IA/U.Porto Seminar - Fingering convection: an unforeseen physical process at work inside stars - 21 abril 2016

Fingering convection: an unforeseen physical process at work inside stars

Silvie Vauclair

University of Toulouse

Resumo

Main-sequence stars were thought to be well-known objects, but they still hide some surprises. An important process had been forgotten in previous studies, which may modify their internal structure and evolution in a non-negligible way. It is a type of double-diffusive convection, referred to as “thermohaline” or “fingering” convection. This occurs every time layers of heavy matter come upon lighter ones. It may happen inside stars due to the accumulation of heavy elements in some regions, as the result of atomic diffusion. It also happens in the case of accretion of heavy matter, coming from planetary disks or from stellar companions, and may lead to important extra-mixing effects. A similar phenomenon occurs at the surface of the white dwarfs which are surrounded by debris disks. I will discuss these processes, which have been studied in details using 3D simulations, and their importance for stellar structure and chemical composition.

21 de abril de 2016 | 13:15

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