binary star

American  

noun

Astronomy.

1. a system of two stars that revolve about their common center of mass.

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binary star British  

noun

1. Sometimes shortened to: binary.  a double star system comprising two stars orbiting around their common centre of mass. A visual binary can be seen through a telescope. A spectroscopic binary can only be observed by the spectroscopic Doppler shift as each star moves towards or away from the earth See also optical double star eclipsing binary

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binary star Scientific  

1. A system of two stars that orbit a common center of mass, appearing as a single star when visible to the unaided eye. The orbital periods of binary stars range from several hours to several centuries. By some estimates, at least half of the stars in the Milky Way galaxy are members of binary star systems.

2. Also called double star

3. ◆ Binary stars are divided into four main classes based on how their dual nature is detected. A visual binary can be resolved telescopically into its two components. Only one star of an astrometric binary is visible, but the unseen component can be identified from its gravitational effect on the visible star, causing it to oscillate slightly, or wobble, against the background of more distant stars. The two components of a spectroscopic binary are identified based on their varying orbital velocities toward or away from Earth as revealed by periodic Doppler shifts in their spectral lines. In an eclipsing binary, the two components orbit each other in such a way that they periodically obscure or eclipse each other as viewed from Earth, causing changes in their observed brightness. Eclipsing binaries are also considered a kind of variable star.

4. ◆ Two stars that lie very close to each other along an observer's line of sight but that are not associated with each other in a gravitational system are known as optical binaries. Although they appear close to each other in the sky, such stars are actually very distant from each other in space.

5. See also multiple star variable star

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Etymology

Origin of binary star

First recorded in 1875–80

Example Sentences

Scientists have known about the existence of such binary star systems in the Milky Way for decades, where one of the stars has become a black hole.

From Science Daily • May 21, 2024

That may be because it’s a binary star, and the two stars move around each other on a mildly elliptical orbit, which could destabilize planetary orbits.

From Scientific American • Oct. 6, 2023

According to NASA, this "suggests that the protostar may in fact be an unresolved binary star," meaning there could actually be two stars beneath this mysterious cloud of molecules.

From Salon • Sep. 14, 2023

In theory, researchers think that this structure is a result of the clash between the red giant and a companion binary star.

From Space Scoop • Aug. 3, 2023

This is a binary with a period of revolution of about sixty years, and is interesting as the first binary star whose orbit was determined.

From Pleasures of the telescope An Illustrated Guide for Amateur Astronomers and a Popular Description of the Chief Wonders of the Heavens for General Readers by Serviss, Garrett Putman