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Empirical Comparisons of Computer Models for Stellar Evolution

Color Magnitude Diagrams (CMDs) are plots that compare stellar absolute magnitudes in different colors. High non-linear correlations among the mass, color and surface temperature of newly formed stars induce a long narrow curved point cloud in a CMD known as the main sequence. Aging stars form new CMD groups of red giants and white dwarfs. The physical processes that govern this evolution are studied with complex computer models used to predict the plotted magnitudes as a function of parameters of scientific interest such as stellar age, mass and metallicity. Here, we describe how we use the computer models as complex likelihood functions in a Bayesian analysis that requires sophisticated computing, corrects for contamination of field stars in the data, accounts for complications caused by binary stars, and aims to compare competing physics-based computer models of stellar evolution.

Joint work with Steven DeGennaro, Department of Astronomy, University of Texas at Austin Ted von Hippel, William Jeffery, Nathan Stein, Elizabeth Jeffery

Key Words: Astrostatistics, Bayesian, Markov chain Monte Carlo, Mixture Models, Model Comparison, Dynamic Computation