The CORALIE survey for southern extra-solar planets. X. A Hot Jupiter orbiting HD 73256

Recent radial-velocity measurements obtained with the CORALIE spectrograph on the 1.2-m Euler Swiss telescope at La Silla unveil the presence of a new Jovian-mass Hot Jupiter around HD 73256. The 1.85-M_Jup planet moves on an extremely short-period (P = 2.5486 d), quasi-circular orbit. The best Keplerian orbital solution is presented together with an unsuccessful photometric planetary-transit search performed with the SAT Danish telescope at La Silla. Over the time span of the observations, the photometric follow-up of the candidate has nevertheless revealed a P =~ 14-d photometric periodicity corresponding to the rotational period of the star. This variation as well as the radial-velocity jitter around the Keplerian solution are shown to be related to the fair activity level known for HD 73256.

Based on observations collected with the CORALIE echelle spectrograph on the 1.2-m Euler Swiss telescope and the Strömgren Automatic Telescope (SAT) at La Silla Observatory, ESO Chile.