Alfred Harrison Joy
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Alfred Harrison Joy
(1883–1973)
An American astronomer best known for his work on stellar distances, the radial motions of stars, and variable stars. After teaching astronomy for a number of years and spending a year at Yerkes Observatory, Joy came to Mount Wilson Observatory in 1915. There he applied Walter Adams's method of spectroscopic parallax to determine the distances of thousands of stars. When he retired nearly half of all published radial velocities of stars had been found at Mount Wilson, largely through his efforts. His measurements of the radial velocities of Cepheid variables confirmed the distance and direction of the galactic center and the Sun's rate of revolution about it. He also invented the classification of T Tauri stars and made extensive studies of them. Although he officially retired in 1948, Joy remained active at Mount Wilson for nearly 66 years.
An American astronomer best known for his work on stellar distances, the radial motions of stars, and variable stars. After teaching astronomy for a number of years and spending a year at Yerkes Observatory, Joy came to Mount Wilson Observatory in 1915. There he applied Walter Adams's method of spectroscopic parallax to determine the distances of thousands of stars. When he retired nearly half of all published radial velocities of stars had been found at Mount Wilson, largely through his efforts. His measurements of the radial velocities of Cepheid variables confirmed the distance and direction of the galactic center and the Sun's rate of revolution about it. He also invented the classification of T Tauri stars and made extensive studies of them. Although he officially retired in 1948, Joy remained active at Mount Wilson for nearly 66 years.
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Alfred Harrison Joy
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Alfred Harrison Joy
This article is about the astronomer. For the 20th century Arctic explorer, see Alfred Harrison (explorer).
Alfred Harrison Joy (September 23, 1882, Greenville, Illinois – April 18, 1973, Pasadena, California) was an astronomer best known for his work on stellar distances, the radial motion of stars, and variable stars.
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Early years
He was born in Greenville, Illinois, the son of F.P. Joy, a prominent clothing merchant in Greenville and one-time mayor of the town.[1] He was educated in Greenville College and gradusted MA in 1904 from Oberlin College.
Career
After graduating, Joy went on to work at the American University of Beirut in the Syrian Protestant College 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.
He was president of the Astronomical Society of the Pacific in 1931 and 1939.
References
- ^ Allan H. Keith, Historical Stories: About Greenville and Bond County, IL. Consulted on August 15, 2007.
External links
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Wiley Book of Astronomy
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