The Properties of Non-Potential Magnetic Field Parameters in a Super-Active Region with Complex Structures and Strong Solar Flares

TL;DR

This paper analyzes the non-potential magnetic field parameters of a super-active solar region, revealing how magnetic complexity and energy storage relate to the occurrence of a major solar flare.

Contribution

It introduces advanced extrapolation techniques to study 3D magnetic structures and identifies key magnetic parameters associated with flare activity in a complex active region.

Findings

High twist and complex magnetic configurations precede flares.

Helicity and free energy decrease after flares, with peaks before eruptions.

Distinct patterns of current density and helicity relate to flare occurrence.

Abstract

In this study, the non-potential magnetic field parameters of active region NOAA 9077 are investigated; this AR experienced a super-strong X5.7 solar flare. Using advanced extrapolation techniques, the 3D magnetic field structure from vector magnetograms is obtained from the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station (HSOS). Then various non-potential parameters are calculated, including current density, shear angle, quasi-separatrix layers (QSLs), twist, and field line helicity. By analyzing the spatial and temporal distributions of these parameters, we aim to shed light on the relationship between magnetic field properties and solar flare occurrence. Our findings reveal that high twist and complex magnetic field configurations are prevalent before flares, while these features tend to weaken after the eruption. Additionally, we observe decreases in helicity and free energy after the flare, while the free energy peaks approximately 1.5 days prior to the onset of the flare. Furthermore, we investigate the distribution of quasi-separatrix layers and twist, finding high degrees of complexity before flares. Multiple patterns of high current density regions suggest unstable magnetic structures prone to flaring, coinciding with shear angle distribution. Relative field line helicity patterns exhibit distinct characteristics compared to current density, concentrating before flares and diverging afterward. Overall, our results highlight the contrasting nature of current density and relative field line helicity patterns in relation to solar flares, in addition to the aforementioned feature in the set of commonly derived non-potential parameters for this particular event.