Julius H. Cahn, researcher on variable stars and planetary nebulae, died 29 July 2009 in Santa Fe at age 89. He was born 29 October 1919 in Chicago, Illinois, the eldest son of Morton D. Cahn and Elizabeth Hofeller Cahn, and grew up in Winnetka, Illinois. Cahn received his bachelors degree in 1942 from Yale University. During World War II, he worked at Camp Evans Signal Laboratory, Belmar, New Jersey, and later at the University of California Berkeley, before serving with the U.S. Army in Europe in 1944. Cahn obtained his PhD in 1948 from Yale University, completing a thesis titled “The Effects of Electrostatic Interactions on the Electronic Velocity Distribution Function.” After completing graduate school, he taught physics at the University of Nebraska (1948-50), spent eight years at the Battelle Memorial Institute in Columbus, Ohio, and twenty-six years at the University of Illinois, Urbana-Champaign, most of that time in the Astronomy Department. His research focus was on Mira variables and planetary nebulae. His most cited paper during his Illinois tenure was “The Distances and Distribution of Planetary Nebulae,” with James Kaler, which listed the photometric distances, or upper limits to the distances, of more than 600 planetary nebulae (Astrophysical Journal Supplement Series 22 (1971)).
Cahn retired in 1985, and he and his wife, Helen Blackhall Cahn, moved to Santa Fe, New Mexico, in 1992. He was a skillful amateur pianist and also played the bass and cello, both solo and with others. He loved cars and motorcycles, and was certified to fly single-engine and twin-engine airplanes, with his wife frequently serving as co-pilot. In his later years, Cahn took up weightlifting and competed in weightlifting meets.