Starspots, Stellar Cycles and Stellar Flares: Lessons from Solar Dynamo Models

TL;DR

This review assesses whether current solar dynamo models can explain stellar activity phenomena such as starspots, stellar cycles, and superflares, highlighting successes and gaps in understanding for solar-like stars.

Contribution

It provides a comprehensive overview of observational data and evaluates the applicability of solar dynamo models to other stars, identifying areas needing further theoretical development.

Findings

Flux transport dynamo model explains some stellar activity features.

Some stellar phenomena remain unexplained by current models.

Uncertainty exists whether different dynamo mechanisms are needed for certain stars.

Abstract

In this review, we discuss whether the present solar dynamo models can be extrapolated to explain various aspects of stellar activity. We begin with a summary of the following kinds of data for solar-like stars: (i) data pertaining to stellar cycles from Ca H/K emission over many years; (ii) X-ray data indicating hot coronal activity; (iii) starspot data (especially about giant polar spots); and (iv) data pertaining to stellar superflares. Then we describe the current status of solar dynamo modelling---giving an introduction to the flux transport dynamo model, the currently favoured model for the solar cycle. While an extrapolation of this model to solar-like stars can explain some aspects of observational data, some other aspects of the data still remain to be theoretically explained. It is not clear right now whether we need a different kind of dynamo mechanism for stars having giant starspots or producing very strong superflares.