Evaporation and condensation of giant interstellar clouds in a hot-gas environment |
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| Authors: | Gerhard Hensler Wolfgang Vieser |
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| Institution: | (1) Institut für Theoretische Physik und Astrophysik, University of Kiel, D-24098 Kiel, Germany |
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| Abstract: | Gas phases of the interstellar medium (ISM) coexist locally, penetrate each other and mix by means of dynamical and plasmaphysical
processes. E.g. heat conduction from the hot to the cooler gas leads to energy and mass exchange between the gas phases. Analytical
solutions exist under which evaporation of cloudy material or condensation of hot gas onto the clouds' surface dominate. Since
these results are derived for stationary and static conditions and under ideal assumptions, they do not necessarily hold for
a dynamical ISM. On the other hand, the mass and energy exchange between the gas phases is of great importance for the energy
budget of the ISM and by this influences the evolution of galaxies. This led us to investigate the evolution of interstellar
clouds in a hot gas by means of numerical simulations. At first, we compare static models with the analytical results and
found that interstellar clouds with parameters requiring analytically evaporation are, in contrast, accreting surrounding
material if self-gravitation and cooling are implied. For the more realistic case, where clouds are embedded in a streaming
hot gas, the models show that Kelvin-Helmholtz instability which leads to the disruption of the clouds is suppressed by heat
conduction so that the clouds are stabilized to survive.
This revised version was published online in September 2006 with corrections to the Cover Date. |
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| Keywords: | interstellar medium heat conduction hydrodynamics |
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