Neutron-capture element abundances in the globular cluster M15

High-resolution, high signal-to-noise ratio, blue-violet spectra of three red giant branch tip stars in M15 have been obtained with the Keck I High-Resolution Echelle Spectrograph. These spectra have been analyzed to determine the abundances of several neutron-capture elements, including the radioactive chronometer element thorium. There are two principal results of this study. First, the abundances of the heavier (Z greater than or equal to 56) elements for each of the three stars is well matched by a scaled solar system r-process abundance distribution. Second, a weighted mean-observed Th/Eu ratio for the stars implies an age fbr the neutron-capture material in M15 stars of 14 +/- 3 Gyr, in reasonable agreement with other recent age estimates for Galactic globular clusters.