Algol is one of the best known variable stars in the sky and a prototype for a class of eclipsing variable stars known as Algol variables . It is a triple star system composed of Beta Persei Aa1, a B-class main sequence star, Beta Persei Aa2, an orange subgiant, and Beta Persei Ab, a dimmer A-class star.

Algol is one of the best known variable stars in the sky and a prototype for a class of eclipsing variable stars known as Algol variables . It is a triple star system composed of Beta Persei Aa1, a B-class main sequence star, Beta Persei Aa2, an orange subgiant, and Beta Persei Ab, a dimmer A-class star.