Studies of the RR Lyrae Variables in the Galactic Field and Globular Clusters and the Morphology of the Horizontal Branch

津恩博士将测量大约400颗天琴座RR变星的金属丰度和径向速度。这些数据将提高我们对运动学对银河系晕中金属丰度和银河系厚盘中恒星数量的依赖关系的了解。这将限制银河系早期演化的模型。将会观测到两个球状星团，这是被认为包含天琴座RR变星的最富金属星团。这些数据和合成水平分支模型的计算将有助于解开富含金属的天琴座RR变星的起源之谜。我们将为银河系中心附近的大约10个球状星团绘制彩色星等图。这些数据将为可能存在的年龄差异设定上限，这反过来将限制银河系演化的模型。关于银河系晕形成的两张最流行且相互竞争的图片预测，铁与氢的丰度比与围绕银河系中心的平均自转速度之间存在着截然不同的关系。目前的数据是否支持其中一种情况，而另一种情况，存在相当大的争议。津恩博士设计了一个观测项目，他预计该项目将排除这两个模型中的一个。

Dr. Zinn will measure the metal abundances and radial velocities of about 400 RR Lyrae variable stars. These data will improve our knowledge of the dependence of kinematics on metal abundance in the halo of our Galaxy and the populations of stars in the thick disk of the Galaxy. This will constrain models of the early evolution of the Galaxy. Two globular clusters, which are the most metal- rich clusters thought to contain RR Lyrae variables, will be observed. These data and computations of synthetic horizontal branch models will help resolve the enigma of the origin of the metal-rich RR Lyrae variables. Color magnitude diagrams will be constructed for about 10 globular clusters of stars close to the Galactic Center. These data will set an upper limit on the age variations that may be present, which in turn will constrain models of galactic evolution. The two most popular, and competing, pictures of the formation of the halo of our Galaxy predict very different relationships between the abundance ratio of iron to hydrogen and the mean rotational velocity about the Galactic Center. There is considerable debate whether the present data support either picture over the other. Dr. Zinn has designed an observational project which he expects will rule out one or the other of the two models.