Astrophysical implications of the proton–proton cross section updates

E Tognelli,S Degl'Innocenti,L.E Marcucci,P.G Prada Moroni

doi:10.1016/j.physletb.2015.01.033

E Tognelli, S Degl'Innocenti + Show 2 more

Open Access

https://doi.org/10.1016/j.physletb.2015.01.033

Copy DOI

Abstract

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 (5×106–3×107 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.

Highlights

At the energies of interest for stellar nucleosynthesis the rate of the proton–proton (p–p) weak capture is too low to be directly measured in laboratory and it can be determined only by means of nuclear physics calculations
The p(p, e+νe)2H reaction drives the efficiency of the p–p chain, which is fundamental for hydrogen burning in stars
A variation of the p–p reaction rate adopted in the stellar models potentially influences the characteristics and the evolutionary times during the central hydrogen burning phase (Main Sequence, MS) of low-mass stars and the age determination of old stellar clusters

Summary

Introduction

At the energies of interest for stellar nucleosynthesis the rate of the proton–proton (p–p) weak capture is too low to be directly measured in laboratory and it can be determined only by means of nuclear physics calculations. S(E) is calculated within the so-called chiral effective field theory framework [7], which allows to reduce the theoretical uncertainty to the order of few h, by constraining systematically both the nuclear potential and the nuclear current operator with a stringent contemporary fit of the trinucleon binding energy and tritium β-decay lifetime This is better than what has been done in Ref. For a better comparison of the differences among the selected evaluations of the p–p rate, and for future reference, we report in Table 1 the values of S(0), S (0), S (0) and S (0) as obtained by Marcucci et al [7], compared with those available in the literature, namely in the NACRE99 [8] and AD11 [6] compilations. We are not able to discuss the differences between the JINA and MSV13 rates because no information about the uncertainty on the JINA rate are available on the JINA web page

Stellar models

Proton–proton cross section and age determination in stellar clusters

Findings

Summary