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Interstellar cloud shapes - A minimum-hypothesis account involving a purely gravitational effectThe effect produced by the anisotropic gravitational field on the shape of a nonspherical, self-gravitating interstellar cloud is examined. The projected axial ratios observed for molecular clouds can be accounted for if clouds are not generally in a state of strict dynamical equilibrium. For clouds having spectral line widths dominated by supersonic turbulent motions, this purely gravitational effect predicts a mean true axial ratio q about 0.3 for both oblate and prolate cloud geometries. Clouds having p less than about 0.3 are likely to be prolate and quite elongated. The observational data on molecular cloud cores, which have essentially thermal line widths, can be fitted equally well to either oblate or prolate spheroids having q between 0.1 and 0.4 with q about 0.2 providing the best match: highly elongated cores are again more likely to be prolate. While other processes certainly operate throughout the Galaxy to influence cloud shape, it appears plausible that at least some clouds may be shaped principally by their anisotropic gravitational field.
Document ID
19930035777
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Fleck, Robert C., Jr.
(Queen Mary and Westfield College London, United Kingdom)
Date Acquired
August 15, 2013
Publication Date
December 10, 1992
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 401
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
93A19774
Distribution Limits
Public
Copyright
Other

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