K-type main-sequence star
The cooler and dimmer (magnitude 7.51) Eta Cassiopeiae B is of stellar classification K7 V; a K-type main-sequence star. It has only 57% of the mass of the Sun and 66% of the Sun's radius. Smaller stars generate energy more slowly, so this component radiates only 6% of the luminosity of the Sun. Its outer atmosphere has an effective temperature of 4,036 K.