2018/12/04 by Baitian Tang, Chao Liu, J. G. Fernández-Trincado +6
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Galactic halo #Globular cluster #Halo #K-type main-sequence star #Kinematics #LAMOST #Stars #Stellar, planetary, and galactic studies #T Tauri star #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/aaf6b1
14 pages, 14 figures, ApJ accepted
arxiv created 2018/12/04 · openalex created_date 2018/12/11 · openalex publication_date 2019/01/20 · arxiv updated 2019/01/30 · openalex updated_date 2026/08/05
Abstract The large amount of chemical and kinematic information available in large spectroscopic surveys has inspired the search for chemically peculiar stars in the field. Though these metal-poor field stars ([Fe/H] < −1) are commonly enriched in nitrogen, their detailed spatial, kinematic, and chemical distributions suggest that various groups may exist, and thus their origin is still a mystery. To study these stars statistically, we increase the sample size by identifying new CN-strong stars with LAMOST DR3 for the first time. We use CN–CH bands around 4000 Å to find CN-strong stars, and further separate them into CH-normal stars (44) and CH-strong (or CH) stars (35). The chemical abundances from our data-driven software and APOGEE DR14 suggest that most CH-normal stars are N-rich, and this cannot be explained by an internal mixing process alone. The kinematics of our CH-normal stars indicate that a substantial fraction of these stars are retrograding, pointing to an extragalactic origin. The chemistry and kinematics of CH-normal stars imply that they may be stars dissolved from globular clusters, or accreted halo stars, or both.