HR: 08:45h
AN: SH51C-04    [Abstracts]
TI: Onset of coronal mass ejections due to loss of confinement of coronal flux ropes
AU: * Fan, Y
EM: yfan@ucar.edu
AF: National Center for Atmospheric Research, 3080 Center Green Dr., Boulder, CO 80301, United States
AU: Gibson, S
EM: sgibson@ucar.edu
AF: National Center for Atmospheric Research, 3080 Center Green Dr., Boulder, CO 80301, United States
AB: Using MHD numerical simulations in a three-dimensional spherical geometry, we model the loss of confinement and eruption of a flux rope emerging quasistatically into a pre-existing coronal arcade field. Our numerical experiments have investigated two distinct triggering mechanisms that led to the eruption of the flux rope. In one case, the overlying arcade field declines with height more slowly such that the emerging flux rope remains confined until a high amount of internal twist is built up, with the rope self-helicity normalized by the square of the rope flux reaching about -1.4, and the flux rope becomes significantly kinked. The kinking motion causes rotation of the tube to an orientation that makes it easier for it to rupture through the arcade field, leading to an eruption. In the second case, the overlying field is made to decline more rapidly with height and the emerging flux rope is found to lose equilibrium and erupt via the torus instability when the flux rope self-helicity normalized by the square of the rope flux is only -0.63, before it becomes kinked. The values of the total relative magnetic helicity normalized by the square of the total anchored flux are, on the other hand, quite close for the two cases when the eruption takes place. We study the eruptive properties resulting from the two mechansisms and compare them with observations.
DE: 7509 Corona
DE: 7513 Coronal mass ejections (2101)
DE: 7519 Flares
DE: 7524 Magnetic fields
DE: 7531 Prominence eruptions
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting