Abundances of neutron capture elements in Population II stars

The authors have presented new heavy-element abundance results for 20 very metal poor stars. It has been demonstrated that the very heavy element abundances correlate only loosely with the Fe abundances: star-to-star scatter exists in excess of observational error, and signals the incomplete mixing of nucleosynthesis products in the galactic halo. Also it has been shown that a distinct r-process pattern is characteristic of the very heavy element abundance patterns. Finally, the onset of large amounts of galactic s-processing at a metallicity of ≈-2 has been identified and has led to the suggestion that the time scale of the buildup of Galactic metallicities to this value was ≡10<SUP>7</SUP>yr.