Duckenfield, Timothy, Anfinogentov, Sergey, Pascoe, D. J. (David J.) and Nakariakov, V. M. (Valery M.) (2018) Detection of the second harmonic of decay-less kink oscillations in the solar corona. Astrophysical Journal Letters, 854 (1). L5. doi:10.3847/2041-8213/aaaaeb

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Abstract

EUV observations of a multi-thermal coronal loop, taken by the Atmospheric Imaging Assembly of the Solar Dynamics Observatory, which exhibits decay-less kink oscillations are presented. The data cube of the quiet-Sun coronal loop was passed through a motion magnification algorithm to accentuate transverse oscillations. Time–distance maps are made from multiple slits evenly spaced along the loop axis and oriented orthogonal to the loop axis. Displacements of the intensity peak are tracked to generate time series of the loop displacement. Fourier analysis on the time series shows the presence of two periods within the loop: ${P}_{1}={10.3}_{-1.7}^{+1.5}$ minutes and ${P}_{2}={7.4}_{-1.3}^{+1.1}$ minutes. The longer period component is greatest in amplitude at the apex and remains in phase throughout the loop length. The shorter period component is strongest further down from the apex on both legs and displays an anti-phase behavior between the two loop legs. We interpret these results as the coexistence of the fundamental and second harmonics of the standing kink mode within the loop in the decay-less oscillation regime. An illustration of seismological application using the ratio P 1/2P 2 ~ 0.7 to estimate the density scale height is presented. The existence of multiple harmonics has implications for understanding the driving and damping mechanisms for decay-less oscillations and adds credence to their interpretation as standing kink mode oscillations.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Magnetohydrodynamics , Sun--Corona, Solar oscillations
Journal or Publication Title:	Astrophysical Journal Letters
Publisher:	IOP Publishing Ltd
ISSN:	2041-8213
Official Date:	7 February 2018
Dates:	Date Event 7 February 2018 Published 26 January 2018 Accepted
Date of first compliant deposit:	29 January 2018
Volume:	854
Number:	1
Article Number:	L5
DOI:	10.3847/2041-8213/aaaaeb
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Science and Technology Facilities Council (Great Britain) (STFC)
RIOXX Funder/Project Grant:	Project/Grant ID RIOXX Funder Name Funder ID UNSPECIFIED British Council http://dx.doi.org/10.13039/501100000308 UNSPECIFIED Korea (South). Munʾgyobu https://viaf.org/viaf/132529252 UNSPECIFIED Science and Technology Facilities Council http://dx.doi.org/10.13039/501100000271

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