A binary star is a stellar system that consists of two stars orbiting around their center of mass. It is estimated that about half of all stars are binary. If binaries orbit in a plane containing our line of sight, they will eclipse each other; these are called eclipsing binaries. When stars eclipse in this way it causes the brightness to vary, and this effects their light-curves because when a star is eclipsing another we see less light. The size of the stars, the distance between them and how much of the other star one star covers also determines how the curve may look.
Eclipsing binary systems are incredibly important at SuperWASP because the effects eclipsing binaries have on light-curves can be similar to that of some planets; as a planet will cause a dip in the brightness of a star when it orbits it like a star would do. Just knowing what kind of eclipsing binary system is present can be difficult enough, without the added challenge of distinguishing planets.
