Stellar magnetic cycles

TL;DR

This paper reviews the current understanding of stellar magnetic cycles, emphasizing the importance of observational data from space missions and ground-based instruments, and discusses star-planet interactions affecting stellar activity.

Contribution

It provides a comprehensive overview of recent observational advances and discusses the implications of star-planet interactions on stellar magnetic cycles.

Findings

Stellar cycles influence stellar energetic output and magnetic environments.

Space-borne photometry has opened new avenues for studying stellar magnetic activity.

Evidence suggests close-in planets may affect their host star's activity cycles.

Abstract

The solar activity cycle is a manifestation of the hydromagnetic dynamo working inside our star. The detection of activity cycles in solar-like stars and the study of their properties allow us to put the solar dynamo in perspective, investigating how dynamo action depends on stellar parameters and stellar structure. Nevertheless, the lack of spatial resolution and the limited time extension of stellar data pose limitations to our understanding of stellar cycles and the possibility to constrain dynamo models. I briefly review some results obtained from disc-integrated proxies of stellar magnetic fields and discuss the new opportunities opened by space-borne photometry, made available by MOST, CoRoT, Kepler, and GAIA, and by new ground-based spectroscopic or spectropolarimetric observations. Stellar cycles have a significant impact on the energetic output and circumstellar magnetic fields of late-type active stars which affects the interaction between stars and their planets. On the other hand, a close-in massive planet could affect the activity of its host star. Recent observations provide circumstantial evidence of such an interaction with possible consequences for stellar activity cycles.