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On the linear analysis of unstable radiative shocks

Publication Type : Journal Article

Publisher : MNRAS

Source : Monthly Notices of the Royal Astronomical Society

Url :

Campus : Amritapuri

School : School of Arts and Sciences

Year : 2005

Abstract : We study the stability properties of strong hydrodynamic shocks and their associated radiative cooling layers. We explore a range of conditions which covers both molecular and atomic gas impacting against a rigid wall. Through a linear analysis employing a cooling function of the form Λ∝ρβTα and a specific heat ratio of γ, we determine the overstability regime in the parameter space consisting of α, β and γ. In general, if α is sufficiently low, the fundamental mode leads to long-wavelength growing oscillations. For the fundamental mode, we find that values of γ corresponding to molecular hydrodynamics lead to a significantly restricted instability range for α in comparison with the shocks in a monatomic medium. The conditions for the growth of higher-order modes, however, are relatively unchanged. This predicts that certain molecular shocks are prone to displaying signatures of small-scale rapid variability. Dissociative shocks, however, can be subject to a large-scale overstability if subsequent molecule formation in the cooling layer abruptly increases the cooling rate. In contrast to the dynamical rippling overstability, the cooling overstability is suppressed for a sufficiently low specific heat ratio.

Cite this Research Publication : B. Ramachandran & Michael D. Smith, “On the linear analysis of unstable radiative shocks”,MNRAS, 357, 707, 2005

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