COR CAROLI

also called Alpha Canum Venaticorum, binary star in the constellation Canes Venatici consisting of a brighter component (A) of visual magnitude 2.9 and a companion (B) of magnitude 5.5. It is the prototype for a group of unusual spectrum-variable stars that show strong and fluctuating absorption lines of silicon, chromium, strontium, or certain rare earths. Europium apparently is concentrated around one magnetic pole, chromium around the other. Cor Caroli (Heart of Charles) was named by Sir Edmond Halley for King Charles II of England.