A steady flow model for quiescent prominences

The normal polarity prominence model of Hood & Anzer (1990) has been modified to include the effect of a steady flow along the magnetic field lines. We consider two isothermal regions that model the hot corona and the cool prominence, considered as a vertical sheet of dense material with infinite length and height but finite width. The magnetic field, pressure and density are assumed to be exponentially decaying in the vertical direction (the velocity is independent of the height in our model) and equations for the horizontal behaviour are determined. Invariance along the prominence direction is assumed, but the magnetic and velocity vectors retain all their components. The introduction of a field aligned flow results in the coronal magnetic field no longer being force free and a pressure deficit allows a siphon flow to occur. Substantial coronal velocities are possible but only sub-sonic (and hence in the low plasma beta corona sub-Alfvenic) flows are considered and these are consistent with observations. Finally, we propose a simple model for the steady supply of material into a prominence to balance the observed draining motions.