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

## TL;DR

This study analyzes long-term photometric data of YZ CMi, revealing cyclic brightness variations, uneven spot distribution, and active longitude shifts, providing insights into stellar activity compared to the Sun.

## Contribution

It presents a detailed long-term analysis of YZ CMi's activity cycles, spot distribution, and active longitude behavior, highlighting differences from solar activity.

## Key findings

- 27.5-year brightness cycle with 0.2-0.3 magnitude amplitude
- Uneven spot distribution with higher concentration at specific longitudes
- Active longitude shifts occurring approximately every 6 years

## Abstract

Manifestations of activity on the YZ CMi (M4.5Ve) flare star which has a rotation period of 2.77 days and belongs to a group of activity-saturated stars, are considered from long-term photometric data together with photographic measurements from 1926 to 2009. Long-term changes in yearly mean brightness of the star are found on a time scale of 27.5 years with an amplitude of $0.2 - 0.3^m$ that indicate variations in development of surface inhomogeneities and a large degree of surface spottedness in the maximum activity. Spots are distributed unevenly over the surface, their concentration is higher at certain longitudes spaced by intervals equal to 0.6 phases of the rotation period. The recovery of active longitude (a possible "flip-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.