Photo 1988, courtesy Observatories of Carnegie Institution of Washington
Olin Chaddock Wilson, Jr.			13 January 1909	1984 Bruce Medalist	13 July 1994

A native Californian, Olin Wilson was educated at the University of California at Berkeley and the California Institute of Technology, where he earned his Ph.D. under Paul Merrill. He spent his entire career at the Mt. Wilson Observatory, where he made spectroscopic studies of stellar chromospheres and stellar activity cycles as well as supernovae, Wolf-Rayet stars, planetary nebulae, and the interstellar medium. By intensive analysis of the H and K lines of ionized calcium he showed that other stars besides the sun have cycles of activity. With M.K. Vainu Bappu he found a means of determining luminosity, and thus distance, of stars from the widths of these two lines. Wilson started the HK project which continues to use Mt. Wilson telescopes to monitor a number of nearby stars in search of starspot cycles. He also investigated spectra of nebulae and eclipsing stars.

Presentation of Bruce medal
Wolff, Sidney & Andrew Fraknoi, Mercury 13, 6, 187 (1984).

Other awards
American Astronomical Society, Henry Norris Russell Lectureship, 1977.

Some offices held
Astronomical Society of the Pacific, President, 1954-55.

Biographical materials
Abt, Helmut, Biographical Memoirs of the National Academy of Sciences 82, 352-371 (2003) [html or pdf ].
Baliunas, Sallie, Biographical Encyclopedia of Astronomers (Springer, NY, 2007), pp. 1227-28.
Mt. Wilson Institute

Obituaries
Preston, George W., PASP 107, 97-103 (1995).

Portraits
AIP Center for History of Physics (3 photos)
Caltech Archives (3 photos)

Named after him
Minor Planet #12138 Olinwilson
The Wilson-Bappu effect or relation (with M.K. Vainu Bappu)

More references