How did a Major Confined Flare Occur in Super Solar Active Region 12192?

TL;DR

This study uses data-driven MHD modeling and observations to understand the physical mechanism behind a major confined X-class solar flare in AR 12192, revealing how magnetic reconnection and current sheet formation led to the flare.

Contribution

The paper presents a novel data-driven MHD simulation that successfully reproduces the magnetic processes of a confined solar flare, explaining its confinement and magnetic dynamics.

Findings

Modeled coronal field was slowly stressed, forming a large-scale current sheet.

Reconnection led to a confined flare with hot flaring loops and ribbons matching observations.

Weaker magnetic implosion effect compared to other X-class flares.

Abstract

We study the physical mechanism of a major X-class solar flare that occurred in the super NOAA active region (AR) 12192 using a data-driven numerical magnetohydrodynamic (MHD) modeling complemented with observations. With the evolving magnetic fields observed at the solar surface as bottom boundary input, we drive an MHD system to evolve self-consistently in correspondence with the realistic coronal evolution. During a two-day time interval, the modeled coronal field has been slowly stressed by the photospheric field evolution,which gradually created a large-scale coronal current sheet, i.e., a narrow layer with intense current, in the core of the AR. The current layer was successively enhanced until it became so thin that a tether-cutting reconnection between the sheared magnetic arcades was set in, which led to a flare. The modeled reconnecting field lines and their footpoints match well the observed hot flaring loops and the flare ribbons, respectively, suggesting that the model has successfully "reproduced" the macroscopic magnetic process of the flare. In particular, with simulation, we explained why this event is a confined eruption-the consequent of the reconnection is the shared arcade instead of a newly formed flux rope. We also found much weaker magnetic implosion effect comparing to many other X-class flares