Standard Solar Model and Solar Neutrinos

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 $R_{\rm CZ}= 0.724{\rm R_\odot}$ and a surface helium mass fraction of $Y_{\rm surf}=0.231$. These results are still in conflict with helioseismology data ($R_{\rm CZ}= 0.713\pm0.001{\rm R_\odot}$ and $Y_{\rm surf}=0.2485\pm0.0035$) 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.

Standard solar models (SSM) are facing nowadays a new puzzle: the solar composition problem. New determinations of solar metal abundances lead SSM calculations to conflict with helioseismological measurements, showing discrepancies that extend from the convection zone to the solar core and can not be easily assigned to deficiencies in the modelling of the solar convection zone. We present updated solar neutrino fluxes and uncertainties for two SSM with high (old) and low (new) solar metallicity determinations. The uncertainties in iron and carbon abundances are the largest contribution to the uncertainties of the solar neutrino fluxes. The uncertainty on the $^{14}$N(p,$\gamma$)$^{15}$O rate is the largest of the non-composition uncertainties to the CNO neutrino fluxes. We propose an independent method to help identify which SSM is the correct one. Present neutrino data can not distinguish the solar neutrino predictions of both models but ongoing measurements can help to solve the puzzle (link to the article).