Peculiarities of long-term spot activity of some late spectral-type stars

We present an analysis of long-term photometric observations of several dozen chromospherically active stars with solar-type activity (both from our own observations and from data available in the literature). The distribution of cold photospheric spots has been modeled based on a zonal model – several hundred models have been obtained. It has been found that the majority of stars have spots located at middle and moderate latitudes, the maximum spot areas can occupy from 7 to 58% of the star’s surface. It is shown that for some stars we can suspect the drift of spots in latitude, both towards the equator and towards the pole. However, the speed of such a drift is several times lower than that of sunspots. The presence of stellar activity cycles in 15 stars was revealed: cycles last from 3 to 28 years and expressed in changes in the brightness of the system, as well as in changes in the total spottedness of the star. The paper is based on a talk presented at the astrophysical memorial seminar “Novelties in Understanding the Evolution of Binary Stars”, dedicated to the 90th anniversary of Professor M.A. Svechnikov.