Olin Chaddock Wilson, Jr.

Olin Chaddock Wilson, Jr.


Date of Birth
January 13, 1909
Date of Death
July 13, 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 used Mt. Wilson telescopes to monitor a number of nearby stars in search of starspot cycles from 1966 to 2002. 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).
Baliunas, Sallie, Biographical Encyclopedia of Astronomers, 2nd ed. (Springer, NY, 2014).


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

Academic genealogy



AIP Center for History of Physics
Caltech Archives

Named after him

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


Papers, etc.

Wilson’s papers are at the Huntington Library. There is an oral history interview, conducted by David DeVorkin in 1978, at the Niels Bohr Library & Archives .

Other References: Historical

Search ADS for works about Wilson

Apt, Helmut A., “Solving Olin Wilson’s Mystery,” PASP 114, 559-62 (2002).

Griffin, R.F., “O.C. Wilson and His K-line Intensities,” Observatory 118, 145-53 (1998).

Hall, Jeffrey C., "Stellar Chromospheric Activity," Living Rev. Sol. Phys. 5, 2 (2008).

Hearnshaw, J. B., The Analysis of Starlight (Cambridge University Press, Cambridge, UK, 1986)

Noyes, R.W., “Olin C. Wilson and the Solar-Stellar Connection,” in Roberto Pallavicini & Andrea K. Dupree, eds., Cool Stars; Stellar Systems; and the Sun, Proceedings of the 9th Cambridge Workshop; held 3-6 October 1995 in Florence; Italy (Astronomical Society of the Pacific, San Francisco,1996), pp. 3-10.

Other References: Scientific

Search ADS for works by Wilson

Merrill, Paul W. & Olin C. Wilson, Jr., ”Comparison of the Paschen and the Balmer Series of Hydrogen Lines in Stellar Spectra,” Ap.J. 80, 19-50 (1934) [Wilson’s doctoral dissertation].

Christie, William H. & O.C. Wilson, “ζ Aurigae: the Structure of a Stellar Atmosphere,” Ap.J. 81, 426 (1935).

Merrill, Paul W., Roscoe F. Sanford, O.C. Wilson, & Cora G. Burwell, “Intensities and Displacements of Interstellar Lines,” Ap.J. 86, 274-310 (1937).

Sanford, Roscoe F., & O.C. Wilson, “On the Doublet Ratio of Interstellar H and K and the Absolute Magnitudes of Wolf-Rayet Stars,” Ap.J. 90, 235-43 (1939).

Wilson, O.C., “Possible Applications of Supernovae to the Study of the Nebular Red Shifts,” Ap.J. 90, 634-36 (1939).

Wilson, O.C., “The New Cassegrain Spectrograph for the Mount Wilson 60-Inch Telescope,” PASP 68, 346-50 (1956).

Wilson, O.C. & M.K. Vainu Bappu, “H and K Emission in Late-Type Stars: Dependence of Line Width on Luminosity and Related Topics,” Ap.J. 125, 661-83 (1957). [reprinted in the centennial edition Ap.J. 525C, 753 (1999) with a modern commentary by Jeffrey L. Linsky]

Hoyle, F. & O.C. Wilson, “Some Theoretical Aspects of H and K Emission in Late-Type Stars,” Ap.J. 128, 604-15 (1958).

Wilson, O.C., “Chromospheric Variations in Main-Sequence Stars,” Ap.J. 226, 379-96 (1978) [an expanded version of the 1977 Henry Norris Russell Lecture].

Vaughan, Arthur H., George W. Preston, & Olin C. Wilson, “Flux Measurements of CA II H and K Emission,” PASP 90, 267-74 (1978).

Wilson, O.C., “Photoelectric Measures of Chromospheric H and K and Hε in Giant Stars,” Ap.J. 257, 179-92 (1982).

Duncan, Douglas K., et al, “CA II H and K measurements made at Mount Wilson Observatory, 1966–1983,” Ap.J. Supp. 76, 383-430 (1991).

Baliunas, S.L., et al, “Chromospheric Variations in Main-Sequence Stars. II,” Ap.J. 438, 269-87 (1995).

Other Works: Popularizations, Fiction, etc.

Wilson, Olin C., “Planetary Nebulae,” Astronomical Society of the Pacific Leaflets 6, 20-27 (1967) [Leaflet #253].

Wilson, O.C., A.H. Vaughan, & D. Mihalas, “The Activity Cycles of Stars,” Scientific American 244, 104 (1981).

Wilson, O., A. Vaughan, R. Kraft, & G. Preston, “Activity Cycles in Other Stars,” Sky & Telescope 62, 312 (1981).