Radiation hydrodynamic instability in a plane-parallel, super-Eddington atmosphere: a mechanism for clump formation

Shun Takeuchi, Ken Ohsuga, Shin Mineshige

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37 Citations (Scopus)

Abstract

In order to understand the physical processes underlying clump formation in outflow from supercritical accretion flow, we performed two-dimensional radiation hydrodynamic (RHD) simulations. We focus our discussion on the nature of RHD instability in marginally optically thick, plane-parallel, super-Eddington atmosphere. Initially we set two-layered atmosphere with a density contrast of 100 exposed to strong, upward continuum-radiation force; the lower layer is denser than the upper one, condition for an RHD instability. We assume non-zero but negligible gravitational force, compared with the radiation force. We find that short wavelength perturbations first grow, followed by growth of longer wavelength patterns, which lead to the formation of clumpy structure. The typical size of clumps (clouds) corresponds to about one optical depth. An anti-correlation between the radiation pressure and the gas pressure is confirmed: this anti-correlation provides a damping mechanism of longer wavelength perturbations than the typical clump size. Matter and radiation energy densities are correlated. These features are exactly what we found in the radiation-magnetohydrodynamic (radiation-MHD) simulations of supercritical outflow.
Original languageEnglish
Article number48
Pages (from-to)1-9
Number of pages9
JournalPublications of the Astronomical Society of Japan
Volume66
Issue number2
DOIs
Publication statusPublished - 1 Apr 2014
Externally publishedYes

Keywords

  • accretion, accretion disks
  • instabilities
  • radiative transfer
  • stars: winds, outflows
  • ISM: clouds

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