Mhd-Modeling of the Propagation of a Coronal Mass Ejection

Hydrodynamic modeling of the propagation of a density perturbation launched upwards in the solar corona has been shown to explain some features of a Coronal Mass Ejection (CME) observed in detail with the SoHO/UVCS, but left open the questions of the evidence of thermal insulation of the CME and of its large expansion factor. We investigate whether the interaction with the coronal magnetic field is able to explain these aspects, by performing magnetohydrodynamic simulations. We solve the ideal MHD equations for a fully ionized compressible plasma with different assumptions on the ambient magnetic field, using the FLASH code. We include the effect of the directional thermal conduction. Preliminary 2-D simulations show that an "open" dipole magnetic field with plasma β ∼ 20 is able to produce a significant thermal insulation of the perturbation and to lead to an expansion factor larger than that obtained with hydrodynamic modeling.