Evolution and Nucleosynthesis of Primordial Low‐Mass Stars

Abstract

We discuss in detail the evolutionary properties of low-mass stars (M ≤ 1 M⊙) having metallicity lower than Z = 10-6from the pre-main sequence up to (almost) the end of the early asymptotic giant branch phase. We also discuss the possibility that the large [C/Fe], [N/Fe] observed on the surface of the most iron-poor star currently known, HE 0107-5240, could be attributed to the autopollution induced by the penetration of the He convective shell into the H-rich mantle during the He core flash of a low-mass, very low metallicity star. On the basis of a quite detailed analysis, we conclude that the autopollution scenario cannot be responsible for the observed chemical composition of HE 0107-5240.