Helium Core White Dwarfs in Globular Clusters

We examine the theoretical implications of a population of low-masshelium-core white dwarfs in globular clusters. In particular, we focus on theobserved population in the core of NGC 6397, where several low-mass white dwarfcanditates have been identified as ``non-flickerers'' by Cool andcollaborators. Age and mass estimates from cooling models, combined withdynamical and evolutionary considerations, lead us to infer that the darkbinary companions are C/O white dwarfs rather than neutron stars. Furthermore,we find that the progenitor binaries very likely underwent an exchangeinteraction within the last 1.e9 years. We examine the prospects for detectinga similar population in other globular clusters, with particular attention tothe case of 47 Tuc.Comment: 30 pages, 9 postscript figures, submitted to Ap