Potential Evidence for the Onset of Alfvénic Turbulence in Trans-equatorial Coronal Loops
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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–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.
De Moortel , I , McIntosh , S , Threlfall , J W , Bethge , C & Liu , J 2014 , ' Potential Evidence for the Onset of Alfvénic Turbulence in Trans-equatorial Coronal Loops ' Astrophysical Journal Letters , vol 782 , no. 2 , L34 . DOI: 10.1088/2041-8205/782/2/L34
Astrophysical Journal Letters
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