- binary star
- two stars, along the same line of sight, that look like one star, or a binary star, but actually are very distant from each other and physically unrelated; optical double
double stardouble star
(plural double stars)
- (astronomy) Two stars which form a stellar system, such that they orbit the point of equilibrium of their gravitational fields; a binary star.
- (astronomy) Two stars that appear to be one when seen with the naked eye, either because they orbit one another (binary stars) or happen to be in the same line of sight even though they are separated by a great distance (optical binaries).