The HARPS search for southern extra-solar planets. IV. Three close-in planets around HD 2638, HD 27894 and HD 63454
We report the discovery of three new planets, detected through Doppler measurements with the instrument harps installed on the ESO 3.6 m telescope, La Silla, Chile. These planets are orbiting the main-sequence stars HD 2638, HD 27894, and HD 63454. The orbital characteristics that best fit the observed data are depicted in this paper, as well as the stellar and planetary parameters. The planets' minimum mass is 0.48, 0.62, and 0.38 MJup for respectively HD 2638, HD 27894, and HD 63454; the orbital periods are 3.4442, 17.991, and 2.817822 days, corresponding to semi-major axis of 0.044, 0.122, and 0.036 AU, respectively. The observational data are carefully analysed for activity-induced effects and we conclude on the reliability of the observed radial-velocity variations as of exoplanetary origin. These three planets support the correlation between the star metallicity and the presence of planets (especially at short orbital distances), pointing towards the peculiar scenario of formation and migration of hot Jupiters.