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Recombination line intensities for hydrogenic ions. III - Effects of finite optical depth and dustThe effect on the recombination spectrum of hydrogen arising from: (1) finite optical thickness in the Lyman lines; (2) the overlapping of Lyman lines near the series limit; (3) the absorption of Lyman lines by dust or photoionization, and (4) the long-wave radiation emitted by dust is examined. Full account is taken of electron and heavy particle collisions in redistributing energy and angular momentum. It is seen that each of these deviations from the classical Case B leads to observable effects, and that dust influences the recombination spectrum in characteristic ways that may make possible new observational constraints on dust properties in nebulosities. On the basis of these calculations it is believed that the uncertainty in the determination of the helium-to-hydrogen abundance ratio in the universe may be larger than currently claimed.
Document ID
19920041836
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Hummer, D. G.
(Joint Institute for Laboratory Astrophysics; NIST Boulder, CO, United States)
Storey, P. J.
(University College London, United Kingdom)
Date Acquired
August 15, 2013
Publication Date
January 15, 1992
Publication Information
Publication: Royal Astronomical Society, Monthly Notices
Volume: 254
ISSN: 0035-8711
Subject Category
Astrophysics
Accession Number
92A24460
Funding Number(s)
CONTRACT_GRANT: NAGW-766
Distribution Limits
Public
Copyright
Other

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