Coronal loops above an Active Region - observation versus model

TL;DR

This study uses high-resolution 3D-MHD simulations driven by Hinode observations to investigate coronal loops above an active region, validating the field-line braiding mechanism and scaling laws against actual solar data.

Contribution

The paper demonstrates that a data-driven 3D-MHD model can accurately reproduce the observed structure and dynamics of coronal loops, supporting the field-line braiding heating mechanism.

Findings

Synthetic loops match observed shapes and locations.

Model loops are slightly over-dense, consistent with observations.

Coronal heating distribution reproduces observed loop dynamics.

Abstract

We conducted a high-resolution numerical simulation of the solar corona above a stable active region. The aim is to test the field-line braiding mechanism for a sufficient coronal energy input. We also check the applicability of scaling laws for coronal loop properties like the temperature and density. Our 3D-MHD model is driven from below by Hinode observations of the photosphere, in particular a high-cadence time series of line-of-sight magnetograms and horizontal velocities derived from the magnetograms. This driving applies stress to the magnetic field and thereby delivers magnetic energy into the corona, where currents are induced that heat the coronal plasma by Ohmic dissipation. We compute synthetic coronal emission that we directly compare to coronal observations of the same active region taken by Hinode. In the model, coronal loops form at the same places as they are found in coronal observations. Even the shapes of the synthetic loops in 3D space match those found from a stereoscopic reconstruction based on STEREO spacecraft data. Some loops turn out to be slightly over-dense in the model, as expected from observations. This shows that the spatial and temporal distribution of the Ohmic heating produces the structure and dynamics of a coronal loops system close to what is found in observations.