Transiting exoplanets from the CoRoT space mission

XXII. CoRoT-16b: a hot Jupiter with a hint of eccentricity around a faint solar-like star^⋆,⋆⋆

¹ Institut d’astrophysique spatiale, Université Paris-Sud 11 & CNRS (UMR 8617), Bât. 121, 91405 Orsay, France
e-mail: marc.ollivier@ias.u-psud.fr
² IAG, Université de Liège, Allée du 6 août 17, Liège 1, Belgium
³ Laboratoire d’Astrophysique de Marseille – LAM, Université d’Aix-Marseille & CNRS, UMR 7326, 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13, France
⁴ Thüringer Landessternwarte, 07778 Tautenburg, Germany
⁵ Université de Nice-Sophia Antipolis, CNRS UMR 6202, Observatoire de la Côte d’Azur, BP 4229, 06304 Nice Cedex 4, France
⁶ Department of Physics and AstronomyAarhus University, 8000 Aarhus C, Denmark
⁷ Institute of Planetary Research, German Aerospace Center, Rutherfordstrasse 2, 12489 Berlin, Germany
⁸ McDonald Observatory, University of Texas at Austin, Austin, 78712 TX, USA
⁹ Research and Scientific Support Department, European Space Agency, Keplerlaan, 2200 AG Noordwijk, The Netherlands
¹⁰ Department of Physics, Denys Wilkinson Building Keble Road, Oxford, OX1 3RH, UK
¹¹ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
¹² Departamento de Astrofísica, Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain
¹³ Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
¹⁴ LESIA, UMR 8109 CNRS, Observatoire de Paris, UVSQ, Université Paris-Diderot, 5 place J. Janssen, 92195 Meudon, France
¹⁵ Institut d’astrophysique de Paris, Université Paris 6 & CNRS (UMR 7095), 98 bd Arago, 75014 Paris, France
¹⁶ Observatoire de Haute-Provence, CNRS & OAMP, 04870 St-Michel l’ Observatoire, France
¹⁷ Rheinisches Institut für Umweltforschung an der Universität zu Köln, Aachener Str. 209, 50931 Köln, Germany
¹⁸ Institute for Astronomy, University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria
¹⁹ Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Brasil
²⁰ Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, Graz, Austria
²¹ Wise Observatory, Tel AvivUniversity, 69978 Tel Aviv, Israel
²² Center for Astronomy and Astrophysics, TU Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
²³ Laboratoire de l’univers et de ses théories, Observatoire de Paris & CNRS (UMR 8102), 5 place Jules Janssen, 92195 Meudon, France

Received: 10 June 2011
Accepted: 16 March 2012

Abstract

Aims. We report the discovery of CoRoT-16b, a low density hot jupiter that orbits a faint G5V star (mV = 15.63) in 5.3523 ± 0.0002 days with slight eccentricity. A fit of the data with no a priori assumptions on the orbit leads to an eccentricity of 0.33 ± 0.1. We discuss this value and also derive the mass and radius of the planet.

Methods. We analyse the photometric transit curve of CoRoT-16 given by the CoRoT satellite, and radial velocity data from the HARPS and HIRES spectrometers. A combined analysis using a Markov chain Monte Carlo algorithm is used to get the system parameters.

Results. CoRoT-16b is a 0.535  −0.083/+0.085 M_J, 1.17  −0.14/+0.16 R_J hot Jupiter with a density of 0.44  −0.14/+0.21 g cm^-3. Despite its short orbital distance (0.0618 ± 0.0015 AU) and the age of the parent star (6.73  ±  2.8 Gyr), the planet orbit exhibits significantly non-zero eccentricity. This is very uncommon for this type of objects as tidal effects tend to circularise the orbit. This value is discussed taking into account the characteristics of the star and the observation accuracy.