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Gravitational instability of a composite system

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The problem of instability arising in a composite system consisting of an infinitely conducting hydromagnetic fluid interacting through gravitational forces with one or more than one neutral gas, is investigated, allowing for a possible relative streaming between the component fluids. Instability criteria are derived for special cases of a two-component (static or relatively streaming) system and for a three-component system consisting of two gases contra-streaming in the presence of a stationary background gas. It is found that for a static system only one unstable mode exists for wave numbers less than a critical value given by the square root of the sum of the squares of the Jeans's wave numbers for individual gases. However, for a configuration, where components are endured with characteristic streaming speeds, there are present simultaneously more than one unstable modes.

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Bora, M.P., Talwar, S.P. Gravitational instability of a composite system. Astrophys Space Sci 184, 193–203 (1991).

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  • Static System
  • Gravitational Force
  • Composite System
  • Stationary Background
  • Unstable Mode