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The Z Velocity Dispersion of Outer H I Disks

Published online by Cambridge University Press:  25 May 2016

John M. Dickey
John M. Dickey*
Affiliation:
University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455, USA

Abstract

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The velocity dispersion of the interstellar gas measured perpendicular to the disk in face-on spiral galaxies shows a remarkable consistency. Typically the width of the velocity distribution decreases monotonically with increasing galactic radius through the luminous, stellar disk; but in the outer disk where there is gas but no stars the velocity dispersion is συ ≃ 7 km s−1 with a scatter of 2 km s–1 at most from one position to another and from one galaxy to another. Trying to understand this number raises questions about the thermal state of the H I in outer, gaseous disks. The most important issue is to understand the dominant heating and cooling processes for the atomic gas.

Information

Type
Chapter 6: How are we to Understand the Large Scale Structure of the ISM?
Information
Symposium - International Astronomical Union , Volume 169: Unsolved Problems of the Milky Way , 1996 , pp. 489 - 495
Copyright
Copyright © Kluwer 1996 

References

Boulanger, F. and Viallefond, F. (1992), Astron. Astrophys. 266, 37.Google Scholar
Bregman, J.N. (1980), Ap. J. 236, 577.CrossRefGoogle Scholar
Dickey, J.M., Hanson, M.M., and Helou, G. (1990), Ap. J. 352, 522.Google Scholar
Heiles, C. (1990), Ap. J. 354, 483.CrossRefGoogle Scholar
Kulkarni, S.R. and Fich, M. (1985), Ap. J. 289, 792.Google Scholar
Lockman, F.J. and Gehman, C., (1991), Ap. J. 382, 182.CrossRefGoogle Scholar
Norman, C.A. and Ikeuchi, S. (1989), Ap.J. 345, 372.CrossRefGoogle Scholar
Oort, J.H. (1932), Bull. Astron. Inst. Neth. 6, 249.Google Scholar
Rownd, B.K., Dickey, J.M., and Helou, G. (1994), A.J. 108, 1638.Google Scholar
Spitzer, L. Jr. (1977), Physical Processes in the Interstellar Medium, (New York : John Wiley), chap. 11.Google Scholar
van der Kruit, P., and Shostak, S. (1984), Astron. Astrophys. , 134, 258.Google Scholar
Wakker, B. (1991), Astron. Astrop. 250, 499.Google Scholar