EDP Sciences
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Volume 395, Number 1, November III 2002
Page(s) 25 - 30
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20021268

A&A 395, 25-30 (2002)
DOI: 10.1051/0004-6361:20021268

Stability of rotating spherical stellar systems

A. Meza

Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306-22, Santiago, Chile

(Received 13 August 2001 / Accepted 30 August 2002)

The stability of rotating isotropic spherical stellar systems is investigated by using N-body simulations. Four spherical models with realistic density profiles are studied: one of them fits the luminosity profile of globular clusters, while the remaining three models provide good approximations to the surface brightness of elliptical galaxies. The phase-space distribution function f(E) of each one of these non-rotating models satisfies the sufficient condition for stability ${\rm d}f/{\rm d}E<0$. Different amounts of rotation are introduced in these models by changing the sign of the z-component of the angular momentum for a given fraction of the particles. Numerical simulations show that all these rotating models are stable to both radial and non-radial perturbations, irrespective of their degree of rotation. These results suggest that rotating isotropic spherical models with realistic density profiles might generally be stable. Furthermore, they show that spherical stellar systems can rotate very rapidly without becoming oblate.

Key words: celestial mechanics -- stellar dynamics -- galaxies: kinematics and dynamics -- instabilities -- methods: N-body simulations

© ESO 2002