INITIATION OF CORONAL MASS EJECTIONS BY MAGNETIC FLUX EMERGENCE IN THE FRAMEWORK OF THE BREAKOUT MODEL

The possible role of magnetic flux emergence in the initiation of coronal mass ejections (CMEs) is investigated in the framework of the breakout model. The ideal MHD equations are solved numerically on a spherical, axisymmetric (2.5-dimensional) domain. An initial multiflux system in steady equilibrium containing a pre-eruptive region consisting of three arcades with alternating magnetic flux polarity is kept in place by the magnetic tension of the overlying closed magnetic field of a helmet streamer. The emergence of new magnetic flux in the central arcade is simulated by means of a time-dependent boundary condition on the vector potential applied at the solar base. Height-time plots of the ejected material, as well as time evolution of the magnetic, kinetic and internal energy in the entire domain as functions of flux emergence rate, are produced. The results show that the emergence of new magnetic flux in the central arcade triggers a CME. The obtained eruption corresponds to a slow CME, and conversion of magnetic energy into kinetic energy is observed.