Weak and Strong Field Dynamos: from the Earth to the stars

TL;DR

This paper explores how dynamo theory explains magnetic field differences in very low mass stars and compares stellar dynamos with planetary ones, focusing on weak and strong field bistability.

Contribution

It applies the concept of weak and strong field dynamo bistability to recent observations of low mass stars, linking stellar magnetism to planetary dynamo models.

Findings

Observations suggest two distinct magnetic field regimes in low mass stars.

Data can be interpreted within the framework of weak and strong field dynamo bistability.

The study bridges stellar and planetary dynamo theories.

Abstract

Observations of magnetism in very low mass stars recently made important progress, revealing characteristics that are now to be understood in the framework of dynamo theory. In parallel, there is growing evidence that dynamo processes in these stars share many similarities with planetary dynamos. We investigate the extent to which the weak \emph{vs} strong field bistability predicted for the geodynamo can apply to recent observations of two groups of very low mass fully-convective stars sharing similar stellar parameters but generating radically different types of magnetic fields. Our analysis is based on previously published spectropolarimetric and spectroscopic data. We argue that these can be interpreted in the framework of weak and strong field dynamos.