The Dynamics of the Globular Star Cluster 47 Tucanae
Abstract
We have created a set of dynamically evolving Fokker-Planck models for the globular star cluster 47 Tucanae. The models are able to reproduce the observed stellar mass function, star-count and velocity-dispersion profiles, the millisecond pulsar accelerations, and the radial distribution of neutron stars within the cluster. The best fitting model indicates that the cluster has not yet undergone core collapse but is likely to do so in the near future. The ratio of the core radius to the half-mass radius is 5% for the best fitting model. We find that roughly 1% of the total mass of the clusters is in the form of 1.4 solar mass objects. If all of these are in the form of neutron stars, it corresponds to a neutron star retention fraction of 20%. The models also contain a substantial population of massive white dwarfs that range in mass up to 1.1 solar masses. The combined contribution by the massive white dwarfs and neutron stars provides the gravitational potential needed to reproduce the velocity dispersion profile and millisecond pulsar accelerations.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2003
- Bibcode:
- 2003AAS...203.5206B