Carbon-enhanced metal-poor stars in the SDSS--APOGEE data base.

We identify six new carbon-enhanced metal-poor (CEMP) stars ([C/Fe]>+0.7 and [Fe/H] < −1.8) and another seven likely candidates within the APOGEE data base following Data Release 12. These stars have chemical compositions typical of metal-poor halo stars, e.g. mean [α/Fe]=+0.24 ± 0.24, based on the APOGEE Stellar Parameters and Chemical Abundances Pipeline results. A lack of heavy-element spectral lines impedes further sub-classification of these CEMP stars, however, based on radial velocity (RV) scatter, we predict most are not CEMP-s stars which are typically found in binary systems. Only one object, 2M15312547+4220551, may be in a binary since it exhibits a scatter in its RV of 1.7 ± 0.6 km s-1 based on three visits over a 25.98 d baseline. Optical observations are now necessary to confirm the stellar parameters and low metallicities of these stars, to determine the heavy-element abundance ratios and improve the precision in the derived abundances, and to examine their CEMP sub-classifications. [ABSTRACT FROM AUTHOR]