The p(p,e+νe)H2 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+νe)H2 reaction rates, we found a maximum difference in the temperature regimes typical of main sequence hydrogen-burning stars (5×10 6 -3×10 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 ‰, thus the p(p,e+νe)H2 reaction rate does not constitute anymore a significant uncertainty source in stellar models.
Tognelli, E., Degl’Innocenti, S., Marcucci, L. E., & Prada Moroni, P. G. (2015). Astrophysical implications of the proton-proton cross section updates. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 742, 189–194. https://doi.org/10.1016/j.physletb.2015.01.033