Resonances of coronal loops

Journal Article · Wed Feb 01 04:00:00 EST 1984 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/161706· OSTI ID:6747170

Hollweg, J V

We study the transmission of energy into coronal loops by Alfven waves. A three-layer model is studied analytically. The three-layer model has a constant Alfven speed (v/sub A/) in the coronal part of the loop, but v/sub A/ varies exponentially with distance in the chromospheres and transition region and the two ends of the loop. We find that the coronal part of the loop acts like a resonant cavity, and that the transmission of energy into the loop is enhanced at certain resonant frequencies. These loop resonances allow enough wave energy to enter the loop, so that the radiation and heat conduction losses can be balanced; the higher order resonances may be energetically more important than the fundamental. Leakage of energy out of the coronal cavity determines the maximum ''quality'' of the resonance. The maximum quality is about 50 for coronal parameters, in contrast to the much larger qualities presented by Ionson. However, if the coronal damping is assumed to be moderately large, so that ..omega../sub i//..omega..roughly-equal(a few tenths), then the leakage becomes unimportant, the quality drops to less than 10, and the predicted coronal velocity fluctuations are compatible with the observed nonthermal coronal motions. Moreover, if the coronal damping is moderate, we find that the coronal heating is independent of the damping rate, in qualitative agreement with Ionson. We suggest that the Alfven waves may be dissipated via a turbulent cascade of their energy to high wavenumbers. If the cascade proceeds at the rate given by Kolmogorov turbulence, we conclude that Alfven waves can heat coronal loops in a manner which is consistent with observations.

• Research Organization: Department of Physics, Space Science Center, University of New Hampshire
• OSTI ID: 6747170
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 277:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
ATMOSPHERES
CHROMOSPHERE
DAMPING
DISSIPATION FACTOR
ENERGY TRANSFER
ENERGY TRANSPORT
FLUID MECHANICS
HEAT TRANSFER
HYDRODYNAMICS
HYDROMAGNETIC WAVES
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MATHEMATICAL MODELS
MECHANICS
RADIATIONS
RESONANCE
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR RADIATION
STAR MODELS
STELLAR ATMOSPHERES
STELLAR CORONAE
STELLAR RADIATION
THERMAL CONDUCTION
WAVE PROPAGATION