The dispersion and mean trends of r-process abundances in metal-poor stars are discussed based on a model of diverse supernova sources for the r-process. This model is unique in that its key parameters are inferred from solar system data independent of stellar observations at low metallicities. It is shown that this model provides a good explanation for the observed dispersion and mean trend of Eu abundances over -3 ≲ [Fe/H] ≲ -1. It is also shown that this model provides a means to discuss r-abundances in general. For example, the Ag abundance in any metal-poor star with observed Eu and Fe abundances can be calculated from the model. This approach is demonstrated with success for two stars and can be further tested by future Ag data. The dispersion and mean trend of Ag abundances in metal-poor stars are also calculated for comparison with future observations.
Bibliographical noteFunding Information:
I thank Jerry Wasserburg for many discussions on Galactic chemical evolution, Friedel Thielemann for calling my attention to the work of Burris et al. (2000), and Evan Skillman, Keith Olive, and an anonymous referee for suggestions that improved this Letter. I also acknowledge Chris Sneden, John Cowan, and their collaborators for providing the continuous stimulus by carrying out extensive observations. This work was supported in part by the Department of Energy under grants DE-FG02-87ER40328 and DE-FG02-00ER41149.
- Galaxy: evolution
- Stars: abundances
- Stars: population II