Paris, May 3, 2007

Success for the first observations by the Corot satellite : An exoplanet discovered and first stellar oscillations

Corot discovers its first exoplanet, named Corot – Exo-1b, and detects its first oscillations in a Sun-like star.

Following its launch into a nearly perfect orbit on 27 December 2006 by a Soyouz 1B launch vehicle from the Russian base in Kazakhstan, the Corot satellite has not only carried out in-flight verifications and calibrations but also its first scientific observations. The satellite is the result of close collaboration between CNES, CNRS and ESA, Germany, Austria, Belgium, Brazil and Spain. It has the dual goal of carrying out the first systematic seismic observations of stars other than the Sun, and undertaking a search for planets similar to our own with an unprecedented level of accuracy. Its findings are eagerly awaited both by scientists and the general public.


Everything on board is working as planned, and indeed in some cases significantly better, which will have a major impact on the mission. Although more time will be needed for the systematic scientific evaluation of the findings now being received, we can today present some initial results which demonstrate the outstanding quality of this satellite.


The two main features of this mission are, on the one hand, that it enables the same stars to be observed uninterruptedly (which has already been achieved for over 60 days), and on the other, that variations in their brightness can be measured with great accuracy.


Since not all sources of noise and disturbances have yet been taken into account, what we present today are basically raw data, which makes these initial results, which already exceed all expectations, appear even more impressive.


For instance, the data for the first exoplanet discovered by Corot (Corot – Exo-1b) is accurate to 3 parts in ten thousand (3 x 10-4) for one hour's observation.  When all the corrections have been carried out, the level of accuracy will reach 50 ppm (5 x 10-5). The accuracy can even reach 20 ppm (2 x 10-5) if the number of transits observed exceeds 25. This means that Corot will be able to observe small Earth-like planets, and that the variations in the starlight reflected by the planet (depending on its reflectance) will be detectable, which will give us information about its composition.


The seismic data is just as impressive. The Sun-like star presented here was observed for the first 60 days of the mission. Here too, the data have not been fully corrected. The accuracy achieved is less than 1 ppm, and the harmonic analysis clearly shows the presence of oscillation modes.


Since 1995, over 200 planets have been discovered orbiting round stars other than the Sun, and detected using the radial velocity method.


COROT is now all set to search for smaller exoplanets thanks to its extremely accurate photometer, which was developed by CNES working in a joint team with CNRS laboratories, among which the main ones are:


·          Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique (CNRS, Observatoire de Paris, Universités de Paris VI et VII),

·          Laboratoire d'Astrophysique de Marseille (CNRS, Université d'Aix-Marseille ; Observatoire Astronomique Marseille Provence),

·          Institut d'astrophysique spatiale (CNRS, Université d'Orsay ; Observatoire des Sciences de l'Univers),

·          Laboratoire d'Astrophysique de Toulouse et Tarbes (CNRS, Université de Toulouse 3 ;

Observatoire Midi-Pyrénées).



You can also consult our web sites:


Corot 1


Transit of a planet (fall in the brightness of the parent star when the planet passes in front of it) as observed by Corot. This is a very hot giant planet. It has a period of 1.5 days and its radius is estimated to be between 1.5 and 1.8 times that of Jupiter. By using ground-based spectroscopic observations, it was also possible to measure the mass of the planet as being 1.3 times that of Jupiter. The parent star is a dwarf star similar to the Sun


Corot 2


Spectral analysis of this light curve showing weak components in the 1.5 to 2 mHz region and the typically regular structure of Sun-like pulsators. These periods, which correspond to the star's oscillation modes, will be interpreted in order to determine its internal structure and age



Annie Baglin, PI
01 45 07 77 37

Philippe CHAUVIN
Communication astronomie
01 44 96 43 36

Sandra Laly
Service de Presse
01 44 76 76 87


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