The event of two neutron stars collapsing is also referred to as the R process, short for rapid neutron capture. It is how atoms heavier than iron are produced.

Kilonova ~ Neutron Star Merger

Flow of mica flakes in solution on Collaborative Landscape.
36″ x 91″
Jesse Higman and Michael James

Photo: Wynne H. Earle
Photo: Wynne H. Earle