Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004aspc..323..109w&link_type=abstract
Star Formation in the Interstellar Medium: In Honor of David Hollenbach, Chris McKee and Frank Shu, ASP Conference Proceedings,
Astronomy and Astrophysics
Astronomy
Scientific paper
Much of the interstellar medium in disk galaxies is in the form of neutral atomic hydrogen, H I. This gas can be in thermal equilibrium at relatively low temperatures, T⪉ 300 K (the cold neutral medium, or CNM) or at temperatures somewhat less than 104 K (the warm neutral medium, or WNM). These two phases can coexist over a narrow range of pressures, Pmin≤ P≤ Pmax. We determine Pmin and Pmax in the plane of the Galaxy as a function of Galactocentric radius R using recent determinations of the gas heating rate and the gas phase abundances of interstellar gas. Over most of the disk of the Galaxy, the H I must be in two phases: the weight of the H I in the gravitational potential of the Galaxy is large enough to generate thermal pressures exceeding Pmin, so that turbulent pressure fluctuations can produce cold gas that is thermally stable; however, the mean density of the H I is too low for the gas to be all CNM. Our models predict the presence of CNM gas to R≃ 16-18 kpc, somewhat farther than previous estimates. Turbulent heating may force a fraction of WNM gas to be in the thermally unstable regime.
No associations
LandOfFree
The Neutral Atomic Phases in the Galactic Disk does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Neutral Atomic Phases in the Galactic Disk, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Neutral Atomic Phases in the Galactic Disk will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1022475