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Title: Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves

Abstract

Evolution of slow magnetoacoustic waves guided by a cylindrical magnetic flux tube that represents a coronal loop or plume, is modeled accounting for the effects of finite gas pressure, weak nonlinearity, dissipation by thermal conduction and viscosity, and the misbalance between the cooling by optically thin radiation and unspecified heating of the plasma. An evolutionary equation of the Burgers–Malthus type is derived. It is shown that the cooling/heating misbalance, determined by the derivatives of the combined radiative cooling and heating function, with respect to the density, temperature, and magnetic field at the thermal equilibrium affect the wave rather strongly. This effect may either cause additional damping, or counteract it, or lead to the gradual amplification of the wave. In the latter case, the coronal plasma acts as an active medium for the slow magnetoacoustic waves. The effect of the cooling/heating misbalance could be important for coronal slow waves, and could be responsible for certain discrepancies between theoretical results and observations, in particular, the increased or decreased damping lengths and times, detection of the waves at certain heights only, and excitation of compressive oscillations. The results obtained open up a possibility for the diagnostics of the coronal heating function by slowmore » magnetoacoustic waves.« less

Authors:
 [1];  [2]; ;  [3]
  1. Centre for Fusion, Space and Astrophysics, Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom)
  2. Institute of Solar-Terrestrial Physics SB RAS, P.O. Box 291, Lermontov St. 126A, Irkutsk 664033 (Russian Federation)
  3. School of Space Research, Kyung Hee University, Yongin, 446-701, Gyeonggi (Korea, Republic of)
Publication Date:
OSTI Identifier:
22679705
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 849; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLIFICATION; DENSITY; DETECTION; EXCITATION; HEATING; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETOACOUSTIC WAVES; MAGNETOACOUSTICS; MAGNETOHYDRODYNAMICS; NONLINEAR PROBLEMS; OSCILLATIONS; PLASMA; RADIATIVE COOLING; STAR EVOLUTION; SUN; THERMAL CONDUCTION; THERMAL EQUILIBRIUM; WAVELENGTHS

Citation Formats

Nakariakov, V. M., Afanasyev, A. N., Kumar, S., and Moon, Y.-J., E-mail: V.Nakariakov@warwick.ac.uk. Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA8EA3.
Nakariakov, V. M., Afanasyev, A. N., Kumar, S., & Moon, Y.-J., E-mail: V.Nakariakov@warwick.ac.uk. Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves. United States. doi:10.3847/1538-4357/AA8EA3.
Nakariakov, V. M., Afanasyev, A. N., Kumar, S., and Moon, Y.-J., E-mail: V.Nakariakov@warwick.ac.uk. Wed . "Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves". United States. doi:10.3847/1538-4357/AA8EA3.
@article{osti_22679705,
title = {Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves},
author = {Nakariakov, V. M. and Afanasyev, A. N. and Kumar, S. and Moon, Y.-J., E-mail: V.Nakariakov@warwick.ac.uk},
abstractNote = {Evolution of slow magnetoacoustic waves guided by a cylindrical magnetic flux tube that represents a coronal loop or plume, is modeled accounting for the effects of finite gas pressure, weak nonlinearity, dissipation by thermal conduction and viscosity, and the misbalance between the cooling by optically thin radiation and unspecified heating of the plasma. An evolutionary equation of the Burgers–Malthus type is derived. It is shown that the cooling/heating misbalance, determined by the derivatives of the combined radiative cooling and heating function, with respect to the density, temperature, and magnetic field at the thermal equilibrium affect the wave rather strongly. This effect may either cause additional damping, or counteract it, or lead to the gradual amplification of the wave. In the latter case, the coronal plasma acts as an active medium for the slow magnetoacoustic waves. The effect of the cooling/heating misbalance could be important for coronal slow waves, and could be responsible for certain discrepancies between theoretical results and observations, in particular, the increased or decreased damping lengths and times, detection of the waves at certain heights only, and excitation of compressive oscillations. The results obtained open up a possibility for the diagnostics of the coronal heating function by slow magnetoacoustic waves.},
doi = {10.3847/1538-4357/AA8EA3},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 849,
place = {United States},
year = {2017},
month = {11}
}