOPHIE on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France.