double star

American  

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.

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double star British  

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

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double star Scientific  

1. See binary star

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Etymology

Origin of double star

First recorded in 1775–85

Example Sentences

And a smaller quibble: movie also purports in an early scene to show the double star Mizar and Alcor, but the photograph on screen is not of them.

From Salon • May 6, 2023

A star like Mizar A, which appears as a single star when photographed or observed visually through the telescope, but which spectroscopy shows really to be a double star, is called a spectroscopic binary.

From Textbooks • Oct. 13, 2016

Throughout April, Mars, Saturn and the red variable double star Antares form a triangular, cosmic congregation.

From Washington Post • Apr. 2, 2016

Alpha Centauri, only four light-years from here, is actually a double star, Alpha Centauri A and Alpha Centauri B. There is a third star, Proxima Centauri, sometimes called Alpha Centauri C, in the system.

From New York Times • Aug. 4, 2014

Castor is a celebrated double star, but its components are far too close to be separated with an opera-glass, or even the most powerful field-glass.

From Astronomy with an Opera-glass A Popular Introduction to the Study of the Starry Heavens with the Simplest of Optical Instruments by Serviss, Garrett Putman