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J. Kieken (Bordeaux Observatory, Floirac, France), F. Selsis (Centro de Astrobiologia, Madrid, Spain), M. Dobrijevic, F. Billebaud, J.-P. Parisot (Bordeaux Observatory, Floirac, France)
Darwin (ESA) is a project of space interferometer aiming at the detection of extra-solar planets and some of their atmospheric components. This instrument will be very powerful to study tempered extrasolar giant planets (like HD 27442 b, a Jupiter-like planet orbiting at 1.18 a.u. from its K2-type primary, Butler et al. 2001) and yet hypothetical objects called “hot Neptunes”, which are giant planets similar to Uranus or Neptune but orbiting closer to their primary. We are developing a numerical model for the simulation of chemical evolution of such giant exoplanet atmospheres, based on a photochemical model for the giant planets of our Solar System. Adapted to new physico-chemical conditions, this model is being coupled to a radiative-convective equilibrium model, that will allow us to calculate atmospheric thermal profiles in an iterative way. Our model will also compute the thermal emission of the planet as could be measured by Darwin. We will investigate the influence of the distance of the planet from its primary on the composition and the thermal structure of its atmosphere, in a migration scenario. In this contribution, I will present the objects we are working on, some technical aspects of the photochemical and radiative transfer codes and first results about photochemical evolution of giant exoplanet atmospheres.
This work is supported by the ``Programme National de Planétologie" / INSU.
If the author provided an email address or URL for general inquiries,
it is as follows:
Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.