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We explore the kinematics and orbital properties of a sample of 323 verymetal-poor stars in the halo system of the Milky Way, selected from thehigh-resolution spectroscopic follow-up studies of Aoki et al. and Yong et al.The combined sample contains a significant fraction of carbon-enhancedmetal-poor (CEMP) stars (22% or 29%, depending on whether a strict or relaxedcriterion is applied for this definition). Barium abundances (or upper limits)are available for the great majority of the CEMP stars, allowing for theirseparation into the CEMP-$s$ and CEMP-no sub-classes. A new method to assignmembership to the inner- and outer-halo populations of the Milky Way isdeveloped, making use of the integrals of motion, and applied to determine therelative fractions of CEMP stars in these two sub-classes for each halocomponent. Although limited by small-number statistics, the data suggest thatthe inner halo of the Milky Way exhibits a somewhat higher relative number ofCEMP-$s$ stars than CEMP-no stars (57% vs. 43%), while the outer halo possessesa clearly higher fraction of CEMP-no stars than CEMP-$s$ stars (70% vs. 30%).Although larger samples of CEMP stars with known Ba abundances are required,this result suggests that the dominant progenitors of CEMP stars in the twohalo components were different; massive stars for the outer halo, andintermediate-mass stars in the case of the inner halo.

Carbon-Enhanced Metal-Poor Stars: CEMP-s and CEMP-no Sub-Classes in the Halo System of the Milky Way