Long-Term Cyclic Variability of YZ CMi in the Context of Solar and Stellar Physics

Abstract

Manifestations of the activity of the YZ CMi (M4.5Ve) flare star with a rotation period of 2.77 days, which is included in the group of activity-saturated stars, are considered based on long-term photometric data, including photographic measurements over the interval from 1926 to 2009. Long-term changes in the yearly mean brightness of the star found on the time scale of 27.5 years with an amplitude of 0.2–0.3^m, that indicate on variations in the development of surface inhomogeneities and a large degree of spottedness in the maximum activity. The spots are distributed unevenly over the surface with an increased concentration at certain longitudes spaced by intervals equal to 0.6 phases of the rotation period. The recovery of the active longitude (a possible “fliр-flop” effect) occurs over a period of about 6 years. We note differences in activity of this star from typical for the Sun and solar-like stars, which are associated with its dynamic characteristics P_cyc and P_rot and its inner structure.