An impression of the system Algol (Beta Persei). A blue spectral class B8 star with a diameter of 3 solar diameters and red-yellow spectral class K2 star of about 3.5 solar diameters are in very close orbit around each other, and a ring of tenuous gas surrounds the blue star, stolen from its partner. A third star, Algol C (right), orbits this central binary at a greater distance, making this a triple star system.Algol is the prototype of an entire class of eclipsing binary stars called Algol systems.