The HARPS search for southern extra-solar planets. XII. A giant planet orbiting the metal-poor star HD 171028

In this paper we present the detection of a 1.8 M_Jup 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.

Based on observations collected at the La Silla Parana Observatory, ESO (Chile) with the HARPS spectrograph at the 3.6 m telescope, under the GTO program 072.C-0488.