Heavy Puzzle Pieces: Nucleosynthesis Models of the Intermediate Neutron-capture Process

Abstract

The quest for the origin of the elements in the universe combines different fields of physics and astronomy, from the smallest scales of nuclear reactions to large scales of giant stars. To understand the chemical history of our universe the abundances of elements heavier than iron are observed in the photospheres of old stars. The vast majority of heavy elements are formed by the slow (s) and rapid (r) neutron-capture processes. However, some observations of heavy-element abundance patterns of old stars are incompatible with either of these processes or even a combination of both.

I will show that these puzzling heavy-element patterns can be explained as the result of a separate neutron-capture process operating at neutron densities intermediate to the s and r process: the i process. Comparing theoretical predictions of i-process nucleosynthesis with the observed abundance patterns gives us new insights into uncertain phases of stellar evolution and will ultimately help us understand the origin of the elements in our universe.