optical double


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Related to optical double: Binary star system

optical double:

see 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
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.

optical double

1. See double star.
2. See double galaxy.
References in periodicals archive ?
It's an easy, uneven optical double, with the primary about three times as bright as the companion.
Eta Draconis is one of the "backbone" stars of the dragon asterism, and a wide optical double.
6, 7 The M-type star 64 Draconis isn't a true double, but forms a wide optical double with 65 Draconis.
10 The cool, dim, yellow-white G9 giant sun 75 Draconis, in the northernmost reaches of the constellation, makes an easy optical double with its neighbor, HD 196565, a yellow-orange KO star.
In contrast, optical doubles are physically unrelated but coincidentally aligned along our line of sight.
On November 21, 1998, I was able to resolve the optical double Lambda (l) Orionis (magnitudes 3.
Theoretically, only a 13/4-inch telescope is needed to split the optical double Otto Struve 111 (OS111) into its components (5.
Optical doubles are at different distances, too far apart to be physically related; they appear close only because they happen to lie very nearly in the same line of sight as viewed from Earth.
I'd be curious to find out whether a more formal identification system for optical doubles exists.