Neutron Capture in Low‐Mass Asymptotic Giant Branch Stars: Cross Sections and Abundance Signatures

The recently improved information on the stellar (n,gamma) cross sections ofneutron-magic nuclei at N = 82, and in particular of 142Nd, turned out torepresent a sensitive test for models of s-process nucleosynthesis. While thesedata were found to be incompatible with the classical approach based on anexponential distribution of neutron exposures, they provide significantlybetter agreement between the solar abundance distribution of s nuclei and thepredictions of models for low mass AGB stars. Particular attention is paid to aconsistent description of s-process branchings in the region of the rare earthelements. It is shown that - in certain cases - the nuclear data aresufficiently accurate that the resulting abundance uncertainties can becompletely attributed to stellar modelling. Thus, the s process becomesimportant for testing the role of different stellar masses and metallicities aswell as for constraining the assumptions for describing the low neutron densityprovided by the 13C source.Comment: 49 pagg., 5 figg., accepted for publication by Ap