EDP Sciences
Issue A&A
Volume 506, Number 1, October IV 2009
The CoRoT space mission: early results
Page(s) 287 - 302
Section Planets and planetary systems
DOI http://dx.doi.org/10.1051/0004-6361/200911933
Published online 11 August 2009

A&A 506, 287-302 (2009)
DOI: 10.1051/0004-6361/200911933

Transiting exoplanets from the CoRoT space mission

VIII. CoRoT-7b: the first super-Earth with measured radius
A. Léger1, D. Rouan2, J. Schneider3, P. Barge4, M. Fridlund5, B. Samuel1, M. Ollivier1, E. Guenther6, M. Deleuil4, H. J. Deeg7, M. Auvergne2, R. Alonso4, S. Aigrain8, A. Alapini8, J. M. Almenara7, A. Baglin2, M. Barbieri4, H. Bruntt2, P. Bordé1, F.  Bouchy9, J. Cabrera10, 3, C. Catala2, L. Carone11, S. Carpano5, Sz. Csizmadia10, R. Dvorak12, A. Erikson10, S. Ferraz-Mello13, B. Foing5, F. Fressin14, D. Gandolfi6, M. Gillon15, Ph. Gondoin5, O. Grasset16, T. Guillot14, A. Hatzes6, G. Hébrard17, L. Jorda4, H. Lammer18, A. Llebaria4, B. Loeillet1, 4, M. Mayor15, T. Mazeh19, C. Moutou4, M. Pätzold11, F. Pont8, D. Queloz15, H. Rauer10, 20, S. Renner10, 21, R. Samadi2, A. Shporer19, Ch. Sotin16, B. Tingley7, G. Wuchterl6, M. Adda2, P. Agogu22, T. Appourchaux1, H. Ballans1, P. Baron2, T. Beaufort5, R. Bellenger2, R. Berlin23, P. Bernardi2, D. Blouin4, F. Baudin1, P. Bodin22, L. Boisnard22, L. Boit4, F. Bonneau22, S. Borzeix2, R. Briet22, J.-T. Buey2, B. Butler5, D. Cailleau2, R. Cautain4, P.-Y. Chabaud4, S. Chaintreuil2, F. Chiavassa22, V. Costes22, V. Cuna Parrho2, F. De Oliveira Fialho2, M. Decaudin1, J.-M. Defise24, S. Djalal22, G. Epstein2, G.-E. Exil2, C. Fauré22, T. Fenouillet4, A. Gaboriaud22, A. Gallic2, P. Gamet22, P. Gavalda22, E. Grolleau2, R. Gruneisen2, L. Gueguen2, V. Guis4, V. Guivarc'h2, P. Guterman4, D. Hallouard22, J. Hasiba18, F. Heuripeau2, G. Huntzinger2, H. Hustaix22, C. Imad2, C. Imbert22, B. Johlander5, M. Jouret22, P. Journoud2, F. Karioty2, L. Kerjean22, V. Lafaille22, L. Lafond22, T. Lam-Trong22, P. Landiech22, V. Lapeyrere2, T. Larqué2, 22, P. Laudet22, N. Lautier2, H. Lecann4, L. Lefevre2, B. Leruyet2, P. Levacher4, A. Magnan4, E. Mazy24, F. Mertens2, J.-M. Mesnager22, J.-C. Meunier4, J.-P. Michel2, W. Monjoin2, D. Naudet2, K. Nguyen-Kim1, J.-L. Orcesi1, H. Ottacher18, R. Perez22, G. Peter23, P. Plasson2, J.-Y. Plesseria24, B. Pontet22, A. Pradines22, C. Quentin4, J.-L. Reynaud4, G. Rolland22, F. Rollenhagen23, R. Romagnan2, N. Russ23, R. Schmidt2, N. Schwartz2, I. Sebbag22, G. Sedes2, H. Smit5, M. B. Steller18, W. Sunter5, C. Surace4, M. Tello22, D. Tiphène2, P. Toulouse22, B. Ulmer25, O. Vandermarcq22, E. Vergnault22, A. Vuillemin4, and P. Zanatta2

1  Institut d'Astrophysique Spatiale, UMR 8617 CNRS, Bât. 121, Université Paris-Sud, 91405 Orsay, France
    e-mail: alain.leger@ias.fr
2  LESIA, UMR 8109 CNRS, Observatoire de Paris, UVSQ, Université Paris-Diderot, 5 place J. Janssen, 92195 Meudon, France
    e-mail: daniel.rouan@obspm.fr
3  LUTH, UMR 8102 CNRS, Observatoire de Paris-Meudon, 5 place J. Janssen, 92195 Meudon, France
4  Laboratoire d'Astrophysique de Marseille, UMR 6110 CNRS, Technopôle de Marseille- Etoile, 13388 Marseille Cedex 13, France
5  Research and Scientific Support Department, European Space Agency, ESTEC, 2200 Noordwijk, The Netherlands
6  Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
7  Instituto de Astrofísica de Canarias, C. via Lactea , 38200 La Laguna, Spain
8  School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
9  Observatoire de Haute Provence, USR 2207 CNRS, OAMP, 04870 St. Michel l'Observatoire, France
10  Institute of Planetary Research, DLR, Rutherfordstr. 2, 12489 Berlin, Germany
11  Rheinisches Institut für Umweltforschung, Universität zu Köln, Abt. Planetenforschung, Aachener Str. 209, 50931 Köln, Germany

12  Institute for Astronomy, University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria
13  Instituto de Astronomia, Geofisica e Ciências Atmosféricas, USP, Sao Paulo, Brazil
14  Observatoire de la Côte d'Azur, Laboratoire Cassiopée, CNRS UMR 6202, BP 4229, 06304 Nice Cedex 4, France
15  Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
16  Laboratoire de Planétologie et Géodynamique, UMR-CNRS 6112, 2 rue de la Houssiniére, 44322 NANTES Cedex 03, France
17  Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France
18  Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria
19  School of Physics and Astronomy, R. and B. Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
20  Center for Astronomy and Astrophysics, TU Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
21  Laboratoire d'Astronomie de Lille, Université de Lille 1, 1 impasse de l'Observatoire, 59000 Lille, France
22  Centre National d'Etudes Spatiales, 2 place Maurice Quentin 75039 Paris Cedex 01, France
23  Institute of Robotics and Mechatronics, DLR, Rutherfordstr. 2, 12489 Berlin, Germany
24  Centre Spatial de Liège, ULG Science Park, av. du Pré-Aly, 4031, Angleur-Liège, Belgique
25  Ingenieurbüro Ulmer, Im Technologiepark 1, 15236 Frankfurt/Oder, Germany

Received 23 February 2009 / Accepted 28 July 2009

Abstract
Aims. We report the discovery of very shallow ( $\Delta F/F \approx 3.4\times 10^{-4}$), periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT  satellite, which we interpret as caused by a transiting companion. We describe the 3-colour CoRoT data and complementary ground-based observations that support the planetary nature of the companion.
Methods. We used CoRoT  colours information, good angular resolution ground-based photometric observations in- and out- of transit, adaptive optics imaging, near-infrared spectroscopy, and preliminary results from radial velocity measurements, to test the diluted eclipsing binary scenarios. The parameters of the host star were derived from optical spectra, which were then combined with the CoRoT  light curve to derive parameters of the companion.
Results. We examined all conceivable cases of false positives carefully, and all the tests support the planetary hypothesis. Blends with separation >0.40´´or triple systems are almost excluded with a $8 \times 10^{-4}$ risk left. We conclude that, inasmuch we have been exhaustive, we have discovered a planetary companion, named CoRoT-7b, for which we derive a period of 0.853 $59 \pm 3 \times 10^{-5}$ day and a radius of $R_{\rm p} = 1.68 \pm 0.09$  $R_{\rm Earth}$. Analysis of preliminary radial velocity data yields an upper limit of 21  $M_{\rm Earth}$  for the companion mass, supporting the finding.
Conclusions. CoRoT-7b  is very likely the first Super-Earth with a measured radius. This object illustrates what will probably become a common situation with missions such as Kepler, namely the need to establish the planetary origin of transits in the absence of a firm radial velocity detection and mass measurement. The composition of CoRoT-7b  remains loosely constrained without a precise mass. A very high surface temperature on its irradiated face, $\approx$1800–2600 K at the substellar point, and a very low one, $\approx$50 K, on its dark face assuming no atmosphere, have been derived.


Key words: techniques: photometric -- techniques: spectroscopic -- planetary systems -- techniques: high angular resolution -- techniques: radial velocities



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Editor-in-Chief: T. Forveille
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