The Case for the Dual Halo of the Milky Way

@article{Beers2012TheCF,
  title={The Case for the Dual Halo of the Milky Way},
  author={Timothy C. Beers and Daniela Carollo and Željko Ivezi{\'c} and Deokkeun An and Masashi Chiba and John E. Norris and Kenneth C. Freeman and Young Sun Lee and Jeffrey A. Munn and Paola Re Fiorentin and T. S. Sivarani and Ronald Wilhelm and Brian Yanny and Donald G. York Michigan State Univ. and Noao and Australian National Univ. and Macquarie Univ. and Australia. and University of Washington and Ehwa Womans Univ. and J Korea and Tohoku Univ. and Japan. and Usno and T. Wiklind Anglo-Australian Observatory and Italy. and Indian Institute of Astrophysics and Bangalore and University of Western Kentucky and Fermilab and University of Chicago},
  journal={The Astrophysical Journal},
  year={2012},
  volume={746},
  pages={34}
}
Carollo et al. have recently resolved the stellar population of the Milky Way halo into at least two distinct components, an inner halo and an outer halo. This result has been criticized by Schonrich et al., who claim that the retrograde signature associated with the outer halo is due to the adoption of faulty distances. We refute this claim, and demonstrate that the Schonrich et al. photometric distances are themselves flawed because they adopted an incorrect main-sequence absolute magnitude… 
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It is shown that the halo is indeed clearly divisible into two broadly overlapping structural components—an inner and an outer halo—that exhibit different spatial density profiles, stellar orbits and stellar metallicities (abundances of elements heavier than helium).
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On the alleged duality of the Galactic halo
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