Astron. Astrophys. 327, 130-136 (1997)

Have many globulars disappeared to the galactic centres? The case of the Galaxy, M 31 and M 87

R. Capuzzo-Dolcetta and L. Vignola

Istituto Astronomico, Universitá di Roma "La Sapienza" Via G.M. Lancisi 29, I-00185 Roma, Italy

Received 14 January 1997 / Accepted 30 April 1997

Abstract

The radial distribution of globular clusters in our Galaxy, M 31 and M 87 is studied and compared with that of halo stars. The globular cluster distributions seem significantly flatter than those of the parent-galaxy stellar bulge. Assuming this is a consequence of an evolution of the globular cluster distribution in these galaxies, a comparison with the (unevolved) stellar distribution allows us to obtain estimates of the number and total mass of clusters lost.

It results that the cluster systems in our Galaxy and in M 31 have been initially about one third richer than now, and twice as abundant in M 87. The estimated mass in form of globular clusters lost is compatible with the nucleus masses of these galaxies.

Key words: galaxies: star clusters - galaxies: evolution - galaxies: nuclei - Galaxy: globular clusters - galaxies: M 31; M 87

Send offprint requests to: R. Capuzzo-Dolcetta

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Contents

• 1. Introduction
• 2. Globular cluster system evolution
  • 2.1. Is dynamical friction an effective cause of GCS evolution ?
  • 2.2. The radial dependence of the GCS luminosity function
• 3. Present and initial radial distributions
  • 3.1. The data sets and interpolations
• 4. Number of clusters missing in our Galaxy and M 31
  • 4.1. Our Galaxy
  • 4.2. Andromeda (M 31)
  • 4.3. Evaluation of globular cluster mass fallen to the galactic centres
  • 4.4. An important source of error
• 5. M 87
• 6. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998
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