Neutron Capture in Evolved Red Giants: A Review

This review traces how our understanding of low- and intermediate-mass stars (hereafter LMS and IMS, respectively) evolved in time, in parallel with our knowledge of slow neutron-capture phenomena (the s-process). I shall focus in particular on the main component of this nucleosynthesis phenomenon, occurring in the above-mentioned stars close to the end of their lifetimes. They start ascending the Asymptotic Giant Branch (AGB), where both H- and He-shells exist, burning alternatively during the phases most relevant to our discussion: the so-called thermal pulses (hence, the name of TP-AGB stages for the final evolutionary period of these stars). I shall outline how such final stages were discovered to be a crucial source for neutron captures. Finally, I will briefly discuss what observational constraints and nuclear measurements have taught us about the status of our theoretical models in this field of nuclear and stellar physics.