The SOPHIE search for northern extrasolar planets. XV. A warm Neptune around the M dwarf Gl 378
Bouchy, F.; Deleuil, M.; Moutou, C.; Montagnier, G.; Ségransan, D.; Bonfils, X.; Santos, N. C.; Udry, S.; Pepe, F.; Bourrier, V.; Mousis, O.; Kiefer, F.; Hébrard, G.; Boisse, I.; Dalal, S.; Delfosse, X.; Díaz, R. F.; Forveille, T.; Dumusque, X.; Demangeon, O.; Arnold, L.; Lopez, T.; Astudillo-Defru, N.; Brugger, B.; Hobson, M. J.; Mignon, L.; Rey, J.; Santerne, A.; Stalport, M.; Wilson, P. A.; Hara, N.; Borgniet, S.; Courcol, B.; Cabrera Salazar, N.
France, Chile, Argentina, Switzerland, Portugal, United States, United Kingdom
Abstract
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.
Based on observations collected with the SOPHIE spectrograph on the 1.93 m telescope at the Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium.