I show that recent observations of r-process abundances in metal-poor stars are difficult to explain if neutron star mergers (NSMs) are the major r-process sources. In contrast, such observations and meteoritic data on 182Hf and 129I in the early solar system support a self-consistent picture of r-process enrichment by supernovae (SNe). While further theoretical studies of r-process production and enrichment are needed for both SNe and NSMs, I emphasize two possible direct observational tests of the SN r-process model: gamma rays from the decay of r-process nuclei in SN remnants and surface contamination of the companion by SN r-process ejecta in binaries.
Bibliographical noteFunding Information:
I thank Petr Vogel and Jerry Wasserburg for many discussions on the r-process. I am also grateful to the referee, Friedel Thielemann, for detailed criticisms that helped improve this Letter. This work was supported in part by the Department of Energy under grant DE-FG02-87ER40328.
- Galaxy: evolution
- Nuclear reactions, nucleosynthesis, abundances
- Stars: neutron
- Supernovae: general