Formation of thin current sheets in the solar atmosphere

In a two-dimensional quadrupolar magnetic field geometry, it is demonstrated that various magnetohydrostatic equilibrium field configurations containing current sheets can be formed either by changes in thermal properties or by footpoint displacement. The shape of current sheets depends on the mass distribution in flux tubes. If the mass per flux tube is maximum at the center of the low-lying bipolar arcades, a current sheet is formed between these two arcades along the separatrix line as the plasma temperature (or the shearing footpoint displacement) is increased above a critical value. If the mass per flux tube is higher in the outer tubes of the bipolar arcades than in the inner ones, a current sheet with a sharp downward-pointed tip hanging at a distance above the bottom boundary is formed when the temperature is decreased below a critical value. Resistive magnetic reconnection in the latter type current sheet results in a magnetic island wrapped in dipped field lines, which is regarded as a plausible prominence field configuration.