A Simple Dynamical Model for Filament Formation in the Solar Corona

Filament formation in the solar corona is considered in the case of a slowly evolving force-free magnetic field. The strong-field approximation is used, which takes into account the magnetohydrodynamic equations of motion, induction, and compressibility. Methods for solving the relevant equations are presented and applied to filament modeling. A three-dimensional calculation is presented, which uses linear force-free magnetic fields. The boundary conditions are chosen to resemble the qualitative linkage model for the formation of filaments, suggested by Martens and Zwaan (2001). Consistent with this model, dense formations, reminiscent of filament pillars, are shown to appear in the corona above the region of converging and canceling magnetic bipoles. The results demonstrate the principal role of magnetic field in the dynamical processes of dense plasma accumulation and support in filaments. The model can be useful for clarifying the role of flux emergence in coronal mass ejection initiation.