Local stability criterion for a gravitating disk of stars

Evgeny Griv, Baruch Rosenstein, Michael Gedalin, David Eichler

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Computer N-body experiments are desribed which test the validities of the original Toomre's (1964) criterion and of a generalized criterion for local stability of Jeans-type perturbations in a self-gravitating, infinitesimally thin, and practically collistonless disk of stars. The fact that the nonaxisymmetric perturbations in the differentially rotating system are more unstable than the axisymmetric ones is taken into account in this generalized criterion. It is shown that for differentially rotating disks, the generalized criterion works as well as Toomre's ordinary criterion does for rigidly rotating ones. A modest discrepancy is observed between the analytical stability criteria and the numerical results. We tentatively attribute this to the shortcomings of the asymptotic density wave theory and possibly additional ones introduced by approximations in the local numerical code employed here. In addition, the linear stability theory of small oscillations of a disk of stars is reexamined by using the method of particle orbit theory. This representation gives new insight into the problem of gravitating disk stability. Certain applications of the theory and the N-body simulations to actual disk-shaped spiral galaxies are explored as well.

Original languageEnglish
Pages (from-to)821-840
Number of pages20
JournalAstronomy and Astrophysics
Issue number3
StatePublished - 1 Dec 1999


  • Galaxies: kinematics and dynamics
  • Galaxies: structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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