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Low-Z solar model: sound speed profile under the convection zone

Auteur

Ayukov Sergey

Institution

Sternberg Astronomical Institute

Theme

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

Abstract

With the low solar heavy elements abundances published in 2004 discrepancy in sound speed profile between models and inversions became much larger than with older, higher abundances. We consider the structure and source of the discrepancy. The most important reason is shallow convection zone but making it deeper with localized opacity modifications does not lead to desired sound speed profile. Global opacity changes can produce models with sound speed profile which is close to inversion but these changes look fairly artificial. The steep dip below the CZ boundary is a distinctive feature which is present in all models, including models with high old Z. We believe it is caused by both temperature and chemical profiles in this region which in turn are defined by diffusion and transition from convection to radiative energy transfer. Overshooting and partial mixing may improve sound speed agreement near CZ boundary. We present solar models which include aforementioned effects or their approximations.

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