Induced mass and wave motions in the lower solar atmosphere. II - Effects of converging and diverging photospheric motions

Abstract

We examine the responses of the magnetic field and the atmospheric plasma to locally converging or diverging mass motions near the photo spheric magnetic neutral line, using a self-consistent, two-dimensional, nonplanar, time-dependent MHD model. This is an exploratory study using an MHD model, where we emphasize the self-consistency of the model, in contrast to using ad hoc realistic assumptions. The numerical results imply the following physical consequences in the solar atmosphere: (1) the development of a general atmospheric circulation with maximum motion occurring along the neutral line in the case of convergence, (2) a rapid rise of field lines and the development of a slow circulation with upward plasma-flow motion along the neutral line in the case of divergence. (3) During these converging and diverging motions, the generated MHD fast modes of rarefaction and compression waves result in a significant cooling and heating of the corona. In addition, a wide range of parameters (i.e., speed of motion and various plasma β<SUP>0</SUP> <SUB>0</SUB>) were examined. We show that the deformation of the magnetic field is strongly dependent on these parameters. Some of the numerical results may be associated with various observed solar phenomena, e.g., the submerging and emerging of magnetic flux and formation of low-lying loops.