Refined parameters and spectroscopic transit of the super-massive planet HD 147506b

In this paper, we report a refined determination of the orbital parameters and the detection of the Rossiter-McLaughlin effect of the recently discovered transiting exoplanet HD 147506b (HAT-P-2b). The large orbital eccentricity at the short orbital period of this exoplanet is unexpected and is distinguishing from other known transiting exoplanets. We performed high-precision radial velocity spectroscopic observations of HD 147506 (HAT-P-2) with the new spectrograph SOPHIE, mounted on the 1.93 m telescope at the Haute-Provence observatory (OHP). We obtained 63 new measurements, including 35 on May 14 and 20 on June 11, when the planet was transiting its parent star. The radial velocity ( RV) anomaly observed illustrates that HAT-P-2b orbital motion is set in the same direction as its parent star spin. The sky-projected angle between the normal of the orbital plane and the stellar spin axis lambda = 0.2(-12.5)(+12.2) is consistent with zero. The planetary and stellar radii were re-determined, yielding R-p = 0.951(- 0.053)(+0.039) R-Jup, R-s = 1.416(-0.062)(+0.040) R-circle dot. The mass (M-p = 8.62(-0.55)(+0.39) M-Jup) and radius of HAT-P-2b indicate a density of 12.5(- 3.6)(+12.6) g cm(-3), suggesting an object in between the known close-in planets with typical density of the order of 1 g cm(-3), and the very low-mass stars, with density greater than 50 g cm(-3).