HR: 14:15h
AN: SP43C-03    [Abstracts]
TI: Maximizing the Energies of Force-Free Coronal Magnetic Flux Ropes
AU: * Wolfson, R
EM: wolfson@middlebury.edu
AF: Middlebury College, Department of Physics, Middlebury, VT 05753 United States
AB: Coronal mass ejections (CMEs) and other solar eruptive events are believed to be powered largely by the release of magnetic energy stored in non-potential magnetic fields in the solar corona. Whatever the CME energy source, there must be sufficient energy available to (1) open the coronal magnetic field, (2) lift the ejecta against solar gravity, and (3) accelerate the ejecta to speeds of typically several hundred km/s. However, the magnetic energy of force-free fields grounded in the solar photosphere is incapable of all three tasks, since the energy of the fully open field is an upper limit to the energies of such fields. Magnetic configurations containing detached flux ropes do not share this limitation. The work presented here describes the maximum energies possible in such flux-rope fields. We explore a two-dimensional parameter space that includes variations in the photospheric magnetic flux distribution as well as a high-latitude cutoff of the region containing non-potential fields. The energy we seek to maximize is the free energy above that of the open-field state, since this is the energy available for tasks (2) and (3) above. The maximum such energy appears to be in the range from 15 to 20 percent of the energy of a fully potential field, and is determined by a tradeoff between the hold-down effect of an overlying potential field and a decrease in the open-field energy as magnetic flux moves poleward.
DE: 7509 Corona
DE: 7513 Coronal mass ejections
DE: 7524 Magnetic fields
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly