The CORALIE survey for southern extra-solar planets^*

X. A Hot Jupiter orbiting HD 73256

¹ Observatoire de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
² Niels Bohr Institute for Astronomy, Physics and Geophysics; Astronomical Observatory, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
³ Royal Observatory of Belgium, Ringlaan 3, 1180 Brussel and Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
⁴ Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal

Corresponding author: S. Udry, stephane.udry@obs.unige.ch

Received: 14 April 2003
Accepted: 27 May 2003

Abstract

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 -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.