The fragmentation of expanding shells I: Limitations of the thin--shell approximation

Abstract

We investigate the gravitational fragmentation of expanding shells in the context of the linear thin--shell analysis. We make use of two very different numerical schemes; the FLASH Adaptive Mesh Refinement code and a version of the Benz Smoothed Particle Hydrodynamics code. We find that the agreement between the two codes is excellent. We use our numerical results to test the thin--shell approximation and we find that the external pressure applied to the shell has a strong effect on the fragmentation process. In cases where shells are not pressure--confined, the shells thicken as they expand and hydrodynamic flows perpendicular to the plane of the shell suppress fragmentation at short wavelengths. If the shells are pressure--confined internally and externally, so that their thickness remains approximately constant during their expansion, the agreement with the analytical solution is better.

13 pages, 10 figures, accepted by MNRAS

References in corpus (10)

• A Triple Main Sequence in the Globular Cluster NGC 2808
• A comparative study of disc-planet interaction
• Triggered massive-star formation on the borders of Galactic HII regions. II. Evidence for the collect and collapse process around RCW 79
• Ionisation-induced star formation I: The collect and collapse model
• Triggered massive-star formation on the borders of Galactic HII regions. IV- Star formation at the periphery of Sh2-212
• HI shells in the outer Milky Way
• The shape of the initial cluster mass function: what it tells us about the local star formation efficiency
• Protostellar collapse: A comparison between SPH and AMR calculations
• Triggered massive-star formation on the borders of Galactic HII regions. III. Star formation at the periphery of Sh2-219
• Self-enrichment in globular clusters. I. An analytic approach

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