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===Globular Cluster Formation During Galaxy-Galaxy Collisions===

The manuscript presented immediately below presents an hypothesis regarding globular cluster formation that came to me as a EUREKA! moment one day (in the mid-to-late 1990s) while I was attending a Physics &amp; Astronomy departmental colloquium at LSU.  The colloquium speaker was, as I recall, someone from U. C. Berkeley with experimental space sciences expertise; and the topic of the colloquium was Galactic cosmic rays &hellip; [[DissertationTopics/GCFormation|<more>]]  

As a matter of course during his presentation, the colloquium speaker reminded the audience &#8212; and me, in particular &#8212; that, in our Galaxy, the dense, cold "protostellar" cores of molecular clouds are coupled to the interstellar magnetic field (only) because the gas is partially ionized by Galactic cosmic rays.  Furthermore, the Galaxy's charged-particle cosmic-ray flux is highest near the mid-plane of the Galaxy's disk because the cosmic rays are trapped by the disk's relatively ordered, large-scale interstellar magnetic field.  All of a sudden, it occurred to me that, if our Galaxy were to collide with another galaxy &hellip; 
* Its disk and, along with it, the interstellar magnetic field would very likely become much less organized;
* Cosmic rays would no longer be well confined to the disk and  &#8212; as a consequence of streaming out of the disk at relativistic speeds &#8212; the flux of cosmic rays would fairly rapidly drop within the Galaxy's molecular clouds;
* The dense, protostellar cores of molecular clouds would fairly rapidly decouple from the magnetic field because the cores would no longer be sufficiently ionized.
EUREKA!  This would create an environment highly conducive to rapid star formation, perhaps throughout an entire giant molecular cloud (GMC) complex.  This would trigger a rapid burst of star formation and, perhaps, a transformation of the GMC into a massive, ''bound'' star cluster.  It is this idea and accompanying reasoning that is fleshed out in the paper that I wrote in 2000 (while on sabbatical leave at Caltech) in collaboration with Nick Scoville and Andrew Strong:

* Original manuscript (submitted to ''The Astrophysical Journal'' in June, 2000): [http://www.vistrails.org/images/Ms_globularClusters.pdf J. E. Tohline, N. Z. Scoville, &amp; A. W. Strong (2000)]

This paper was never published because the journal referee (see [[DissertationTopics/GCFormation#RefereeReport|accompanying material]]) requested a more extensive demonstration of the proposed model's viability, which I considered to be well beyond the scope and essential purpose of this paper.  I remain firmly convinced that the idea has a great deal of merit.  I offer this original manuscript as a foundation on which an appropriately qualified graduate student might build a more extensive demonstration of the viability of this proposed mechanism for globular cluster formation.