The distortions in the light curves of MM herculis

The RS CVn-type eclipsing binary MM Her was observed photoelectrically in B and V colours. The light curves obtained in 1984 and 1985 are presented. It was found that the depths of the primary minima are decreased from 1983 to 1985. However, the amplitude of the wave-like distortion outside the eclipses was detected to increase since 1976. The period of migration was determined to be about 3.57±0.08 years. © 1987 D. Reidel Publishing Company