Martens-Kuin models of normal and inverse polarity filament eruptions and coronal mass ejections

Abstract

An analysis is made of the Martens-Kuin filament eruption model in relation to observations of coronal mass ejections (CMEs). The field lines of this model are plotted in the vacuum or infinite resistivity approximation with two background fields. The first is the dipole background field of the model and the second is the potential streamer model of Low. The assumption is made that magnetic field evolution dominates compression or other effects which is appropriate for a low-β coronal plasma. The Martens-Kuin model predicts that, as the filament erupts, the overlying coronal magnetic field lines rise in a manner inconsistent with observations of CMEs associated with eruptive filaments. Initially, the bright arc of a CME broadens in time much more slowly than the dark cavity between it and the filament, whereas in the model they broaden at the same rate or the bright arc broadens more rapidly than the dark cavity, depending on the background field. Thus, this model and, by generalization the whole class of so-called Kuperus-Raadu configurations in which a neutral point occurs below the filament, are of questionable utility for CME modeling. An alternate case is considered in which the directions of currents in the Martens-Kuin model are reversed resulting in a so-called normal polarity configuration of the filament magnetic field. In this case, a neutral line occurs above the current-carrying filament. The background field lines now distort to support the filament and help eject it. While the vacuum field results make this configuration appear very promising, a full two- or more-dimensional MHD simulation is required to properly analyze the dynamics resulting from this configuration.