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.

We present spectropolarimetric analysis of umbral dots and a light bridge fragment that show dark lanes in G‐band images. Umbral dots show upflow as well as associated positive Stokes V area asymmetry in their central parts. Larger umbral dots show downflow patches in their surrounding parts that are associated with negative Stokes V area asymmetry. Umbral dots show weaker magnetic field in central part and higher magnetic field in peripheral area. Umbral fine structures are much better visible in total circularly polarized light than in continuum intensity. Umbral dots show a temperature deficit above dark lanes. The magnetic field inclination shows a cusp structure above umbral dots and a light bridge fragment. We compare our observational findings with 3D magnetohydrodynamic simulations.

We present high spatial resolution observations of short lived transients, ribbon and jets like events above a pore in Ca II H images where fine structure like umbral dots, lightbridge and penumbral micro filaments are present in the underlying photosphere. We found that current layers are formed at the edges of convective fine structure due to the shear between their horizontal field and the ambient vertical field. High vertical electric current density patches are observed in the photosphere around these events which indicates the formation of a current sheet at the reconnection site. In the framework of past studies, low altitude reconnection could be the mechanism that produces such events. The reconnection is caused by an opposite polarity field produced by the bending of field lines by convective downflows at the edge of the pore fine structures.

We present high resolution observations of fine structures at pore boundaries. The inner part of granules towards umbra show dark striations which evolve into a filamentary structure with dark core and ‘Y’ shape at the head of the filaments. These filaments migrate into the umbra similar to penumbral filaments. These filaments show higher temperature, lower magnetic field strength and more inclined field compared to the background umbra. The optical depth stratification of physical quantities suggests their similarity with penumbral filaments. However, line-of-sight velocity pattern is different from penumbral filaments where they show downflows in the deeper layers of the atmosphere while the higher layers show upflows. These observations show filamentation in a simple magnetic configuration.

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