Free collapse of a rotating sphere of stars.
Abstract
The free-fall collapse of a system of 115,000 stars was studied by means of a three-dimensional simulation on the ILLIAC IV computer. The system started from a spherical shape with uniform density and rigid rotation which balanced the gravitational force in the equatorial plane. The system settled down into a 'hot' prolate 'bar' in about two initial rotation periods. This bar rotates about a short axis and is a long-lived form. Detailed discussion of the development of this system leads to several important dynamical inferences: (1) the first collapse does not become triaxial, and the prolate form follows much later; (2) forms seen in projection along the rotation axis are strikingly similar to forms seen in disk galaxy simulations, notwithstanding an unusual thickness along the rotation axis (this strengthens confidence in disk galaxy simulations); (3) many elliptical galaxies must be prolate objects rotating about a short axis and seen in projection; and (4) collapse models of galaxy formation lead to strongly anisotropic velocity dispersions, which are not in agreement with observation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1978
- DOI:
- 10.1086/156242
- Bibcode:
- 1978ApJ...223..122M
- Keywords:
-
- Computerized Simulation;
- Galactic Evolution;
- Gravitational Collapse;
- Star Clusters;
- Elliptical Galaxies;
- Free Fall;
- Illiac 4 Computer;
- Stellar Motions;
- Three Dimensional Models;
- Astrophysics;
- Collapse:Stellar Systems