Chemical Abundances and the Formation and Evolution of the Galactic Bulge

克里斯蒂安·约翰逊博士被授予NSF天文学和天体物理学博士后奖学金，以在加州大学洛杉矶分校开展一项研究和教育计划。约翰逊博士将大幅增加沿短轴和离轴场对银河系凸起中红巨星(RGB)的光谱观测数量。该计划将首次将化学丰度的测定扩展到轻奇Z元素和重中子俘获元素，样本中约有1000颗膨胀巨星。这些数据将与约翰逊博士论文工作的结果相结合，该论文对半人马座欧米茄中的约1000颗RGB恒星进行了全面的化学分析，以深入了解两个独立的“球状”系统的化学演化，这两个系统显示出显著的自我浓缩迹象，但金属丰度范围几乎为1,000倍。约翰逊还将开发一个光谱合成网络工具，旨在帮助普通公众、本科生、非理科专业的本科生和高级本科生更容易获得恒星丰富的工作。该网络工具旨在作为一个有指导的教程，使学生和普通公众能够在学习恒星演化和核合成的背景下，积极参与确定恒星的化学成分。约翰逊博士将开发与网络工具相关的活动，这些活动适合在非理科专业和高级本科生课堂上使用。

Dr. Christian Johnson is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the University of California, Los Angeles. Dr. Johnson will increase dramatically the number of spectroscopic observations of red giant branch (RGB) stars in the Galactic bulge along both minor axis and off-axis fields. This program will for the first time extend the determination of chemical abundances to light odd-Z elements and heavy neutron-capture elements in a sample of ~1,000 bulge giants. These data will be combined with the results of Dr. Johnson's dissertation work, a comprehensive chemical analysis of ~1,000 RGB stars in Omega Centauri, to provide insight into the chemical evolution of two independent "spheroidal" systems exhibiting signs of significant self-enrichment but that span a metallicity range of nearly a factor of 1,000.Dr. Johnson will also develop a spectrum synthesis webtool designed to help make stellar abundance work more accessible to the general public, undergraduate non-science majors, and advanced undergraduates. The webtool is intended to be a guided tutorial that allows students and the general public to actively participate in determining the chemical composition of stars in the context of learning about stellar evolution and nucleosynthesis. Dr. Johnson will develop activities associated with the webtool that are appropriate for use in both non-science major and advanced undergraduate classes.