The rotation-magnetic field relation

TL;DR

This paper reviews current understanding of how stellar rotation influences magnetic field generation in solar-type stars, highlighting open questions especially in young and fully convective stars.

Contribution

It summarizes recent insights into the rotation-magnetic field relation and discusses unresolved issues in stellar magnetic activity and rotational braking mechanisms.

Findings

Magnetic flux generation is facilitated by rotation in solar-type stars.

Rotational braking becomes less effective at the threshold to fully convective interiors.

Large-scale magnetic fields can still be generated in fully convective stars.

Abstract

Today, the generation of magnetic fields in solar-type stars and its relation to activity and rotation can coherently be explained, although it is certainly not understood in its entirety. Rotation facilitates the generation of magnetic flux that couples to the stellar wind, slowing down the star. There are still many open questions, particularly at early phases (young age), and at very low mass. It is vexing that rotational braking becomes inefficient at the threshold to fully convective interiors, although no threshold in magnetic activity is seen, and the generation of large scale magnetic fields is still possible for fully convective stars. This article briefly outlines our current understanding of the rotation-magnetic field relation.