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Astron. Astrophys. 323, 599-605 (1997)

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

C. Denker

Universitäts-Sternwarte, Geismarlandstr. 11, D-37083 Göttingen, Germany present address: Big Bear Solar Observatory, California Institute of Technology, Pasadena, CA 91125, USA

Received 27 August 1996 / Accepted 9 January 1997


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 Na D2 (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.

Key words: Sun: activity – granulation – sunspots – methods observational – techniques: interferometric

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998