The HARPS search for southern extra-solar planets^*

I. HD 330075 b: A new “hot Jupiter”

¹ Observatoire de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland e-mail: Francesco.Pepe@obs.unige.ch
² Physikalisches Institut Universität Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
³ Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53, 414 rue de la Piscine, 38041 Grenoble Cedex 9, France
⁴ Laboratoire d'Astrophysique de Marseille, Traverse du Siphon BP 8, 13376 Marseille Cedex 12, France
⁵ ESO La Silla Observatory, Alonso de Cordova 3107, Vitacura Casilla 19001, Santiago 19, Chile
⁶ ESO Head Quarter, Karl-Schwarzschild-Str. 2, 85748 Garching b. München, Germany
⁷ Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal

Received: 4 March 2004
Accepted: 11 May 2004

Abstract

We report on the first extra-solar planet discovered with the brand new HARPS instrument. The planet is a typical “hot Jupiter” with and an orbital period of 3.39 days, but from the photometric follow-up of its parent star HD 330075 we can exclude the presence of a transit. The induced radial-velocity variations exceed 100 m s^-1 in semi-amplitude and are easily detected by state-of-the-art spectro-velocimeters. Nevertheless, the faint magnitude of the parent star () benefits from the efficient instrument: with HARPS less than 10 observing nights and 3 h of total integration time were needed to discover the planet and characterize its orbit. The orbital parameters determined from the observations made during the first HARPS run in July 2003 have been confirmed by 7 additional observations carried out in February 2004. The bisector analysis and a photometric follow-up give no hint for activity-induced radial-velocity variations, indicating that the velocity curve is best explained by the presence of a low-mass companion to the star. In this paper we present a set of 21 measurements of excellent quality with weighted rms as low as 2.0 m s^-1. These measurements lead to a well defined orbit and consequently to the precise orbital parameters determination of the extra-solar planet HD 330075 b.