RESEARCH
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The SOPHIE search for northern extrasolar planets. IX. Populating the brown dwarf desert

P. A. Wilson, G. Hébrard, N. C. Santos, J. Sahlmann, G. Montagnier, N. Astudillo-Defru, I. Boisse, F. Bouchy, J. Rey, L. Arnold, X. Bonfils, V. Bourrier, B. Courcol, M. Deleuil, X. Delfosse, R. F. Díaz, D. Ehrenreich, T. Forveille, C. Moutou, F. Pepe, A. Santerne, D. Ségransan, S. Udry

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 MJup, 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 MJup to a mass of 0.35 ± 0.03 M. The orbital parameters of two previously known substellar candidates are improved.

Keywords
techniques: radial velocities, stars: general, brown dwarfs

Notes
Based on observations collected with the SOPHIE spectrograph on the 1.93 m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium.The radial velocity measurements are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A144

Astronomy and Astrophysics
Volume 588, Article Number A144, Number of pages 16
2016 April

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia