OGLE-TR-3: A possible new transiting planet

Abstract

Recently, 59 low-luminosity object transits were reported from the Optical Gravitational Lensing Experiment (OGLE). Our follow-up low-resolution spectroscopy of 16 candidates provided two objects, OGLE-TR-3 and OGLE-TR-10, which have companions with radii compatible with those of gas-giant planets. Further high-resolution spectroscopy revealed a very low velocity variation (<500 ms-1) of the host star OGLE-TR-3 which may be caused by its unseen companion. An analysis of the radial velocity and light curve results in M < 2.5 MJup R < 1.6 RJup, and an orbital separation of about 5R⊙, which makes it the planet with the shortest period known. This allows to identify the low-luminosity companion of OGLE-TR-3 as a possible new gas-giant planet. If confirmed, this makes OGLE-TR-3 together with OGLE-TR-56 the first extrasolar planets detected via their transit light curves.