Monte Carlo simulations of star clusters - VII. The globular cluster 47 Tuc

Mirek Giersz, Douglas C. Heggie

Research output: Contribution to journalArticlepeer-review

Abstract

We describe Monte Carlo models for the dynamical evolution of the massive globular cluster 47 Tuc (NGC 104). The code includes treatments of two-body relaxation, most kinds of three- and four-body interactions involving primordial binaries and those formed dynamically, the Galactic tide, and the internal evolution of both single and binary stars. We arrive at a set of initial parameters for the cluster which, after 12 Gyr of evolution, gives a model with a fairly satisfactory match to surface brightness and density profiles, the velocity dispersion profile, the luminosity function in two fields and the acceleration of pulsars. Our models appear to require a relatively steep initial mass function for stars above about turnoff, with an index of about 2.8 (where the Salpeter mass function has an index of 2.35), and a relatively flat initial mass function (index about 0.4) for the lower main sequence. According to the model, the current mass is estimated at 0.9 million solar masses, of which about 34 per cent consists of remnants. We find that primordial binaries are gradually taking over from mass loss by stellar evolution as the main dynamical driver of the core. Despite the high concentration of the cluster, core collapse will take at least another 20 Gyr.

Original languageEnglish
Pages (from-to)2698-2713
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume410
Issue number4
DOIs
Publication statusPublished - Feb 2011

Keywords

  • methods: numerical
  • globular clusters: individual: 47 Tuc
  • globular clusters: individual: NGC 104
  • RESIDUAL-GAS EXPULSION
  • MASS BLACK-HOLES
  • DYNAMICAL PROPERTIES
  • STELLAR-SYSTEMS
  • OMEGA-CENTAURI
  • GLOBULAR-CLUSTER-47 TUCANAE
  • VELOCITY DISPERSION
  • PRIMORDIAL BINARIES
  • MILLISECOND PULSARS
  • PROPER MOTIONS

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