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Astérosismologie d'étoiles de séquence principale ou évoluées, en relation avec l'expérience spatiale CoRoT, et les instruments au sol HARPS et SOPHIE

Abstract : The work presented in this thesis focuses on asteroseismology of solar-type stars, and more specifically on central stars of planetary systems. The analysis of waves propagating in these stars can help constraining their internal structure. The two first chapters describe the theory and the stellar oscillations and the numerical tools used for this work. The third part deals with HD 52265, target of the CoRoT mission with a planet. We computed preliminary models for this star, taking into account the spectroscopic constraints, and we made some asteroseismic predictions. During this study, we found a seismic signature characteristic of the stellar core. This phenomenon is induced by a strong helium gradient in the core. We studied this effect in the general case of solar-type stars and we showed that it always happens, at the end of the main sequence or at the beginning of the subgiant branch. This characteristic signature can be used to constrain the stellar core. The fifth chapter is devoted to the star 51 Peg. We observed this star with the SOPHIE spectrograph at the Observatoire de Haute Provence in 2007 and we detected its oscillations. The analysis of the data led to the identification of 21 pulsation modes. Finally, we present a new seismic analysis of the exoplanet-host star µ Arae, observed and analysed by Bazot et al. in 2004. Asteroseismology coupled with spectroscopy allowed us to determine the helium abundance of the star, and its parameters: mass, age, radius, size of the convective core and its possible extension due to overshooting. These results show that asteroseismology is a powerful tool to bring constraints on the internal structure of stars.
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Submitted on : Wednesday, December 2, 2009 - 11:13:08 AM
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Melanie Soriano. Astérosismologie d'étoiles de séquence principale ou évoluées, en relation avec l'expérience spatiale CoRoT, et les instruments au sol HARPS et SOPHIE. Astrophysique [astro-ph]. Université Paul Sabatier - Toulouse III, 2009. Français. ⟨tel-00438082⟩

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