Confinement of the Solar Tachocline by Dynamo Action in the Radiative Interior

TL;DR

This paper presents the first 3-D global solar simulation demonstrating that a self-excited dynamo can confine the solar tachocline, challenging previous beliefs about magnetic field amplification and storage in the Sun.

Contribution

It introduces a novel 3-D simulation showing dynamo-driven confinement of the solar tachocline, with non-axisymmetric magnetism originating in the convection zone and influencing the radiative interior.

Findings

Dynamo action can confine the tachocline in simulations.

Magnetic fields are amplified throughout the radiative interior.

Non-axisymmetric magnetism originates in the convection zone.

Abstract

A major outstanding problem in solar physics is the confinement of the solar tachocline, the thin shear layer that separates nearly solid-body rotation in the radiative interior from strong differential rotation in the convection zone. Here, we present the first 3-D, global solar simulation in which a tachocline is confined by a self-excited dynamo. The non-axisymmetric magnetism is initially built in the convection zone and then diffusively imprints downward. Additionally, the field is locally amplified throughout the radiative interior by vigorous horizontal motions that arise from equatorial Rossby waves and possibly shear instabilities. Our work thus challenges the long-held notion that the Sun's dynamo magnetic field is amplified only as deep as the tachocline and stored in a quiescent radiative interior.