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S. Stevenson (Wesleyan University), D. Chappell (University of La Verne), J. Scalo (University of Texas at Austin)
We develop a set of parametric algebraic equations describing the shape, velocity field, and surface density of the interface layer formed between two colliding thin shells. The solutions are exact in the limit that fluid advection and momentum conservation of the shells dominate both internal pressure effects and driving forces. Thus, they are most appropriate to interactions between shells when the zero-pressure snowplow assumption is valid. We briefly examine the gravitational instability of the interaction layer and compare the resulting growth rate with the growth rate in the individual shells.
We also examine global statistics of pair-wise interactions in a system of expanding shells using Monte-Carlo simulations. The simulations may be relevant to either interacting superbubbles driven by cluster winds or to the interaction of smaller-scale shells driven by protostellar winds. Results include the mass spectra of interaction structures, velocity histograms, and dependence of the shell collision rate on both the porosity of the interstellar medium and the morphology of the interface layer.
The author(s) of this abstract have provided an email address for comments about the abstract: chappell@ulv.edu