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Effect of a radiation cooling and heating function on standing longitudinal oscillations in coronal loops
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Kumar, Sanjay, Nakariakov, V. M. (Valery M.) and Moon, Y. -J. (2016) Effect of a radiation cooling and heating function on standing longitudinal oscillations in coronal loops. The Astrophysical Journal, 824 (1). doi:10.3847/0004-637X/824/1/8 ISSN 0004-637X.
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WRAP_9877890-px-210316-kumar_sanjay_vmn_110216.pdf - Accepted Version - Requires a PDF viewer. Download (855Kb) | Preview |
Official URL: http://dx.doi.org/10.3847/0004-637X/824/1/8
Abstract
Standing long-period (with the periods longer than several minutes) oscillations in large hot (with the temperature higher than 3 MK) coronal loops have been observed as the quasi-periodic modulation of the EUV and microwave intensity emission and the Doppler shift of coronal emission lines, and have been interpreted as standing slow magnetoacoustic (longitudinal) oscillations. Quasi-periodic pulsations of shorter periods, detected in thermal and non-thermal emissions in solar flares could be produced by a similar mechanism. We present theoretical modelling of the standing slow magnetoacoustic mode, showing that this mode of oscillation is highly sensitive to peculiarities of the radiative cooling and heating function. We generalised the theoretical model of standing slow magnetoacoustic oscillations in a hot plasma, including the effects of the radiative losses, and accounting for plasma heating. The heating mechanism is not specified and taken empirically to compensate the cooling by radiation and thermalconduction. It is shown that the evolution of the oscillations is described by a generalised Burgers equation. Numerical solution of an initial value problem for the evolutionary equation demonstrates that different dependences of the radiative cooling and plasma heating on the temperature lead to different regimes of the oscillations, including growing, quasi-stationary and rapidly decaying. Our findings provide a theoretical foundation for probing the coronal heating function, and may explain the observations of decayless long-period quasi-periodic pulsations in flares. The hydrodynamic approach employed in this study should be considered as a zero-order approximation in the modelling of physical phenomena associated with flares.
Item Type: | Journal Article | ||||||||
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Subjects: | Q Science > QA Mathematics Q Science > QB Astronomy Q Science > QC Physics |
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||||
Library of Congress Subject Headings (LCSH): | Sun--Corona , Sun--Corona--Magnetic fields , Solar oscillations , Magnetohydrodynamics | ||||||||
Journal or Publication Title: | The Astrophysical Journal | ||||||||
Publisher: | Institute of Physics Publishing, Inc. | ||||||||
ISSN: | 0004-637X | ||||||||
Official Date: | 3 June 2016 | ||||||||
Dates: |
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Volume: | 824 | ||||||||
Number: | 1 | ||||||||
DOI: | 10.3847/0004-637X/824/1/8 | ||||||||
Status: | Peer Reviewed | ||||||||
Publication Status: | Published | ||||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||||
Date of first compliant deposit: | 30 March 2016 | ||||||||
Date of first compliant Open Access: | 1 August 2016 | ||||||||
Funder: | European Research Council (ERC), Korea (South).Munʼgyobu | ||||||||
Grant number: | 321141(ERC) |
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