S-process abundances in globular clusters: M4 vs. M5 and NGC 1851

Abstract

We present s-process abundances for giant stars in the globular clusters M4, M5, and NGC 1851. We find that all s-process elements are overabundant in M4 relative to M5. Curiously, the abundances of Cu and Zn are also overabundant in M4 which may offer clues to the synthesis of these elements. For NGC 1851, we find that the abundances of the s-process elements Zr and La exhibit a large dispersion. The abundances of Zr and La also appear to have a bimodal distribution reinforcing the idea that there are two stellar populations in this cluster.