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The SOPHIE search for northern extrasolar planets XV. A warm Neptune around the M dwarf Gl 378

M. Hobson, X. Delfosse, N. Astudillo-Defru, I. Boisse, R. F. Díaz, F. Bouchy, X. Bonfils, T. Forveille, L. Arnold, S. Borgniet, V. Bourrier, B. Brugger, N. Cabrera, B. Courcol, S. Dalal, M. Deleuil, O. Demangeon, X. Dumusque, C. Moutou, F. Pepe, J. Rey, A. Santerne, N. C. Santos, M. Stalport, D. Ségransan, S. Udry, P. A. Wilson


We present the detection of a warm Neptune orbiting the M dwarf Gl 378, using radial velocity measurements obtained with the SOPHIE spectrograph at the Observatoire de Haute-Provence. The star was observed in the context of the SOPHIE exoplanet consortium’s sub-programme dedicated to finding planets around M dwarfs. Gl 378 is an M1 star, of solar metallicity, at a distance of 14.96 pc. The single planet detected, Gl 378 b, has a minimum mass of 13.02 MEarth and an orbital period of 3.82 days, which place it at the lower boundary of the hot Neptune desert. As one of only a few such planets around M dwarfs, Gl 378 b provides important clues to the evolutionary history of these close-in planets. In particular, the eccentricity of 0.1 may point to a high-eccentricity migration. The planet may also have lost part of its envelope due to irradiation.

techniques: radial velocities; planetary systems; stars: late-type; stars: individual: G1 378

Astronomy and Astrophysics
Volume 625, Article Number A18, Number of pages 8
2019 May

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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