Variable Star Atlas - W Ursae Majoris-Type Binary
Eclipsing binary stars are stellar systems consisting of two or more stars where the orbital plane of the components align with the line of sight of an observer; this alignment can result in eclipses. These eclipses are seen as a characteristic dimming in the system's brightness when seen from Earth. The subclass W Ursae Majoris-Type binary, or EW-Type, are known as contact eclipsing binaries. Systems in this subclass contain stars with extremely close orbits, so close in fact that they begin to share their outer envelopes. The two stars have nearly the same temperature, which makes their primary and secondary minima almost indistinguishable from one another. Their light curves are characterized by rounded peaks and sharp minima along with an overall symmetric shape. Most contact binaries have periods of less than 1 day.