Astrophysical implications of the proton-proton cross section updates

TL;DR

This study assesses how recent updates to the proton-proton reaction rate influence stellar models, finding minimal impact on cluster age estimates and solar neutrino flux predictions, and confirming low uncertainty levels in the reaction rate.

Contribution

It provides a detailed analysis of the effects of updated proton-proton reaction rates on stellar models, demonstrating their limited influence on key astrophysical predictions.

Findings

Maximum 3% difference in temperature regimes of hydrogen-burning stars

Cluster age determination varies by less than 1% due to reaction rate updates

Solar neutrino flux predictions can differ by up to 8%

Abstract

The p(p,e^+ \nu_e)^2H reaction rate is an essential ingredient for theoretical computations of stellar models. In the past several values of the corresponding S-factor have been made available by different authors. Prompted by a recent evaluation of S(E), we analysed the effect of the adoption of different proton-proton reaction rates on stellar models, focusing, in particular, on the age of mid and old stellar clusters (1-12 Gyr) and on standard solar model predictions. By comparing different widely adopted p(p,e^+ \nu_e)^2H reaction rates, we found a maximum difference in the temperature regimes typical of main sequence hydrogen-burning stars (5x10^6 - 3x10^7 K) of about 3%. Such a variation translates into a change of cluster age determination lower than 1%. A slightly larger effect is observed in the predicted solar neutrino fluxes with a maximum difference, in the worst case, of about 8%. Finally we also notice that the uncertainty evaluation of the present proton-proton rate is at the level of few \permil, thus the p(p,e^+ \nu_e)^2H reaction rate does not constitute anymore a significant uncertainty source in stellar models.