Models of Magnetic Flux Sheets

We present results of numerical model calculations of magnetic flux concentrations in the solar photosphere. Using a 2D slab geometry we solve the nonlinear MHD equations for a compressible medium incorporating partial ionization effects and a full radiative transfer (grey, LTE). An adaptive Moving Finite Element code is employed. We are able to analyze our results by computing the profiles of the four Stokes parameters (of various spectral lines) emerging from the flux concentrations and comparing them with observations. We find good agreement between synthetic and observed Stokes V-profiles in the visible and infrared. A major new result is the appearance of a temperature enhancement in the upper layers in the upper layers of the flux concentration which are heated by illumination from the hot bottom. We obtain a large positive continuum intensity contrast of the flux sheet.