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.
@article{arxiv.1407.0251,
title = {The GAPS programme with HARPS-N@TNG IV: A planetary system around XO-2S},
author = {S. Desidera and A. S. Bonomo and R. U. Claudi and M. Damasso and K. Biazzo and A. Sozzetti and F. Marzari and S. Benatti and D. Gandolfi and R. Gratton and A. F. Lanza and V. Nascimbeni and G. Andreuzzi and L. Affer and M. Barbieri and L. R. Bedin and A. Bignamini and M. Bonavita and F. Borsa and P. Calcidese and J. M. Christille and R. Cosentino and E. Covino and M. Esposito and P. Giacobbe and A. Harutyunyan and D. Latham and M. Lattanzi and G. Leto and G. Lodato and C. Lovis and A. Maggio and L. Malavolta and L. Mancini and A. F. Martinez Fiorenzano and G. Micela and E. Molinari and C. Mordasini and U. Munari and I. Pagano and M. Pedani and F. Pepe and G. Piotto and E. Poretti and M. Rainer and I. Ribas and N. C. Santos and G. Scandariato and R. Silvotti and J. Southworth and R. Zanmar Sanchez},
journal= {arXiv preprint arXiv:1407.0251},
year = {2014}
}