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Globular cluster formation - The fossil recordProperties of globular clusters which have remained unchanged since their formation are used to infer the internal pressures, cooling times, and dynamical times of the protocluster clouds immediately prior to the onset of star formation. For all globular clusters examined, it is found that the cooling times are much less than the dynamical times, implying that the protoclusters must have been maintained in thermal equilibrium by external heat sources, with fluxes consistent with those found in previous work, and giving the observed rho-T relation. Self-gravitating clouds cannot be stably heated, so that the Jeans mass forms an upper limit to the cluster masses. The observed dependence of protocluster pressure upon galactocentric position implies that the protocluster clouds were in hydrostatic equilibrium after their formation. The pressure dependence is well fitted by that expected for a quasi-statically evolving background hot gas, shock heated to its virial temperature. The observations and inferences are combined with previous theoretical work to construct a picture of globular cluster formation.
Document ID
19930032129
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Murray, Stephen D.
(Cambridge Univ. Inst. of Astronomy, United Kingdom)
Lin, Douglas N. C.
(Queen Mary and Westfield College London, United Kingdom)
Date Acquired
August 15, 2013
Publication Date
November 20, 1992
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 400
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
93A16126
Funding Number(s)
CONTRACT_GRANT: NSF AST-89-14173
CONTRACT_GRANT: NSF INT-90-24676
Distribution Limits
Public
Copyright
Other

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