Joy, Alfred Harrison (1883–1973)
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 a total of nearly 66 years.
Adapted
in part from the biographical
entry at The Bruce Medalists website
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