In this paper we present the detection of a 1.8 M _ { \mathrm { 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 .