Changes between Version 4 and Version 5 of u/erica/SFconcepts


Ignore:
Timestamp:
03/11/15 13:57:21 (10 years ago)
Author:
Erica Kaminski
Comment:

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  • u/erica/SFconcepts

    v4 v5  
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    12 '''Warm nuclear medium''' - Traced by 21 cm line of hydrogen (emitted by neutral hydrogen atom), ~800 K, is intercloud gas. Has a very low density (~0.5 / cm^3^), but a substantial filling fraction (30-60%).
     12'''Warm nuclear medium''' - Traced by 21 cm line of hydrogen (emitted by neutral hydrogen atom), ~800 K, is intercloud gas. Has a very low density (~0.5 / cm^3^), but a substantial filling fraction (30-60%). It is dominate at low pressures.
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    15 '''Cold nuclear medium''' - Also traced by 21 cm line of hydrogen. Is about 100 K and organized in diffuse HI clouds. Occupies about 1-4% the total volume, and on average a cloud is about 10 pc across and has a density of 50 / cm^3^.
     15'''Cold nuclear medium''' - Also traced by 21 cm line of hydrogen. Is about 100 K and organized in diffuse HI clouds. Occupies about 1-4% the total volume, and on average a cloud is about 10 pc across and has a density of 50 / cm^3^. It is dominate at high pressures.
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    17 The concept of warm and cold nuclear medium as equilibrium phases of the ISM were introduced in the paper by [http://adsabs.harvard.edu/abs/1969ApJ...155L.149F Field, Goldsmith, and Habing (1969)]. Afterward, an additional phase was introduced into the mix, the hot ionized medium by [http://adsabs.harvard.edu/abs/1977ApJ...218..148M McKee and Ostriker (1977)]. There are other components in the ISM such as dust, cosmic rays, for example. The exact concentration, filling fractions, and dynamic vs. equilibrium state of the material is not well understood, however, as [http://adsabs.harvard.edu/abs/1995ApJ...455..536P Vazquez-Semadeni, Passot, Pouquet (1994)] point out.
     17The concept of warm and cold nuclear medium as equilibrium phases of the ISM were introduced in the paper by [http://adsabs.harvard.edu/abs/1969ApJ...155L.149F Field, Goldsmith, and Habing (1969)]. The concept is motivated by terrestrial water at sea level. At that equilibrium pressure, a phase transition occurs between water liquid and water vapor. It is though that HI behaves similarly.
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     19Afterward, an additional phase was introduced into the mix, the hot ionized medium by [http://adsabs.harvard.edu/abs/1977ApJ...218..148M McKee and Ostriker (1977)]. There are other components in the ISM such as dust, cosmic rays, for example. The exact concentration, filling fractions, and dynamic vs. equilibrium state of the material is not well understood, however, as [http://adsabs.harvard.edu/abs/1995ApJ...455..536P Vazquez-Semadeni, Passot, Pouquet (1994)] point out.