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Astro*Dictionary by Michael Erlewine





1 article for "Adams, Walter Sydney"

Adams, Walter Sydney [Astro*Index]

(1876-1956) American astronomer. Born at Antioch, Syria; died at Pasadena, California.

In 1914, he proved that, solely from its spectrum, it was possible to tell whether a star was a giant or a dwarf. He also deduced a star's luminosity from its spectrum. By comparing this luminosity with a star's apparent brightness, he calculated the star's distance. His method, which became known as spectroscopic parallax, allowed Hertzsprung to deduce the distance of some Cepheid variables. In 1915, Adams was able to study the spectrum of the dim companion star of Sirius, in spite of the glare of Sirius. He found it to be an extremely hot star, and calculations proved it to be extremely dense; he had discovered the first white dwarf. After other white dwarfs were discovered, Eddington, in the 1920s, showed that they must have super-intense gravitational fields, which would produce a red-shift in accordance with Einstein's Theory of General Relativity. Adams searched for such a star and, in 1925, found one which was not exactly the size predicted by Einstein, but was close enough to serve as a check of the theory. His spectroscopic work on Venus, in 1932, showed that its atmosphere contained large amounts of carbon dioxide.

See also:
♦ Light Spectrum ♦ Giant Star


Astro*Index Copyright © 1997 Michael Erlewine