2014A&A...561L...1B

The exoplanet KOI-142b (Kepler-88b) shows transit timing variations (TTVs) with a semi-amplitude of ∼12h, 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 ∼10.92days 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^+0.0021_–0.0018days, 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 ±0.25days and a minimum planetary mass of 0.76^+0.32_0.16M_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.