Verwichte, E. (Erwin), Foullon, C. (Claire) and Van Doorsselaere, Tom. (2010) Spatial seismology of a large coronal loop arcade from TRACE & EIT observations of its transverse oscillations. Astrophysical Journal, Vol.717 (No.1). pp. 458-467. ISSN 0004-637X

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Abstract

We present a study of transverse loop oscillations in a large coronal loop arcade, using observations from the Transition Region And Coronal Explorer (TRACE) and Extreme-ultraviolet Imaging Telescope (EIT). For the first time we reveal the presence of long-period transverse oscillations with periods between 24 minutes and 3 hr. One loop bundle, 690 Mm long and with an oscillation period of 40 minutes, is analyzed in detail and its oscillation characteristics are determined in an automated manner. The oscillation quality factor is similar to what has been found earlier for oscillations in much shorter loops. This indicates that the damping mechanism of transverse loop oscillations is independent of loop length or period. The displacement profile along the whole length of the oscillating loop is determined for the first time and consistently between TRACE and EIT. By comparing the observed profile with models of the three-dimensional geometry of the equilibrium and perturbed loop, we test the effect of longitudinal structuring (spatial seismology) and find that the observations cannot unambiguously distinguish between structuring and non-planarity of the equilibrium loop. Associated intensity variations with a similar periodicity are explained in terms of variations in the line-of-sight column depth. Also, we report intensity oscillations at the loop footpoint, which are in anti-phase with respect to the intensity oscillations in the loop body. Lastly, this observation offers the first opportunity to use the transverse oscillations of the arcade to model the Alfven speed profile in the global corona.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Magnetic fields, Magnetohydrodynamics, Sun -- Corona, Solar oscillations
Journal or Publication Title:	Astrophysical Journal
Publisher:	IOP Publishing
ISSN:	0004-637X
Official Date:	1 July 2010
Volume:	Vol.717
Number:	No.1
Number of Pages:	10
Page Range:	pp. 458-467
Identification Number:	10.1088/0004-637X/717/1/458
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Engineering and Physical Sciences Research Council (EPSRC), UK Science and Technology Facilities Council (STFC), Seventh Framework Programme (European Commission) (FP7)
Grant number:	220555 (FP7)
URI:	http://wrap.warwick.ac.uk/id/eprint/5694

Data sourced from Thomson Reuters' Web of Knowledge

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