Résumé / Abstract Seminaire_IAP
« Radii, Masses, Densities, and Occurrence of Exoplanets within 0.25 AU of Solar-type stars »

Geoffrey W. Marcy
Dept. Astron., Univ. California (Berkeley, California, Etats-Unis d'Amérique)

We report the observed distribution of planet radii, masses, and orbital distances for orbital periods less than 50 days around Solar-type (GK) stars from. We draw from extensive Kepler and Doppler measurements that offer good completeness for planets with radii as small as 2.0 Earth-radii. We include the photometric signal-to-noise ratio for all 156,000 target stars to determine planet detectability as a function of planet radius and orbital period for each target. We consider Kepler target stars within the "Solar subset" having Teff = 4100--6100 K, logg= 4.0--4.9, and stars brighter than Kepler magnitude 15. The resulting occurrence of planets as a function of planet radius and orbital period increases strongly toward the smallest radii (2 Earth-radii) and toward longer orbital periods (up to 50 days, 0.25 AU). The distribution of planet radii increases rapidly with smaller planet size. This high occurrence of smaller planets supports core-accretion theory but disagrees with the theory of migration in a gaseous disk that predicts a desert at Super-Earth and Neptune sizes for close-in orbits, which is not seen. We explore the densities of exoplanets by combining radii from Kepler with masses from Doppler measurements.
vendredi 30 septembre 2011 - 11:00
Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris
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