A system of two stars that revolve around each other under their mutual gravitation; SYN. binary, double star.
Pair of stars moving in orbit around their common center of mass. Observations show that most stars are binary, or even multiple—for example, the nearest star system to the Sun, Alpha Centauri.
One of the stars in the binary system Epsilon Aurigae may be the largest star known. Its diameter is 2,800 times that of the Sun. A spectroscopic binary is a binary in which two stars are so close together that they cannot be seen separately, but their separate light spectra can be distinguished by a spectroscope.
Another type is the eclipsing binary.