On the Effects of Finite Disk Thickness and Gas Content on Spiral Structure.
Abstract
The density wave theory of spiral structure in disk galaxies outlined previously by Lin and Shu (Astrophys. J. 140, 646, 1964; Proc. Nati. Acad. Scj. 55, 229,1966; Proc. IAU-URSI, Symp. No. 31,1967) is extended to include the effects of finite disk thickness and the presence of a fair amount of interstellar gas. In the theory based on a model of infinitesimal thickness, there exists a decided discrepancy between the theoretically predicted values of the stellar velocity dispersion required for stability and those actually observed in our own Galaxy. With the consideration of the effect of the finite thickness of the disks of stars and gas, this discrepancy disappears. The numerical form of the resultant dispersion relation between wave frequency and wavelength for spiral~waves does not differ appreciably from that obtained on the basis of the simple theory. The relative participation of gas and stars in the spiral structure of our own Galaxy is found to be about the same in the solar vicinity. In the interior parts, stars will play the more important role. Frank H. Shu is currently at the State University of New York, Stony Brook.
- Publication:
-
The Astronomical Journal Supplement
- Pub Date:
- 1968
- Bibcode:
- 1968AJS....73R.201S