Observationally driven 3D MHD model of the solar corona above an active region

TL;DR

This paper presents a 3D MHD model of the solar corona driven by observed magnetic and velocity data, successfully reproducing observed coronal structures and dynamics, and supporting field-line braiding as the main heating mechanism.

Contribution

The study introduces a data-driven 3D MHD model that incorporates spectral synthesis to directly compare simulated and observed coronal emissions, validating the field-line braiding heating mechanism.

Findings

Simulated coronal loops match observed locations and Doppler shifts.

Model reproduces siphon flows and mass draining in coronal loops.

Field-line braiding is confirmed as the dominant heating process.

Abstract

Aims. The goal is to employ a 3D magnetohydrodynamics (MHD) model including spectral synthesis to model the corona in an observed solar active region. This will allow us to judge the merits of the coronal heating mechanism built into the 3D model. Methods. Photospheric observations of the magnetic field and horizontal velocities in an active region are used to drive our coronal simulation from the bottom. The currents induced by this heat the corona through Ohmic dissipation. Heat conduction redistributes the energy that is lost in the end through optically thin radiation. Based on the MHD model, we synthesized profiles of coronal emission lines which can be directly compared to actual coronal observations of the very same active region. Results. In the synthesized model data we find hot coronal loops which host siphon flows or which expand and lose mass through draining. These synthesized loops are at the same location as and show similar dynamics in terms of Doppler shifts to the observed structures. This match is shown through a comparison with Hinode data as well as with 3D stereoscopic reconstructions of data from STEREO. Conclusions. The considerable match to the actual observations shows that the field-line braiding mechanism leading to the energy input in our corona provides the proper distribution of heat input in space and time. From this we conclude that in an active region the field-line braiding is the dominant heating process, at least at the spatial scales available to current observations.