One of the U.S. PIs, Peter A. Wehinger, Susan Wyckoff, and their graduate student, Marvin Kleine, will visit their Australian counterpart, Dr. Bruce A. Peterson of the Australian National University, once in each of three years. The goals of this research are to determine the carbon isotope abundance ratio in a sample of bright comets, and to determine the 12C/13C abundance ratio in the local interstellar medium by observing absorption lines of molecules and molecular ions (CN, CH, and CH+) in the lines-of-sight of bright 0- and B-type stars. Also proposed is the development of a full fluorescence model for CN to improve the accuracy with which we can determine the carbon and nitrogen isotope ratios in comets. The researchers will use the Mount Stromolo Observatory's 1.9 meter telescope located near Canberra, Australia, with its coude-echelle spectrograph and photo-counting array. In the Northern Hemisphere, the investigators will use the Kitt Peak National Observatory coude-feed telescope and echelle spectrograph. The research, which is essentially a continuation of a successful collaborative effort begun with Comet Halley in 1986 with U.S.-Australia Cooperative Science Program support, is important because of what it may reveal about the formation of the early universe. Additional financial support for the domestic U.S. research comes from NASA and NSF grants.
