Acceleration of a spherical neutral shell produced by an ionization-shock front in an inhomogeneous interstellar medium

We numerically model the formation and acceleration of a neutral gas shell as an ionization-shock front propagates in a spherical cloud by taking into account the photoionization and radiative heating of the gas, the spectral radiative transfer. We suggest and implement an approximation of the cooli...

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Bibliographic Details
Published in:Astronomy letters 2009-03, Vol.35 (3), p.167-174
Main Authors: Kotova, G. Yu, Krasnobaev, K. V.
Format: Article
Language:English
Subjects:
Astronomy
Astrophysics
Astrophysics and Astroparticles
Average velocity
Cosmology
Gases
Ionization
Ions
Observations and Techniques
Physics
Physics and Astronomy
Radiative transfer
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Summary:We numerically model the formation and acceleration of a neutral gas shell as an ionization-shock front propagates in a spherical cloud by taking into account the photoionization and radiative heating of the gas, the spectral radiative transfer. We suggest and implement an approximation of the cooling function that allows calculations to be performed in a wide range of gas ionization fractions and temperatures. The total mass, average velocity, and thickness of the shell have been determined. The results are compared with approximate formulas known in the literature. Based on the parameters of the shell found, we estimate its acceleration, characteristic scales, and the growth times of unstable perturbations. We analyze the influence of the cloud particle density, cloud radius, stellar temperature, and radiation spectrum on the integrated characteristics of the neutral gas in the layer between the ionization and shock fronts. The distribution of matter in the shell and its thickness are shown to differ significantly from those used in approximate models.
ISSN:1063-7737
1562-6873
DOI:10.1134/S1063773709030037