Modelling CMEs close to the Sun
Abstract
It is now widely accepted that large-scale solar eruptive phenomena like flares, eruptive prominences or filaments, and coronal mass ejections (CMEs) are magnetically driven. They are different observational manifestations of a more general process, namely a large-scale disruption of the coronal magnetic field ("solar eruption" in the following). It is also widely accepted that the energy necessary to drive solar eruptions is stored in the low corona, in form of sheared and twisted magnetic fields which are held in equilibrium prior to eruption by the ambient coronal field. An eruption occurs if this equilibrium is driven or perturbed such that it becomes unstable. In spite of this general understanding, the detailed processes which initiate and drive solar eruptions are not yet well understood. Several mechanisms have been proposed in the last decades. In recent years, the availability of 3D MHD simulations has helped to test the models and has greatly increased our understanding of these processes. In this talk, I will review current theoretical models and corresponding numerical simulations of solar eruptions. I will outline their differences and similarities and briefly discuss how current and future observations can help us to constrain the models. The simulation results indicate a flux rope instability or loss of equilibrium to be the canonical driving mechanism of solar eruptions in their fast acceleration phase close to the Sun, and they point towards a relatively large variety of possible mechanisms that initiate that phase. As an example for such an initiation mechanism, I will present new simulations which show how the eruption of a pre-existing 3D coronal flux rope can be triggered by magnetic flux emergence.
- Publication:
-
European Solar Physics Meeting
- Pub Date:
- September 2008
- Bibcode:
- 2008ESPM...12.3.32T