Seminars
Giovedi 12 Ottobre 2017, h. 11:30
Aula L. Rosino Dipartimento di Fisica e Astronomia
Sebastien Salmon
Università di Liegi
A new light on the Solar problem
ABSTRACT
The Sun, because it is the star for which we have the largest set of observational constraints, is a calibration reference for theoretical stellar models. Among others, the study of the Sun oscillations – helioseismology - has provided strong constraints on the Sun internal rotation profile, the location of the base of its convective envelope, or the helium abundance of its envelope. Standard Solar Models built in the nineties were a major success of stellar physics since they presented a good agreement with helioseismology. However, in the past decade, the abundances of elements in the Sun were revised by Asplund et al., leading to a large decrease of the solar metallicity. As a consequence, Standard Solar Models with revised abundances now fail to reproduce most of the helioseismic constraints. This stalemate, known as the Solar problem, questions the accuracy of the equation of state, opacities and other ingredients used in the stellar models. Remarkably, this led the Los Alasmos group to compute new stellar opacities for the community.
To shed a new light on this problem, we have developed in our team new helioseismic diagnosis, thanks to which we are able to derive the Sun envelope metallicity, as well as the entropy and Ledoux discriminant internal profiles. We present here the results of these new helioseismic inversions, and their consequences for Solar Models, including those with the new Los Alamos opacities.
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