Description:

Stars in nearly all globular clusters show complex relations among the abundances light elements (up to Na).  Many also show anti-correlations of Mg and Al.  A rare few display variations in K.  Until now, only one cluster (M15) conclusively showed any star-to-star variation in neutron-capture elements, like Eu.  Using a trick of stellar evolution, I show that these variations are primordial, not caused by external pollution.  I also show evidence that M92 also has variations in neutron-capture abundances among the first generation of stars but not the second.  The evidence points to a very prompt, rare source of r-process enrichment.

Speaker: Evan Kirby, Professor, University of Notre Dame, South Bend

Host: Professor Giacomo Fragione