NORMAL AND OUTLYING POPULATIONS OF THE MILKY WAY STELLAR HALO AT [Fe/H] <−2

@article{Cohen2013NORMALAO,
  title={NORMAL AND OUTLYING POPULATIONS OF THE MILKY WAY STELLAR HALO AT [Fe/H] <−2},
  author={Judith G. Cohen and Norbert Christlieb and Ian B. Thompson and Andrew R. McWilliam and Stephen A. Shectman and Dieter Reimers and Lutz Wisotzki and Evan N. Kirby},
  journal={The Astrophysical Journal},
  year={2013},
  volume={778}
}
From detailed abundance analysis of >100 Hamburg/ESO candidate extremely metal-poor (EMP) stars we find 45 with [Fe/H] < −3.0 dex. We identify a heretofore unidentified group: Ca-deficient stars with sub-solar [Ca/Fe] ratios and the lowest neutron-capture abundances; the Ca-deficient group comprises ∼10% of the sample, excluding Carbon stars. Our radial velocity distribution shows that the carbon-enhanced stars with no s-process enhancements, CEMP-no, and which do not show C2 bands are not… 
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