Astérosismologie des étoiles pré-séquence principale de masse intermédiaire (étoiles Ae/Be de Herbig) par une approche spectroscopique de haute-résolution

Abstract : Herbig Ae/Be stars are pre-main sequence stars of intermediate mass (2-10 Msun) showing signs of intense activity and strong winds. The origin of their tremendous activity is still not understood in the frame of current theoretical evolutionary models. As of today, growing observational evidences tend to indicate that the energy needed to produce this activity might be of internal origin, but no definite answer has been provided. Solving this still open question is a major concern for testing young stellar evolutionary theory. This could be done by constraining the internal structure of these objects using asteroseismic techniques, i.e. the observation, analysis and modelling of stellar pulsation frequencies and modes. Such a study implies to caracterise and to constrain the theoretical PMS instability strip that Herbig stars cross for a significant fraction of their evolution to the main sequence. Having this aim, I studied first the prototype Ae Herbig star HD 104237. I carried a study of its photospheric fundamental parameters, which was necessary for a further asteroseismic modelling. The analysis of the photospheric line profile variations of this star confirmed the presence of multi-periodic oscillations and enabled the detection of several non-radial pulsations. I could identify some of the pulsation modes and modelled these pulsations in an adiabatic framework. This has supplied interesting leads about the excitation mechanism of the observed pulsations of HD 104237. I then extended my study to 4 others Herbig stars that were observed with HARPS (ESO) in the course of my thesis. Preliminary results of the asteroseismic analysis are presented in my manuscript.
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Aurélie Fumel. Astérosismologie des étoiles pré-séquence principale de masse intermédiaire (étoiles Ae/Be de Herbig) par une approche spectroscopique de haute-résolution. Astrophysique stellaire et solaire [astro-ph.SR]. Université Paul Sabatier - Toulouse III, 2011. Français. ⟨tel-00720621⟩

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