CoRoT finds transiting planet in synchronous orbit

Launched in December 2006, CoRoT is the first space mission designed to
search for extra-solar planets. It uses transits, the tiny dips in a star's
flux when a planet passes in front of it, to detect the planets and
measure, in combination with complementary ground-based observations, their
masses and radii. Because it is free of the perturbing effect of the
Earth's atmosphere, the satellite is expected to detect planets down to 1.5
Earth radii.

The most recent discovery of the CoRoT exoplanet programme is being
presented this week at the Cool Stars 15 meeting in St Andrews.

CoRoT-Exo-4b is a Jupiter-like planet (0.72 Jupiter masses, 1.17 Jupiter
radii) in a 9.2 day orbit, which makes it one of the longest period
transiting planets found yet. Thanks to CoRoT's continuous coverage over
several months, the CoRoT team were able to track variations in the host
star's brightness as dark spots on its surface rotate in and out of view,
and deduce its rotation period. They found that the star, whose mass is
1.16 Solar masses, is rotating synchronously with the planet's orbit, which
is somewhat surprising as the planet is thought to be too low mass and too
distant from its star to have had much effect on its rotation. Dr Suzanne
Aigrain, from the University of Exeter, who led the analysis of the
photometric data, said: "It is possible that the CoRoT-Exo-4 system just
formed that way, which in itself would be interesting. CoRoT will no doubt
find many more transiting planets, and by systematically measuring their
host stars' rotation periods we will gain valuable insight into how stars
interact with their planets". Dr Claire Moutou, from the Laboratoire
d'Astrophysique de Marseille (LAM), who led the spectroscopic follow-up,
mentioned that "the planet occupies a previously empty space on the
mass-period relation for transiting planets, which is a diagnostic of
planetary formation and evolution processes".

Credits: CoRoT is primarily a mission of the French space agency CNES, with
contributions from Austria, Belgium, Germany, Spain, Brazil and the
European Space Agency. The ground-based follow-up of the CoRoT detection
was done with the spectrographs SOPHIE on the 180cm telescope at the
Observatoire de Haute Provence (France), HARPS on the 3.6m telescope at La
Silla observatory (Chile) and UVES on the 8.2m Very Large Telescope at
Paranal observatory (Chile), the 1m telescope at the Wise Observatory in
Israel, the 1m Euler telescope at La Silla, and the 3.6m
Canada-France-Hawaii telescope.

Contacts:

- Dr Suzanne Aigrain (University of Exeter): 07786 245 237;
S.Aigrain exeter.ac.uk

- Dr Claire Moutou (Laboratoire d'Astrophysique de Marseille):
Claire.Moutou oamp.fr

- Dr Annie Baglin (mission PI - Observatoire de Paris Meudon):
Annie.Baglin obspm.fr