Abstract
view Abstract Citations (9) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Effects of Interstellar Gas on the Oscillations and the Stability of Galaxies Vandervoort, Peter O. Abstract The modes of oscillation that would occur in galaxies that are purely stellar systems can be substantially modified in galaxies that contain interstellar gas. Thus the number of modes of a given kind is generally greater when gas is present than when it is absent. Moreover, the conditions under which a galaxy is unstable with respect to certain modes in the absence of gas are modified and complicated by the presence of gas. In particular, interstellar gas can induce instability with respect to certain modes that would otherwise be stable. In the present investigation, such effects of the gas are illustrated for modes of oscillation in homogeneous spheroids composed of uniformly rotating subsystems of stars and gas. It is shown for these systems that the critical value of the ratio of rotational to gravitational energy for the onset of instability with respect to the formation of a bar is a function of the eccentricity of the spheroidal figure, the fraction of the system that is gas, and the ratio of the angular velocities of the stellar and gaseous subsystems. It is also shown that slowly rotating systems of this kind are dynamically unstable with respect to a pulsation mode if the ratio of specific heats of the gas is less than a determinate critical value which depends on the eccentricity of the figure, the fraction of the system that is gas and the ratio of the angular velocities of the two subsystems. Publication: The Astrophysical Journal Pub Date: December 1991 DOI: 10.1086/170808 Bibcode: 1991ApJ...383..498V Keywords: Computational Astrophysics; Galactic Rotation; Galaxies; Interstellar Gas; Oscillations; Systems Stability; Eccentricity; Equilibrium Equations; Galactic Structure; Gravitational Effects; Interstellar Matter; Perturbation Theory; Astrophysics; GALAXIES: INTERNAL MOTIONS; GALAXIES: INTERSTELLAR MATTER; INSTABILITIES; STARS: STELLAR DYNAMICS full text sources ADS |
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