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| Titel |
Analysis of non-thermal velocities in the solar corona |
| VerfasserIn |
L. Contesse, S. Koutchmy, C. Viladrich |
| 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 ; 22, no. 8 ; Nr. 22, no. 8 (2004-09-07), S.3055-3062 |
| Datensatznummer |
250014986
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| Publikation (Nr.) |
 copernicus.org/angeo-22-3055-2004.pdf |
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| Zusammenfassung |
| We describe new ground-based spectroscopic observations made
using a 40-cm aperture coronagraph over a whole range of radial distances
(up to heights of 12' above the limb) and along four different heliocentric
directions N, E, S and W. The analysis is limited to the study of the
brightest forbidden emission line of Fe XIV at 530.3nm, in order to reach
the best possible signal-to-noise ratio. To make the results statistically more
significant, the extracted parameters are averaged over the whole length of
the slit, and measurements are repeated fives times at each position; the
corresponding dispersions in the results obtained along the slit are given.
Central line profile intensities and full line widths (FWHM) are plotted and
compared to measurements published by other authors closer to the limb. We
found widths and turbulent (non-thermal) velocities of significantly higher
values above the polar regions, especially when a coronal hole is present
along the line of sight. We do not see a definitely decreasing behaviour of
widths and turbulent velocities in equatorial directions for larger radial
distances, as reported in the literature, although lower values are measured
compared to the values in polar regions. The variation in the high corona is
rather flat and a correlation diagram indicates that it is different for
different regions and different radial distances. This seems to be the first
analysis of the profiles of this coronal line, up to large heights above the
limb for both equatorial and polar regions. |
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