3D MHD modeling of twisted coronal loops

TL;DR

This study models a single coronal loop using MHD simulations to understand magnetic interactions, heating, and plasma dynamics, producing realistic EUV and X-ray emissions consistent with observed active region loops.

Contribution

It presents a comprehensive 3D MHD model of a coronal loop including non-uniform magnetic fields and anomalous diffusivity, advancing realistic simulation of loop heating and plasma flows.

Findings

Plasma heated to ~3 MK within 2/3 hours.

Upflows reach ~100 km/s with densities above 10^9 cm^-3.

Heating is more intense and structured in the low corona.

Abstract

We perform MHD modeling of a single bright coronal loop to include the interaction with a non-uniform magnetic field. The field is stressed by random footpoint rotation in the central region and its energy is dissipated into heating by growing currents through anomalous magnetic diffusivity that switches on in the corona above a current density threshold. We model an entire single magnetic flux tube, in the solar atmosphere extending from the high-beta chromosphere to the low-beta corona through the steep transition region. The magnetic field expands from the chromosphere to the corona. The maximum resolution is ~30 km. We obtain an overall evolution typical of loop models and realistic loop emission in the EUV and X-ray bands. The plasma confined in the flux tube is heated to active region temperatures (~3 MK) after ~2/3 hr. Upflows from the chromosphere up to ~100 km/s fill the core of the flux tube to densities above 10^9 cm^-3. More heating is released in the low corona than the high corona and is finely structured both in space and time.