3D MHD simulations of coronal loops heated via magnetic braiding I. Continuous driving

TL;DR

This study uses 3D MHD simulations to investigate how magnetic braiding and reconnection can sustain high temperatures in coronal loops, supporting nanoflare heating theories through synthetic observations and detailed current sheet analysis.

Contribution

It provides the first high-resolution 3D MHD simulation demonstrating continuous heating in braided coronal loops via magnetic reconnection and current sheet dissipation.

Findings

Magnetic energy is intermittently released through reconnection.

High-temperature plasma is maintained over indefinite times.

Synthetic observations match expected coronal signatures.

Abstract

The nature and detailed properties of the heating of the million-degree solar corona are important issues that are still largely unresolved. Nanoflare heating might be dominant in active regions and quiet Sun, although direct signatures of such small-scale events are difficult to observe in the highly conducting, faint corona. The aim of this work is to test the theory of coronal heating by nanoflares in braided magnetic field structures. We analyze a 3D MHD model of a multistrand flux tube in a stratified solar atmosphere, driven by twisting motions at the boundaries. We show how the magnetic structure is maintained at high temperature and for an indefinite time, by intermittent episodes of local magnetic energy release due to reconnection. We forward-modelled optically thin emission with SDO/AIA and MUSE and compared the synthetic observations with the intrinsic coronal plasma properties, focusing on the response to impulsive coronal heating. Currents build up and their impulsive dissipation into heat are also investigated through different runs. In this first paper, we describe the proliferation of heating from the dissipation of narrow current sheets in realistic simulations of braided coronal flux tubes at unprecedented high spatial resolutions.