New Results in Modeling the Hemispheric Pattern of Solar Filaments

Abstract

New results in modeling the hemispheric pattern of solar filaments through magnetic flux transport and magnetofrictional simulations are presented. The simulations consider for the first time what type of chirality forms along the polarity inversion line lying in between two magnetic bipoles as they interact. Such interactions are important for filament formation, as observations by F. Tang show that the majority of filaments form in between bipolar regions rather than within a single magnetic bipole. The simulations also include additional physics of coronal diffusion and a radial outflow velocity at the source surface, which was not included in previous studies. The results clearly demonstrate for the first time not only the origin of the dominant hemispheric pattern but also why exceptions to it may occur. The dominant hemispheric pattern may be attributed to the dominant range of bipole tilt angles and helicities in each hemisphere. Exceptions to the hemispheric pattern are found to only occur in cases of no initial helicity or for helicity of the minority type in each hemisphere when large positive bipole tilt angles (α > 20°) are used. As the simulations show a clear dependence of the hemispheric pattern and its exceptions on observational quantities, this may be used to check the validity of the results. Future programs to consider this are put forward.