Continuum models for gas in disturbed galaxies. II - Stability of simplified model systems
Abstract
An investigation is carried out of the stability to small perturbations of simplified model equations describing the macroscopic behavior of an isotropic galactic cloud system. Consideration is given to various combinations of sources and sinks of cloud number, mass, and internal energy. It is found that when spatial gradients, velocity fields, and gravity are ignored, the various source term models are in general surprisingly stable for a wide range of the controlling parameters when an equilibrium solution exists. When cloud collisions give rise to net fragmentation rather than coalescence (which corresponds to large cloud velocity dispersions), equilibrium solutions usually do not exist. It is noted that such a situation must arise in direct galactic collisions and also during star formation bursts, in which large amounts of energy may be imparted to cloud motions from steller winds and explosions. An analysis is made of the dispersion relations for two different source terms models (similar to the 'Oort' model) which include spatial gradients, a velocity field, and gravity.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1984
- DOI:
- 10.1086/161677
- Bibcode:
- 1984ApJ...277..132S
- Keywords:
-
- Astronomical Models;
- Galactic Structure;
- Interstellar Gas;
- Molecular Clouds;
- Nebulae;
- Collisions;
- Gravitation;
- Interacting Galaxies;
- Magnetohydrodynamics;
- Mathematical Models;
- Oort Cloud;
- Oscillations;
- Thermal Stability;
- Velocity Distribution;
- Astrophysics