What does binary star mean?

A binary star refers to two stars that revolve around a common center.

Binary stars also refer to morning glory and weaver girl. In China mythology, they are a loving couple. Legend has it that magpies cross the bridge on July 7 every year, so that they can meet each other across the Milky Way. Tang Du Fu's "Twelve Judges for Xue": "In peace, there are two stars, Yin and Han." Astronomers found that there are many of them. There is a mechanical connection between the two stars, and they revolve around each other. Such two stars are called binary stars.

A binary star refers to two stars that revolve around a common center. For one of them, the other is its "companion star". Relative to other stars, the position looks very close. The word Lianxing was coined by friedrich herschel in 1802. According to his definition, the connected star system is a system composed of two stars according to the law of gravity.

Characteristics of binary stars

There are many kinds of conjoined stars. One star moves around another star, or both of them move around each other and have gravitational interaction with each other. This is also called a physical binary star. The two stars look very close, but the actual distance is very far. This is called an optical binary star. Generally speaking, binary stars refer to physical binary stars, unless otherwise specified. According to different observation methods, binary stars that can be observed through astronomical telescopes are called visual binary stars; Binary stars that can only be distinguished by analyzing spectral changes are called spectral binary stars.

In addition, another star orbits another star, and a third star orbits them. This is called a triad. By analogy, there are four stars and so on, which are called multiple stars. This is especially important for conjoined satellites in astrophysics, because the mass of two stars can be determined by observing their rotating orbits. This can also calculate the mass of many independent stars.