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Nonlinear Dynamics of Ionization Fronts in HII Regions

  • Akira Mizuta
  • Jave O. Kane
  • Marc W. Pound
  • Bruce A. Remington
  • Dmitri D. Ryutov
  • Hideaki Takabe
Conference paper

Abstract

Hydrodynamic instability of an accelerating ionization front (IF) is investigated with 2D hydrodynamic simulations, including absorption of incident photoionizing photons, recombination in the HII region, and radiative molecular cooling. When the amplitude of the perturbation is large enough, nonlinear dynamics of the IF triggered by the separation of the IF from the cloud surface is observed. This causes the second harmonic of the imposed perturbation to appear on the cloud surfaces, whereas the perturbation in density of ablated gas in the HII region remains largely single mode. This mismatch of modes between the IF and the density perturbation in the HII region prevents the strong stabilization effect seen in the linear regime. Large growth of the perturbation caused by Rayleigh-Taylor-like instability is observed late in time.

Keywords

HII regions ISM: molecules ISM: kinematics and dynamics Hydrodynamics Instabilities Methods: numerical ISM individual object: M16 

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Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Akira Mizuta
    • 1
  • Jave O. Kane
    • 2
  • Marc W. Pound
    • 3
  • Bruce A. Remington
    • 2
  • Dmitri D. Ryutov
    • 2
  • Hideaki Takabe
    • 4
  1. 1.Max-Planck-Institute für AstrophysikGarchingGermany
  2. 2.Lawrence Livermore National LaboratoryUniversity of CaliforniaLivermoreUSA
  3. 3.Department of AstronomyUniversity of MarylandCollege ParkUSA
  4. 4.Institute of Laser EngineeringOsaka UniversitySuita, OsakaJapan

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