There are even groups of three or more stars orbiting each other.
Both stars orbit around each other every 5.73 days.
The two stars orbit each other every 0.13 days.
Picture ten million or more bright, young stars orbiting a tiny dark spot, and you'll see the problem making out what's going on.
Both stars orbit each other at an average distance of 1,200 astronomical units.
The stars are orbiting about each other in an eccentric orbit one every 17.36 days.
But there were a few bright spots other than the imaginary stars orbiting my head.
These stars orbit each other at a distance of 1 AU about once every six months.
If there are other stars orbiting a black hole, their orbit can be used to determine its mass and location.
The two stars orbit each other with a period of 1.46 days and an eccentricity of 0.088.