An analysis of high-resolution Stokes observations of two light bridges in active region NOAA 8990 is presented. The observations were recorded with the La Palma Stokes Polarimeter attached to the Swedish Vacuum Solar Telescope. The stratification over the solar atmosphere of different physical parameters is retrieved from these data using the Stokes inversion based on response functions (SIR). Our results confirm previous observations of features such as the decrease in magnetic field strength and the increase in inclination in the light bridges. We also confirm a temperature increase in these structures with respect to the surrounding umbrae. The maps of the magnetic field strength and of the orientation of the magnetic field vector indicate the presence of a canopy structure above the light bridges. We derive the vertical component of electric current density (J z ) from the configuration of the magnetic field. The increased temperature found in the upper layers is studied in the context of the proposed canopy topology and could also explain the recently observed chromospheric heating processes found above light bridges.

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A 90 minute time series of high spatial resolution white-light images of solar granulation, obtained at the Swedish Vacuum Solar Tower (Observatorio del Roque de los Muchachos, La Palma), was analyzed to study how the physical properties of the granules changed with size. The observational material was corrected for global motions and for the instrumental proÐle, and a subsonic Ðlter was applied. A deÐni-tion of granular border was adopted using the inÑection points of the intensity of the images, and the granular cells were deÐned as areas including, in addition to the granules, one-half of their surrounding intergranular lanes. Using time series to investigate the average behavior of solar granulation has three strong advantages : the Ðrst is the possibility of removing the acoustic waves ; second, the possibility of estimating the e †ect of the variability of seeing on our results ; and, third, the opportunity to attain high statistical signiÐcance in the analysis as a result of the large number of extracted granules (61,138).It is shown that the granules of the sample can be classiÐed according to their mean and maximum intensities and their fractal dimension into two regimes, with diameters smaller than and larger than 1A .4, respectively. A broad transition region in which both regimes coexist was found. The resolved internal brightness structure of both the granules and the intergranular lanes shows a linear increase of the number of substructures with the granular and intergranular areas. The diameters of these substructures range between our e †ective resolution limit and with preferential sizes at and (D0A .3) D1A .5, 0A .65 0A .55, respectively. Moreover, it seems that large and small granules are unevenly distributed with respect to the large-scale vertical Ñows. Thus smaller granules are more concentrated along downdrafts whereas larger ones preferentially occupy the updrafts. Finally, a physical scenario compatible with the existence of these two granular populations is discussed.

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This paper presents the analysis of high-resolution Stokes observations of eight different umbral dots in a sunspot. The spectra were recorded with the La Palma Stokes Polarimeter, attached to the Swedish Vacuum Solar Telescope. The observed line profiles have been inverted to yield the height stratifications of temperature, magnetic field, and line-of-sight velocity, as well as their respective Wilson depressions. We report on systematic differences in the properties of umbral dots with respect to the nearby umbra, including small upflows ($100 m s À1 ), higher temperatures ($1 kK), and weaker fields ($500 G) with more horizontal orientations ($10 ). The field weakening is strongly correlated with the Wilson depression, suggesting that it may be due to an opacity effect (as one is looking at higher layers). The inclination excess, on the other hand, is real and cannot be ascribed to formation height issues. The results obtained from our semiempirical modeling are discussed within the context of the currently existing scenarios for the subsurface structure of sunspots. The observational signatures revealed by our analysis fit well within both the ''spaghetti'' and the monolithic models.

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Context. Solar pores are small sunspots lacking a penumbra that have a prevailing vertical magnetic-field component. They can include light bridges at places with locally reduced magnetic field. Like sunspots, they exhibit a wide range of oscillatory phenomena. Aims. A large isolated pore with a light bridge (NOAA 11005) is studied to obtain characteristics of a chromospheric filamentary structure around the pore, to analyse oscillations and waves in and around the pore, and to understand the structure and brightness of the light bridge. Methods. Spectral imaging observations in the line Ca II 854.2 nm and complementary spectropolarimetry in Fe I lines, obtained with the DST/IBIS spectrometer and HINODE/SOT spectropolarimeter, were used to measure photospheric and chromospheric velocity fields, oscillations, waves, the magnetic field in the photosphere, and acoustic energy flux and radiative losses in the chromosphere. Results. The chromospheric filamentary structure around the pore has all important characteristics of a superpenumbra: it shows an inverse Evershed effect and running waves, and has a similar morphology and oscillation character. The granular structure of the light bridge in the upper photosphere can be explained by radiative heating. Acoustic waves leaking up from the photosphere along the inclined magnetic field in the light bridge transfer enough energy flux to balance the entire radiative losses of the light-bridge chromosphere. Conclusions. A penumbra is not a necessary condition for the formation of a superpenumbra. The light bridge is heated by radiation in the photosphere and by acoustic waves in the chromosphere.