A Transiting Extrasolar Giant Planet around the Star OGLE-TR-10

We report a transiting extrasolar giant planet around the star OGLE-TR-10 (orbitalperiod=3.1 days), which was uncovered as a candidate by the OGLE team in their photometric survey toward the Galactic center. We observed OGLE-TR-10 spectroscopically over a period of 2 yr (2002-2004), using the HIRES instrument with an iodine cell on the Keck I telescope, and measured small radial velocity variations that are consistent with the presence of a planetary companion. This confirms the earlier identification of OGLE-TR-10b by our team and also recently by Bouchy and coworkers as a possible planet. In addition, in this paper we are able to rule out a blend scenario as an alternative explanation. From an analysis combining all available radial velocity measurements with the OGLE light curve, we find that OGLE-TR-10b has a mass of 0.57+/-0.12M_J and a radius of 1.24+/-0.09R_J. These parameters bear close resemblance to those of the first known transiting extrasolar planet, HD 209458b.