rotating variable

A rotating variable is a star that changes in brightness as it spins around, due to variations in brightness on its surface or to a non-spherical shape (see ellipsoidal variable). Irregular surface brightness may be due to the presence of large starspots (see BY Draconis star) or magnetic effects, as in magnetic variables (see Alpha2 Canum Venaticorum star and SX Arietis star) or oblique rotators (stars in which the spin axis and magnetic axis are out of alignment).