July 16, 2010, 1:00 pm - 2:00 pm

July 16, 2010, 1:00 pm - 2:00 pm

Coronal Mass Ejection Initiation and the Partial Torus Instability

Oscar Olmedo (George Mason University)

The initiation mechanism of coronal mass ejections is studied in the context of the partial torus instability. The equations that describe the motion of the flux rope are analyzed to explicitly show how the flux rope can evolve from a stable configuration to eruption. The flux rope is modeled as a current-carrying partial torus loop with its two footpoints anchored in the photosphere. It is found that the decay index of the external magnetic field plays a crucial role in determining the stability criteria of the flux rope. It is found that this index is a function of the parameters that define the geometry of the flux rope; they are the apex height of the flux rope, the footpoint separation, and the arc length of the loop above the photosphere, which is a function of the former. The role that poloidal flux injection plays in this theory, which is interpreted as either of photospheric or coronal origin, is examined. It is demonstrated that the partial torus instability helps us to understand the confinement, growth, and eventual eruption of a flux-rope CME.