The SOPHIE search for northern extrasolar planets XV. A Warm Neptune around the M-dwarf Gl378

TL;DR

This paper reports the discovery of a Warm Neptune orbiting the M-dwarf Gl378, providing insights into the characteristics and evolution of close-in Neptunes around low-mass stars.

Contribution

It presents the detection of a Warm Neptune around an M-dwarf using radial velocity data, highlighting its position near the Hot Neptune desert and implications for planetary migration.

Findings

Gl378 b has a minimum mass of 13.02 Earth masses.

Orbital period of 3.82 days places it near the Hot Neptune desert.

Eccentricity of 0.1 suggests possible high-eccentricity migration.

Abstract

We present the detection of a Warm Neptune orbiting the M-dwarf Gl378, 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 exoplanets consortium's subprogramme dedicated to finding planets around M-dwarfs. Gl378 is an M1 star, of solar metallicity, at a distance of 14.96 pc. The single planet detected, Gl378 b, has a minimum mass of 13.02 $\rm M_{Earth}$ 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, Gl378 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.