Equilibria of rotating, isothermal clouds. II. Structure and dynamical stability

Journal Article · Sun May 01 04:00:00 EDT 1983 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/160942· OSTI ID:5839510

Stahler, S W

Numerical results are presented for the structure of differentially rotating, isothermal clouds. The equilibria can be characterized by two parameters: a dimensionless mass M and the rotational parameter ..beta..(0< or =..beta..< or = (1)/(3) ). Within the class of dynamically stable equilibria, clouds with low M and ..beta.. have small density contrasts (ratio of density at the center to density at the cloud boundary) and resemble Maclaurin spheroids; clouds with high M and ..beta.. have larger density contrasts and eccentricities. At any fixed ..beta.., there exists a critical mass M*( ..beta..) which is marginally dynamically unstable to axisymmetric perturbations. Stability is diagnosed by investigating the change in M as a function of density contrast at fixed ..beta... This ''static method'' is proved rigorously for the present case by showing that there exists a conserved free energy G for isothermal perturbations. Clouds with MM*( ..beta..), should they exist, must be unstable. The structure of unstable equilibria with MM*( ..beta..). Stable, disklike configurations are obtained for subcritical masses. The disks actually reached with the collapse codes agree well with the results of this study.

• Research Organization: Center for Radiophysics and Space Research, Cornell University
• OSTI ID: 5839510
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 268:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

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71 CLASSICAL AND QUANTUM MECHANICS
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HYDRODYNAMICS
MASS
MATHEMATICAL MODELS
MECHANICS
MOTION
NEBULAE
NUMERICAL SOLUTION
OSCILLATION MODES
ROTATION
STABILITY
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