EDP Sciences
Free access
Volume 366, Number 1, January IV 2001
Page(s) 276 - 280
Section Diffuse matter in space
DOI http://dx.doi.org/10.1051/0004-6361:20000347

A&A 366, 276-280 (2001)
DOI: 10.1051/0004-6361:20000347

Axisymmetric instabilities in gravitating discs with mass spectrum

V. G. Ortega1, E. Volkov2, 1 and I. Monte-Lima1

1  Observatorio Nacional, DAGE, Rua Gen. Jose Cristino 77, Sao Cristovao, CEP 20921-400, Rio de Janeiro, RJ, Brazil
2  Sobolev Astronomical Institute, St. Petersburg State University, Russia

(Received 21 February 2000 / Accepted 3 October 2000)

Starting from an axisymmetric, differentially rotating thin disc at equilibrium, in which the velocity dispersion is not large and in which the particles are characterized by a mass distribution and by a relationship between mass and velocity dispersion, we consider the stability of such a configuration against small axisymmetric disturbances. The analysis is performed kinetically and the behaviour of the marginal stability curves for different values of the system's parameters is investigated. Specifically, we consider the implications of changes in the parameters characterizing the mass spectrum range and the law relating the mass and velocity dispersion. Our results show that the characteristics of the system can significantly affect the critical stability parameters. We point out that such effects may strongly influence the evolution of the interstellar medium in disc galaxies.

Key words: ISM: kinematics and dynamics -- ISM: clouds -- ISM: molecules

Offprint request: V. G. Ortega, vladimir@on.br

© ESO 2001