Evolution of the cycles of magnetic activity of the Sun and Sun-like stars in time

TL;DR

This study uses wavelet analysis to examine the evolution of magnetic activity cycles in the Sun and Sun-like stars, revealing multiple overlapping cycles with varying periods that change over time.

Contribution

It introduces a wavelet-based method to analyze the temporal evolution of magnetic activity cycles in the Sun and stars, highlighting the variability of cycle periods over time.

Findings

Multiple activity cycles coexist with varying periods.

Cycle periods change significantly over observation times.

Low-frequency variations influence overall activity patterns.

Abstract

We applied the method of continuous wavelet-transform to the time-frequency analysis to the sets of observations of relative sunspot numbers, sunspot areas and to 6 Mount Wilson HK-project stars with well-defined magnetic cycles. Wavelet analysis of these data reveals the following pattern: at the same time there are several activity cycles whose periods vary widely from the quasi-biennial up to the centennial period for the Sun and vary significant during observations time of the HK-project stars. These relatively low-frequency periodic variations of the solar and stellar activity gradually change the values of periods of different cycles in time. This phenomenon can be observed in every cycles of activity