DYNAMICAL EVOLUTION OF A CORONAL STREAMER – FLUX ROPE SYSTEM – II. A Self-Consistent Non-Planar Magnetohydrodynamic Simulation

Abstract

The dynamical response of a helmet streamer to a flux-rope escape from the sub-photosphere is examined in a physically self-consistent manner within the approximation of axisymmetric three-dimensional magnetohydrodynamics (i.e., so-called ‘2$\frac{1}{2}$ D’). In contrast to the previous planar analyses of Paper I (Wu, Guo, and Wang, 1995), the present study shows, with the inclusion of out-of-plane components of magnetic and velocity fields, that the magnetic configuration represents a helical flux rope instead of a planar bubble as shown in Paper I. Because of this more physically realistic configuration, we are able to examine the dynamical evolution of the helical flux rope's interaction with the helmet streamer. This process leads to the formation of two parts of the solar mass ejection; (i) the expulsion of the helmet dome due to eruption of this flux rope, and (ii) the flux rope's eruption itself. When this two-part feature propagates out to the interplanetary space, it exhibits all the physical characteristics of observed interplanetary magnetic clouds. These numerical simulations also show that the dynamical behavior of the streamer – flux rope system has three distinct states: (i) quasi-equilibrium, (ii) non-equilibrium, and (iii) eruptive state depending on the energy level of the flux rope.