[P-EM14] Frontiers in solar physics

[PEM14-02] Numerical Modeling of Solar Flares

★Invited Papers

*Daiki Yamasaki^1,2,3 (1.Astronomical Observatory, Kyoto University, 2.Center for Solar-Terrestrial Research, New Jersey Institute of Technology, 3.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)

Keywords:Solar flares, Magnetohydrodynamics, Numerical simulations

Solar flares are rapid energy-release phenomena via magnetic reconnection in the solar corona. It is widely accepted that the eruption of dark filaments which are the cool and dense plasma cloud in the hot solar corona drives magnetic reconnection during solar flares. Plasma materials of dark filaments are supported by a bundle of helical magnetic field lines, magnetic flux ropes (MFRs). However, due to observational limitations, it is hard to obtain the magnetic field structures of the MFRs directly, and the formation process and the eruption mechanism of the MFRs have not yet been cleared. To understand the evolution of the three-dimensional (3D) coronal magnetic field including MFRs, we performed a nonlinear force-free field extrapolation and a data-constrained magnetohydrodynamic simulation using a series of photospheric vector magnetic field data obtained from the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory. In these studies, we focused on two large-scale solar flares which have GOES flare class larger than X1: an X9 flare observed in an active region (AR) NOAA 12673 of 2017 September and an X1 flare observed in an AR NOAA 12887 of 2021 October. Both of the flares were accompanied by dark filament eruptions. According to the investigation of the AR NOAA 12673, we found that a large MFR concerning the X9 flare formed 2 days before the onset of the flare. We suggested that the magnetic field reconfiguration via magnetic reconnection of several M flares took place two days before the onset of the X9 flare suppressed the MFR. From the results of the study on the AR NOAA 12887, we found that both the torus instability and the formation of the magnetic arcade below the MFR during the eruption contributed to the acceleration of the erupting MFR of the X1 flare. In this talk, we will also briefly introduce the recent studies of solar flares focused on the temporal evolution of the 3D coronal magnetic field by using extrapolation techniques.