Rotation-induced mixing and thermohaline instability in low- and intermediate-mass stars.
Consequences on the Galactic evolution of light elements.
Geneva Observatory, University of Geneva, June 2012
Numerous spectroscopic observations provide compelling evidence for non-canonical processes that modify the surface abundances of low- and intermediate mass stars beyond the predictions of standard stellar theory. In this thesis, we compute a grid of stellar evolutionary models for various masses and metallicities and including, for the first time, rotation-induced mixing and thermohaline instability. This grid allows us to study the effects of these two transport processes on the stellar structure, on the surface abundances, and on asteroseismic properties of low- and intermediate-mass stars. On the other hand, we study the effects of thermohaline instability and rotation-induced mixing on the evolution of the light elements in the Milky Way. We conclude that thermohaline mixing is the dominant physical process in low-mass red giants governing the chemical composition of their atmospheres, and it is the only physical mechanism known so far to solve the so-called "Helium-3 problem" plaguing in the literature since many years.
Text in english can be download here : University of Geneva or on These en ligne