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The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge

Abstract

Globular star clusters are compact and massive stellar systems old enough to have witnessed the entire history of our Galaxy, the Milky Way. Although recent results1,2,3 suggest that their formation may have been more complex than previously thought, they still are the best approximation to a stellar population formed over a relatively short timescale (less than 1 Gyr) and with virtually no dispersion in the iron content. Indeed, only one cluster-like system (ω Centauri) in the Galactic halo is known to have multiple stellar populations with a significant spread in iron abundance and age4,5. Similar findings in the Galactic bulge have been hampered by the obscuration arising from thick and varying layers of interstellar dust. Here we report that Terzan 5, a globular-cluster-like system in the Galactic bulge, has two stellar populations with different iron contents and ages. Terzan 5 could be the surviving remnant of one of the primordial building blocks that are thought to merge and form galaxy bulges.

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Figure 1: MAD image of Terzan 5 in the K band.
Figure 2: The two horizontal branch clumps of Terzan 5.
Figure 3: Radial distribution of the two horizontal branch populations in Terzan 5.
Figure 4: Iron abundance and ages of the two populations.

References

  1. Gratton, R., Sneden, C. & Carretta, E. Abundance variations within globular clusters. Annu. Rev. Astron. Astrophys. 42, 385–440 (2004)

    Article  ADS  CAS  Google Scholar 

  2. Piotto, G. in The Ages of Stars (ed. Montmerle, T.) 233–244 (IAU Symp. 258, Cambridge Univ. Press, 2009)

    Google Scholar 

  3. Lee, J.-W., Kang, Y.-W., Lee, J. & Lee, Y.-W. Enrichment by supernovae in globular clusters with multiple populations. Nature 10.1038/nature08565 (this issue)

  4. Norris, J. E. & Da Costa, G. S. The giant branch of Omega Centauri. IV. Abundance patterns based on echelle spectra of 40 red giants. Astrophys. J. 447, 680–705 (1995)

    Article  ADS  CAS  Google Scholar 

  5. Sollima, A. et al. Metallicities, relative ages, and kinematics of stellar populations in ω Centauri. Astrophys. J. 634, 332–343 (2005)

    Article  ADS  CAS  Google Scholar 

  6. Marchetti, E. et al. On-sky testing of the multi-conjugate adaptive optics demonstrator. The Messenger 129, 8–13 (2007); available at 〈http://www.eso.org/sci/publications/messenger/archive/no.129-sep07/messenger-no129-8.pdf

    ADS  Google Scholar 

  7. Ortolani, S., Barbuy, B. & Bica, E. NTT VI photometry of the metal-rich and obscured bulge globular cluster Terzan 5. Astron. Astrophys. 308, 733–737 (1996)

    ADS  Google Scholar 

  8. Valenti, E., Ferraro, F. R. & Origlia, L. Near-infrared properties of 24 globular clusters in the Galactic Bulge. Astron. J. 133, 1287–1301 (2007)

    Article  ADS  Google Scholar 

  9. Cohn, H. N., Lugger, P. M., Grindlay, J. E. & Edmonds, P. D. Hubble Space Telescope/NICMOS observations of Terzan 5: stellar content and structure of the core. Astrophys. J. 571, 818–829 (2002)

    Article  ADS  Google Scholar 

  10. Ortolani, S. et al. HST NICMOS photometry of the reddened bulge globular clusters NGC 6528, Terzan 5, Liller 1, UKS 1 and Terzan 4. Astron. Astrophys. 376, 878–884 (2001)

    Article  ADS  Google Scholar 

  11. Ortolani, S., Barbuy, B., Bica, E., Zoccali, M. & Renzini, A. Distances of the bulge globular clusters Terzan 5, Liller 1, UKS 1, and Terzan 4 based on HST NICMOS. Astron. Astrophys. 470, 1043–1049 (2007)

    Article  ADS  CAS  Google Scholar 

  12. Origlia, L. & Rich, R. M. High-resolution infrared spectra of bulge globular clusters: the extreme chemical abundances of Terzan 4 and Terzan 5. Astron. J. 127, 3422–3430 (2004)

    Article  ADS  CAS  Google Scholar 

  13. McLean, I. S. et al. Design and development of NIRSPEC: a near-infrared echelle spectrograph for the Keck II telescope. Proc. SPIE 3354, 566–578 (1998)

    Article  ADS  Google Scholar 

  14. Harris, W. E. A catalog of parameters for globular clusters in the Milky Way. Astron. J. 112, 1487–1488 (1996)

    Article  ADS  Google Scholar 

  15. Piotto, G. et al. Hubble Space Telescope observations of Galactic globular cluster cores. II. NGC 6273 and the problem of horizontal-branch gaps. Astron. J. 118, 1727–1737 (1999)

    Article  ADS  Google Scholar 

  16. Beccari, G., Ferraro, F. R., Lanzoni, B. & Bellazzini, M. A population of binaries in the asymptotic giant branch of 47 Tucanae? Astrophys. J. 652, L121–L124 (2006)

    Article  ADS  CAS  Google Scholar 

  17. Icke, V. & Alcaino, G. Is Omega Centauri a merger? Astron. Astrophys. 204, 115–116 (1988)

    ADS  CAS  Google Scholar 

  18. Marín-Franch, A. et al. The ACS survey of galactic globular clusters. VII. Relative ages. Astrophys. J. 694, 1498–1516 (2009)

    Article  ADS  Google Scholar 

  19. Ibata, R. A., Gilmore, G. & Irwin, M. J. A dwarf satellite galaxy in Sagittarius. Nature 370, 194–196 (1994)

    Article  ADS  Google Scholar 

  20. Bellazzini, M. et al. The nucleus of the Sagittarius Dsph galaxy and M54: a window on the process of galaxy nucleation. Astron. J. 136, 1147–1170 (2008)

    Article  ADS  CAS  Google Scholar 

  21. Hurley-Keller, D. & Mateo, M. in Astrophysical Ages and Times Scales (eds von Hippel, T., Simpson, C. & Manset, N.) 322–324 (ASP Conf. Ser. Vol. 245, Astron. Soc. Pacif., 2001)

    Google Scholar 

  22. Harbeck, D. et al. Population gradients in local group dwarf spheroidal galaxies. Astron. J. 122, 3092–3105 (2001)

    Article  ADS  Google Scholar 

  23. Immeli, A., Samland, M., Gerhard, O. & Westera, P. Gas physics, disk fragmentation, and bulge formation in young galaxies. Astron. Astrophys. 413, 547–561 (2004)

    Article  ADS  CAS  Google Scholar 

  24. Belokurov, V. et al. Cats and dogs, hair and a hero: a quintet of new Milky Way companions. Astrophys. J. 654, 897–906 (2007)

    Article  ADS  Google Scholar 

  25. Lanzoni, B. et al. The surface density profile of NGC 6388: a good candidate for harboring an intermediate-mass black hole. Astrophys. J. 668, L139–L142 (2007)

    Article  ADS  CAS  Google Scholar 

  26. Pietrinferni, A., Cassisi, S., Salaris, M. & Castelli, F. A large stellar evolution database for population synthesis studies. I. Scaled solar models and isochrones. Astrophys. J. 612, 168–190 (2004)

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

We thank the MAD team at ESO and in particular P. D’Amico for performing the observations with MAD. This research was supported by “Progetti Strategici di Ateneo 2006” (University of Bologna), “Progetti di Ricerca di Interesse Nazionale 2007 and 2008” (Istituto Nazionale di Astrofisica), Agenzia Spaziale Italiana, and the Ministero dell'Istruzione, dell'Universitá e della Ricerca. We also acknowledge support from the ESTEC Faculty Visiting Scientist Programme. R.M.R. is supported by the NSF and STScI; and R.T.R. is partially supported by STScI. This research has made use of the ESO/ST-ECF Science Archive facility, which is a joint collaboration of the ESO and the Space Telescope – European Coordinating Facility. Part of the data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA. The Observatory was made possible by the financial support of the W. M. Keck Foundation.

Author Contributions F.R.F. designed the study and coordinated the activity. E.D., A.M., G.B., E.V. and G.C. analysed the photometric dataset. R.M.R. and L.O. secured and analysed the Keck spectra. A.M. designed the reddening correction routine. M.B. performed radial distributions tests. E.D. and M.B performed the proper motion analysis. F.R.F., B.L. and L.O. wrote the paper. S.M.R., R.M.R., R.T.R. and M.B. critically contributed to the paper presentation. All authors contributed to discussion of the results and commented on the manuscript.

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Correspondence to F. R. Ferraro.

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Ferraro, F., Dalessandro, E., Mucciarelli, A. et al. The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge. Nature 462, 483–486 (2009). https://doi.org/10.1038/nature08581

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