The GAPS programme with HARPS-N at TNG

IV. A planetary system around XO-2S^⋆,⋆⋆

¹ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
e-mail: silvano.desidera@oapd.inaf.it
² INAF – Osservatorio Astrofisico di Torino, via Osservatorio 20, 10025 Pino Torinese, Italy
³ Osservatorio Astronomico della Regione Autonoma Valle d’Aosta, Fraz. Lignan 39, 11020 Nus ( Aosta), Italy
⁴ INAF – Osservatorio Astrofisico di Catania, via S.Sofia 78, 95123 Catania, Italy
⁵ Dipartimento di Fisica e Astronomia Galileo Galilei – Università di Padova, via Marzolo 8, 35131 Padova, Italy
⁶ Landessternwarte Königstuhl, ZAH, Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany
⁷ Dip. di Fisica e Astronomia Galileo Galilei – Università di Padova, Vicolo dell’Osservatorio 2, 35122 Padova, Italy
⁸ Fundación Galileo Galilei - INAF, Rambla José Ana Fernandez Pérez 7, 38712 Breña Baja, Spain
⁹ INAF – Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
¹⁰ INAF – Osservatorio Astronomico di Trieste, via Tiepolo 11, 34143 Trieste, Italy
¹¹ INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Italy
¹² Dept. of Physics, University of Perugia, via A. Pascoli 1, 06123 Perugia, Italy
¹³ INAF – Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
¹⁴ Instituto de Astrofisica de Canarias, C/via Lactea s/n, 38200 La Laguna, Spain
¹⁵ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA
¹⁶ Dipartimento di Fisica, Università di Milano, via Celoria 16, 20133 Milano, Italy
¹⁷ Obs. Astronomique de l’Univ. de Genève, 51 ch. des Maillettes, Sauverny, 1290 Versoix, Switzerland
¹⁸ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹⁹ INAF − IASF Milano, via Bassini 15, 20133 Milano, Italy
²⁰ Inst. de Ciencies de l’Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, 08193 Bellaterra, Spain
²¹ Centro de Astrofísica, Universidade do Porto, rua das Estrelas, 4150-762 Porto, Portugal
²² Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal
²³ Astrophysics Group, Keele University, Keele ST5 5BG, UK

Received: 4 June 2014
Accepted: 28 June 2014

Abstract

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.