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Relationship between oscillatory thermal instability and dynamical thin-shell overstability of radiative shocks
1Space Science Division Code 7674L, Naval Research Laboratory, Washington, DC 20375, USA. jlaming@ssd5.nrl.navy.mil
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|December 17, 2004
Summary
Radiative cooling in astrophysical shocks is stable to certain instabilities, contrary to previous models. This study clarifies the complex interplay between cooling laws and shock dynamics, offering new insights into shock behavior.
Area of Science:
- Astrophysics
- Plasma Physics
- Computational Fluid Dynamics
Background:
- Radiative shocks are crucial in astrophysical phenomena.
- Previous models suggested oscillatory instabilities in cooling gas.
- Understanding shock stability is key to astrophysical modeling.
Purpose of the Study:
- To analytically investigate radiative cooling behind radiative shocks.
- To determine the stability of specific cooling laws (Lambda proportional to T^alpha) against dynamical thin-shell overstability.
- To reconcile previous findings on shock instabilities.
Main Methods:
- Analytic treatment of radiative cooling.
- Utilizing solutions from Chevalier and Imamura.
- Analysis within the steady-state radiative shock approximation.
Main Results:
- Cooling laws causing oscillatory instability (Chevalier and Imamura) are stable to dynamical thin-shell overstability in gamma=5/3 gas.
- Conversely, dynamical thin-shell overstability is stable to these cooling laws.
- Fundamental features of observed dynamical overstability (Grun et al.) are explained.
Conclusions:
- The study provides a stable framework for radiative shock modeling.
- It clarifies the relationship between cooling laws and shock dynamics.
- Offers a new perspective on astrophysical shock stability.