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| Paper: |
Chromospheric Multi-Wavelength Observations near the Solar Limb: Techniques and Prospects |
| Volume: |
463, 2nd ATST-EAST Workshop in Solar Physics: Magnetic Fields from the Photosphere to the Corona |
| Page: |
257 |
| Authors: |
Beck, C.; Rezaei, R. |
| Abstract: |
Observations of chromospheric spectral lines near and beyond the solar limb
provide information on the solar chromosphere without any photospheric
contamination. For ground-based observations near and off the limb with
real-time image correction by adaptive optics (AO), some technical
requirements have to be met, such as an AO lock point that is independent of
the location of the field of view observed by the science instruments,
both for 1D and 2D instruments. We show how to obtain simultaneous
AO-corrected spectra in Ca II H, Hα, Ca II IR at 854 nm,
and He I at 1083 nm with the instrumentation at the German Vacuum Tower
Telescope in Izaña, Tenerife. We determined the spectral properties of an
active-region macrospicule inside the field of view in the four chromospheric
lines, including its signature in polarization in He I at 1083 nm.
Compared to the line-core intensities, the Doppler shifts of the lines change
on a smaller spatial scale in the direction parallel to the limb, suggesting
the presence of coherent rotating structures or the passage of upwards
propagating helical waves on the surfaces of expanding flux tubes. |
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