Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-08T04:50:08.776Z Has data issue: false hasContentIssue false
  • English
  • Français

Structure and Evolution of Giant Molecular Clouds

Published online by Cambridge University Press:  30 March 2016

Antony A. Stark
Antony A. Stark*
Affiliation:
AT&T Bell LaboratoriesHOH L231, Box 400 Holmdel, NJ 07733USA

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The mechanism of spiral structure in galaxies is a puzzle that is only partly understood. Galaxies do not revolve like solid bodies, so the spiral patterns cannot be entirely material in nature. Yet the observable tracers of spiral structure are unquestionably material: young stars, dust and gas. These objects must be organized by a collective, wave phenomenon, the spiral density wave in the disk star population. The density wave is a small (≈ 10%) local increase in the density of stars. The interstellar medium responds to the increased gravitational force by forming Giant Molecular Clouds (GMCs), concentrations of 105 M⊙ or more of interstellar matter in a region about 50 pc across. In a sense the GMCs are the spiral arms: in other galaxies, dust, gas and young star populations trace spiral structure; in the solar vicinity, these populations are seen to be associated with GMCs. This paper briefly reviews observational data supporting the hypothesis that spiral structure results from the agglomerative build-up of GMCs from smaller clouds, that this growth occurs preferentially in spiral arms, and that GMCs subsequently self-destruct because of the formation of massive stars.

Type
Joint Discussions
Information
Highlights of Astronomy , Volume 7: Highlights of Astronomy. As presented at the XIXth General Assembly of the IAU, 1985 , 1986 , pp. 507 - 511
Copyright
Copyright © Reidel 1986

References

Blitz, L. and Stark, A. A. 1986 Ap. J. (Letters), 300.Google Scholar
Burton, W. B. 1970 Astr. Ap., 10, 76.Google Scholar
Clemens, D. 1985 Ap. J., 295, 422.Google Scholar
Cohen, R. S., Cong, H., Dame, T. M. and Thaddeus, P. 1980 Ap. J. (Letters), 239, L53.Google Scholar
Cowie, L. L. 1980 Ap. J., 236, 862.Google Scholar
Cowie, L. L. 1981 Ap. J., 245, 66.Google Scholar
Kwan, J. 1979 Ap. J., 229, 567.Google Scholar
Scoville, N. Z. and Hersh, K. 1979 Ap. J., 229, 578.Google Scholar
Solomon, P. M. and Sanders, D. B. 1980 in Giant Molecular Clouds in the Galaxy, ed. Solomon, P. M. and Edmunds, M. G. (Pergamon: Oxford) p. 41.CrossRefGoogle Scholar
Solomon, P. M. 1986 in Proc. I.A.U. 115 in press.CrossRefGoogle Scholar
Stark, A. A. 1979 Ph. D. thesis, Princeton University.Google Scholar
Stark, A. A. 1983 in Kinematics, Dynamics and Structure of the Milky Way ed. Shuter, W. L. H. (Reidel: Dordrecht) p. 127.CrossRefGoogle Scholar
Stark, A. A. 1986 in Proc. I.A.U. 115 in press.CrossRefGoogle Scholar
Toomre, A. 1985 personal communication.Google Scholar
Zuckerman, B. and Evans, 1974 Ap. J. (Letters), 192, L149.CrossRefGoogle Scholar