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Radical formation, chemical processing, and explosion of interstellar grainsThe ultraviolet radiation in interstellar space is shown to create a sufficient steady-state density of free radicals in the grain mantle material consisting of oxygen, carbon, nitrogen, and hydrogen to satisfy the critical condition for initiation of chain reactions. The criterion for minimum critical particle size for maintaining the chain reaction is of the order of the larger grain sizes in a distribution satisfying the average extinction and polarization measures. The triggering of the explosion of interstellar grains leading to the ejection of complex interstellar molecules is shown to be most probable where the grains are largest and where radiation is suddenly introduced; i.e., in regions of new star formation. Similar conditions prevail at the boundaries between very dark clouds and H II regions. When the energy released by the chemical activity of the free radicals is inadequate to explode the grain, the resulting mantle material must consist of extremely large organic molecules which are much more resistant to the hostile environment of H II regions than the classical dirty-ice mantles made up of water, methane, and ammonia.
Document ID
19760038761
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Greenberg, J. M.
Date Acquired
August 8, 2013
Publication Date
January 1, 1976
Subject Category
Astrophysics
Accession Number
76A21727
Funding Number(s)
CONTRACT_GRANT: NGR-33-011-043
Distribution Limits
Public
Copyright
Other

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