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Uranian H Ly-alpha emission - The interstellar wind sourceIUE observation of Uranian emissions in hydrogen Lyman alpha (H Ly-alpha) over the past four years have recently been summarized by Clarke et al. (1985). Over this time period they find an average H Ly-alpha brightness of 1260 R which they estimate is composed of 200 R of solar scattered radiation and 1060 R from a collisional source. A third component, not considered by previous authors, is the reflection of H Ly-alpha emissions from the interstellar wind. Hydrogen in the interstellar wind forms an extended source of H Ly-alpha whose importance relative to the solar flux increases with distance from the sun. The present paper demonstrates that scattering of interstellar H Ly-alpha is more important than scattering of solar H Ly-alpha for reasonable values of H column abundance and, in fact, may make up 10-40 percent of the observed signal. Large H column abundances are still required to explain the H Ly-alpha brightness solely on the basis of resonant scattering; therefore it is likely that the emissions are due in part to collisional sources and in part to the scattering of interstellar H Ly-alpha with solar scattering playing a minor role.
Document ID
19860042239
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Yelle, R. V.
(Arizona Univ. Tucson, AZ, United States)
Sandel, B. R.
(Arizona, University Tucson, United States)
Date Acquired
August 12, 2013
Publication Date
February 1, 1986
Publication Information
Publication: Geophysical Research Letters
Volume: 13
ISSN: 0094-8276
Subject Category
Astrophysics
Accession Number
86A26977
Funding Number(s)
CONTRACT_GRANT: NAGW-610
Distribution Limits
Public
Copyright
Other

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