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Show 92 Dan Filler college of science A globular cluster (GC) is a gravitationally bound stellar system, composed of anywhere between tens of thousands to millions of stars. There exist approximately 150 GCs in the Milky Way, and we have chosen to analyze two RGB stars in the distant, outer halo cluster M53. The metal poor cluster ([Fe/H] = -2.02 ± 0.15), is approximately 60,000 light years from the galactic center, and is thought to contain some of the oldest stars in the Galaxy. By measuring the size of absorption features, designated as the equivalent width (EW), we are able to ascertain the stellar parameters of temperature, gravitational acceleration at the surface of the star, and the overall chemical enrichment from which they formed. Combining model atmospheres and EWs using a series of radiative transfer calculations in the program MOOG, allowed us to compute elemental abundances. Unlike observations of other GCs using larger samples of stars, there is no O depletion, 0.46 < [O/Fe] < 0.48, and the range of the star to star abundance variations in Na are small, -0.09 < [Na/Fe] < -0.02. To determine if star-to-star abundance variations exist in the cluster a larger sample of stars is needed. Among the iron peak elements vanadium, cobalt and nickel, abundances are [V/Fe] = -0.02 ± 0.21, [Co/Fe] 0.22 ± 0.20, [Ni/Fe] =0.07 ± 0.20 respectively. Alpha element abundances are in accord with other GCs of comparable metallicity: [Ca/Fe] = 0.39 ± 0.20, [Ti I/Fe] = 0.21 ± 0.20, [Ti II/Fe] = 0.34 ± 0.20. The slow neutron capture process contribution as indicated by barium [Ba II/Fe] = -0.05 ± 0.30, is in accordance with the barium abundance found in M92, [Ba/Fe] = -0.14 ± 0.03, a cluster of similar metallicity. The rapid neutron capture process as indicated by the abundance of europium is [Eu/Fe] = 0.43 ± 0.20, and is in accord with other Galactic GCs. ELEMENTAL COMPOSITION OF STARS IN THE GLOBULAR CLUSTER M 53 Dan Filler (Inese I. Ivans) Department of Physics and Astronomy University of Utah UNDERGRADUATE RESEARCH ABSTRACTS Inese I. Ivans |