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Stabilization of generalized polytropes
Author(s) -
Polyachenko E.V.,
Polyachenko V.L.,
Shukhman I.G.
Publication year - 2013
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.201311923
Subject(s) - polytropic process , isotropy , physics , anisotropy , limit (mathematics) , instability , stability (learning theory) , zero (linguistics) , classical mechanics , mathematical physics , mathematical analysis , mechanics , quantum mechanics , mathematics , linguistics , philosophy , machine learning , computer science
Stabilization of classical generalized polytropic models is studied. We discuss some contradictions found in the literature: on the one hand, calculations of the growth rates in the framework of linear stability theory and N‐body simulations show that these systems are stable if the velocity anisotropy parameter of the stellar distribution is lower than some finite positive value. On the other hand, instability is shown to persist up to the isotropic limit (zero anisotropy parameter). We demonstrate that stabilization of generalized polytropic models cannot be adequately described by approximate equations derived for nearly radial orbits. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)