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Caractères de planètes extrasolaires : des observations de planètes géantes en transit aux modèles de planètes de taille terrestre

Abstract : In slightly more than ten years, several hundreds of planets have been discovered in orbit around other stars than the Sun. Meanwhile, very little is known about the nature of these exoplanets, at the exception of their masses. Nowadays, we can start characterizing them more precisely: measuring their sizes, thus estimating their mean densities and sketching their internal structures; determining the presence of an atmosphere and its composition. In this thesis, we associate observations obtained with various techniques to theoretical modeling in order to describe different kinds of exoplanets. Comparing observations from the Spitzer Space Telescope, which we are analyzing, to a predictive model, we search for atmospheric water vapour in the hot Jupiter HD189733b. We also obtain accurate measurements of the planetary radius, the stellar radius, and the impact parameter at 3.6 and 5.8 microns. Next, we use internal structure and protoplanetary disk models to constrain the nature of OGLE2005-BLG-390Lb, a light and cold planet detected through gravitational microlensing. We show that an ocean could have existed underneath an ice shell on this planet, now entirely frozen, and examine the possible composition of the ice. We propose that such properties could be shared by many other worlds throughout the Galaxy. Finally, we describe a limb transmission model to simulate theoretical spectra of transiting Earth-size planets, and conclude that ocean-planets around late-type stars would be the best possible targets for a future space mission aimed at characterizing exoplanets.
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https://tel.archives-ouvertes.fr/tel-00181150
Contributor : David Ehrenreich <>
Submitted on : Tuesday, October 23, 2007 - 11:47:58 AM
Last modification on : Friday, May 29, 2020 - 4:00:08 PM
Long-term archiving on: : Sunday, April 11, 2010 - 11:37:25 PM

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  • HAL Id : tel-00181150, version 1

Citation

David Ehrenreich. Caractères de planètes extrasolaires : des observations de planètes géantes en transit aux modèles de planètes de taille terrestre. Astrophysique [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2007. Français. ⟨tel-00181150⟩

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