SOPHIE velocimetry of Kepler transit candidates
X. KOI-142 c: first radial velocity confirmation of a non-transiting exoplanet discovered by transit timing

S. C. C. Barros, R. F. Díaz, A. Santerne, G. Bruno, M. Deleuil, J. -M. Almenara, A. S. Bonomo, F. Bouchy, C. Damiani, G. Hébrard, G. Montagnier, C. Moutou

Abstract
The exoplanet KOI-142b (Kepler-88b) shows transit timing variations (TTVs) with a semi-amplitude of ~12 h, which earned it the nickname “king of transit variations”. Only the transit of planet b was detected in the Kepler data with an orbital period of ~10.92 days and a radius of ~0.36 R_Jup. The TTVs together with the transit duration variations of KOI-142b were analysed recently, finding a unique solution for a companion-perturbing planet. An outer non-transiting companion was predicted, KOI-142c, with a mass of 0.626 ± 0.03 M_Jup and a period of 22.3397_-0.0018^+0.0021 days, which is close to the 2:1 mean-motion resonance with the inner transiting planet. We report an independent confirmation of KOI-142c using radial velocity observations with the SOPHIE spectrograph at the Observatoire de Haute-Provence. We derive an orbital period of 22.10 ± 0.25 days and a minimum planetary mass of 0.76_0.16^+0.32 M_Jup, both in good agreement with the predictions by previous transit timing analysis. Therefore, this is the first radial velocity confirmation of a non-transiting planet discovered with TTVs, providing an independent validation of the TTVs technique.

Keywords
planetary systems – stars: fundamental parameters – techniques: spectroscopic – techniques: radial velocities – stars: individual: KIC5446285 – stars: individual: Kepler-88

Notes
Based on observations collected with the NASA Kepler satellite and with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France.
Tables 2 and 3 are available in electronic form at http://www.aanda.org

Astronomy and Astrophysics
Volume 561, Page L1_1
January 2014

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