RUI: Blue Straggler Formation and Evolution in Globular Clusters

Vassar College, Poughkeepsie NY

Investigators

Abstract

AST-0071165 LOMBARDI The formation and evolution of blue straggler stars in glob-ular clusters will be modeled by using hydrodynamic simulations to determine the remnants of stellar mergers. These models of remnants will then be used to initiate stellar evolution calculations. By combining the theoretical evolutionary tracks with dynamical models of globular clusters, it will be possible to predict the observable characteristics of blue stragglers, including their numbers, luminosities, colors, and radial distribution in the globular cluster. These hydrodynamic simulations will be the first to use realistic models for the main sequence parent stars in single-single star collisions, single-binary collisions, binary-binary collisions, and binary coa-lescences. Based on these results, a set of simple algorithms will be developed that can be used to generate the structure of merger remnants without actually running large-scale hydrodynamic simulations. These subsequent stellar evolution cal-culations will be the first to treat rotating merger remnants and the first to examine chemical mixing in blue stragglers due to meridional circulation. Detailed comparisons with observations will be made and the results of the comparisons will place interesting limits on cluster mass functions and binary fractions. In this way, the results of the research will enable one to probe the nature of stellar populations in the dense environments of globular clusters. This project is funded by the Division of Astronomical Sciences. ***