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Record Details

Record 70 of 9712
Recombination line intensities for hydrogenic ions. III - Effects of finite optical depth and dust
Author and Affiliation:
Hummer, D. G.(Joint Institute for Laboratory Astrophysics, NIST)
Storey, P. J.(University College, London, United Kingdom)
Abstract: The 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.
Publication Date: Jan 15, 1992
Document ID:
19920041836
(Acquired Nov 22, 1995)
Accession Number: 92A24460
Subject Category: ASTROPHYSICS
Document Type: Journal Article
Publication Information: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 254; 277-290
Publisher Information: United Kingdom
Contract/Grant/Task Num: NAGW-766
Financial Sponsor: NASA; United States
Organization Source: NASA; Washington, DC, United States
Description: 14p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: COMPUTATIONAL ASTROPHYSICS; COSMIC DUST; HYDROGEN IONS; LINE SPECTRA; RECOMBINATION REACTIONS; BALMER SERIES; INTERSTELLAR MATTER; LYMAN ALPHA RADIATION; LYMAN BETA RADIATION; PHOTOIONIZATION
Imprint And Other Notes: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711), vol. 254, Jan. 15, 1992, p. 277-290. Research supported by SERC.
Miscellaneous Notes: Research supported by SERC
Availability Source: Other Sources
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