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Detection of three periodicities in a single oscillating coronal loop

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Van Doorsselaere, Tom, Birtill, D. C. C. and Evans, G. R.. (2009) Detection of three periodicities in a single oscillating coronal loop. Astronomy & Astrophysics, Vol.508 (No.3). pp. 1485-1491. ISSN 0004-6361

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Official URL: http://dx.doi.org/10.1051/0004-6361/200912753

Abstract

Context. TRACE 171 Å observations of transverse loop oscillations on May 13, 2001 have been studied by De Moortel & Brady (2007). They found hints of 3 periodicities present in this event. Aims. The aim of this article is to improve the analysis, and measure the periodicities more accurately in order to do coronal seismology. Methods. We create multiple (x, t)-slices across the loop, and determine the oscillatory parameters within those slices. We then use statistical methods to reduce the errors on the measured oscillations parameters. Results. We find two populations with a clearly distinct period. The population at the loop top has a period of 895 ± 2 s, while the population in the loop leg has a period of 452 ± 1 s. The fact that the ratio of these two periods is roughly 2 and the geometry of the problem suggests that two harmonics are observed. In the residues, we confirm the presence of a 3rd harmonic with period 309 ± 15 s using two separate data analysis techniques. The three periods are then used to do a seismological estimate of the loop expansion and the density scale height.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Magnetohydrodynamics, Solar oscillations, Sun -- Corona, Sun -- Loop prominences
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
ISSN:	0004-6361
Date:	December 2009
Volume:	Vol.508
Number:	No.3
Page Range:	pp. 1485-1491
Identification Number:	10.1051/0004-6361/200912753
Status:	Peer Reviewed
Access rights to Published version:	Open Access
Funder:	Seventh Framework Programme (European Commission) (FP7/2007-2013)
Grant number:	220555 (FP7/2007-2013)
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URI:	http://wrap.warwick.ac.uk/id/eprint/3422