double stars

A binary star is a star system consisting of two stars orbiting around their common barycenter. Systems of two, three, four, or even more stars are called multiple star systems. These systems, especially when more distant, often appear to the unaided eye as a single point of light, and are then revealed as double (or more) by other means. Research over the last two centuries suggests that half or more of visible stars are part of multiple star systems.

Double Star is a science fiction novel by Robert A. Heinlein, first serialized in Astounding Science Fiction (February, March, April 1956) and published in hardcover the same year. It received the 1956 Hugo Award for Best Novel (his first).

In observational astronomy, a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope.