New Solar Composition: The Problem With Solar Models Revisited

We construct updated solar models with different sets of solar abundances, including the most recent determinations by Asplund et al. (2009). The latter work predicts a slightly larger solar metallicity compared to previous measurements by the same authors but significantly lower than the recommended value from a decade ago. The new solar models incorporate an updated equation of state and new determinations of nuclear cross-sections important for calculations of solar neutrino fluxes. We compare the results of our models with determinations of the solar structure inferred through helioseismology measurements. The model that uses the most recent solar abundance determinations predicts the base of the solar convective envelope to be located at RCZ = 0.724R⊙ and a surface helium mass fraction of Ysurf = 0.231. These results are still in conflict with helioseismology data (RCZ = 0.713± 0.001R⊙ and Ysurf = 0.2485± 0.0035) but the disagreement is less severe than with previous low-metallicity solar compositions. We find the improved input physics in the models has minor effects on the solar model structure and we confirm that the model using high (older) metallicity determinations gives consistent results with helioseismology. Using the new solar abundances, we calculate the magnitude by which radiative opacities should be modified in order to restore agreement with helioseismology. We also present the solar neutrino fluxes predicted by the new models. Subject headings: Sun: helioseismology Sun: interior Sun: abundances neutrinos