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Issue A&A
Volume 398, Number 2, February I 2003
Page(s) L15 - L18
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20021848



A&A 398, L15-L18 (2003)
DOI: 10.1051/0004-6361:20021848

Letter

Oscillations in the wings of sunspot transition region lines

N. Brynildsen1, P. Maltby1, O. Kjeldseth-Moe1 and K. Wilhelm2

1  Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway
    e-mail: nils.brynildsen@astro.uio.no;per.maltby@astro.uio.no;olav.kjeldseth-moe@astro.uio.no
2  Max-Planck-Institut für Aeronomie, 37191 Katlenburg-Lindau, Germany
    e-mail: wilhelm@linmpi.mpg.de

(Received 4 November 2002 / Accepted 15 December 2002 )

Abstract
We explore a new approach to the investigation of optically thin emission lines by comparing the intensity variations in opposite wings of the spectral lines and apply the method to investigate the oscillations above sunspots. The observations show that it is easier to detect the 3 min oscillations above sunspots in the short wavelength ("blue") wing than in the long wavelength ("red") wing of the lines. The observed oscillations are compatible with the spectral line signatures of upwardly propagating acoustic waves.


Key words: Sun: sunspot oscillations -- Sun: transition region -- EUV radiation -- line wing

Offprint request: P. Maltby, per.maltby@astro.uio.no




© ESO 2003


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