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Title: POTENTIAL EVIDENCE FOR THE ONSET OF ALFVÉNIC TURBULENCE IN TRANS-EQUATORIAL CORONAL LOOPS

This study investigates Coronal Multi-channel Polarimeter Doppler-shift observations of a large, off-limb, trans-equatorial loop system observed on 2012 April 10-11. Doppler-shift oscillations with a broad range of frequencies are found to propagate along the loop with a speed of about 500 km s{sup –1}. The power spectrum of perturbations travelling up from both loop footpoints is remarkably symmetric, probably due to the almost perfect north-south alignment of the loop system. Compared to the power spectrum at the footpoints of the loop, the Fourier power at the apex appears to be higher in the high-frequency part of the spectrum than expected from theoretical models. We suggest this excess high-frequency power could be tentative evidence for the onset of a cascade of the low-to-mid frequency waves into (Alfvénic) turbulence.
Authors:
;  [1] ;  [2] ;  [3] ;  [4]
  1. School of Mathematics and Statistics, University of St. Andrews, St. Andrews, Fife KY16 9SS (United Kingdom)
  2. High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States)
  3. Kiepenheuer Institute for Solar Physics, D-79104 Freiburg (Germany)
  4. Earth and Space Science School, University of Science and Technology of China, NO. 96, JinZhai Road, Hefei (China)
Publication Date:
OSTI Identifier:
22363965
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 782; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALFVEN WAVES; COMPARATIVE EVALUATIONS; DISTURBANCES; DOPPLER EFFECT; MAGNETOHYDRODYNAMICS; OSCILLATIONS; POLARIMETRY; POTENTIALS; STELLAR CORONAE; SUN; SYMMETRY; TURBULENCE; VELOCITY