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| Paper: |
The three phase model of the interstellar medium - Where does it stand now? |
| Volume: |
12, The Evolution of the Interstellar Medium |
| Page: |
3 |
| Authors: |
McKee, Christopher F. |
| Abstract: |
The structure of the interstellar medium (ISM) is governed by energy injection by stars. Both warm neutral gas and ionized gas extend well above the Galactic plane; the weight of this gas is supported primarily by turbulent motions. In the absence of this turbulence, the scale height of the ISM would be substantially smaller than observed. Interstellar turbulence is generated primarily by supernovae: random supernovae generate a three-phase medium in which hot, low-density gas surrounds warm and cold clouds and determines their pressure; supernovae in large associations of massive stars generate superbubbles, in which the hot gas is dominant. The observed level of turbulence is shown to require a large filling factor for supernova remnants, supporting the three-phase model of the ISM. The observational status of the three phase model is reviewed, with a summary of both its successes and its problems. |
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