A 2D NUMERICAL STUDY OF EXPLOSIVE EVENTS IN THE SOLAR ATMOSPHERE

Two-dimensional (2D) compressible magnetohydrodynamic simulations are performed to explore the idea that the asymmetric reconnection between newly emerging intranetwork magnetic field Aux and pre-existing netwo rk flux causes the explosive events in the solar atmosphere. The depen dence of the reconnection rare as a function of time on the density an d temperature of the emerging flux are investigated. For a Lundquist n umber of L(u) = 5000 we find that the tearing mode instability can lea d to the formation and growth of small magnetic islands. Depending on the temperature and density ratio of the emerging plasma, the magnetic island can be lifted upward and convected out of the top boundary, or is suppressed downward and convected out of the top boundary, or is s uppressed downward nad submerged below the bottom boundary. The motion s of the magnetic islands with different direction are accompanied res pectively with upward or downward high velocity flow which might be as sociated with the red- and blue-shifted components detected in the exp losive events.