Plasmoids and Resulting Blobs due to the Interaction of Magnetoacoustic Waves with a 2.5D Magnetic Null Point

摘要

We performed a numerical study for interpreting observations of plasma blobs occurring in the solar corona. Considering all of the previous studies and the presence of magnetic null points together with propagating magnetohydrodynamic waves in the solar corona, we guessed that the interaction of fast magnetoacoustic waves with null points could give rise to blobs under coronal conditions. The outcome of these interactions contributes to coronal jets and flares that directly affects us on Earth. The propagation of magnetoacoustic waves in the vicinity of a magnetic null point contributes to the high current density accumulation at the small scale around the magnetic null point, which has significant magnetic gradients. When nonlinearity becomes dominant, the variation of current density could result in instabilities and thus anomalous resistivity. Moreover, it is demonstrated that plasmoids with eruption events take place in the solar corona without considering the transition region. In our numerical simulation results, it is interesting that plasma blobs manifest themselves in many parameters, including current density, temperature, plasma density, flows, and magnetic fields, simultaneously and consistent with the generation of plasmoids. In this work, it is found that plasmoid instability is the reason for the plasma blobs and tiny blobs are produced by the tearing instability occurring in thin current sheets.