Astrophysical Models of r-Process Nucleosynthesis: An Update

An update on astrophysical models for nucleosynthesis via rapid neutron capture, the r process, is given. A neutrino-induced r process in supernova helium shells may have operated up to metallicities of ~10^-3 times the solar value. Another r-process source, possibly neutron star mergers, is required for higher metallicities.Comment: 8 pages, invited talk given at 11th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG11), Wako, Japa

Nucleosynthesis in Metal-Free and Metal-Poor Stars

There have been a number of important recent developments in theoretical and observational studies of nucleosynthesis, especially regarding nucleosynthetic sources at low metallicities. Those selected for discussion here include the origin of Li6, the primary production of N, the s-process, and the supernova sources for three groups of metals: (1) C to Zn with mass numbers A<70, (2) Sr to Ag with A~90-110, and (3) r-process nuclei with A~130 and above.Comment: 8 pages, no figures, published in "Proceedings of First Stars III," Eds. Brian W. O'Shea, Alexander Heger & Tom Abe

Recent Progress in Understanding Nucleosynthesis via Rapid Neutron Capture

I discuss the recent progress in our understanding of nucleosynthesis via rapid neutron capture, the r-process, based on meteoritic data for the early solar system and observations of stars at low metallicities. At present, all data require that there be two distinct kinds of r-process events and suggest that supernovae are associated with these events. The diversity of supernova sources for the r-process may depend on whether a neutron star or black hole is formed in an individual supernova. This dependence, if substantiated by future observations discussed here, has important implications for properties of nuclear matter.Comment: 7 pages including 2 figures, to appear in the Proceedings of the 7th Conference on the Intersections of Particle and Nuclear Physic