The HARPS survey for southern extra-solar planets II. A 14 Earth-masses exoplanet around μ Arae

N. C. Santos (1, 2) , François Bouchy (3) , M. Mayor (2) , F. Pepe (2) , D. Queloz (2) , S. Udry (2) , C. Lovis (2) , M. Bazot (4) , W. Benz (5) , Jean-Loup Bertaux (6) , G. Lo Curto (7) , X. Delfosse (8) , C. Mordasini (5) , D. Naef (2, 7) , J. -P. Sivan (3) , S. Vauclair (4)

1 CAAUL - Centro de Astronomia e Astrofísica da Universidade de Lisboa
2 ObsGE - Observatoire Astronomique de l'Université de Genève
3 LAM - Laboratoire d'Astrophysique de Marseille
4 LATT - Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées
5 Physikalisches Institut [Bern]
6 SA - Service d'aéronomie
7 ESO - European Southern Observatory
8 LAOG - Laboratoire d'Astrophysique de Grenoble

In this letter we present the discovery of a very light planetary companion to the star mu Ara (HD160691). The planet orbits its host once every 9.5days, and induces a sinusoidal radial velocity signal with a semi-amplitude of 4.1 m/s, the smallest Doppler amplitude detected so far. These values imply a mass of m2 sini = 14 earth-masses. This detection represents the discovery of a planet with a mass slightly smaller than that of Uranus, the smallest ``ice giant" in our Solar System. Whether this planet can be considered an ice giant or a super-earth planet is discussed in the context of the core-accretion and migration models.

Mots clés: radial velocities; planetary systems; HD 160691; stars

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

N. C. Santos, François Bouchy, M. Mayor, F. Pepe, D. Queloz, et al.. The HARPS survey for southern extra-solar planets II. A 14 Earth-masses exoplanet around μ Arae. Astronomy and Astrophysics - A&A, 2004, 426 (1), pp.L19-L23. ⟨10.1051/0004-6361:200400076⟩. ⟨hal-00082280⟩