Element Settling in the Solar Interior |
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Authors: | Sylvie Vauclair |
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Institution: | (1) Laboratoire d'Astrophysique Observatoire Midi-Pyrénées Toulouse, France |
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Abstract: | Element settling inside the Sun now becomes detectable from the comparison of the observed oscillation modes with the results
of the theoretical models. This settling is due, not only to gravitation, but also to thermal diffusion and radiative acceleration
(although this last effect is small compared to the two others). It leads to abundance variations of helium and heavy elements
of ≅ 10% below the convective zone. Although not observable from spectroscopy, such variations lead to non-negligible modifications
of the solar internal structure and evolution. Helioseismology is a powerful tool to detect such effects, and its positive
results represent a great success for the theory of stellar evolution. Meanwhile, evidences are obtained that the element
settling is slightly smoothed down, probably due to mild macroscopic motions below the convective zone. Additional observations
of the abundances of both 7Li and 3He lead to specific constraints on these particular motions.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | Sun: abundances helioseismology diffusion processes element settling |
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