Enrichment by supernovae in globular clusters with multiple populations

Abstract

The most massive globular cluster in the Milky Way, ω Centauri, is thought to be the remaining core of a disrupted dwarf galaxy1,2, as expected within the model of hierarchical merging3,4. It contains several stellar populations having different heavy elemental abundances supplied by supernovae5—a process known as metal enrichment. Although M 22 appears to be similar to ω Cen6, other peculiar globular clusters do not7,8. Therefore ω Cen and M 22 are viewed as exceptional, and the presence of chemical inhomogeneities in other clusters is seen as ‘pollution’ from the intermediate-mass asymptotic-giant-branch stars expected in normal globular clusters9. Here we report Ca abundances for seven globular clusters and compare them to ω Cen. Calcium and other heavy elements can only be supplied through numerous supernovae explosions of massive stars in these stellar systems10, but the gravitational potentials of the present-day clusters cannot preserve most of the ejecta from such explosions11. We conclude that these globular clusters, like ω Cen, are most probably the relics of more massive primeval dwarf galaxies that merged and disrupted to form the proto-Galaxy.

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Figure 1: Colour–magnitude diagrams for M 22.
Figure 2: Colour–magnitude diagrams for ω Cen, M 22, NGC 1851, NGC 2808, M 4, M 5, NGC 6752 and NGC 6397.
Figure 3: Differences in chemical compositions between double RGB sequences in M 22 and NGC 1851.

References

  1. 1

    Lee, Y.-W. et al. Multiple stellar populations in the globular cluster ω Centauri as tracers of a merger event. Nature 402, 55–57 (1999)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Bekki, K. & Freeman, K. C. Formation of ω Centauri from an ancient nucleated dwarf galaxy in the young Galactic disc. Mon. Not. R. Astron. Soc. 346, L11–L15 (2003)

    ADS  Article  Google Scholar 

  3. 3

    Freeman, K. C. in The Globular Cluster-Galaxy Connection (eds Smith, G. H & Brodie, J. P.) 608–614 (ASP Conf. Ser., Vol. 48, Astronomical Society of the Pacific, 1993)

    Google Scholar 

  4. 4

    Diemand, J., Kuhlen, M. & Madau, P. Formation and evolution of galaxy dark matter halos and their substructure. Astrophys. J. 667, 859–877 (2007)

    ADS  Article  Google Scholar 

  5. 5

    Johnson, C. I. et al. A large sample study of red giants in the globular cluster Omega Centauri (NGC 5139). Astrophys. J. 698, 2048–2065 (2009)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Marino, A. F. et al. A double stellar generation in the globular cluster NGC 6656 (M22). Two stellar groups with different iron and s-process element abundance. Astron. Astrophys. 505, 1099–1113 (2009)

    ADS  CAS  Article  Google Scholar 

  7. 7

    Carretta, E. et al. Properties of second generation stars in globular clusters. Preprint at 〈http://arXiv.org/abs/0811.3591v1〉 (2008)

  8. 8

    Georgiev, I. Y. et al. Globular cluster systems in nearby dwarf galaxies II. Nuclear star clusters and their relation to massive Galactic globular clusters. Mon. Not. R. Astron. Soc. 396, 1075–1085 (2009)

    ADS  Article  Google Scholar 

  9. 9

    Ventura, P. D. et al. Predictions for self-pollution in globular cluster stars. Astrophys. J. 550, L65–L69 (2001)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Timmes, F. X., Woosley, S. E. & Weaver, T. A. Galactic chemical evolution: hydrogen through zinc. Astrophys. J. 98 (Suppl.). 617–658 (1995)

    ADS  CAS  Article  Google Scholar 

  11. 11

    Baumgardt, H., Kroupa, P. & Parmentier, G. The influence of residual gas expulsion on the evolution of the Galactic globular cluster system and the origin of the Population II halo. Mon. Not. R. Astron. Soc. 384, 1231–1241 (2008)

    ADS  CAS  Article  Google Scholar 

  12. 12

    Anthony-Twarog, B. J. et al. Ca II H and K filter photometry on the uvby system. I-The standard system. Astron. J. 101, 1902–1914 (1991)

    ADS  CAS  Article  Google Scholar 

  13. 13

    Zinn, R. The globular cluster system of the Galaxy. I. The metal abundances and reddening of 79 globular clusters from integrated light measurements. Astrophys. J. 42 (Suppl.). 19–40 (1980)

    ADS  CAS  Article  Google Scholar 

  14. 14

    Zinn, R. & West, M. J. The globular cluster system of the Galaxy. III. Measurements of radial velocity and metallicity for 60 clusters and a compilation of metallicities for 121 clusters. Astrophys. J. 55 (Suppl.). 45–66 (1984)

    ADS  CAS  Article  Google Scholar 

  15. 15

    Stetson, P. B. DAOPHOT: A computer program for crowded-field stellar photometry. Publ. Astron. Soc. Pacif. 99, 191–222 (1987)

    ADS  Article  Google Scholar 

  16. 16

    Stetson, P. B. The center of the core-cusp globular cluster M15: CFHT and HST observations, ALLFRAME reductions. Publ. Astron. Soc. Pacif. 106, 250–280 (1994)

    ADS  Article  Google Scholar 

  17. 17

    Norris, J. & Freeman, K. C. The chemical inhomogeneity of M22. Astrophys. J. 266, 130–143 (1983)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Richter, P., Hilker, M. & Richtler, T. Strömgren photometry in globular clusters: M55 & M22. Astron. Astrophys. 350, 476–484 (1999)

    ADS  CAS  Google Scholar 

  19. 19

    Anthony-Twarog, B. J., Twarog, B. A. & Craig, J. CN and Ca abundance variations among the giants in M22. Publ. Astron. Soc. Pacif. 107, 32–48 (1995)

    ADS  Article  Google Scholar 

  20. 20

    Decressin, T., Charbonnel, C. & Meynet, G. Origin of the abundance patterns in Galactic globular clusters: constraints on dynamical and chemical properties of globular clusters. Astron. Astrophys. J. 475, 859–873 (2007)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Yong, D. & Grundahl, F. An abundance analysis of bright giants in the globular cluster NGC1851. Astrophys. J. 672, L29–L32 (2008)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Lee, J.-W. et al. Chemical inhomogeneity in red giant branch stars and RR Lyrae variables in NGC1851: two subpopulations in red giant branch. Astrophys. J. 695, L78–L82 (2009)

    ADS  CAS  Article  Google Scholar 

  23. 23

    Cudworth, K. M. Proper motions, membership, and photometry in the globular cluster M22. Astron. J. 92, 348–357 (1986)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Brown, J. A. & Walllerstein, G. High-resolution CCD spectra of stars in globular clusters. VII. Abundances of 16 elements in 47 Tuc, M4, and M22. Astron. J. 104, 1818–1830 (1992)

    ADS  CAS  Article  Google Scholar 

  25. 25

    Lee, Y.-W., Gim, H. B. & Casetti-Dinescu, D. Kinematic decoupling of globular clusters with the extended horizontal branch. Astrophys. J. 661, L49–L52 (2007)

    ADS  CAS  Article  Google Scholar 

  26. 26

    Piotto, G. et al. Metallicities on the double main sequence of ω Centauri imply large helium enhancement. Astrophys. J. 621, 777–784 (2005)

    ADS  CAS  Article  Google Scholar 

  27. 27

    Pflamm-Altenburg, J. & Kroupa, P. Recurrent gas accretion by massive star clusters, multiple stellar populations and mass threshold for spherical stellar systems. Mon. Not. R. Astron. Soc. 397, 488–494 (2009)

    ADS  Article  Google Scholar 

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Acknowledgements

J.-W.L. thanks A. Walker for providing the CTIO Ca filter transmission curve, D. Yong for NGC 1851 spectroscopic data before publication, and A. Yushchenko for discussions on spectrum synthesis. Support for this work was provided by the National Research Foundation of Korea to the Astrophysical Research Center for the Structure and Evolution of the Cosmos (ARCSEC). This work was based on observations made with the CTIO 1.0-m telescope, which is operated by the SMARTS consortium.

Author Contributions J.-W.L. performed observations, data analysis, interpretation, model simulations and writing of the manuscript; Y.-W.K. participated in observation planning; and J.L. performed part of the observations and data analysis. Y.-W. L. performed interpretation and writing of the manuscript. All authors discussed the results and commented on the manuscript.

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Correspondence to Jae-Woo Lee or Young-Wook Lee.

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This file contains Supplementary Notes and Data, Supplementary References, Supplementary Table 1-3 and Supplementary Figures 1-16 with Legends. (PDF 2185 kb)

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Lee, J., Kang, Y., Lee, J. et al. Enrichment by supernovae in globular clusters with multiple populations. Nature 462, 480–482 (2009). https://doi.org/10.1038/nature08565

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