Searching for alternative sources of r-process elements

Rapid neutron capture (r-process) nucleosynthesis produces roughly half of the elements in the Periodic Table more massive than iron. The unusual conditions required for a successful r-process, in particular the requisite high flux of (unstable) free neutrons, have made the astrophysical site(s) in which the r-process occurs an enduring mystery. Observations of the first detected neutron star merger, GW170817, in both electromagnetic and gravitational radiation yielded evidence that merging neutron stars, long favored theoretically as r-process sources, did indeed undergo heavy element nucleosynthesis. However, these same observations suggested that neutron star mergers may not be unique in their ability to produce r-process elements. I will present new insights on r-process sources, with a particular focus on rare supernova explosions, and discuss how radiation from explosive r-process transients may help us unlock the origin of the heaviest elements in the Universe.