Journal ArticleDOI
Molecular cooling and thermal balance of dense interstellar clouds
TLDR
The cooling produced by line emission from a variety of molecular and atomic species, including those observed as well as theoretically expected in dense interstellar clouds, was analyzed in detail in this article, and the contribution of a number of gas heating machanisms which may be present in interstellar clouds including heating by cosmic rays, H/sub 2/ formation, gravitational collapse, and magnetic ion-neutral slip heating.Abstract:
We analyze in detail the cooling produced by line emission from a variety of molecular and atomic species, including those observed as well as theoretically expected in dense interstellar clouds. At molecular hydrogen densities less than 3 x 10/sup 4/ cm/sup -3/ and kinetic temperatures between 10 K and 40 K, /sup 12/CO is the dominant coolant. At n (H/sub 2/) =3 x 10/sup -3/, however, C c, O/sub 2/, and the rarer isotopic species of carbon monoxide together contribute half of the total cooling. As n (H/sub 2/) is increased beyond 3 x 10/sup 4/ cm/sup -3/, a large number of species including water, hydrides, molecular ions, and less abundant diatomic molecules collectively dominate the cooling. The cooling per H/sub 2/ molecule, ..lambda../n (H/sub 2/), is only very weakly density-dependent for n (H/sub 2/) greater than a few times 10/sup 2/ cm/sup -3/. At a density of 4 x 10/sup 3/ cm/sup -3/, ..lambda..=2.6 x 10/sup -26/T/sub kin//sup 2.2/ ergs cm/sup -3/ s/sup -1/. The rate of energy transfer by dust-gas collisions results in infrared emission by dust grains being a significant coolant for the gas only for n (H/sub 2/) >1.5 x 10/sup 4/ cm/sup -3/. We evaluatemore » the contribution of a number of gas heating machanisms which may be present in interstellar clouds including heating by cosmic rays, H/sub 2/ formation, gravitational collapse, and magnetic ion-neutral slip heating. For clouds with kinetic temperatures approx.10 K, cosmic ray heating alone may be sufficient to balance the gas cooling for 3 x 10/sup 2/< or =n (H/sub 2/) < or =10/sup 4/ cm/sup -3/, these conditions being in good agreement with the observationally determined characteristics of dark clouds.« lessread more
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Control of star formation by supersonic turbulence
TL;DR: A review of the successes and problems of both the classical dynamical theory and the standard theory of magnetostatic support, from both observational and theoretical perspectives, is given in this paper.
Control of Star Formation by Supersonic Turbulence
TL;DR: A review of the successes and problems of both the classical dynamical theory and the standard theory of magnetostatic support, from both observational and theoretical perspectives, is given in this article.
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Cool Gas in High-Redshift Galaxies
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Cold Dark Clouds: The Initial Conditions for Star Formation
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FIRE-2 simulations: physics versus numerics in galaxy formation
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TL;DR: The Feedback In Realistic Environments (FIRE) project explores feedback in cosmological galaxy formation simulations as mentioned in this paper, which has been used to explore new physics (e.g. magnetic fields).