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either of two large aquatic rodents, Castor fiber and Castor canadensis, known for their engineering feats. They were once widespread in N and central Eurasia except E Siberia, and in North America from the arctic tree line to the S United States.
..... Click the link for more information. .
Castor(kăs`tər), bright star in the constellation GeminiGemini
[Lat.,=the twins], northern constellation lying on the ecliptic (the sun's apparent path through the heavens) between Taurus and Cancer, N of Canis Minor; it is one of the constellations of the zodiac. Gemini is traditionally depicted as two men.
..... Click the link for more information. ; Bayer designation α Geminorum; 1992 position R.A. 7h34.1m, Dec. +31°54'. Slightly dimmer than PolluxPollux,
brightest star in the constellation Gemini; Bayer designation Beta Geminorum; 1992 position R.A. 7h44.8m, Dec. +28°03'. An orange giant of spectral class K0 III, it is the nearest giant star, lying at a distance of 35 light-years.
..... Click the link for more information. , with which it forms the Twins, Castor has an apparent magnitudemagnitude,
in astronomy, measure of the brightness of a star or other celestial object. The stars cataloged by Ptolemy (2d cent. A.D.), all visible with the unaided eye, were ranked on a brightness scale such that the brightest stars were of 1st magnitude and the dimmest stars
..... Click the link for more information. of 1.58, which still makes it one of the 25 brightest stars in the sky. Castor is actually a six-star system, being a visual triple each component of which is a binary starbinary star
or binary system,
pair of stars that are held together by their mutual gravitational attraction and revolve about their common center of mass. In 1650 Riccioli made the first binary system discovery, that of the middle star in the Big Dipper's handle, Zeta
..... Click the link for more information. ; the three components are an eclipsing binary and a pair of spectroscopic binaries. The two brightest components are white, main-sequence stars of spectral classesspectral class,
in astronomy, a classification of the stars by their spectrum and luminosity. In 1885, E. C. Pickering began the first extensive attempt to classify the stars spectroscopically.
..... Click the link for more information. A1 and A5. The system is about 50 light-years distant.
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Castor(kass -ter, kahss -) (α Gem) A white star that is the second-brightest in the constellation Gemini. It is a visual triple star, the two brighter components having an orbital period of about 470 years; the third component, a flare star, is located some distance away. All three are spectroscopic binaries. mv : 1.9 (A), 2.9 (B), 1.57 (AB); Mv : 0.5 (AB); spectral type: A1 V (A), A2 V (B); distance: 15 pc.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
A multiple star of spectral classification A0 in the constellation Gemini; the star α Geminorum.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
1. the brownish aromatic secretion of the anal glands of a beaver, used in perfumery and medicine
2. the fur of the beaver
3. a less common name for beaver
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005