Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-12-06
Astrophys.SpaceSci.284:819-832,2003
Astronomy and Astrophysics
Astrophysics
14 pages, 1 figure, in "The Evolution of Galaxies. III - From simple approaches to self-consistent models", proceedings of the
Scientific paper
10.1023/A:1024054129337
Gas processes affecting star formation are reviewed with an emphasis on gravitational and magnetic instabilities as a source of turbulence. Gravitational instabilities are pervasive in a multi-phase medium, even for sub-threshold column densities, suggesting that only an ISM with a pure-warm phase can stop star formation. The instabilities generate turbulence, and this turbulence influences the structure and timing of star formation through its effect on the gas distribution and density. The final trigger for star formation is usually direct compression by another star or cluster. The star formation rate is apparently independent of the detailed mechanisms for star formation, and determined primarily by the total mass of gas in a dense form. If the density distribution function is a log-normal, as suggested by turbulence simulations, then this dense gas mass can be calculated and the star formation rate determined from first principles. The results suggest that only 10**(-4) of the ISM mass actively participates in the star formation process and that this fraction does so because its density is larger than 10**5 cm-3, at which point several key processes affecting dynamical equilibrium begin to break down.
No associations
LandOfFree
Gas Phase Processes Affecting Galactic Evolution 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 Gas Phase Processes Affecting Galactic Evolution, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas Phase Processes Affecting Galactic Evolution will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-86314