Two-dimensional speckle spectroscopy of the moustache phenomenon on the Sun

This paper deals with a detailed morphological and photometric investigation of solar small-scale features in the vicinity of an irregular sunspot group. The observations were performed with the Vacuum Tower Telescope at the Observatorio del Teide/Tenerife on May 18, 1994. The speckle masking method has been applied to reconstruct almost diffraction limited filtergrams in two different wavelength regions. For this purpose, we used the two-dimensional spectrometer of the Universitäts-Sternwarte Göttingen which was slightly modified for the speckle observations. In the narrow-band filtergrams, we studied the intensity enhancement in the inner wings of the strong chromospheric absorption line NaD2 (moustache phenomenon). The corresponding filtergrams in the white-light channel show a clear correlation of photospheric filigree and the moustache phenomenon. The bandwidth of the small-passband channel amounts to 0.014 nm. This is the highest spectral resolution reached with speckle masking imaging so far.