Development, Operation and Maintenance of the Automated Plate Scanner

在我们理解银河系和恒星演化的基本不确定性中，有一些问题涉及恒星的含量和演化如何取决于化学成分，恒星形成的初始质量函数可能存在的变化，特别是星系的形态类型。这里概述的研究计划将提供一些必要的观测数据，以开始回答这些问题。具体地说，将对附近的SB型螺旋星系M31进行恒星含量调查。对M31中最亮恒星的初步调查结果表明，它们的亮度低于Sc螺旋星系和麦哲伦不规则星系中的对应恒星。这第一次观察表明，最大质量恒星的形成和演化可能取决于其形态类型。将对特殊的半人马座A星系中的恒星形成区域进行调查。将对非常明亮的超巨星进行研究，这些恒星在赫茨斯普龙格-罗素(HR)图中定义了光度上限，并包括哈勃-桑达奇变星和较冷的超巨星。对具有异常强氢线的特殊A型超巨星的定量光谱研究已经开始。这些恒星可能是处于氦燃烧阶段的进化程度更高的超巨星。它们在HR图上的识别和位置对于恒星演化研究是非常重要的。

Among the basic uncertainties in our understanding of both galactic and stellar evolution are questions concerning how the stellar content and evolution of the stars may depend on chemical composition, possible variations in the initial mass function of star formation, and especially on the morphological type of the galaxy. The research program outlined here will provide some of the observational data necessary to begin answering these questions. Specifically, a stellar content survey of the nearby Sb-type spiral galaxy M31 will be carried out. The initial results of a survey of the brightest stars in M31 show that they are less luminous than their counterparts in Sc spirals and the Magellanic irregular galaxies. This first look suggests that the formation and evolution of the most massive stars may depend on the morphological type. An investigation of the star forming regions in the peculiar galaxy Centaurus A will be done. Studies of the very luminous hypergiant stars, which define the upper luminosity boundary in the Hertzsprung-Russell (HR) diagram and includes the Hubble-Sandage variables and the cooler hypergiants, will be carried out. A quantitative spectroscopic study of the peculiar A-type supergiant stars with anomalously strong hydrogen lines has begun. These stars may be the more evolved supergiant stars in the Helium burning stage. Their identification and location on the HR diagram is very important for stellar evolution studies.