Why globular clusters are so spherical.
Abstract
A Maclaurin spheroid model is applied to simulate the evolution of globular-cluster ellipticities. It is found that cluster ellipticities can decrease significantly over cluster lifetimes, as excess angular momentum is lost to escaping stars on relaxation time scales. The anomalous sphericity of globular clusters in comparison with elliptical galaxies is due to the large difference in their relaxation times. Globular clusters have aged for many relaxation times and thus have become appreciably more spherical than they were initially, while elliptical galaxies have not relaxed significantly from their initial equilibrium configurations.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1976
- DOI:
- 10.1086/154885
- Bibcode:
- 1976ApJ...210..757S
- Keywords:
-
- Astronomical Models;
- Galactic Evolution;
- Galactic Structure;
- Globular Clusters;
- Relaxation Time;
- Angular Momentum;
- Astrophysics;
- Cosmology;
- Elliptical Galaxies;
- Spheres;
- Astrophysics