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

TL;DR

This paper reports the discovery and characterization of KOI-196b, a non-inflated hot-Jupiter with a high albedo, detected via Kepler photometry and SOPHIE radial velocities, with unique properties among close-in exoplanets.

Contribution

First detailed characterization of KOI-196b, revealing a non-inflated hot-Jupiter with high albedo and detection of secondary transit and phase variation using Kepler data.

Findings

KOI-196b has a radius smaller than Jupiter, indicating a non-inflated planet.

Detected secondary transit with a depth of 64 ppm and optical phase variation.

Measured a high geometric albedo of 0.30, higher than most hot-Jupiters.

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\pm0.6s 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 0.841\pm0.032 Rjup and a mass of 0.49\pm0.09 Mjup, orbits a G2V star with R* = 0.996\pm0.032 Rsun, M*= 0.94\pm0.09 Msun, [Fe/H] = -0.10\pm0.16 dex, Teff= 5660\pm100 K and an age of 7.7\pm3.4 Gy. KOI-196b is one the rare close-in hot-Jupiters with a radius smaller than Jupiter suggesting 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 Ag = 0.30\pm0.08 which is higher than most of the transiting hot-Jupiters with a measured Ag. Assuming no heat recirculation, we find a day-side temperature of Tday = 1930\pm80 K. KOI-196b seems to be one of the rare hot-Jupiters located in the short-period hot-Jupiter desert.