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Abstract. This paper provides a short review of some of the basic concepts related to the origin of coronal mass ejections (CMEs). The various ideas which have been put forward to explain the initiation of CMEs are categorized in terms of whether they are force-free or non-force-free and ideal or nonideal. A few representative models of each category are examined to illustrate the principles involved. At the present time there is no model which is sufficiently developed to aid forecasters in their efforts to predict CMEs, but given the current pace of research, this situation could improve dramatically in the near future.

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In 1978, W. Van Tend and M. Kuperus proposed a simple catastrophe model for magnetically driving coronal mass ejections, prominence eruptions, and two‐ribbon flares. Their model, which is based on simple circuit concepts, suggests that a stable configuration containing a current filament will lose equilibrium when the filament current exceeds a critical value. Here we use a two‐dimensional numerical simulation to test how the Van Tend‐Kuperus model works in an ideal MHD fluid. The simulation exhibits the expected loss of mechanical equilibrium near the predicted critical value, but the current filament moves only a short distance upward before coming to rest at a new equilibrium. However, this new equilibrium contains a current sheet which is resistively unstable to magnetic reconnection, and if magnetic reconnection occurs rapidly, the filament can continue to move upward at Alfvénic speeds.

Abstract. Using a simple model for the onset of solar eruptions, we investigate how an existing magnetic configuration containing a flux rope evolves in response to new emerging flux. Our results show that the emergence of new flux can cause a loss of ideal MHD equilibrium under certain circumstances, but the circumstances which lead to eruption are much richer and more complicated than one might expect given the simplicity of the model. The model results suggest that the actual circumstances leading to an eruption are sensitive not only to the polarity of the emerging region, but also to several other parameters, such as the strength, distance, and area of the emerging region. It has been suggested by various researchers that the emergence of new flux with an orientation which allows reconnection with the preexisting flux (a process sometimes referred to as tether cutting) will generally lead to alestabilization of the coronal or prominence magnetic field. Although our results can replicate such behavior for certain restricted classes of boundary conditions, we find that, in general, there is no simple, universal relation between the orientation of the emerging flux and the likelihood of an eruption.