Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates. III. Accurate Radius and Period for OGLE‐TR‐111‐b

Abstract

We present accurate V-band photometry for a planetary transit of OGLE-TR-111 acquired with VIMOS at the ESO Very Large Telescope. The measurement of this transit allows to refine the planetary radius, obtaining Rp= 1.01 0.06 RJ. Given the mass of Mp = 0.53 MJ previously measured from radial velocities, we confirm that the density is rhop= 0.6 0.2 g/cm 3. We also revise the ephemeris for OGLE-TR-111-b, obtaining an accurate orbital period P= 4.014484 0.000014 days, and predicting that the next observable transits would occur around December 2006, and after that only in mid-2008. Even though this period is different from previously published values, we cannot yet rule out a constant period.