Structure of two-dimensional magnetostatic equilibria in the presence of gravity

We report the results of an analytical study of several 2D (x-invariant) models describing the equilibrium of a plasma occupying the half-space (z > 0) and submitted to a magnetic field and to a constant vertical gravitational field. These models differ from each other by the assumptions which are made on the way matter is spatially distributed. In models 1 and 2 (directly aimed to describe the magnetic support of solar prominences), the plasma is taken to be concentrated in a vertical sheet and in a filament, respectively, the external supporting field being a constant-a force-free field, while in model 3, the plasma is taken to occupy all the half-space and to have a uniform temperature. For each of these models, we establish general results concerning in particular the existence and the uniqueness of solutions, thus bringing about several interesting "nonequilibrium" phenomena.