Abstract
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.
Original language | English |
---|---|
Article number | L34 |
Number of pages | 6 |
Journal | Astrophysical Journal Letters |
Volume | 782 |
Issue number | 2 |
Early online date | 20 Feb 2014 |
DOIs | |
Publication status | Published - 20 Feb 2014 |
Externally published | Yes |
Keywords
- Magnetohydrodynamics (MHD)
- Sun: atmosphere
- Sun: corona
- Sun: oscillations
- Turbulence
- Waves