The Rossiter-McLaughlin effect of CoRoT-3b and HD 189733b

We present radial-velocity sequences acquired during three transits of the exoplanet HD 189733b and one transit of CoRoT-3b. We applied a combined Markov-chain Monte-Carlo analysis of spectroscopic and photometric data on these stars, to determine a full set of system parameters including the projected spin-orbit misalignment angle of HD 189733b to an unprecedented precision via the Rossiter-McLaughlin effect: β = 0.85 ◦ +0.32 −0.28 . This small but non-zero inclination of the planetary orbit is important to understand the origin of the system. On CoRoT-3b, results seem to point towards a non-zero inclination as well with β = 37.6 ◦ +10.0 −22.3 , but this remains marginal. Systematic effects due to non-Gaussian cross-correlation functions appear to be the main cause of significant residuals that prevent an accurate determination of the projected stellar rotation velocity V sin(I) for both stars.