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Atmosphère des planètes extrasolaires géantes : un modèle d'équilibre radiatif

Abstract : Direct, and particularly spectroscopic, observations will allow the determination of the nature and chemical composition of the "hot Jupiters'" atmosphere. Preliminarily, it is essential to build a theoretical atmospheric model in order to constrain the observational techniques. In that framework we have developed a radiative equilibrium model of the Jupiter-like extrasolar planets irradiated by their parent star. The modeling determines not only the mean thermal structure, but also the stellar reflected spectrum and the thermal emission spectrum for planets orbiting the primary from 0.05 to 1 astronomical unit. the model atmosphere is limited at the bottom by an optically-thick cloud. In all cases, a major result is that the modelled atmosphere does not show any temperature inversion in contrast with the giant planets in the Solar System. Except for the farthest (and coldest) planet among the sample of the modelled planets in this work, we find that the atmosphere is subadiabatic in the whole grid of pressure. This result validates the hypothesis of radiative equilibrium. We also discuss the vertical distribution (conditional upon the orbital distance) of the chemical species in the atmosphere , assuming solar elemental abundances. The thermal emission spectra are dominated by the bands of water vapor, seen in absorption, and reveals a window in the 4-micron region. Compared to the latter, a flux peak is more and more strong at 10 microns for the coldest planets of the sample. Finally, we investigated the detectability of spectral signatures from "hot Jupiters", using the ground-based giant telescopes (VLT, Keck,. . .) in noninterferometric mode. Synthesized spectra have been calculated for 51 Peg b (Teff=1200 K) in the nu3 band of methane and in the fundamental band of carbon monoxide.
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Contributor : Cedric Goukenleuque <>
Submitted on : Sunday, July 10, 2005 - 2:11:25 PM
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  • HAL Id : tel-00009725, version 1


Cédric Goukenleuque. Atmosphère des planètes extrasolaires géantes : un modèle d'équilibre radiatif. Astrophysique [astro-ph]. Université Pierre et Marie Curie - Paris VI, 1999. Français. ⟨tel-00009725⟩



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