Globular Cluster kinematics and abundances:
What fraction of GC stars are binaries? Estimates approach 30% but vary from cluster to cluster as well as across the clusters. What effect do binaries have on the cluster CMDs? Is there evidence for binary coalescence and unusual stellar properties such as peculiar abundance ratios that might signal a higher binary fraction in the past that now is lost in apparently single stars?
Requires thousands of spectra per cluster to probe the radial dependence, and several dozen clusters to determine the dispersion in cluster binary statistics. When possible, it is desirable to get close to the main sequence at moderate spectral dispersion to measure binary velocities and some chemical composition indicators.