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Polarimetric Measurements of the Fine Structure of a Sunspot Penumbra

Published online by Cambridge University Press:  12 April 2016

J. Hofmann
Affiliation:
Institut für Astronomie und Astrophysik der Universität Würzburg, Am Hubland, 8700 Würzburg, F.R.Germany
F.-L. Deubner
Affiliation:
Institut für Astronomie und Astrophysik der Universität Würzburg, Am Hubland, 8700 Würzburg, F.R.Germany
B. Fleck
Affiliation:
Institut für Astronomie und Astrophysik der Universität Würzburg, Am Hubland, 8700 Würzburg, F.R.Germany
W. Schmidt
Affiliation:
Kiepenheuer-Institut für Sonnenphysik, Schöneckstraße 6, 7800 Freiburg, F.R., Germany

Abstract

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Observations of a fairly regular sunspot penumbra near disk center have been carried out using a Stokes V polarimeter at the German Vacuum-Tower-Telescope in Izaña, Tenerife. We obtained two-dimensional spectral data by scanning the limb oriented sector of the penumbra in steps of 1” with the slit parallel to the solar limb. From Stokes V and Stokes I spectra of four magnetic sensitive lines (Fe I 5247.1, Cr I 5247.6, Fe I 5250.2, and Fe I 5250.7) obtained with 1024 × 1024 pixel CCDs we have determined Doppler shifts and several magnetic parameters. The results of a correlation analysis point out a clear relation between continuum brightness and magnetic field inclination in the sense of steeper field lines in the bright penumbral filaments. There is also a doubtless connection between intensity and Doppler shift. We did find indications for a correlation between field strength and brightness which is not uniform across the penumbra, though.

Type
Session 1. Structure of Active Regions
Copyright
Copyright © Astronomical Society of the Pacific 1993

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