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Issue A&A
Volume 392, Number 3, September IV 2002
Page(s) 1095 - 1104
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20021182



A&A 392, 1095-1104 (2002)
DOI: 10.1051/0004-6361:20021182

Temporal and spatial variations of the magnetic field vector in sunspots

A. Settele1, M. Sigwarth2, 3 and K. Muglach4

1  ESA Research and Scientific Support Department (RSSD), ESTEC, Keplerlaan 1, 2201 AZ, Noordwijk, The Netherlands
2  National Solar Observatory/Sacramento Peak PO Box 62 Sunspot, NM 88349-0062, USA
3  Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany
    e-mail: msig@kis.uni-freiburg.de
4  Astrophysikalisches Institut Potsdam, Telegrafenberg A27, 14473 Potsdam, Germany
    e-mail: kmuglach@aip.de

(Received 21 February 2002 / Accepted 28 May 2002 )

Abstract
In order to look for magnetic field vector oscillations in sunspots we used data measured with the Advanced Stokes Polarimeter at the Dunn Solar Telescope. We analyzed two time series of 65 and 110 min that were taken by scanning repeatedly a 6 $^{\prime\prime} . $2 $4 \times 75^{\prime\prime}$ field of view, while obtaining the full Stokes vector in the lines FeI 630.15 nm and 630.25 nm. An inversion was carried out and a Fast Fourier Transform (FFT) analysis was used to find oscillatory phenomena. We discuss possible unwanted effects that lead to apparent magnetic field oscillations and find an average amplitude of ( $B, \psi$) 5.8 G/0.23° rms by excluding these effects, which also means that only 6% and 22% of the two sunspot umbrae respectively remained for analysis. If we smooth the power spectra over $2\times2$ pixels, all significant power disappears.


Key words: Sun: sunspots -- Sun: magnetic fields -- Sun: oscillations

Offprint request: A. Settele, asettele@rssd.esa.int

SIMBAD Objects in preparation



© ESO 2002


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