Comparison of Two Methods for Deriving the Magnetic Field in a Filament Channel

Abstract

Understanding the magnetic structure of filament channels is difficult but essential for identifying the mechanism (s) responsible for solar eruptions. In this paper we characterize the magnetic field in a well-observed filament channel with two independent methods, prominence seismology and magnetohydrodynamics flux-rope modeling, and compare the results. In 2014 May and June, active region 12076 exhibited a complex of filaments undergoing repeated oscillations over the course of 12 days. We measure the oscillation periods in the region with both Global Oscillation Network Group Hα and Solar Dynamics Observatory (SDO) Advanced Imaging Assembly EUV images, and then utilize the pendulum model of large-amplitude longitudinal oscillations to calculate the radius of curvature of the fields supporting the oscillating plasma from the derived periods. We also employ the regularized Biot–Savart laws formalism to construct a flux-rope model of the field of the central filament in the region based on an SDO Helioseismic and Magnetic Imager magnetogram. We compare the estimated radius of curvature, location, and angle of the magnetic field in the plane of the sky derived from the observed oscillations with the corresponding magnetic-field properties extracted from the flux-rope model. We find that the two models are broadly consistent, but detailed comparisons of the model and specific oscillations often differ. Model observation comparisons such as these are important for advancing our understanding of the structure of filament channels.

Data-constrained Magnetohydrodynamic Simulation of an Intermediate Solar Filament Eruption

“…In this case, the combined magnetic field is not force free since the Lorentz force component exerted by B P on the flux rope generally cannot balance the hoop force of the flux rope due to its curvature. It should be further relaxed to a forcefree state by, e.g., a magneto-frictional method (Guo et al 2016a(Guo et al , 2016b or a zero-β MHD relaxation method (Titov et al 2021;Kucera et al 2022). Guo et al (2019b) implemented the RBSL method in the Message Passing Interface Adaptive Mesh Refinement Versatile Advection Code (MPI-AMRVAC; Keppens et al 2003Keppens et al , 2012Keppens et al , 2021Keppens et al , 2023Porth et al 2014;Xia et al 2018), and thus far used it in a Cartesian coordinate system.…”