January 13, 1909–July 13, 1994

BY HELMUT A.ABT

OLIN C.WILSON was a stellar spectroscopist who spent his entire research career (1932–82) observing at the Mt. Wilson and Palomar observatories. He is known for being the first person to derive activity cycles in other stars analogous to the 11-year solar cycle. He also showed that the widths of the chromospheric Ca II emission lines in late-type stars provide accurate measures of their luminosities— the Wilson-Bappu effect. He is known for showing the complex internal motions in planetary nebulae and the Orion nebula; the latter shows evidence of shock waves and turbulence that is non-Kolmogoroff. He also demonstrated that many Wolf-Rayet stars are members of double stars and that they are under-massive. He also showed that the chromosphere of the supergiant zeta Aurigae consists of sheets or clumps, not a smoothly varying density gradient.

Olin Wilson was born in San Francisco, California, on January 13, 1909. His father was a lawyer who had moved to California in 1904, and his mother came from Iowa. They lived just south of Golden Gate Park. Fortunately they were not seriously affected by the earthquake and fire of 1906. His father worked downtown and rode the streetcars; they did not have a car. Their income was only moderate. Olin