The GAPS programme with HARPS-N@TNG IV: A planetary system around XO-2S
  We performed an intensive radial velocity monitoring of XO-2S, the wide companion of the transiting planet-host XO-2N, using HARPS-N at TNG in the framework of the GAPS programme. The radial velocity measurements indicate the presence of a new planetary system formed by a planet that is slightly more massive than Jupiter at 0.48 au and a Saturn-mass planet at 0.13 au. Both planetary orbits are moderately eccentric and were found to be dynamically stable. There are also indications of a long-term trend in the radial velocities. This is the first confirmed case of a wide binary whose components both host planets, one of which is transiting, which makes the XO-2 system a unique laboratory for understanding the diversity of planetary systems. 
S. Desidera, A.S. Bonomo, R.U. Claudi, M. Damasso, K. Biazzo, A.   Sozzetti, F. Marzari, S. Benatti, D. Gandolfi, R. Gratton...
astro-ph.EP