Nulclear Chart

How is Gold produced in the universe? The above image shows the part of the nuclear chart between Lanthan (Z=57) and Erbium (Z=68), with 33 stable isotopes (black color). How did the form? In a supernova 5 billion years ago? Quite possible, as supernova are the site of the r-process (rapid neutron cature process). However, so far no selfconsistent model managed to reproduce the solar system r-process abundances! Is most r-process material formed at the mass cut, close to the proto-neutron star? Or in the helium shell when it is hit by the supernova shock wave? Or does the r-process take place in merging neutron stars? Find more details in the Nucleosynthesis Lecture Notes here .