On the Relation Between Upflow Velocities and Coronal Non-thermal Velocities as Measured by Hinode/EIS

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Abstract
Upflows at coronal temperatures are typically present at the edges of active regions, where plasma escapes into the upper atmosphere. This study focuses on NOAA Active Regions 12665 and 12685 which are in different evolutionary stages, they display varying activity levels, and have a large difference in their magnetic field structure. Our targets were followed by Hinode/EIS as the ARs crossed the solar disk, and we used Fe XII maps to track their evolution. We separated time periods with nearly stationary flows from the non-stationary ones, in order to isolate the effects of solar rotation and activity on both the line-of-sight and non-thermal velocities. We confirmed the presence of a strong positive correlation between the Doppler and non-thermal velocity during both time periods and with different levels of activity. These results help us differentiate the physical origin of non-thermal velocities, such as Alfvén waves, MHD turbulence, magnetic reconnection, and multi-stream components. Our results favour the latter.

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