Seismological Tests of Solar Models Calculated with the NACRE Reaction Rates and the Grevesse and Sauval 1998 Mixture

Abstract

We examine the effects of the Grevesse & Sauval solar mixture and the European Nuclear Astrophysics Compilation of Reaction Rates (NACRE) nuclear reaction rates on the calculated neutrino fluxes and the p-mode oscillation spectrum of calibrated standard solar models. Calibrated solar models with the NACRE reaction rates are in good agreement with the helioseismic constraints, i.e., the low-degree p-mode oscillation spectrum, the small frequency separations, the depth of the convection zone, and the helium abundance in the convection zone. The use of the Grevesse & Sauval solar mixture slightly worsens the agreement by producing a shallower convection zone. We exploit the uncertainties in abundance determinations, the nuclear reaction rates, and the neutrino capture rates to reduce the predicted neutrino fluxes: the predicted 8B flux can be brought well within the observational error bars of the Kamiokande experiment. The predicted chlorine and gallium event rates, though still higher than the observational values, are reduced by 47% and 24%, respectively. The models with the neutrino flux reductions do about as well as the reference model in satisfying the current constraints of helioseismology. We also perform g-mode calculations: these modes are much more sensitive to the core structure than the p-modes. Confirmed detection and identification of only one g-mode, with an accuracy of within only 1/10 of 1% on its period, would be enough to discriminate between our different models and assess the extent to which standard physics is able to give a partial answer to the neutrino problems.