| Autor: |
L. D. Gardner, Alexander Panasyuk, Steven R. Cranmer, Ruth Esser, Silvano Fineschi, Raid Suleiman, Richard A. Frazin, Leonard Strachan, Giancarlo Noci, J. L. Kohl |
| Rok vydání: |
1999 |
| Předmět: |
|
| Zdroj: |
The Astrophysical Journal. 510:L59-L62 |
| ISSN: |
0004-637X |
| DOI: |
10.1086/311793 |
| Popis: |
Spectral line profiles have been measured for H I λ1216, O VI λλ1032, 1037, and Mg X λ625 in a polar coronal hole observed during 1997 September 15-29, at projected heliographic heights ρ between 1.34 and 2.0 R☉. Observations of H I λ1216 and the O VI doublet from 1997 January for ρ=1.5-3.0 R☉ are provided for comparison. The O VI lines are well fit to a narrow and broad component which appear to be associated with regions of higher and lower spectral radiance, respectively. The narrow components dominate at low heights and become a small fraction of the lines at higher heights. Mg X λ625 is observed to have a narrow component at ρ=1.34 R☉ which accounts for only a small fraction of the observed spectral radiance. In the case of the broad components, the values of v1/e for O VI are only slightly larger than those for H I at ρ=1.34 R☉ but are significantly larger at ρ=1.5 R☉ and much larger for ρ>1.75 R☉. In contrast, the Mg X values are less than those of H I up to 1.75 and then increase rapidly up to at least ρ=2.0 R☉ but never reach the values of O VI. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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