RELATIONSHIP BETWEEN PHOTOMETRIC PERIOD AND SURFACE DIFFERENTIAL ROTATION IN CHROMOSPHERICALLY ACTIVE STARS

We present a quantitative investigation of the relationship between the photometric periods of late-type chromospherically active stars showing spot activity and their photometric period variation interval as the proxy of the surface differential rotation. The results show that as the photometric period increases, the magnitude of the surface differential rotation also increases. However, there is a noticeable distinction between main sequence and evolved stars. Comparing a main sequence star and an evolved star with the same photometric period, it turns out that the magnitude of the surface differential rotation of the main sequence star appears greater than that of the evolved star. The distinction is apparent around short photometric periods but tends to disappear towards longer photometric periods.