| two stars that appear as one if not viewed through a telescope with adequate magnification, such as two stars that are separated by a great distance but are nearly in line with each other and an observer (optical double star), or those that are relatively close together and comprise a single physical system (physical double star). |
| binary star n. A stellar system consisting of two stars orbiting about a common center of mass and often appearing as a single visual or telescopic object. Also called double star. |
| double star n. See binary star. |
