Observational Manifestations of Solar Magnetoconvection: Center-to-Limb Variation

Abstract

We present the first center-to-limb G-band images synthesized from high-resolution simulations of solar mag- netoconvection. Toward the limb the simulations show hilly granulation with dark bands on the far side, bright granulation walls, and striated faculae, similar to observations. At disk center G-band bright points are flanked by dark lanes. The increased brightness in elements is due to their lower density compared with the surrounding intergranular medium. One thus sees deeper layers where the temperature is higher. At a given geometric height, the elements are cooler than the surrounding medium. In the G band, the contrast is further increased by the destruction of CH in the low-density elements. The optical depth unity surface is very corrugated. Bright granules have their continuum optical depth unity 80 km above the mean surface, the elements 200-300 km below. The horizontal temperature gradient is especially large next to flux concentrations. When viewed at an angle, the deep elements' optical surface is hidden by the granules and the bright points are no longer visible, except where the magnetic valleys are aligned with the line of sight. Toward the limb, the low density in the strong elements causes unit line-of-sight optical depth to occur deeper in the granule walls behind than for rays not going through elements, and variations in the field strength produce a striated appearance in the bright granule walls. Subject headings: convection — fields — MHD — Sun: faculae, plages — Sun: photosphere