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A search for interplanetary He II, 304-A emissionA survey of a region of the sky around the antisolar direction in the earth's shadow was surveyed by the extreme ultraviolet telescope on the Apollo-Soyuz mission, whose 170-620 A channel is primarily sensitive to the H II, 304-A and He I, 584-A resonance. A sharp decrease in intensity was found as the line of sight sweeps into the shadow region. Once the line of sight is contained within the shadow, a residual signal above instrumental background was observed that was independent of view direction and spacecraft position. An upper limit at the 2sigma confidence level to a possible He II, 304-A component that can escape detection by the instrument corresponds to 0.002 R, or to a column density of 10 to the 9th ions/sq cm scattering at line center. The brightest possible sources for such emissions are multiple scattering from plasmaspheric He(+) in the shadow and scattering from He(+) created by the photoionization of the interstellar wind neutral helium.
Document ID
19820029726
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Paresce, F.
(California, University Berkeley, CA, United States)
Fahr, H.
(California Univ. Berkeley, CA, United States)
Lay, G.
(Bonn, Universitaet Bonn, Germany)
Date Acquired
August 10, 2013
Publication Date
November 1, 1981
Publication Information
Publication: Journal of Geophysical Research
Volume: 86
Subject Category
Astrophysics
Accession Number
82A13261
Funding Number(s)
CONTRACT_GRANT: NGR-05-003-450
CONTRACT_GRANT: NAS9-13799
Distribution Limits
Public
Copyright
Other

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