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

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.

30 pages, 16 figures, invited review published in Science China - Physics, Mechanics & Astronomy

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• Stellar Chromospheric Activity Database of Solar-like Stars Based on the LAMOST Low-Resolution Spectroscopic Survey
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• The GAPS programme at TNG XXVI. Magnetic activity in M stars: spectroscopic monitoring of AD Leonis
• Flaring Activities of Fast Rotating Stars have Solar-like Latitudinal Distribution
• Hemispheric Distribution of Solar Active Regions During Solar Cycles 23-25