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| Paper: |
Spectroscopic Observations of Continuous Outflows and Propagating Waves in Active Region NOAA 10942 with Hinode/EIS |
| Volume: |
455, 4th Hinode Science Meeting: Unsolved Problems and Recent Insights |
| Page: |
219 |
| Authors: |
Nishizuka, N.; Hara, H. |
| Abstract: |
We analyze "sit-and-stare" mode observations of continuous outflows
and waves with the Extreme ultraviolet Imaging Spectrometer (EIS) on
board Hinode, whose slit was located along the open field lines
at the edge of active region NOAA 10942 on February 20, 2007. We found
both intensity and velocity disturbances in
Fe xii 195.12 Å propagating along the field lines with
apparent speeds of 140 km s-1. The Doppler shifts shows mean
upward velocities of 30–50 km s-1 and small velocity
disturbances with amplitudes of 5–15 km s-1 in phase with
intensity disturbances of 3–5% amplitude relative to the mean
intensity. Not only a quasi-periodicity of 10–13 minutes but also
“tad pole'' signatures—which may be evidence of propagating
waves—were observed at the footpoints of the loops. Covariation of
intensity and Doppler velocity is consistent with upward motion of
propagating slow-mode magnetoacoustic waves. The energy flux of the
waves was estimated to be 1–3× 105 erg s-1 cm–2,
which is not enough to account for coronal heating but sufficient for
solar wind acceleration. High temporal spectroscopic observation also
revealed intermittent signatures of line broadening at the footpoints
of the loops. Each of them seems to correspond to the footpoints of
propagating disturbances. This may indicate that the origins of flows
and waves are unresolved explosive events at the lower atmosphere, by
analogy to spectroscopic observations of a jet. |
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