A series of observational tests of theories of the structure and evolution of low mass stars will be performed. Specifically, counts of globular cluster stars (i.e., luminosity functions) will be employed to determine evolutionary timescales. Also, internally-consistent photometry will be measured to compare stellar properties (luminosity, temperature) at different phases of evolution and at the same points of evolution across different clusters. Three aspects of the cluster colormagnitude diagrams will be examined: 1) The epoch of red giant branch ascent, including red giant evolutionary timescales, the red giant branch bump (its luminosity and sharpness), and the location of the red giant branch-tip; 2) horizontal branch and asymptotic giant branch morphologies, distributions, and evolution; and 3) blue stragglers and their radial distributions, distributions on the cluster color magnitude diagrams, and the presence of unusual blue straggler populations. The statistical nature of these investigations requires quality photometry of large samples of cluster stars which will be extracted from previously obtained wide field (for cluster outskirts) and high resolution (for cluster cores) images obtained at national and international observatories telescopes (plus archival images, including the Hubble Space Telescope where possible). Novel (within the astronomical community) statistics will also be employed in the analysis to assess significance/confidence levels of trends and relations. Undergraduate and Master's students at San Diego will be heavily involved in this work - both with the reduction and analysis of the astronomical data and the application of advanced statistical methods. The training of a graduate student at UCSC is also supported here. The final photometry will also be made publicly available.
