RS Canum Venaticorum star

A member of a class of variable stars that are both eclipsing and variable outside eclipse. Both members of the binary system are usually G stars (sometimes F or K stars) and show extreme solar-like activity. The variation outside eclipse is thought to be caused by extensive "star-spots" coming in and out of view as the stars rotate. X-ray emission is detected from hot coronae around these stars, and powerful flares, similar to those that erupt on the Sun, are sometime seen.