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The Theory of Visual Binaries: Edward Sion

Among the several students remaining in limbo when I left was Edward M.Sion, who went on persistently to complete his M.A. thesis, which was devoted to the theory of visual binaries. He did this the hard way by sending me (at LASL) completed sections via "snail" mail, and I would check over the mathematics and make suggestions. It pleased me greatly when he successfully finished his thesis and passed his oral exam in 1969.

He then was able to go to the University of Pennsylvania where he got his Ph.D.; his thesis there, completed in 1975, was titled Multi-Modal Non-Adiabatic Oscillations and Pulsational Stability of Hot Degenerate Dwarfs (advisor: Samuel C. Vila). When I was a student at Yerkes such a subject was considered pretty sophisticated (not to Chandra of course!), and I recall having to give a review of Rosseland's monograph The Pulsation Theory of Variable Stars . It seemed strange to me that so much of the book was devoted to adiabatic pulsations, which cannot give rise to light variations. Chandra chided me rather vigorously saying that the author was mainly interested in the mathematics of pulsation theory, rather than light variation problems. And what was I doing in the early 70's while Ed Sion was writing his Ph.D. thesis? I was involved with others at LASL programming a related problem, viz., the coupled radiation hydrodynamics of a rapidly expanding nuclear fireball in air! Perhaps Ed Sion would have felt perfectly at home here in Los Alamos!

But he has stayed in astronomy, working on late stages of stellar evolution, accretion onto degenerate stars, models of thermonuclear shell flashes, cataclysmic and symbiotic variable stars. He is now (1998) Professor of Astronomy and Astrophysics at Villanova University. In addition to research and teaching he is one of the associate (scientific) editors of the Ap.J..

In the last six years he has had observing time on the Hubble Space Telescope, resulting in fifteen refereed papers about properties of white dwarfs: spectroscopic studies, the first rotation rates, and the discovery of proton capture elements with greatly enhanced abundances pointing to a past classical nova (thermonuclear) explosion. He writes that he has travelled a lot to meetings in Europe, Israel, Russia, China and Australia.

He is married to K.U. alumna Miriam Kay Kangas, who is a psychiatrist working in the field of family therapy and as a social worker, and they have two children.