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Paper: Interaction of Shocks with Interstellar Clouds as a Pre-stage to Star Formation
Volume: 474, Numerical Modeling of Space Plasma Flows (ASTRONUM2012)
Page: 72
Authors: Johansson, E. P. G.; Ziegler, U.
Abstract: Shock-cloud interactions should be commonplace throughout the interstellar medium and are believed to be an important triggering mechanism for star formation. We have used the NIRVANA code to study the radiative interaction between a small interstellar cloud and a shock wave as a pre-stage to star formation. The setup is a spherical cloud with radius 1.5 pc, density 17 cm-3 and 100 times denser than the background, that is struck by a planar Ms = 30 shock. The MHD simulations are in 3D with radiative heating and cooling as well as anisotropic heat conduction at a resolution of 100 cells per cloud radius using AMR. To our knowledge, this is the first study to simultaneously combine these physical effects in 3D. Our simulations do reproduce dense, cold fragments similar to those of Mellema, Kurk, & Röttgering (2002), Fragile et al. (2004). We do not reach the conditions for Jeans instability but we do observe lasting cloud density increases of typically a factor of ∼103. In our set of simulations, the configuration that produces the most dense condensations is that of a weak but non-zero initial magnetic field (β = 103) perpendicular to the shock normal.
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