AAS 204th Meeting, June 2004
Session 67 Solar Input to the Heliosphere
SPD Topical Session, Wednesday, June 2, 2004, 2:30-4:00pm, 4:15-6:00pm, 704/706

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[67.03] CME Acceleration and Shock Development

S. T. Wu, T. X. Zhang (The University of Alabama in Huntsville)

The CME induced shocks theoretically depend on their acceleration process. The cause of the CME acceleration could be related to the Sunís surface conditions. In this study, we will present numerical MHD simulation results to illustrate this scenario. Specifically, we have chosen a streamer and flux-rope model as the initial magnetic topology for the formation of a CME due to solar surface activity. Three distinct solar surface activities are: (i) injection of magnetic flux into the flux rope causing the additional Lorentz force to destabilize the streamer and flux-rope configuration to launch a CME, (ii) draining the plasma from the flux-rope, triggering the magnetic buoyancy force to launch a CME and (iii) additional heating resulting from an active region loop causing the expansion of the flux-rope to launch a CME. Twelve cases have been performed using these three basic physical processes. The results show that the combination of these three processes will launch an explosive fast CME (i.e. constant speed CME) and that mass draining results in the launch of a slow CME that is then accelerated. The explosive fast CME produces a strong shock near the solar surface while the slow CME induced shock is rather weak and further away from the solar surface.

As a final remark, a discussion of the lower boundary conditions for the implementation of the numerical simulation will be briefly presented.

This work is supported by NASA Grant NAG5-12843 and NSF grant ATM 0316115.

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