Observations of Dark Lanes in Umbral Fine Structure from the<i>Hinode</i>Solar Optical Telescope: Evidence for Magnetoconvection

Abstract

An analysis of high-resolution G-band images of active region NOAA 10930 is presented. The observations were recorded with the Broadband Filter Imager (BFI) attached to the Solar Optical Telescope (SOT) on board the Hinode mission. We observed dark lanes in umbral dots up to six folds in larger ones. Formation of umbral dots from dark core penumbral filament shows dark lanes. The evolution of the light bridge from the dark core penumbral filament is observed, which further disintegrates into umbral dots. These observations are compatible with the simulations of three-dimensional radiative magnetoconvection with gray radiative transfer in sunspot umbra by Schüssler & Vögler, which support the notion that these structures appear as a result of magnetoconvection.