Potential evidence for the onset of alfvénic turbulence in trans-equatorial coronal loops
De Moortel, I., McIntosh, S., Threlfall, J., Bethge, C., & Liu, J. (2014). Potential evidence for the onset of alfvénic turbulence in trans-equatorial coronal loops. The Astrophysical Journal Letters, 782, L34. doi:10.1088/2041-8205/782/2/L34
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... Show moreThis 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. Show less
