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Paper: Can Thermal Instability Grow behind a Shock Wave in HI and Molecular Clouds?
Volume: 476, New Trends in Radio Astronomy in the ALMA Era
Page: 335
Authors: Aota, T.; Inoue, T.; Aikawa, Y.
Abstract: We performed one-dimensional hydrodynamic simulations with detailed cooling, heating and chemical processes to examine the thermal stability of shocked gas in CNM and molecular clouds. We find that both CNM and molecular clouds can be thermally unstable in the cooling layer behind the shock wave. We have calculated the e-folding number of the thermal instability to estimate the amplification of the density fluctuation in the shocked gas. Density perturbations in the CNM grow by a factor of exp(5) ≃ 150, whereas the perturbations in the molecular clouds grow only by a factor of a few behind a high Mach number shock. The amplification factor is larger in the shock with lower densities and higher velocities in clouds. Although the amplification factor per shock is relatively small in molecular clouds, thermal instability by multiple shocks can be an important mechanism to form fine structures in molecular clouds.
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