Investigations of the Stellar and Cluster Populations of the Inner Galactic Halo

银河系内晕的恒星和星团群的研究

• 批准号: 9319229
• 负责人: Robert Zinn
• 金额: $ 15万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-01 至 1997-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9319229&HistoricalAwards=false
• 关键词: Investigations; Stellar; Cluster; Populations; Inner

9319229 Zinn Recent investigations have indicated that the flattening of the galactic halo and the morphology of the horizontal branch (i.e. the relative frequencies of red and blue HB stars) of the halo vary with distance from the galactic center. The work of Dr. Zinn and other astronomers on the system of globular clusters suggests that this is due to the composite nature of the halo. The globular clusters of the inner halo have characteristics that are indicative of very old ages. While this Old halo population extends into the outer halo, at large galactocentric distances, the majority of clusters belong to a separate population, termed the Young halo. The properties of the Old halo clusters suggests that this system is a relic of the collapse of the Galaxy that ultimately produced the galactic disk and bulge, while those of the Young halo suggest that it is the debris of one or more large satellite galaxy (similar to the Large Magellanic Cloud) that merged with the Milky Way and was tidally disrupted in the process. The research carried out with this award is designed to test this hypothesis for the structure and formation of the galactic halo and to provide valuable information on the inner halo even if the hypothesis needs to be discarded. Observations of a selected sample of RR Lyrae variable stars will indicate if the stellar population of the inner halo is kinematically similar to the Old halo globular clusters. Samples of halo stars near the Sun will be examined for evidence that they are a mixture of the Old and Young halos. The results obtained by these investigations will provide a more detailed picture of the inner halo and the relationship between the globular cluster system and the stellar halo. They will therefore further our understanding of the evolution of our galaxy.

小行星9319229 最近的研究表明，星系晕的扁平度和晕的水平分支的形态（即红、蓝HB星的相对频率）随距星系中心的距离而变化。 津恩博士和其他天文学家对球状星团系统的研究表明，这是由于晕的复合性质。内晕的球状星团具有非常古老的特征。 虽然这个老晕人口延伸到外晕，在大的银河系中心距离，大部分的集群属于一个单独的人口，称为年轻的晕。 旧晕星系团的性质表明，这个系统是银河系坍缩的遗迹，最终产生了银河系盘和凸起，而年轻晕的性质表明，它是一个或多个大型卫星星系（类似于大麦哲伦云）的碎片，与银河系合并，并在此过程中被潮汐破坏。 该奖项的目的是测试这一假设的结构和形成的星系晕，并提供有价值的信息，即使假设需要放弃。 对一个选定的天琴座RR变星样本的观测将表明内晕的恒星数量是否与旧晕球状星团的运动学相似。 太阳附近的晕星样本将被检查，以寻找它们是老晕和年轻晕混合物的证据。 这些研究结果将提供更详细的内晕图像以及球状星团系统与恒星晕之间的关系。因此，它们将进一步加深我们对银河系演化的理解。