The SOPHIE search for northern extrasolar planets

IX. Populating the brown dwarf desert^⋆,⋆⋆

¹ Institut d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre & Marie Curie, 98bis boulevard Arago, 75014 Paris, France
e-mail: pwilson@iap.fr
² Observatoire de Haute-Provence, CNRS, Université d’Aix-Marseille, 04870 Saint-Michel-l’Observatoire, France
³ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
⁴ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
⁵ European Space Agency, European Space Astronomy Centre, PO Box 78, Villanueva de la Canada, 28691 Madrid, Spain
⁶ Univ. Grenoble Alpes, IPAG, 38000 Grenoble, France
⁷ CNRS, IPAG, 38000 Grenoble, France
⁸ Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
⁹ Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
¹⁰ Canada-France-Hawaii Telescope Corporation, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743, USA

Received: 16 October 2015
Accepted: 4 February 2016

Abstract

Radial velocity planet search surveys of nearby solar-type stars have shown a strong scarcity of brown dwarf companions within ~5 AU. There is presently no comprehensive explanation for this lack of brown dwarf companions; therefore, increasing the sample of such objects is crucial to understand their formation and evolution. Based on precise radial velocities obtained using the SOPHIE spectrograph at Observatoire de Haute-Provence we characterise the orbital parameters of 15 companions to solar-type stars and constrain their true mass using astrometric data from the Hipparcos space mission. The nine companions not shown to be stellar in nature have minimum masses ranging from ~13 to 70 M_Jup, and are well distributed across the planet/brown dwarf mass regime, making them an important contribution to the known population of massive companions around solar-type stars. We characterise six companions as stellar in nature with masses ranging from a minimum mass of 76 ± 4 M_Jup to a mass of 0.35 ± 0.03 M_⊙. The orbital parameters of two previously known substellar candidates are improved.