Letter

Nature 462, 480-482 (26 November 2009) | doi:10.1038/nature08565; Received 10 June 2009; Accepted 1 October 2009

Enrichment by supernovae in globular clusters with multiple populations

Jae-Woo Lee1, Young-Woon Kang1, Jina Lee1 & Young-Wook Lee2

  1. Department of Astronomy and Space Science, ARCSEC, Sejong University, Seoul 143-747, Korea
  2. Center for Space Astrophysics, Yonsei University, Seoul 120-749, Korea

Correspondence to: Jae-Woo Lee1Young-Wook Lee2 Correspondence and requests for materials should be addressed to J.-W.L. (Email: jaewoolee@sejong.ac.kr) or Y.-W.L. (Email: ywlee2@yonsei.ac.kr).

The most massive globular cluster in the Milky Way, omega 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 omega Cen6, other peculiar globular clusters do not7, 8. Therefore omega 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 omega 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 omega 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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