This proposal requests funds to permit Dr. Kam-Ching Leung, Professor of Physics and Astronomy, University of Nebraska-Lincoln, to pursue with Dr. Il-Seong Nha, Yonsei University, Korea, for a period of 24 months, a program of cooperative research on contact and semidetached systems of case B mass exchange in binary star systems. These scientists will make a photoelectric observational study of a number of such systems with periods ranging from long to very long (11 days to 96 days). The results of this research could be used for checking or comparing the predictions of theoretical models and for construction of future theoretical models of binary star systems. This project deals with observations and analysis of the regular changes in brightness of a relatively unobserved category of binary stars which are close enough to each other so as to alter each other's evolution but far enough apart that the period of revolution is many days. The investigation of these binary stars is important for understanding the evolution of stars and for understanding the more complicated, often explosive, binary stars. This project is relevant to the objectives of the U.S.-Korea Cooperative Science Program which seeks to increase the level of cooperation between U.S. and Korean scientists and engineers through the exchange of scientific information, ideas, skills, and techniques and through collaboration on problems of mutual benefit. The U.S. and Korean collaborators are highly respected scientists who have extensive research experience and productive publication records in the field of the proposal.
