We examine the effect of element diffusion on the evolution of the Sun. We include partial ionization and diffusion of all elements, a new network of nuclear reactions which includes the reactions of the light elements like Li7 and Be9, and we follow the full evolution and depletion of these elements from the pre-main-sequence phase to the present stage. Our major conclusions are : The effect of diffusion on the predicted primordial hydrogen and helium abundances is ΔX = +0.025, ΔY = -0.024. However, the global effect of diffusion on the structure of the Sun is small, as was found by Bahcall & Pinsonneault. More specifically, we find that diffusion leads to ΔTc/T = +0.003, Δpc/p = 0.01 [where AQC = Q (with diffusion) - Q(no diffusion) for a quantity Q at the center] at the center and ΔTs/T = +0.05%, Δps/p = 0.09% at the surface. [Here ΔQs = Q(with diffusion) - Q(no diffusion) for a quantity Q on the surface]. We obtain the depletion of light elements Li7 and Be9 due to both diffusion and nuclear reactions and find that diffusion enhances the depletion at the surface by 1.08.
- Sun evolution
- Sun: interior