1998/09/21 by Sylvie Vauclair, Vauclair, Sylvie, Olivier Richard +1
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9809259
3 pages with 4 figures included, To appear in SOHO6/GONG98 Proceedings "Structure and Dynamics of the Interior of the Sun and Sun-like Stars", ESA Publications Division, ESA SP-418
arxiv created 1998/09/21 · arxiv updated 2009/12/01
Improvements induced by helioseismology show that microscopic diffusion cannot be neglected in solar models. Helium and metal diffusion is now generally introduced in the computations. They cannot however explain the observed lithium depletion. Macroscopic motions are needed to bring up to the convection zone the nuclearly depleted matter. Such motions also lead to a better agreement between the sound velocity in the model and that deduced from the inversion of seismic modes. On the other hand, they must not bring up too much 3He, as we now know that the 3He/4He ratio cannot have changed by more than 10 percent during these last 3 Gyr. Here we present new consistent solar models in which the 3He constraint is satisfied. The fact that 3He must remain constant while 7Li must be depleted leads to strong constraints on the effective macroscopic diffusion coefficient allowed below the solar convection zone.