Alfred Harrison Joy

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Alfred Harrison Joy
Alfred Harrison Joy

Alfred Harrison Joy (September 23, 1883, Greenville, Illinois - April 18, 1973, Pasadena, California) was an astronomer best known for his work on steller distances, the radial motion of stars, and variable stars. He was born in Greenville, Illinois. After graduating from Greenville College, Joy went on to work at the American University of Beirut as a professor of astronomy and the director of the observatory. He was forced to return to the U.S. in 1915 because of World War I. In the United States he worked at the Mount Wilson Observatory from 1915 to 1952. There, he and his colleagues ascertained the spectral type, absolute magnitude, and stellar distance of over 5,000 stars. Joy also discovered the T-Tauri type star. He studied the Doppler displacement of the spectral lines of stars to determine their radial velocities deducing a star's absolute dimensions, masses, and the orbital elements of some specific stars. He won the Bruce Medal in 1950.

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