Abstract We have measured the line widths and nonthermal velocities in 12 solar regions, using the high resolution EUV data taken by Hinode/EIS. We find that there exists a positive correlation between the intensity and nonthermal velocity for the Fe XII emission line and some other lines. The correlation coefficients decrease from the disk center to the limb. However, the nonthermal velocities of a particular spectral line do not vary much in different regions, so they are considered isotropic. In particular, we find that for a coronal loop structure, the largest widths and nonthermal velocities occur at the footpoints, where outflows appear. Based on these observational results, we discuss several physical processes responsible for the coronal heating.
Keywords line: profiles— Sun: corona—Sun: UV radiation
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