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The velocity distribution of interstellar gas observed in strong UV absorption linesObservations of three strong interstellar UV absorption lines of N I (1199 A), N II (1083 A), and Si III (1206 A) in 47 stars of widely varying distance and a variety of spectral types are analyzed to obtain a velocity distribution function for the interstellar gas. A technique based on the maximum and minimum velocities observed along a line of sight is adopted because of heavy line blending, and results are discussed for both power-law and exponential distribution functions. The expected distribution of radiative-phase supernova remnants (SNRs) in the interstellar medium is calculated as a function of SNR birthrate and of the interstellar density in which they evolve. The results are combined with observed distance estimates, and it is shown that an interstellar density in excess of 0.1 per cu cm would be required to keep the SNRs sufficiently confined so that their cross sections are consistent with the observed number of components. The alternative possibility is considered that SNRs do not enter the radiative phase before escaping from the Galaxy or colliding with neighboring remnants.
Document ID
19780061632
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Cowie, L. L.
(Princeton Univ. Observatory NJ, United States)
York, D. G.
(Princeton University New Observatory, Princeton, N.J., United States)
Date Acquired
August 9, 2013
Publication Date
August 1, 1978
Publication Information
Publication: Astrophysical Journal
Subject Category
Astrophysics
Accession Number
78A45541
Funding Number(s)
CONTRACT_GRANT: NAS5-23576
CONTRACT_GRANT: NGL-31-001-007
Distribution Limits
Public
Copyright
Other

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