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| Paper: |
Propagating Intensity Disturbances in Fan-like Coronal Loops: Flows or Waves? |
| Volume: |
455, 4th Hinode Science Meeting: Unsolved Problems and Recent Insights |
| Page: |
227 |
| Authors: |
Wang, T.; Ofman, L.; Davila, J. M. |
| Abstract: |
Quasi-periodic intensity disturbances propagating upward along the
coronal structure have been extensively studied using EUV imaging
observations from SOHO/EIT and TRACE. They were interpreted as either
slow mode magnetoacoustic waves or intermittent upflows. In this study
we aim at demonstrating that time series of spectroscopic observations
are critical to solve this puzzle. Propagating intensity and Doppler
shift disturbances in fanlike coronal loops are analyzed in multiple
wavelengths using sit-and-stare observations from Hinode/EIS. We
find that the disturbances did not cause the blue-wing asymmetry of
spectral profiles in the warm (∼1.5 MK) coronal lines. The
estimated small line-of-sight velocities also did not support the
intermittent upflow interpretation. In the hot (∼2 MK) coronal
lines the disturbances did cause the blue-wing asymmetry, but the
double fits revealed that a high-velocity minor component is steady
and persistent, while the propagating intensity and Doppler shift
disturbances are mainly due to variations of the core component,
therefore, supporting the slow wave interpretation. However, the
cause for blueward line asymmetries remains unclear. |
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