The GAPS programme with HARPS-N@TNG IV: A planetary system around XO-2S

摘要

We performed an intensive radial velocity monitoring of XO-2S, the widecompanion of the transiting planet-host XO-2N, using HARPS-N at TNG in theframework of the GAPS programme. The radial velocity measurements indicate thepresence of a new planetary system formed by a planet that is slightly moremassive than Jupiter at 0.48 au and a Saturn-mass planet at 0.13 au. Bothplanetary orbits are moderately eccentric and were found to be dynamicallystable. There are also indications of a long-term trend in the radialvelocities. This is the first confirmed case of a wide binary whose componentsboth host planets, one of which is transiting, which makes the XO-2 system aunique laboratory for understanding the diversity of planetary systems.