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Astronomy & Astrophysics manuscript no. aa2152 January 15, 2005 (DOI: will be inserted by hand later)

Summary: Astronomy & Astrophysics manuscript no. aa2152 January 15, 2005
(DOI: will be inserted by hand later)
Coronal oscillations in the vicinity of a sunspot as observed by
Chia-Hsien Lin 1 , D. Banerjee 2 , J.G. Doyle 1 , E. O'Shea 1 , and C.R. Foley 3
1 Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
2 Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India
3 Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT,
the date of receipt and acceptance should be inserted later
Abstract. In this paper, we present results from a time series analysis of data from the Grazing Incidence
Spectrometer (GIS), onboard SoHO. Our observations were concentrated at the boundary between the quiet
Sun and an active region, close to a sunspot plume. The dominant oscillations in all the lines studied are of
periods longer than 5 minutes. Although our observations were not taken directly above the sunspot, the 3-min
oscillations, which are normally associated with the umbra, are seen in several spectral lines, suggesting some
leakage perhaps via plume structures. The oscillations of coronal lines form wavepackets, and are intermittent
with no obvious decay. The average time scale of the intermittence is of the order of 20 minutes, which would
correspond to a source size of 2 arcsec.
Key words. Sun: Corona: Oscillations: loops:
1. Introduction


Source: Armagh Observatory


Collections: Physics