RESEARCH
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The HARPS search for southern extra-solar planets
XXIV. Companions to HD85390, HD90156 and HD103197: a Neptune analogue and two intermediate-mass planets

C. Mordasini, M. Mayor, S. Udry, C. Lovis, D. Sťgransan, W. Benz, J.-L. Bertaux, F. Bouchy, G. Lo Curto, C. Moutou, D. Naef, F. Pepe, D. Queloz, N. C. Santos

Abstract
We report the detection of three new extrasolar planets orbiting the solar type stars HD85390, HD90156 and HD103197 with the HARPS spectrograph mounted on the ESO 3.6-m telescope at La Silla observatory. HD85390 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 analogue 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. HD90156 is orbited by a warm Neptune analogue with a minimum mass of 17.98 M (1.05 M), a period of 49.8 days (a=0.25 AU) and an eccentricity of 0.31. HD103197 has an intermediate mass planet on a circular orbit (P = 47.8 d, Msin i = 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.

Keywords
planetary systems - techniques: radial velocities - stars: individual: HD85390 - stars: individual: HD90156 - stars: individual: HD103197 - planetary systems: formation

Notes
Based on observations made with the HARPS instrument on the ESO 3.6m telescope at La Silla Observatory under the GTO programme ID 072.C-0488.
Individual radial velocities are available electronically at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/526/A111

Astronomy and Astrophysics
Volume 526, Number of pages A111_1
2011 February

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Instituto de Astrof√≠sica e Ci√™ncias do Espa√ßo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia