A star system in which two or more stars orbit each other around a center of mass. They can share material between themselves.

Two stars that revolve about each other.

A binary star are two stars rotating around a common center of mass. About half of the stars in the sky are binary systems.

Two stars that orbit around a common center of mass. An X-ray binary is a special case where one of the stars is a collapsed object such as a white dwarf, neutron star, or black hole. In an X-ray binary, the separation between the stars is small enough so that matter is transferred from the normal star to the collapsed star, producing X-rays in the process.

A double star system; two (or more) stars revolving about a common center of gravity

Pairs of stars that orbit around their common center of mass