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Prog. Theor. Phys. Supplement No.96 (1988) pp. 50-62
Chapter 4. The Equilibrium and the Stability of Rotating Isothermal Clouds
Masayoshi Kiguchi,
Shinji Narita,*
Shoken M. Miyama** and
Chushiro Hayashi***
Research Institute for Science and Technology, Kinki University, Osaka 577
*Department of Electronics, Doshisha University, Kyoto 602
**Department of Physics, Kyoto University, Kyoto 606
***Momoyama Yogoro-cho, Fusimi-ku, Kyoto 612
(Received December 2, 1988)
Abstract:
We review the equilibrium structure of rotating isothermal clouds. First, we describe the equilibrium structure obtained under the assumption that the clouds are axisymmetric and embedded in a stationary external medium. Next, we describe the stability of these clouds examined by following the evolution from the equilibrium state.
We find from this study that (1) the clouds with the density contrast from center to edge greater than 800 are unstable to global contraction or expansion. (2) the clouds with rotation energy greater than 0.44 times gravitational energy are unstable to ring formation, and (3) the clouds with rotation energy greater than 0.27 times gravitational energy are unstable to nonaxial deformation. The deformation grows to form spiral arms.
We find further that (1) the maximum mass of clouds is 4 times that of nonrotating clouds, (2) the maximum mean rotation velocity is 2cs, where cs is the sound velocity, (3) the maximum mean density is 6 times the edge density, and (4) for each cloud, the maximum height of the boundary surface from the equatorial plane is nearly given by 0.3cs2/√GPe, where Pe is the external pressure.
URL :
http://ptp.ipap.jp/link?PTPS/96/50/
DOI : 10.1143/PTPS.96.50
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