Chemical Tagging N-rich Field Stars with High-resolution Spectroscopy
  We measure chemical abundances for over 20 elements of 15 N-rich field stars
with high resolution ($R \sim 30000$) optical spectra. We find that Na, Mg, Al,
Si, and Ca abundances of our N-rich field stars are mostly consistent with
those of stars from globular clusters (GCs). Seven stars are estimated to have
[Al/Fe$]>0.5$, which is not found in most GC "first generation" stars. On the
other hand, $\alpha$ element abundances (especially Ti) could show
distinguishable differences between in situ stars and accreted stars. We
discover that one interesting star, with consistently low [Mg/Fe], [Si/Fe],
[Ca/Fe], [Ti/Fe], [Sc/Fe], [V/Fe], and [Co/Fe], show similar kinematic and
[Ba/Eu] as other stars from the dissolved dwarf galaxy
"$Gaia$-Sausage-Enceladus". The $\alpha$-element abundances and the iron-peak
element abundances of the N-rich field stars with metallicities $-1.25 \le {\rm
[Fe/H]} \le -0.95$ show consistent values with Milky Way field stars rather
than stars from dwarf galaxies, indicating that they were formed in situ. In
addition, the neutron capture elements of N-rich field stars show that most of
them could be enriched by asymptotic giant branch (AGB) stars with masses
around $3 - 5\, M_{\odot}$.
