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| Paper: |
Multi-wavelength Observations of Coronal Holes |
| Volume: |
346, Large-scale Structures and their Role in Solar Activity |
| Page: |
251 |
| Authors: |
de Toma, G.; Arge, C. |
| Abstract: |
Historically, coronal holes have been observed as regions of reduced emission on the solar disk in X-Ray and EUV wavelengths or as regions of reduced brightness in coronagraph images at the limb. They are usually identified with the footpoints of magnetic field lines open into the heliosphere as derived from potential field or MHD model extrapolations. Because the appearance of coronal holes is different at different wavelengths, and there are no observational data to directly determine which regions on the Sun are magnetically open or closed, the identification of coronal holes has always been difficult. We have combined relative intensity images in EUV wavelengths from space, with ground based observations in the He I 1083nm line, Hα line, and magnetograms to identify coronal hole regions more objectively. |
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