Collaborative Research: Stellar Physics from Cluster-Wide Samples in Globular Star Clusters

AST-0507785 / AST-0507697埃里克·桑德奎斯特/迈克尔·博尔特圣地亚哥州立大学/加州圣克鲁斯大学合作研究：来自球状恒星望远镜中望远镜宽范围样本的恒星物理学摘要将对低质量恒星的结构和演化理论进行一系列观测测试。具体来说，球状星团恒星的数量（即，光度函数）将被用来确定进化的时间尺度。此外，内部一致的测光将被测量，以比较恒星的性质（光度，温度）在不同阶段的演变和在同一点的演变在不同的集群。本文将从三个方面来研究星系团的色星等图：1）红巨星分支上升的时代，包括红巨星演化时标、红巨星分支隆起（2）水平分支和渐近巨星分支的形态、分布和演化;（3）蓝离散星及其径向分布，在星团色图上的分布，以及异常蓝离散星的存在。这些调查的统计性质需要质量测光的大样本的集群starswhich将提取从以前获得的宽领域（集群外围）和高分辨率（集群核心）的国家和国际天文台望远镜获得的图像（加上档案图像，包括哈勃太空望远镜在可能的情况下）。新的（在天文学界）统计数据也将被用于分析，以评估趋势和关系的显著性/置信水平。圣地亚哥的本科生和硕士生将大量参与这项工作-无论是减少和分析天文数据，还是应用先进的天文学方法。在UCSC研究生的培训也得到了支持。最终的光度测量也将公开提供。

AST-0507785 / AST-0507697Eric Sandquist / Michael BolteSan Diego State University / University of California Santa CruzCollaborative Research: Stellar Physics from Cluster-Wide Samples in GlobularStar ClustersABSTRACTA series of observational tests of theories of the structure and evolution of low mass stars will beperformed. Specifically, counts of globular cluster stars (i.e., luminosity functions) will beemployed to determine evolutionary timescales. Also, internally-consistent photometry will bemeasured to compare stellar properties (luminosity, temperature) at different phases of evolutionand at the same points of evolution across different clusters. Three aspects of the cluster colormagnitudediagrams will be examined: 1) The epoch of red giant branch ascent, including red giantevolutionary timescales, the red giant branch bump (its luminosity and sharpness), and thelocation of the red giant branch-tip; 2) horizontal branch and asymptotic giant branch morphologies,distributions, and evolution; and 3) blue stragglers and their radial distributions, distributions on thecluster color magnitude diagrams, and the presence of unusual blue straggler populations. Thestatistical nature of these investigations requires quality photometry of large samples of cluster starswhich will be extracted from previously obtained wide field (for cluster outskirts) and highresolution (for cluster cores) images obtained at national and international observatories telescopes(plus archival images, including the Hubble Space Telescope where possible). Novel (within theastronomical community) statistics will also be employed in the analysis to assesssignificance/confidence levels of trends and relations.Undergraduate and Master's students at San Diego will be heavily involved in this work - both withthe reduction and analysis of the astronomical data and the application of advanced statisticalmethods. The training of a graduate student at UCSC is also supported here. The final photometrywill also be made publicly available.