Advertisement

Numerical Experiments on the Escape from Non-Isolated Clusters and the Formation of Multiple Stars

  • Avram Hayli
Conference paper
Part of the Astrophysics and Space Science Library book series (ASSL, volume 31)

Abstract

Isolated and non isolated clusters with a mass distribution have been studied by numerical techniques. The rates of escape of stars and of kinetic energy are compared with Hénon’s theoretical expressions. Multiple encounters play a very important role in the escape phenomenon, at least for clusters with a small number of stars. This leads to a theoretical underestimate of the rates of escape when the stars have equal masses and to an overestimate when masses are unequal.

For non isolated clusters, the tidal field of the Galaxy is responsible for one half of the rate of escape of the stars. The energy of a star escaping because of the tidal effect grows slowly while that of a star escaping after an encounter increases very rapidly. The stars escaping because of the tidal effect leave the cluster in the vicinity of the equilibrium points.

Encounters and the tidal field are not efficient enough to explain why very old open clusters are not observed. Other escape mechanisms have to be considered.

Very stable subsystems are formed which are not destroyed under the influence of the galactic tide. Separation between stars can be as low as 1000 UA.

Keywords

Equilibrium Point Massive Star Equal Mass Galactic Plane Tidal Effect 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Aarseth, S.J.: 1968, Bull. Astron. (3) 3, 105.Google Scholar
  2. Albada, T. S. van: 1968a, Bull. Astron. Inst. Neth. 19, 479.ADSGoogle Scholar
  3. Albada, T. S. van: 1968b, Bull. Astron. Inst. Neth. 20, 57.ADSGoogle Scholar
  4. Hayli, A.: 1967, Bull. Astron. (3) 2, 67.Google Scholar
  5. Hayli, A.: 1967, Bull. Astron. (3) 2, 189.Google Scholar
  6. Hayli, A.: 1967, Thèse de Doctoral d’Etal, Université ?Paris.Google Scholar
  7. Hénon, M.: 1960, Ann. Astrophys. 23, 668.ADSGoogle Scholar
  8. Hénon, M.: 1969, Astron. Astrophys. 2, 151.ADSGoogle Scholar
  9. Hoerner, S. von: 1960, Z. Astrophys. 50, 184.MathSciNetADSzbMATHGoogle Scholar
  10. Janin, G.: 1969, private communication.Google Scholar
  11. Spitzer, L.: 1958, Astrophys. J. 127 (1), 17.ADSCrossRefGoogle Scholar
  12. Szebehely, V.: 1967, Theory of Orbits, Academic Press, London and New York.Google Scholar

Copyright information

© D. Reidel Publishing Company, Dordrecht, Holland 1972

Authors and Affiliations

  • Avram Hayli
    • 1
  1. 1.Institut d’Astrophysique et Collège de FranceParisFrance

Personalised recommendations