The HARPS search for southern extra-solar planets - XXIV. Companions to HD?85390, HD?90156, and HD?103197: a Neptune analog and two intermediate-mass planets

摘要

We report the detection of three new extrasolar planets orbiting the solar type stars HD?85390, HD?90156 and HD?103197 with the HARPS spectrograph mounted on the ESO 3.6-m telescope at La?Silla observatory. HD?85390 has a planetary companion with a projected intermediate mass (42.0???M⊕) on a 788-day orbit (a?=?1.52?AU) with an eccentricity of 0.41, for which there is no analog in the solar system. A drift in the data indicates the presence of another companion on a long-period orbit, which is however not covered by our measurements. HD?90156 is orbited by a warm Neptune analog with a minimum mass of 17.98?M⊕ (1.05? ), a period of 49.8 days (a?=?0.25?AU), and an eccentricity of?0.31. HD?103197 has an intermediate-mass planet on a circular orbit (P?=?47.8 d, M sini?=?31.2???M⊕). We discuss the formation of planets of intermediate mass (~30–100?M⊕), which should be rare inside a few?AU according to core accretion formation models.