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Astrophysics and Space Science

, Volume 119, Issue 2, pp 279–285 | Cite as

Colour gradients in globular clusters

  • M. G. Pastoriza
  • E. L. D. Bica
  • M. V. F. Copetti
  • H. A. Dottori
Article
  • 23 Downloads

Abstract

Radial colour gradients in the globular clusters NGC 2808, NGC 1851, NGC 5139, NGC 5139, NGC 6388, NGC 6441, NGC 6541, NGC 6723, and NGC 7099 were searched byB-V and DDO photoelectric photometry, using a set of circular diaphragms. Two of the observed globular clusters, NGC 5139 (ωCen) and NGC 7099 (M30), showedB-V and C(45–48) colour gradients; the colour C(42–45) is essentially constant in these clusters, which means that the physical reason for those gradients cannot be attributed to chemical composition variations, since C(42–45) is a good metal abundance indicator.B-V colours in the external regions of NGC 5139 and NGC 7099 were obtained by synthesizing the observed HR diagrams of these clusters. The ages and the relaxation times for NGC 5139 and NGC 7099 indicate that mass segregation must have taken place in both clusters, which is probably related to the observed colour gradients.

Keywords

Colour Relaxation Time Composition Variation Globular Cluster Physical Reason 
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.

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References

  1. Alcaino, G.: 1973,Atlas of Globular Clusters with Colour Magnitude Diagrams, Univ. Católica de Chile.Google Scholar
  2. Alcaino, G. and Liller, W.: 1980,Astron. J. 85, 1330.Google Scholar
  3. Bica, E. L. D. and Pastoriza, M. G.: 1983,Astrophys. Space Sci. 91, 99.Google Scholar
  4. Chun, M. S. and Freeman, K. C.: 1979,Astrophys. J. 227, 93.Google Scholar
  5. Dickens, R. J. and Woolley, R. v. d. R.: 1967,Roy. Obs. Bull. 128, E255.Google Scholar
  6. Dottori, H. A. and Bevilaqua, C. M.: 1980,Astrophys. Space Sci. 73, 327.Google Scholar
  7. Janes, K. A.: 1979,Dudley Obs. Rep. 14, 103.Google Scholar
  8. Kraft, R. P.: 1979,Ann. Rev. Astron. Astrophys. 17, 309.Google Scholar
  9. Madore, B. F.: 1980, in D. Hanes and B. Madore (eds.),Globular Clusters, Cambridge Univ. Press, Cambridge, p. 21.Google Scholar
  10. McClure, R. D.: 1976,Astron. J. 81, 182.Google Scholar
  11. McClure, R. D.: 1979,Dudley Obs. Rep. 14, 83.Google Scholar
  12. McClure, R. D. and Norris, J.: 1974,Astrophys. J. 193, 139.Google Scholar
  13. McClure, R. D. and Van den Bergh, S.: 1968,Astron. J. 73, 313.Google Scholar
  14. Norris, J. and Bessel, M. S.: 1975,Astrophys. J. 201, L75.Google Scholar
  15. Rabin, D.: 1982,Astrophys. J. 261, 85.Google Scholar
  16. Scaria, K. K. and Bappu, M. K. V.: 1981,J. Astrophys. Astron. 2, 215.Google Scholar
  17. Smith, H. A.: 1981,Astron. J. 86, 538.Google Scholar
  18. Van den Bergh, S.: 1983,Astrophys. J. Suppl. 51, 29.Google Scholar
  19. Zinn, R.: 1980,Astrophys. J. Suppl. 42, 19.Google Scholar

Copyright information

© D. Reidel Publishing Company 1986

Authors and Affiliations

  • M. G. Pastoriza
    • 1
    • 2
  • E. L. D. Bica
    • 1
    • 2
  • M. V. F. Copetti
    • 1
    • 2
  • H. A. Dottori
    • 1
    • 2
  1. 1.Instituto de FísicaUniversidade Federal do Rio Grande do SulPorto AlegraBrasil
  2. 2.Departamento de MatemáticaUniversidade Federal de Santa MariaSanta MariaBrasil

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