Astronomy & Astrophysics

Free access article

Issue		A&A Volume 365, Number 3, January III 2001
Page(s)		588 - 597
Section		Diffuse matter in space
DOI		10.1051/0004-6361:20000478

A&A 365, 588-597 (2001)
DOI: 10.1051/0004-6361:20000478

Speckle spectro-polarimetry of solar magnetic structures

M. Koschinsky¹, F. Kneer¹ and J. Hirzberger^{1, 2}

¹ Universitäts-Sternwarte Göttingen, Geismarlandstr. 11, 37083 Göttingen, Germany
² Institut für Geophysik, Astrophysik und Meteorologie, Universtät Graz, Universitätsplatz 5, 8010 Graz, Austria

(Received 19 July 2000 / Accepted 23 October 2000 )

Abstract
We present speckle observations of small-scale magnetic structures on the Sun. They were obtained with the "Göttingen"Fabry-Perot interferometer (FPI) in the Vacuum Tower Telescope at the Observatorio del Teide, Tenerife, from quiet and active regions close to disc center. A Stokes V polarimeter was added to the FPI to measure V profiles in the Fe I 6302.5 Åline. The setup allows image reconstruction with speckle methods. The achieved spatial resolution in the magnetograms is $0\hbox{$.\!\!^{\prime\prime}$ }4$ - $0\hbox{$.\!\!^{\prime\prime}$ }5$ . We describe the observational technique and the data reduction. The results from small-scale magnetic flux elements in a very quiet region, in an active region with pores and abnormal granulation, and in a sunspot with its surroundings are discussed. In the quiet Sun, granular dynamics dominate the time evolution of the magnetic elements. Flux occurs in both bright intergranular points and in dark intergranular spaces. Likewise, with the present spatial resolution, no preference of magnetic flux in abnormal granulation in an active region can be found. Flux occurs in both bright (abnormal) small-scale granules and in the darker spaces in between them. The small sunspot studied has very little magnetic flux in its ambient quiet regions, especially no strong, conspicuous concentrations of returned flux, i.e. of flux with polarity opposite to that in the sunspot.

Key words: Sun: faculae, plages -- Sun: magnetic fields -- techniques: image processing -- techniques: polarimetric

Offprint request: M. Koschinsky, mkosch@uni-sw.gwdg.de

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