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Diffusion segregation of heavy elements in the Sun

Auteur

Gorshkov Alexey

Institution

Sternberg Astronomical Institute

Theme

Solar and stellar modelling
Auteur(s) supplémentaire(s)Baturin, Vladimir
Institution(s) supplémentaire(s)Sternberg Astronomical Institute

Abstract

Lowering of heavy element abundances Z according to modern determinations represent a problem of the solar modeling. We consider if a diffusion settling can help to conform solar models with the low photospheric content. We estimate settling of several heavy elements
such as C, N, O and Fe from the solar convective zone during evolution according to the Bahcall & Thoul technique. Acceleration of settling due
to partial ionization and radiation-driven slowing are taken into account. Diffusion profile in modern sun reveals a narrow region under
the convective zone where heavy elements abundance remains almost unchanged
due to specific effect of thermal diffusion. A rate of the element settling from the convective zone depends on the convective zone depth
and on the overshooting mixing around the low convective boundary.
According to our results, diffusion settling is fairly small in comparison to a difference between photospheric Z and the abundances
needed to provide the acceptable convective zone depth in solar model.
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