Castor (star)
Castor C, or YY Geminorum, was discovered to change in brightness with a regular period. It is an eclipsing binary with additional changes due to areas of different brightness on the surface of one or both stars, as well as irregular flares. The Castor C stars orbit in less than a day. Castor C is believed to be in a orbit around Castor AB, but with an extremely long period of several thousand years. It is 73″ distant from the bright stars in the system