LESIA - Observatoire de Paris

Impact of atomic diffusion on the structure and surface abundances of G and F type stars : stellar parameter determinations and effects of rotation

mercredi 28 février 2018, par Morgan Deal (LESIA)

Jeudi 1er mars 2018 à 11h00 , Lieu : Salle de conférence du bâtiment 17

Atomic diffusion, including the effect of radiative accelerations on individual elements, leads to variations of the chemical composition inside the stars as well as the surface abundances evolution. Indeed the accumulation in specific layers of the elements, which are the main contributors of the local opacity, modifies the internal stellar structure and surface abundances. Here we show that the variations of the chemical composition induced by atomic diffusion in G and F type stars can lead to an increase of the iron surface abundance and to an increase of the Rosseland mean opacity at the bottom of the surface convective zone. This induces a modification of the size of the surface convective zone, of the radius of the star, of some seismic parameters, and more importantly of [Fe/H]. We also show the effect of the coupling between rotation and atomic diffusion is this kind of stars. These processes need to be taken into account in stellar evolution models as the observations are more and more precise, especially in the context of the future space missions TESS and PLATO.

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