The Influence of Magnetic Flux Tubes on Their Environment

Abstract

We present new calculations for model atmospheres in magnetic flux tubes extending vertically through the photosphere and convection zone of the Sun. This study is a continuation of earlier work by Hasan & Kalkofen (1994) on the equilibrium structure of intense magnetic flux tubes. We construct static models of flux tubes by solving the equations of energy transport and radiative transfer. The most significant aspect of our study is the inclusion of multidimensional radiative transfer in cylindrical geometry and the influence of the flux tube on the ambient medium. Our models satisfy the condition of radiative equilibrium; the lower boundary intensity includes the effect of convection. We determine the structure of the thermal boundary layer at the interface of the flux tube and the ambient medium. We find that the temperature does not change abruptly from its value on the flux tube axis to the ambient value far from the tube. Rather, there is a transition layer at the interface, where there is a significant horizontal temperature gradient. Detailed calculations have been carried out to examine the physical conditions in this layer as well as its horizontal extent.