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Cold atomic gas in the inner GalaxyA new set of 21 cm H I absorption spectra were obtained toward 21 compact continuum sources in the Galactic plane is presented. The 21 cm line velocity-averaged absorption coefficient as a function of Galactocentric distance is calculated. The result for distances within 2 kpc of the sun agrees with the local value found from absorption toward pulsars of 5-7 km/s/kpc. Overall, the absorption coefficient decreases to about half of its local value inside a Galactocentric radius of about 4 kpc. This decrease is shown to be primarily due to an increase in the mean line-of-sight distance between absorbing atomic clouds. Thus, the cool phase of the atomic gas is less abundant in the inner Galaxy than at the solar circle. The absorption spectra are similar in appearance to existing (C-12)O spectra. The spectral regions which show H I absorption also show CO emission.
Document ID
19890043800
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Garwood, Robert W.
(Minnesota Univ. Minneapolis, MN, United States)
Dickey, John M.
(Minnesota, University Minneapolis, United States)
Date Acquired
August 14, 2013
Publication Date
March 15, 1989
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 338
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
89A31171
Funding Number(s)
CONTRACT_GRANT: NSF AST-82-16879
CONTRACT_GRANT: JPL-957243
Distribution Limits
Public
Copyright
Other

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