Alfred Harrison Joy (1883-1973)is 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 Dopplar displacement of the spectral lines of stars to determine their radial velocities deducing a star's absolute dimensions, masses, and orbital elements of some specific stars.
AlfredHarrisonJoy was an American astronomer most famous for his work on stellar distances, the radial motions of stars and variable stars.
Joy and his colleagues also studied the Doppler displacement of the spectral lines of some stars to determine their radial velocities.
Joy later became interested in the parts of the Galaxy where dark, absorbing clouds of gas and dust exist, and by carefully observing these areas he found examples of a particular kind of variable star, called a T-Tauri star, which is strongly associated with these areas.
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