Pillars, Jets, and Dynamical Features
Matthias Gritschneder, KIAA, Peking University
We present iVINE, a new implementation ionizing radiation in the tree-SPH code VINE. The UV-radiation is propagated into the simulated domain under the assumption of plane-parallel infall. To simplify the ray-tracing we use the 'on-the-spot'-approximation. With this code we study of the UV-radiation of massive stars on the turbulent interstellar medium (ISM). This parameter study includes different levels and driving scales of the turbulence, different ionizing flux as well as different temperatures and densities of the cold gas. We find a clear correlation between the initial state of the turbulent cold cloud and the final morphology and physical properties of the structures adjacent to the HII region. From the simulations we are able to derive a criterion for the formation of pillar-like structures and thus the formation of cores and stars. Gravitational collapse occurs regularly on the tips of the structures. We also derive column densities and velocity profiles of our simulations and find these to be in very good agreement with the observations of trunks and cores. Furthermore the ionization is able to drive the turbulence in the cold gas more efficiently than previously estimated. In addition we compare the results of our simulations with the 3D photoionization code MOCASSIN to determine the accuracy of iVINE. From this comparison we are able to derive a new simplified prescription to include the effects of the diffuse radiation field into iVINE.
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