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Coronal loop seismology using damping of standing kink oscillations by mode coupling II. additional physical effects and Bayesian analysis
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Pascoe, D. J. (David J.), Anfinogentov, Sergey, Nisticò, Giuseppe, Goddard, Paul and Nakariakov, V. M. (2017) Coronal loop seismology using damping of standing kink oscillations by mode coupling II. additional physical effects and Bayesian analysis. Astronomy and Astrophysics, 600 . A78. doi:10.1051/0004-6361/201629702 ISSN 0004-6361.
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Official URL: https://doi.org/10.1051/0004-6361/201629702
Abstract
Context. The strong damping of kink oscillations of coronal loops can be explained by mode coupling. The damping envelope depends on the transverse density profile of the loop. Observational measurements of the damping envelope have been used to determine the transverse loop structure which is important for understanding other physical processes such as heating. Aims. The general damping envelope describing the mode coupling of kink waves consists of a Gaussian damping regime followed by an exponential damping regime. Recent observational detection of these damping regimes has been employed as a seismological tool. We extend the description of the damping behaviour to account for additional physical effects, namely a time-dependent period of oscillation, the presence of additional longitudinal harmonics, and the decayless regime of standing kink oscillations. Methods. We examine four examples of standing kink oscillations observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We use forward modelling of the loop position and investigate the dependence on the model parameters using Bayesian inference and Markov Chain Monte Carlo (MCMC) sampling. Results. Our improvements to the physical model combined with the use of Bayesian inference and MCMC produce improved estimates of model parameters and their uncertainties. Calculation of the Bayes factor also allows us to compare the suitability of different physical models. We also use a new method based on spline interpolation of the zeroes of the oscillation to accurately describe the background trend of the oscillating loop. Conclusions. This powerful and robust method allows for accurate seismology of coronal loops, in particular the transverse density profile, and potentially reveals additional physical effects.
Item Type: | Journal Article | ||||||
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Subjects: | Q Science > QB Astronomy | ||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||
Library of Congress Subject Headings (LCSH): | Solar atmosphere, Sun -- Corona, Solar magnetic fields, Magnetohydrodynamics, Solar oscillations | ||||||
Journal or Publication Title: | Astronomy and Astrophysics | ||||||
Publisher: | EDP Sciences | ||||||
ISSN: | 0004-6361 | ||||||
Official Date: | 4 April 2017 | ||||||
Dates: |
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Volume: | 600 | ||||||
Article Number: | A78 | ||||||
DOI: | 10.1051/0004-6361/201629702 | ||||||
Status: | Peer Reviewed | ||||||
Publication Status: | Published | ||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||
Date of first compliant deposit: | 20 January 2017 | ||||||
Date of first compliant Open Access: | 6 July 2017 | ||||||
Funder: | European Research Council (ERC), Science and Technology Facilities Council (Great Britain) (STFC) | ||||||
Grant number: | SeismoSun Research Project No. 321141 (ERC), Grant ST/L000733/1 (STFC) |
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