Splitting Flux Ropes: Modeling the Eruption of Magnetic Structures at the Sun

Sarah Gibson

Magnetic fields control the structure and dynamics of the solar corona. Coronal mass ejections (CMEs) and solar flares are examples of episodic releases of magnetic energy into thermal, radiative, and kinetic energy. Erupting CMEs are routinely interpreted as possessing a helical magnetic flux rope structure. An ongoing controversy remains, however, as to whether a precursor flux rope exists as a magnetohydrodynamic equilibrium state in the corona prior to eruption, or whether it is formed during eruption. This is an important question to resolve, since CME initiation models and space weather predictions depend upon a clear understanding of the configuration of pre-CME magnetic fields and their evolution during eruption.

I will describe an alternative which lies between the two extremes of a totally erupting, pre-existing rope, and a rope that forms completely in situ during eruption, i.e., a precursor flux rope that splits in two and reconnects with surrounding fields during eruption. I will demonstrate that such a partially-expelled flux rope can satisfy a variety of CME-related observations, before, during, and after the eruption.