Heavy Puzzle Pieces: Learning About the i Process from Pb Abundances

We examine the observed heavy-element abundances of two types of objects that show enrichments in s-process elements but whose abundance patterns are generally incompatible with s-process predictions: CEMP-i stars and Pb-poor post-AGB stars, with representative metallicities around and respectively. We can explain these abundance patterns, including the puzzlingly low Pb abundances of post-AGB stars, as results of i-process nucleosynthesis. To do this we use nuclear-network calculations to study heavy-element production at different constant neutron densities up to. The constraints posed by measured Pb abundances in these objects, allow us to characterise the neutron densities and exposures of the process responsible for creating the observed heavy-element abundances.