HR: 16:15h
AN: P54A-02    [Abstracts]
TI: Mass- radius relationships for Super-Earths and Water-rich planets: an estimate of the uncertainties.
AU: * Grasset, O
EM: olivier.grasset@univ-nantes.fr
AF: Planetology Department Nantes university, 2 rue de la Houssinià¨re, Nantes, 44322, France
AU: Schneider, J
EM: Jean.Schneider@obspm.fr
AF: LUTH, Paris observatory, Paris, 92195, France
AU: Sotin, C
EM: christophe.sotin@univ-nantes.fr
AF: Jet Propulsion Laboratory, California Technology Institute Oak Grove Drive, Pasadena, 4800, United States
AU: Tinetti, G
EM: tinetti@iap.fr
AF: LUTH, Paris observatory, Paris, 92195, France
AB: The investigation of planetary systems opens the perspective of discovering new types of planets, unknown in our Solar System. In particular, the recent discovery of exoplanets with intermediate masses (5 Earth masses or more) is a confirmation of the existence of Super-Earths. One important aspect of these planets is that they are potentially habitable, in the sense of bearing a significant amount of liquid surface water. In addition, recent planet formation models predict that intermediate mass planets exist at various distances from their parent star. These models predict a substantial migration extent for the planets, which therefore are likely to start their formation beyond the ice-line. Hence, they contain a large amount of water. Our goal is to investigate if the confrontation of future data to current understanding of M-R relationships will allow for the distinction between these two families. We have studied the relationship between mass and radius up to 100 Earth mass. The bulk composition of the planetary body is described using four parameters: [Fe/Si], [Mg/Si], the silicate Mg number, and the amount of water. The model allows us to investigate a large range of putative exoplanets depending on their silicate composition, the amount of water, and temperature conditions. The accuracy of M-R relationships is determined by investigating the dependency of M-R scaling laws on compositional effects, temperature variation, and the choice of equation of state. It will be shown that important radii variations are observed depending on the chosen parameters and equation of state, which induces large uncertainties on M-R relationships above 20 Earth masses. Nonetheless, a distinction between these two families and planets with thick atmospheres such as Uranus will be possible.
DE: 5430 Interiors (8147)
DE: 5724 Interiors (8147)
DE: 8147 Planetary interiors (5430, 5724, 6024)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting