Important structural information about the structure of the hot "chromospheres" of cool stars can be inferred best by studying the shapes of strong "resonance" spectral lines, such as the Lyman-alpha line from neutral hydrogen and the H and K lines of ionized calcium. In this one-year award the Co-Investigator, Dr. Kenneth Gayley, will develop simple probabilistic formalisms that may extend our insight into the "partial redistribution" process by which the wings of these resonance lines are formed. The goal of this study is to see whether it is feasible to adopt shortcuts that reflect realistic physical assumptions in lieu of complex numerical simulations, which few astrophysicists are in a position to formulate and implement. If successful, this feasibility study is expected to have application to a variety of problems, including the atmosphere of the Sun, active galactic nuclei, and quasars.
