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Open Access Publications from the University of California

Production of Elephant Trunks in HII Regions by Radiation-Magnetohydrodynamic Instabilities

  • Author(s): Fierlinger, Katharina
  • Krumholz, Mark
  • Grittschneder, Matthias
  • et al.
Abstract

Recent SPH and grid code simulations showed, that ionizing radiation can amplify overdensities in turbulent molecular clouds and produce molecular pillars. The relevance of magnetic fields for the structure and stability of molecular clouds is still under discussion. We investigate whether an ionization front hitting a medium with small distortions of the magnetic field can produce the observed pillar-like structures in star forming regions (e.g. Eagle Nebula). Numerical MHD simulations with the Athena 2.0 grid code with ionizing radiation were performed. It turns out that the ionizing radiation drives a shock wave into the cold magnetized cloud and amplifies overdensities seeded by Alfven waves. Alfven waves can be seeds for molecular pillars. However, the magnetic field in structures created by Alfven waves makes these regions hostile to star formation.

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