Modeling the atmosphere of extrasolar giant planets

The discovery of the first extrasolar planet transiting its star, HD209458b, provides new informations on this kind of objects : the Pegasides. However, static radiative models of atmosphere fail to explain the constraints inferred on on its radius and atmospheric composition (ref. Charbonneau et al. 2002). We developed a radiative model for the atmosphere of the Pegasides. A static case was first built. We determined a mean thermal structure for HD209458b and its atmospheric composition. We confirmed the important role of alkali metals in the thermal balance of Pegasides. In a second step, we introduced a rotation of the atmosphere mimicking a constant-with-height zonal wind. The zonal wind yields temperature contrasts which can explain the observations of Charbonneau et al. (2002). More generally, we studied the role of some parameters such as the planet-to-star distance or the wind velocity.