An Isaac Newton Institute Workshop

MAGNETOHYDRODYNAMICS OF STELLAR INTERIORS <br> Supported by the European Commission, Sixth Framework Programme - <br> Marie Curie Conferences and Training Courses - MSCF-CT-2003-503674

Understanding facular granules and lanes

Author: Oskar Steiner (Kiepenheuer-Institut fuer Sonnenphysik )

Abstract

Recent high resolution observations by Lites et al.~(2004) show details of facular granules at 0.12 arcsec, including dark facular lanes. For an interpretation of these data a basic facular model is constructed, consisting of a magnetic flux sheet embedded in a plane parallel atmosphere. The model explains the wide brightening limbward of the facular magnetic field by a radiative transfer effect due to the reduced opacity of the rarefied flux-sheet atmosphere and the dark narrow lane centerward of the facular granule as a consequence of its cool deep layers and ambient cooling by the hot walls. These results carry over to the case of a flux concentration in dynamic interaction with convective motion.