COROT


A space mission dedicated to the sismology of celestial bodies and to the study of extrasolar planets

update: 27 November 2003

News

COROT is a space mission approved by the French Space Agency CNES, with a participation of Austria, Belgium, Brazil, Germany, Spain, ESA and ESTEC.

It is dedicated to stellar sismology and the the study of extrasolar planets.
It is the first approved space mission dedicated to these subjects.
It is to be launched in June 2006.

The spacecraft consists of a ~ 30 cm telescope with an array of CCD's as detectors. It will monitor the lightcurves of well chosen stars.


The present page is only about the extra-solar planets part of the mission.
Other COROT web sites are at:

  1. The occultation method of detection of planets
    1. History of the photometric detection method
      The idea of the detection of planets by their transits was originally proposed by O. Struve (1952), incidentally in a paper on spectroscopy.
      It was then investigated quantitatively by Rosenblatt (1971) and revisited by Borucki et al. (1984, 1988) who proposed the idea of a dedicated space mission.
      It was subsequently proposed by Schneider 1988) that a mission dedicated to stellar sismology could also search for planets by transits.
    2. Principles of the method; what can be learned about the planets
      The occultation method searches for planetary transits when the planet passes in front of its parent star. The main pertinent parameters are:
      1. The luminosity drop eta of the star :
        eta   =  (RPl/R*)2
      2. The geometric probability p of occultations
        p   =   R*/a
      3. The duration D of the transit
        D   =   (P/pi).(R*/a)
      where a is the orbital distance to the star and P the orbital period of the planet.

      The occultation method gives acces to:

      1. The orbital period, and thus the orbital distance to the star, of the planet
      2. The radius of the planet deduced from the luminosity drop during the transit
      3. The inclination i of the planetary orbit; this quantity becomes astrophysically interesting when compared to the equatorial plane of the parent star (deduced from its V.sin i and rotation period (Hale et. al. 1992).
    3. Advantages of the method
      1. The occultation method is one of the very few methods capable to detect Earth-sized planets in the Habitable Zone (HZ) of their parent star within the few next years.
        The HZ around a star is defined as the orbital distance at which the planet temperature allows for liquid water. This is of paramount importance for the search for Life in the Universe.
      2. It is a first step toward subsequent spectroscopic studies of the planet atmosphere (by absorption of the parent star's light) during the transit (Schneider 1994, Schneider & Doyle 1995, Coustenis et al. 1996)

  2. The COROT mission: extrasolar planets part
    The details of the payload are not entirely fixed. The incident beam after the main mirror is divided into two parts, one dedicated to sismology, the other to planetary transits.
    The planetary transits sector has two CCD's. The lightcurves of stars will be monitored in two colors. The overall potential of COROT is to detect several tens of Earth sized planets.

  3. References
    (for a more complete list, see the Extrasolar Planets Bibliography)

    1. BORUCKI, W. J., ALLEN L. E., TAYLOR W. S., YOUNG A. T. & SCHAEFER A. R., 1988
      A photometric approach to detecting earth-sized planets
      in Bioastronomy - The next steps; Proceedings of the Ninety-ninth IAU Colloquium, Balaton, Hungary, June 22-27, 1987, G. Marx (ed.), Kluwer
      abstract
    2. BORUCKI W. J. & SUMMERS A. L., 1984
      The photometric method of detecting other planetary systems
      Icarus, 58, 121
      abstract
    3. COUSTENIS A., SCHNEIDER J., BOCKELEE-MORVAN D., RAUER H., WITTEMBERG R., CHASSEFIERE E., GREENE T., PENNY A. & GUILLOT T., 1996
      Spectroscopy of 51 Peg B: Search for Atmospheric Signatures
      Planets Beyond the Solar System and the Next Generation of Space Missions
      Baltimore 16-18 October 1996
      abstract
    4. DELEUIL M., BARGE P., LEGER A. & SCHNEIDER J.,1996
      Detection of Earth-like Planets with the COROT Space Mission
      Planets Beyond the Solar System and the Next Generation of Space Mission, STScI, Baltimore 16 - 18 October 1996
      abstract
    5. HALE A. & DOYLE L., 1994
      The photometric method of extrasolar planets detection revisited
      Astr. & Spa. Sci., 212, 335
      abstract
    6. ROSENBLATT F. 1971
      A two-color photometric method for detection of extra-solar planetary systems
      Icarus, 14, 71
    7. SCHNEIDER J., 1996
      Photometric search for extrasolar planets
      Astr. & Spa. Sci., 241, 35
    8. SCHNEIDER J., 1994
      On the search for O2 in extrasolar planets.
      Astr. & Spa. Sci., 212, 321
      abstract
    9. SCHNEIDER J., 1988
      La recherche des planetes extrasolaires.
      in Journees d'exobiologie, CNES, 16 Nov. Raulin & Brack Eds. p. 93
    10. SCHNEIDER J. & CHEVRETON M., 1990
      The photometric search for earth-sized extrasolar planets by occultation in binary systems
      Astron. & Astrophys., 232, 251
      abstract
    11. SCHNEIDER J. & DOYLE L. R., 1995
      Ground-based detection of terrestrial extrasolar planets by photometry : the case for CM Draconis
      Earth, Moon & Planets, 71, 153
    12. STRUVE O., 1952
      The Observatory, 72, 199

  4. Other sites relevant to COROT