The Magnetic Connection between the Convection Zone and Corona in the Quiet Sun

Abstract

To understand the dynamic, magnetic, and energetic connection between the convectively unstable layers below the visible surface of the Sun and the overlying solar corona, we have developed a new three-dimensional magnetohydrodynamic code capable of simultaneously evolving a model convection zone and corona within a single computational volume. As a first application of this numerical model, we present a series of simulations of the quiet Sun in a domain that encompasses both the upper convection zone and low corona. We investigate whether the magnetic field generated by a convective surface dynamo can account for some of the observed properties of the quiet-Sun atmosphere. We find that (1) it is possible to heat a model corona to X-ray-emitting temperatures with the magnetic fields generated from a convective dynamo and an empirically based heating mechanism consistent with the observed relationship between X-ray emission and magnetic flux observed at the visible surface; (2) within the limitations of our numerical models of the quiet Sun, resistive and viscous dissipation alone are insufficient to maintain a hot corona; (3) the quiet-Sun model chromosphere is a dynamic, non-force-free layer that exhibits a temperature reversal in the convective pattern in the relatively low density layers above the photosphere; (4) the majority of the unsigned magnetic flux lies below the model photosphere in the convectively unstable portion of the domain; (5) horizontally directed magnetic structures thread the low atmosphere, often connecting relatively distant concentrations of magnetic flux observed at the surface; and (6) low-resolution photospheric magnetograms can significantly underestimate the amount of unsigned magnetic flux threading the quiet-Sun photosphere.