SOPHIE velocimetry of Kepler transit candidates

IV. KOI-196b: a non-inflated hot Jupiter with a high albedo ^⋆

¹ Laboratoire d’Astrophysique de Marseille, Université d’Aix-Marseille & CNRS, 38 rue Frédéric Joliot-Curie, 13388 Marseille Cedex 13, France
e-mail: alexandre.santerne@oamp.fr
² Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis boulevard Arago, 75014 Paris, France
³ Observatoire de Haute-Provence, Université d’Aix-Marseille & CNRS, 04870 Saint Michel l’Observatoire, France

Received: 2 August 2011
Accepted: 12 September 2011

Abstract

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 $\mathrm{65}{\mathrm{0}}_{{}^{-300}\mathrm{+}\mathrm{2500}_{\mathrm{+}\mathrm{2500}}}^{{}_{\mathrm{+}\mathrm{2500}}}$ 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 $\mathrm{6}{\mathrm{4}}_{{}^{-12}\mathrm{+}\mathrm{10}_{\mathrm{+}\mathrm{10}}}^{{}_{\mathrm{+}\mathrm{10}}}$ 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.