What we do and do not know about the s-process in AGB stars Original Research Article

AGB stars are the source for the main component of the s-process. Here we discuss both the properties which are reasonably well known and those which still suffer from substantial uncertainties. In the former case, we are fairly sure that the s-process contribution from AGB stars comes from masses between about 1 and 3 M⊙, and the dominant neutron source is the 13C(α,n)16O reaction. In the latter category remains the formation mechanism for the 13C-pocket. Attempts at including rotation seem to inhibit neutron capture reactions. Explaining the observations seems to require a spread in the size of the 13C-pocket so some stochastic process, such as rotation, must be involved.