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Issue A&A Volume 404, Number 1, June II 2003 Page(s) L1 - L4 Section Letters DOI 10.1051/0004-6361:20030763

A&A 404, L1-L4 (2003)
DOI: 10.1051/0004-6361:20030763

Letter

Propagating EUV disturbances in the Solar corona: Two-wavelength observations

D. B. King¹, V. M. Nakariakov¹, E. E. Deluca², L. Golub² and K. G. McClements<sup>3

1</sup>  Physics Department, University of Warwick, Coventry, CV4 7AL, UK
    e-mail: kingd@astro.warwick.ac.uk; valery@astro.warwick.ac.uk
²  Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA02138, USA
    e-mail: deluca@head-cfa.harvard.edu
³  UKAEA Culham Division, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB, USA
    e-mail: k.g.mcclements@ukaea.org.uk

(Received 23 January 2003 / Accepted 19 March 2003 )

Abstract
Quasi-periodic EUV disturbances simultaneously observed in 171 Å and 195 Å TRACE bandpasses propagating outwardly in a fan-like magnetic structure of a coronal active region are analysed. Time series of disturbances observed in the different bandpasses have a relatively high correlation coefficient (up to about 0.7). The correlation has a tendency to decrease with distance along the structure: this is consistent with an interpretation of the disturbances in terms of parallel-propagating slow magnetoacoustic waves. The wavelet analysis does not show a significant difference between waves observed in different bandpasses. Periodic patterns of two distinct periods: 2-3 min and 5-8 min are detected in both bandpasses, existing simultaneously and at the same distance along the loop, suggesting the nonlinear generation of the second harmonics.

Key words: magnetohydrodynamics (MHD) -- waves -- Sun: activity -- Sun: corona -- Sun: oscillations -- Sun: UV radiation

Offprint request: D. B. King, kingd@astro.warwick.ac.uk

© ESO 2003

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