First Results from the Soho Ultraviolet Coronagraph Spectrometer
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is being used to observe the extended solar corona from 1.25 to 10 R from Sun center. Initial observations of polar coronal holes and equatorial streamers are described. The observations include measurements of spectral line profiles for HI L...
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Published in | Solar physics Vol. 175; no. 2; pp. 613 - 644 |
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Main Authors | , , , , , , , , , , , , , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Dordrecht
Springer Nature B.V
01.10.1997
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Subjects | |
Online Access | Get full text |
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Summary: | The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is being used to observe the extended solar corona from 1.25 to 10 R from Sun center. Initial observations of polar coronal holes and equatorial streamers are described. The observations include measurements of spectral line profiles for HI Lα and Lβ, Ovi 1032 Å and 1037 Å, Mgx 625 Å, Fexii 1242 Å and several others. Intensities for Mgx 610 Å, Sixii 499 Å, and 520 Å, Sx 1196 Å, and 22 others have been observed. Preliminary results for derived H^sup 0^, O^sup 5+^, Mg^sub 9+^, and Fe^sup 11+^ velocity distributions and initial indications of outflow velocities for O^sup 5+^ are described. In streamers, the H^sup 0^ velocity distribution along the line of sight (specified by the value at e^sup -1^, along the line of sight) decreases from a maximum value of about 180 km s^sup -1^ at 2 R to about 140 km s^sup -1^ at 8 R. The value for O^sup 5+^ increases with height reaching a value of 150 km s^sup -1^ at 4.7 R. In polar coronal holes, the O^sup 5+^ velocity at e^sup -1^ is about equal to that of H^sup 0^ at 1.7 R and significantly larger at 2.1 R. The O^sup 5+^ in both streamers and coronal holes were found to have anisotropic velocity distributions with the smaller values in the radial direction.[PUBLICATION ABSTRACT] |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0038-0938 1573-093X |
DOI: | 10.1023/A:1004903206467 |