We identify six new CEMP stars ([C/Fe]>+0.7 and [Fe/H]< -1.8) and another seven likely candidates within the APOGEE database 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 ASPCAP pipeline results. A lack of heavy element spectral lines impedes further sub-classification of these CEMP stars, however, based on radial velocity 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 radial velocity of 1.7 ±0.6 km s−1 based on three visits over a 25.98 day 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.
@article{arxiv.1707.02310,
title = {Carbon-enhanced metal-poor stars in the SDSS-APOGEE database},
author = {Collin L. Kielty and Kim A. Venn and Nicholas B. Loewen and Matthew D. Shetrone and Vinicius M. Placco and Farbod Jahandar and Szabolcs Mészáros and Sarah L. Martell},
journal= {arXiv preprint arXiv:1707.02310},
year = {2017}
}
Comments
20 pages, 9 tables, 9 figures: Accepted for publication in MNRAS