Obiturary: William Morgan, Astronomy & Astrophysics
William Wilson Morgan (A.B.'27, Ph.D.'31), the Bernard E. and Ellen C. Sunny Distinguished Service Professor Emeritus in Astronomy & Astrophysics and one of the leading contributors to 20th-century astronomy, died June 21 at his home in Williams Bay, Wis. He was 88.
Morgan conducted research at the University's Yerkes Observatory in Williams Bay for more than 60 years. He was widely recognized for his discovery of the spiral arms of the Milky Way and for his system for classifying stellar brightness and spectra. His announcement of the finding that our galaxy has a spiral structure was received by his peers at a 1951 meeting of the American Astronomical Society with an unprecedented standing ovation.
"That was the first time that the existence of a spiral pattern was established without question," said Subrahmanyan Chandrasekhar, the Morton D. Hull Distinguished Service Professor Emeritus in Astronomy & Astrophysics. "He was certainly one of the more distinguished astronomers of this century."
Donald Osterbrock, former director of the Lick Observatory in California and a student of Morgan's, said, "He was an outstanding scientist. He did extremely important work in astronomy that opened up a lot of new thinking about stellar evolution, star formation and our own star system."
"He had a special way of looking at nature that inspired his work and that of all his students," said Richard Kron, Director of Yerkes Observatory. "When he looked at stellar spectra, he thought less in terms of atomic physics and more in terms of natural patterns. He constantly referred to his interest in the visual arts as an inspiration for his discoveries in astronomy."
In addition to his discovery of the Milky Way's spiral structure, Morgan is known for his development of three classification systems: the MK system, a two-dimensional classification system for stellar spectra and luminosity; the Yerkes system of classification of the optical forms of galaxies; and a precisely defined photoelectric method, called the UBV system, for determining the brightness of stars.
With Philip Keenan, Morgan developed the MK system, which for the first time allowed astronomers to determine the luminosity of stars directly from observations of their spectra -- the detailed colors and bright and dark bands in the light emitted by all stars. Morgan then used the MK system to determine the distances of bright stars within the Milky Way, and in so doing discovered the galaxy's spiral structure.
In 1943, with Keenan and Edith Kellman, Morgan wrote the Atlas of Stellar Spectra, a fundamental work that is still widely used by astronomers today.
Morgan's accomplishments were recognized with the National Academy of Sciences' Draper Medal, the Astronomical Society of the Pacific's Bruce Gold Medal, the Royal Astronomical Society's Herschel Medal and the American Astronomical Society's Russell Lectureship. Morgan was a member of the National Academy of Sciences, the American Academy of Arts and Sciences, and the Pontifical Academy of Sciences.
He received his A.B. in 1927 and his Ph.D. in 1931 from the University and joined the faculty as Instructor the following year. He became Assistant Professor in 1936, Associate Professor in 1943 and Professor in 1947 and was named the Bernard E. and Ellen C. Sunny Distinguished Service Professor in 1966. He served as Director of the Yerkes and McDonald Observatories from 1960 to 1963.
Morgan is survived by his wife, Jean; a sister, Sally Selder; two children, William of Rhinelander, Wis., and Emily of Madison, Wis.; and two grandchildren. His first wife, Helen Montgomery Barrett, died in 1963.