Rich exoplanet harvest for CoRoT: seven new planets with diverse characteristics

Today, the CoRoT team, that includes IAP researchers, announces the discovery of one brown dwarf and six new planets with diverse characteristics. CoRoT, a space telescope operated by the French space agency CNES, discovers exoplanets when they pass in front of their stars, via the so-called transit method. Once CoRoT detects a transit, additional observations are made from the ground, notably with the spectrographs HARPS (ESO) and Sophie (INSU-CNRS). Although astronomers cannot see the planets directly, they use the space- and ground-based data to measure the sizes, masses, and orbits of these new planets precisely. This is why, among all known exoplanets, it is those that transit which yield the most complete information about planet formation and evolution.

CoRoT-8b: the smallest in this batch
At about 70% of the size and mass of Saturn, CoRoT-8b is moderately small among the previously known transiting exoplanets. Its internal structure should be similar to that of ice giants, like Uranus and Neptune in the Solar System. It is the smallest planet discovered by the CoRoT team so far after CoRoT-7b, the first transiting Super-Earth.

CoRoT-10b: the eccentric giant
The orbit of CoRoT-10b, is so elongated that the planet passes both very close to and very far away from its star. The amount of radiation it receives from the star varies tenfold in in-tensity, and scientists estimate that its surface temperature may increase from 250 to 600°C, all in the space of 13 Earth-days (the length of the year on CoRoT-10b).

CoRoT-11b: the planet whose star does the twist
CoRoT-11, the host star of CoRoT-11b, rotates around its axis in 40 hours. For compari-son, the Sun’s rotation period is 26. It is particularly difficult to confirm planets around rapidly rotating stars, so this detection marks a significant achievement for the CoRoT team.

CoRoT-12b, 13b and 14b: a trio of giants
These three planets all orbit close to their host star but have very different properties. Al-though CoRoT-13b is smaller than Jupiter, it is twice as dense. This suggests the presence of a massive rocky core inside the planet. On the other hand, CoRoT-12b and 14b are 16 and 15 times larger than the Earth, respectively.

CoRoT-15b: the brown dwarfe
CoRoT-15b’s mass is about 60 times that of Jupiter. This makes it incredibly dense, about 40 times more so than Jupiter. For that reason, it is classified as a brown dwarf, intermedi-ate in nature between planets and stars. Brown dwarfs are much rarer than planets, which makes this discovery all the more exciting.

CoRoT detects planets by searching for transits, minute periodic dim-mings of a star which occur when a planet in orbit around them crosses the stellar disk. This is a complex and time-consuming endeavour, which requires follow-up observations from the ground, but it has the unique advantage of yielding both the size and the mass of the planet, and thus its mean density. This gives a first order estimate of the bulk composition of the planet (is it a gaseous giant like Jupiter, or a terrestrial planet like Earth, or something in between). Together with the orbital characteristics, which can be particularly well determined for transiting planets, these parameters are key to understand-ing how different kinds of planets form and evolve. In the last fifteen years, astronomers have discovered over 450 exoplanets, of which only 82 transit across their host star. 15 of those were first spotted by CoRoT.

The CoRoT satellite has been developed and is exploited by CNES in partnership with labora-tories associated to CNRS-INSU, including the Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique (CNRS, Observatoire de Paris, Université Pierre et Marie Curie, Université Denis Diderot), the Laboratoire d’Astrophysique de Marseille (CNRS, Université Aix-Marseille 1, Observatoire Astronomique de Marseille Provence, OSU/INSU), the Institut d’Astrophysique Spatiale in Orsay (CNRS, Université Paris-Sud 11, OSU/INSU), the Institut d'Astrophysique de Paris (CNRS, Université Pierre et Marie Curie, OSU/INSU), the Laboratoire Cassiopée for astrophysics, mecaniscs and data analysis (Observatoire de la Côte d'Azur, OSU/INSU, CNRS, Université de Nice Sophia-Antipolis), the Observatoire Midi Pyrénées in Toulouse (Observatoire des Sciences de l’Univers du CNRS-INSU et de l’Université Paul Sabatier). The project also benefits from significant participations from Austria, Belgium, the European Space Agency (ESA), Germany, Spain, and Brazil.

Rich exoplanet harvest for CoRoT
Rich exoplanet harvest for CoRoT


IAP contacts:
François Bouchy
Observatoire de Haute-Provence
Institut d’Astrophysique de Paris
98bis, bd Arago
F-75014 Paris
bouchy à
Tél. : 33-4-9270-6494
Guillaume Hébrard
Institut d’Astrophysique de Paris
98bis, bd Arago
F-75014 Paris
hebrard à
Tél. : 33-1-4432-8078
Fax : 33-1-4432-8001

14 June 2010