A Data-constrained Magnetohydrodynamic Simulation of the X1.0 Solar Flare of 2021 October 28

TL;DR

This study uses data-constrained MHD simulations to analyze the 2021 October 28 X1.0 solar flare, revealing that both torus instability and magnetic reconnection contribute to the eruption process.

Contribution

It introduces a novel data-constrained MHD simulation approach to dissect the mechanisms behind a specific solar flare eruption.

Findings

Reproduced filament eruption consistent with observations.

Identified two contributing mechanisms: torus instability and magnetic reconnection.

Reconnection accelerates the eruption process.

Abstract

The solar active region NOAA 12887 produced a strong X1.0 flare on 2021 October 28, which exhibits X-shaped flare ribbons and a circle-shaped erupting filament. To understand the eruption process with these characteristics, we conducted a data-constrained magnetohydrodynamics simulation using a nonlinear force-free field of the active region about an hour before the flare as the initial condition. Our simulation reproduces the filament eruption observed in the Ha images of GONG and the 304 angstrom images of SDO/AIA and suggests that two mechanisms can possibly contribute to the magnetic eruption. One is the torus instability of the pre-existing magnetic flux rope (MFR), and the other is upward pushing by magnetic loops newly formed below the MFR via continuous magnetic reconnection between two sheared magnetic arcades. The presence of this reconnection is evidenced by the SDO/AIA observations of the 1600 angstrom brightening in the footpoints of the sheared arcades at the flare onset. To clarify which process is more essential for the eruption, we performed an experimental simulation in which the reconnection between the sheared field lines is suppressed. In this case too, the MFR could erupt, but at a much reduced rising speed. We interpret this result as indicating that the eruption is not only driven by the torus instability, but additionally accelerated by newly formed and rising magnetic loops under continuous reconnection.