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optical double star

noun
1.
See under double star.

double star

noun, Astronomy
1.
two stars that appear as one if not viewed through a telescope with adequate magnification, such as two stars that are separated by a great distance but are nearly in line with each other and an observer (optical double star) or those that are relatively close together and comprise a single physical system (physical double star)
Compare binary star.
Origin
1775-1785
1775-85
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for optical double star

optical double star

noun
1.
two stars that appear close together when viewed through a telescope but are not physically associated and are often separated by a great distance Compare binary star

double star

noun
1.
two stars, appearing close together when viewed through a telescope; either physically associated (binary star) or not associated (optical double star) See also binary star, optical double star
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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optical double star in Science
double star  
See binary star.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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