Formation and eruption of filament channel in solar active region 12975: insights from observations and simulations of magnetic field evolution

Abstract

We studied the magnetic field evolution of active region (AR) 12975 using a time-dependent magnetofrictional model. This AR produced two consecutive coronal mass ejections associated with M-class flares on 2022 March 28. The AR exhibited a simple bipolar configuration, with new bipolar flux emerging from March 27. These emerging flux regions evolved through shear motions, forming a filament-channel that ultimately erupted on March 28 at 12:00 UT. The simulation, initialized at 12:00 UT on March 26, is driven by electric fields derived from a time-series of photospheric vector-magnetograms. It reproduces the observed coronal evolution, including the gradual development of a sigmoidal, twisted flux rope (FR) over approximately 50 hr. The modeled temporal evolution of magnetic energy and helicity within the computational domain is consistent with the observed injection of both quantities. Furthermore, the ratio of current-carrying to total relative helicity reaches 0.23 at the time of observed eruption; however, the torus-unstable regime is attained when the helicity ratio reaches 0.32, approximately 7 hr after the observed eruption. Notably, the FR forms adjacent to preexisting magnetic fields, and a substantial portion of the coronal structure does not belong to the FR system. Consequently, the derived helicity thresholds vary and deviate from the proposed value of 0.29. While reproducing filament formation with high morphological accuracy, this study underscores the challenges involved in modeling and evaluating the eruptive behavior of different ARs.