Development, Operation and Maintenance of the Automated Plate Scanner

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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.