Transiting exoplanets from the CoRoT space mission^⋆

XV. CoRoT-15b: a brown-dwarf transiting companion

¹ Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France
e-mail: bouchy@iap.fr
² Observatoire de Haute Provence, CNRS/OAMP, 04870 St Michel l’Observatoire, France
³ Laboratoire d’Astrophysique de Marseille, 38 rue Frédéric Joliot-Curie, 13388 Marseille Cedex 13, France
⁴ Université de Nice-Sophia Antipolis, CNRS UMR 6202, Observatoire de la Côte d’Azur, BP 4229, 06304 Nice Cedex 4, France
⁵ Department of Physics, Denys Wilkinson Building Keble Road, Oxford, OX1 3RH, UK
⁶ Rheinisches Institut für Umweltforschung an der Universität zu Köln, Aachener Strasse 209, Köln 50931, Germany
⁷ McDonald Observatory, The University of Texas, Austin, TX 78712, USA
⁸ Instituto de Astrofosica de Canarias, 38205 La Laguna, Tenerife, Spain
⁹ Departamento de Astrofísica, Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain
¹⁰ Observatoire de l’Université de Genève, 51 chemin des Maillettes, 1290 Sauverny, Switzerland
¹¹ LESIA, UMR 8109 CNRS, Observatoire de Paris, UPMC, Université Paris-Diderot, 5 place J. Janssen, 92195 Meudon, France
¹² Institut d’Astrophysique Spatiale, Université Paris XI, 91405 Orsay, France
¹³ Institute of Planetary Research, German Aerospace Center, Rutherfordstrasse 2, 12489 Berlin, Germany
¹⁴ University of Vienna, Institute of Astronomy, Türkenschanzstr. 17, 1180 Vienna, Austria
¹⁵ IAG, University of Sao Paulo, Brazil
¹⁶ Research and Scientific Support Department, ESTEC/ESA, PO Box 299, 2200 AG Noordwijk, The Netherlands
¹⁷ Thüringer Landessternwarte, Sternwarte 5, Tautenburg 5, 07778 Tautenburg, Germany
¹⁸ University of Liège, Allée du 6 août 17, Sart Tilman, Liège 1, Belgium
¹⁹ Space Research Institute, Austrian Academy of Science, Schmiedlstr. 6, 8042 Graz, Austria
²⁰ School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
²¹ Center for Astronomy and Astrophysics, TU Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
²² LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France

Received: 24 June 2010
Accepted: 30 September 2010

Abstract

We report the discovery by the CoRoT space mission of a transiting brown dwarf orbiting a F7V star with an orbital period of 3.06 days. CoRoT-15b has a radius of 1.12 R_Jup and a mass of 63.3 ± 4.1 M_Jup, and is thus the second transiting companion lying in the theoretical mass domain of brown dwarfs. CoRoT-15b is either very young or inflated compared to standard evolution models, a situation similar to that of M-dwarf stars orbiting close to solar-typestars. Spectroscopic constraints and an analysis of the lightcurve imply a spin period in the range 2.9–3.1 days for the central star, which is compatible with a double-synchronisation of the system.