Henriksen 9624716 A five-year research and education plan will be carried out. The goals of the activities are to (1) establish and maintain a research program which produces a significant contribution to an important and interesting area of astronomical research, (2) to strengthen educational opportunities in astronomy at the University of North Dakota, (3) to increase the involvement and interest of Native Americans in astronomy research and in the University of North Dakota, (4) to stimulate interest in astronomy research within the University and within the state of North Dakota. The understanding of galaxy evolution in clusters of galaxies has posed a persistent challenge to astronomers for approximately 20 years, beginning with discovery of the Butcher-Oemler Effect. Photometric and spectroscopic observations of galaxies in clusters showing this effect have confirmed this observational enigma and increased our understanding of the problem. The problem stated succinctly is, "How does the galaxy population in clusters change from being dominated by late-type spirals at a redshift of z = 0.2 to being dominated by early-type galaxies in the galaxy population at the present epoch". The recent discovery that substructure is found in many clusters of galaxies in both the optical and the X-ray region of he electromagnetic spectrum suggests that galaxies must experience violent mergers of subclusters as rich clusters are formed. Even well known rich clusters, such as the Coma cluster of galaxies and the A2256 cluster of galaxies, are still accreting groups of galaxies so that mergers must be an ongoing phenomenon in cluster evolution. The study of the evolution of galaxies in clusters through the analysis of the data from observations of the X-ray emission from clusters of galaxies with substructure will be carried out. Simulations of the cluster tidal effect on disk galaxies during mergers and accretions will be developed and analyzed. The simulations wi ll be formulated to emphasize predicting observable quantities, such as changes in the galaxy disk due to star formation, disk deformation, and loss of metals to the intracluster medium. These quantities will be compared to data obtained at current ground-based observatories, space-based observatories (ASCA and the Hubble Space Telescope), and future observatories such as the Advanced X-ray Astrophysics Facility (AXAF). The analysis of these data will contribute significantly to our understanding of two important and closely linked areas: evolution of the intracluster medium and galaxy evolution. Educational activities to be carried out outside the classroom will include (1) upgrading and modernizing the curricula in three courses, which are currently severely underenrolled, when compared to the same courses taught at other Universities, (2) providing undergraduate and graduate students research opportunities in astronomy, and (3) providing astrophysics graduate students the opportunity to gain practical experience in the laboratory working on high energy detector development. It is a stated future direction of the University of North Dakota to include more computer-based, interactive learning for students and to strengthen ties with the Native American community in North Dakota.
