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Space Science Reviews

, Volume 84, Issue 1–2, pp 139–144 | Cite as

The Low Metallicity Tail of the Halo Metallicity Distribution Function

  • T.C. Beers
  • S. Rossi
  • J.E. Norris
  • S.G. Ryan
  • P. Molaro
  • R. Rebolo
Article

Abstract

Ongoing spectroscopy and photometry of stars selected in the HK objective-prism/interference-filter survey of Beers and colleagues has resulted in the identification of many hundreds of additional stars in the halo (and possibly the thick disk) of the Galaxy with abundances [Fe/H] ≤ -2.0. A new calibration of the technique for estimation of metal abundance based on a CaII K index as a function of broadband B - V color is applied to obtain metallicities for stars observed with the SSO 2.3m and INT 2.5m telescopes. This new data is combined with other samples of extremely metal-deficient stars (Ryan and Norris, 1991a; Beers et al., 1992; Carney et al., 1994) to form a large database of objects of low metallicity. The combined sample is examined and compared with expectations derived from a Simple Model of Galactic chemical evolution. There appears to be a statistically-significant deficit of stars more metal-weak than [Fe/H] = -3.0. An abundance of [Fe/H] ≈ -4.0 can be taken as the low-metallicity limit for presently-observable stars in the Galaxy.

Keywords

Color Spectroscopy Distribution Function Simple Model Large Database 
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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Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • T.C. Beers
    • 1
  • S. Rossi
    • 1
  • J.E. Norris
    • 2
  • S.G. Ryan
    • 3
  • P. Molaro
    • 4
  • R. Rebolo
    • 5
  1. 1.Department of Physics & AstronomyMichigan State UniversityUSA
  2. 2.Mt. Stromlo & Siding Springs Observatory, Australian National UniversityAUSTRALIA
  3. 3.Royal Greenwich ObservatoryCambridgeUK
  4. 4.Osservatorio Astronomico di TriesteITALY
  5. 5.Instituto de Astrofisica de CanariasTenerifeCANARY ISLANDS

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