The Effects of Chemical Variations on the Integrated Light Spectra of Local Group Globular Clusters

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One goal of astronomy is to figure out the composition of stars. For nearby stars this is done by spreading out the starlight into a rainbow spectrum. Individual atoms in the star's atmosphere take away very specific colors, leaving dark lines behind in the spectrum. Each line can be matched to its specific element, and the darkness of the line tells how much of that element is in the star. This method does not work for distant stars, however, since the starlight blends together into a single object; to figure out the composition of those stars, the spectrum from the entire galaxy or cluster must be used. The integrated spectrum contains light from thousands to billions of stars, and in order to determine what each star is made of the population must be simulated using models. The models require initial guesses, such as the composition of the stars--if these guesses are incorrect the final results will also be incorrect. This project seeks to perform tests on chemically anomalous clusters to see how incorrect assumptions in the current methods will affect the final results. We will then apply our findings to newly discovered star clusters on the outskirts of the Andromeda Galaxy.