The origin of the light r-process elements

The observational identification of neutron star mergers as heavy element nucleosynthesis sites though observations of the Kilonova associated with GW170817 provides a key puzzle piece in the quest to understand the origin of the heavy elements. However, what exactly neutron star mergers contribute to the chemical evolution of the Galaxy, and what role other heavy element synthesis sites play, remains an open question. This is particularly true for the elements just above iron, from about germanium to silver. Observations of chemical abundances in metal poor stars  provide strong evidence that in addition to the s-process, multiple processes contribute to these elements. Disentangling these different contributions requires reliable nuclear data, high fidelity stellar models, and a large body of observational data. I will discuss some of the possible production sites and processes of the "light" heavy elements, and some recent experimental work at NSCL related to the weak r-process in core collapse supernovae.