Delta Coronae Borealis : a chromospherically active giant ?

It has been discovered accidentally that the bright G-giant, δ CrB, shows roughly sinusoidal light variations of amplitude 0.06 mag and period about 45 days. Since the star is not a spectroscopic binary, it is suggested that the variation is caused by the star having an active chromosphere, the rotation (of period 45 days) revealing starspots. The star would thus be similar to λ And. An IUE spectrum supports the suggestion of an active chromosphere.