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

天文学的一个目标是弄清楚恒星的组成。对于附近的恒星，这是通过将星光扩散成彩虹光谱来实现的。恒星大气层中的单个原子带走了非常特殊的颜色，在光谱中留下了暗线。每一条线都可以与它的特定元素相匹配，这条线的黑暗程度告诉我们，恒星中有多少元素。然而，这种方法不适用于遥远的恒星，因为星光混合在一起形成一个单一的物体；为了计算出这些恒星的组成，必须使用整个星系或星系团的光谱。综合光谱包含从数千到数十亿颗恒星的光，为了确定每一颗恒星是由什么组成的，必须使用模型来模拟种群。这些模型需要最初的猜测，比如恒星的组成--如果这些猜测是错误的，最终结果也将是错误的。该项目试图对化学异常的星系团进行测试，以了解当前方法中的不正确假设将如何影响最终结果。然后，我们将把我们的发现应用于仙女座星系外围新发现的星团。

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.