A&A 474, 647-651 (2007)
DOI: 10.1051/0004-6361:20078129

The HARPS search for southern extra-solar planets

XII. A giant planet orbiting the metal-poor star HD 171028

N. C. Santos^{1, 2}, M. Mayor², F. Bouchy³, F. Pepe², D. Queloz², and S. Udry<sup>2

1</sup>  Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
    e-mail: nuno@astro.up.pt
²  Observatoire de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
³  Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France

(Received 21 June 2007 / Accepted 7 August 2007)

Abstract
In this paper we present the detection of a 1.8  planet in a 538-day period trajectory orbiting the metal-poor star HD 171028 ([Fe/H] = -0.49). This planet is the first to be discovered in the context of a HARPS program searching for planets around metal-poor stars. Interestingly, HD 171028 is one of the least metal-poor stars in the sample. This discovery is placed in the context of the models of planet formation and evolution.

Key words: stars: planetary systems -- planetary systems: formation -- techniques: radial velocity -- stars: abundances

© ESO 2007

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