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A new criterion for bar-forming instability in rapidly rotating gaseous and stellar systems. 2: Nonaxisymmetric formWe have previously introduced the parameter alpha as an indicator of stability to m = 2 nonaxisymmetric modes in rotating, self-gravitating, axisymmetric, gaseous (alpha less than or approximately equal to 0.34) and stellar (alpha less than or approximately equal to 0.25) systems. This parameter can be written as alpha = (ft/2)(exp 1/2), where t is defined as T/(absolute value of W), T is the total rotational kinetic energy, W is the total gravitational potential energy, and f is a function characteristic of the topology/connectedness and the geometric shape of a system. In this paper, we extend the stability criterion to nonaxisymmetric equilibrium systems by determining empirically the appropriate form of the function f for ellipsoids and elliptical disks and cylinders. We test the validity of this extension of the stability indicator alpha by considering its predictions for previously published, gaseous and stellar, nonaxisymmetric models. The formulation and critical values account accurately for the stability properties of m =2 modes in gaseous Riemann S-type ellipsoids (including the Jacobi and Dedekind ellipsoids) and elliptical Riemann disks as well as in stellar elliptical Freeman disks and cylinders: all these systems are dynamically stable except the stellar elliptical Freeman disks that exhibit a relatively small region of m = 2 dynamical instability. A partial disagreement in the case of stellar Freeman ellipsoids in maximum rotation may be due to the fact that the region of instability has not been previously determined with sufficient accuracy.
Document ID
19950054607
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Christodoulou, Dimitris M.
(University of Virginia, Charlottesville, VA United States)
Shlosman, Isaac
(University of Kentucky, Lexington, KY United States)
Tohline, Joel E.
(Louisiana State University Baton Rouge, LA, United States)
Date Acquired
August 16, 2013
Publication Date
April 20, 1995
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 443
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A86206
Funding Number(s)
CONTRACT_GRANT: NSF AST-90-08166
CONTRACT_GRANT: NAGW-2447
CONTRACT_GRANT: NAGW-2376
CONTRACT_GRANT: NAGW-3839
CONTRACT_GRANT: NAGW-1510
Distribution Limits
Public
Copyright
Other

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