Kulkarni, Shrinivas R. and Heiles, Carl (1988) Neutral Hydrogen and the Diffuse Interstellar Medium. In: Galactic and Extragalactic Radio Astronomy. Springer Study Edition. Springer-Verlag , New York, pp. 95-153. ISBN 9780387965758. https://resolver.caltech.edu/CaltechAUTHORS:20130307-144919438
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Abstract
Neutral atomic hydrogen (HI) is an important component of the interstellar medium (ISM). The Galaxy has been estimated to contain about 4.8 x 10^9 M_⊙ of HI (Henderson et al. 1982)*. Estimates for the total amount of H_2 range from 3.5 x 10^9 M_⊙ (Sanders et al. 1984), nearly equal to the HI estimate, to a value that is only 25% of the HI estimate (Bloemen et al. 1986). Galactic HI constitutes about 4.4% of the mass of the visible matter (Bahcall et al. 1983). The mean surface density distribution of HI is roughly constant from about 4 kpc to 20 kpc; however, HI dominates H_2 in mass beyond Galactocentric radius 8 kpc (Blitz et al. 1983). Unlike H_2, HI is not concentrated in a small number of giant clouds. Estimates of the "filling factor", the fraction of the Galactic interstellar space occupied by hydrogen, range from 20% to 90%. These factors establish the preeminence of atomic hydrogen in the dynamics and evolution of the ISM.
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| Additional Information: | © 1988 Springer-Verlag. This work was supported in part by National Science Foundation grant no. AST 85-13422, awarded to C. Heiles, and a Robert A. Millikan Fellowship to S.R. Kulkarni. | |||||||||
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| Series Name: | Springer Study Edition | |||||||||
| DOI: | 10.1007/978-1-4612-3936-9_3 | |||||||||
| Record Number: | CaltechAUTHORS:20130307-144919438 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20130307-144919438 | |||||||||
| Official Citation: | Kulkarni, S. and C. Heiles (1988). Neutral Hydrogen and the Diffuse Interstellar Medium. Galactic and Extragalactic Radio Astronomy. G. Kellerman and K. Kellerman, Springer US: 95-153. | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 37391 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | Tony Diaz | |||||||||
| Deposited On: | 04 Apr 2013 23:20 | |||||||||
| Last Modified: | 09 Nov 2021 23:28 |
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