paper

Chemodynamics of newly identified giants with globular cluster like abundance patterns in the bulge, disk, and halo of the Milky Way

arXiv:1904.05369 · doi:10.1093/mnras/stz1848

Abstract

The latest edition of the APOGEE-2/DR14 survey catalogue and the first \texttt{Payne} data release of APOGEE abundance determinations by Ting et al. are examined. We identify 31 previously unremarked metal-poor giant stars with anomalously high levels of nitrogen in the chemical space defined by [Fe/H] and [N/Fe]. The APOGEE chemical abundance patterns of such objects revealed that these are chemically distinct from the Milky Way (MW) in most chemical elements. We have found all these objects have a [N/Fe], and are thus identified here as nitrogen-rich stars. An orbital analysis of these objects revealed that a handful of them shares the orbital properties of the bar/bulge, and possibly linked to tidal debris of surviving globular clusters trapped into the bar component. 3 of the 31 stars are actually halo interlopers into the bulge area, which suggests that halo contamination is not insignificant when studying N-rich stars found in the inner Galaxy, whereas the rest of the N-rich stars share orbital properties with the halo population. Most of the newly identified population exhibit chemistry similar to the so-called \textit{second-generation} globular cluster stars (enriched in aluminum, [Al/Fe]), whereas a handful of them exhibit lower abundances of aluminum, [Al/Fe], which are thought to be chemically associated with the \textit{first-generation} of stars, as seen in globular clusters, or compatible with origin from a tidally disrupted dwarf galaxy.

24 pages, 13 figures, 9 tables, submitted to MNRAS. Comments welcome!

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