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


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.


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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Audouze, J., and Silk, J.: 1995, ‘The First Generation of Stars: First Steps Toward Chemical Evolution of Galaxies’, ApJ 451, L49–L52.Google Scholar
  2. Beers, T.C., and Sommer-Larsen, J.: 1995, ‘Kinematics of Metal-Poor Stars in the Galaxy’, ApJS 96, 175–221.Google Scholar
  3. Beers, T.C., Preston, G.W., and Shectman, S.A.: 1992, ‘A Search for Stars of Very Low Metal Abundance. II.’, AJ 103, 1987–2034.Google Scholar
  4. Beers, T.C., Preston, G.W., Shectman, S.A., and Kage, J.A.: 1990, ‘Estimation of Stellar Metal Abundance. I. Calibration of the CaII K Index’, AJ 100, 849–883.Google Scholar
  5. Beers, T.C., Rossi, S., Norris, J.E., Ryan, S.G., and Shefler, T.: 1997, ‘Estimation of Stellar Metal Abundance. II. Refinements of the CaII K Technique and the Auto-correlation Technique’, in preparation.Google Scholar
  6. Carney, B.W., Latham, D.W., Laird, J.B., and Aguilar, L.A.: 1994, ‘A Survey of Proper Motion Stars. XII. An Expanded Sample’, AJ 107, 2240–2289.Google Scholar
  7. Edvardsson, B., Andersen, J., Gustafsson, B., Lambert, D.L., Nissen, P.E., and Tomkin, J.: 1993, ‘The Chemical Evolution of the Galactic Disk. I. Analysis and Results’, A&A 275, 101–152.Google Scholar
  8. Green, E.M., Demarque, P., and King, C.R.: 1987, ‘The Revised Yale Isochrones and Luminosity Functions’, Yale University Observatory, New Haven.Google Scholar
  9. Hartwick, F.D.A.: 1976, ‘The Chemical Evolution of the Galactic Halo’, ApJ 209, 418–423.Google Scholar
  10. Kurucz, R.L.: 1993, ‘CD-ROM 13: ATLAS9 Stellar Atmospheres Programs and 2 km/s Grid’, Smithsonian Astrophysical Observatory, Cambridge.Google Scholar
  11. Morrison, H.L., Flynn, C., and Freeman, K.C.: 1990, ‘Where Does the Disk Stop and the Halo Begin? Kinematics in a Rotation Field’, AJ 100, 1191–1222.Google Scholar
  12. Ratnatunga, K.U. and Freeman, K.C.: 1987, ‘Field K Giants in the Galactic Halo. II. Improved Abundance and Kinematic Parameters’, ApJ 339, 126–148.Google Scholar
  13. Ryan, S.G., and Norris, J.E.: 1991a, ‘Subdwarf Studies. II. Abundances and Kinematics from Medium Resolution Spectra’, AJ 101, 1835–1864.Google Scholar
  14. Ryan, S.G., and Norris, J.E.: 1991b, ‘Subdwarf Studies. III. The Halo Metallicity Distribution’, AJ 101, 1865–1878.Google Scholar
  15. Ryan, S.G., Norris, J.E., and Beers, T.C.: 1996, ‘Extremely Metal-Poor Stars. II. Elemental Abundances and the Early Chemical Enrichment of the Galaxy’, ApJ 471, 254–278.Google Scholar

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

Personalised recommendations