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| Titel |
Solar stereoscopy – where are we and what developments do we require to progress? |
| VerfasserIn |
T. Wiegelmann, B. Inhester, L. Feng |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 27, no. 7 ; Nr. 27, no. 7 (2009-07-23), S.2925-2936 |
| Datensatznummer |
250016601
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2925-2009.pdf |
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| Zusammenfassung |
| Observations from the two STEREO-spacecraft give us for the first time the possibility
to use stereoscopic methods to reconstruct the 3-D solar corona. Classical stereoscopy
works best for solid objects with clear edges. Consequently an application of classical
stereoscopic methods to the faint structures visible in the optically thin coronal plasma
is by no means straight forward and several problems have to be treated
adequately: 1) First there is the problem of identifying one-dimensional structures
– e.g. active region coronal loops or polar plumes- from the two individual EUV-images
observed with STEREO/EUVI.
2) As a next step one has the association problem to find corresponding structures in
both images. This becomes more difficult as the angle between STEREO-A and B increases.
3) Within the reconstruction problem stereoscopic methods are used to compute the
3-D-geometry of the identified structures.
Without any prior assumptions, e.g., regarding the footpoints
of coronal loops, the reconstruction problem
has not one unique solution.
4) One has
to estimate the reconstruction error or accuracy of the reconstructed 3-D-structure,
which depends on the accuracy of the identified structures in 2-D, the separation
angle between the spacecraft, but also on the location, e.g., for east-west
directed coronal loops the reconstruction error is highest close to the loop top.
5) Eventually we are not only interested in the 3-D-geometry of loops or plumes,
but also in physical parameters like density, temperature, plasma flow, magnetic
field strength etc. Helpful for treating some of these problems are coronal magnetic
field models extrapolated from photospheric measurements, because observed EUV-loops
outline the magnetic field. This feature has been used for a new method dubbed
"magnetic stereoscopy". As examples we show recent application to active region
loops. |
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