Numerical Simulations of Coronal Heating through Footpoint Braiding

TL;DR

This study uses advanced 3D radiative MHD simulations to investigate the spatial and temporal characteristics of coronal heating, revealing episodic, structured heating along magnetic loops with scale-dependent behaviors.

Contribution

It provides a detailed analysis of coronal heating mechanisms in realistic 3D MHD models, highlighting the role of current sheets and magnetic topology in heating distribution and intermittency.

Findings

Heating is episodic and highly structured in space.

Heating occurs along loop-shaped magnetic structures and moves with magnetic fields.

Small-scale heating is concentrated in current sheets and is highly intermittent.

Abstract

Advanced 3D radiative MHD simulations now reproduce many properties of the outer solar atmosphere. When including a domain from the convection zone into the corona, a hot chromosphere and corona are self-consistently maintained. Here we study two realistic models, with different simulated area, magnetic field strength and topology, and numerical resolution. These are compared in order to characterize the heating in the 3D-MHD simulations which self-consistently maintains the structure of the atmosphere. We analyze the heating at both large and small scales and find that heating is episodic and highly structured in space, but occurs along loop shaped structures, and moves along with the magnetic field. On large scales we find that the heating per particle is maximal near the transition region and that widely distributed opposite-polarity field in the photosphere leads to a greater heating scale height in the corona. On smaller scales, heating is concentrated in current sheets, the thicknesses of which are set by the numerical resolution. Some current sheets fragment in time, this process occurring more readily in the higher-resolution model leading to spatially highly intermittent heating. The large scale heating structures are found to fade in less than about five minutes, while the smaller, local, heating shows time scales of the order of 2 minutes in one model and 1 minutes in the other, higher-resolution, model.