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| Paper: |
Chemical Fingerprinting of Stellar Populations in the Milky Way Halo |
| Volume: |
458, Galactic Archaeology: Near-Field Cosmology and the Formation of the Milky Way |
| Page: |
209 |
| Authors: |
Chou, M.-Y.; Majewski, S. R.; Cunha, K.; Smith, V. V.; Patterson, R. J; Martínez-Delgado, D. |
| Abstract: |
The idea of “chemically fingerprinting” stars to their birth
systems has been discussed over the last decade. Here we present
an investigation of the chemical abundance patterns of halo
substructures using high-resolution spectra. In particular, we
study the abundances of the α-like element titanium (Ti)
and the s-process elements yttrium (Y) and lanthanum (La) for M
giant candidates of the Galactic Anticenter Stellar Structure
(GASS, also known as the Monoceros Ring) and the
Triangulum-Andromeda (TriAnd) Star Cloud. We apply “chemical
fingerprinting” to the GASS/Monoceros Ring and TriAnd Star Cloud,
to explore the origins of the two systems and the hypothesized
connections between them. GASS has been debated either to
originate from a part (e.g., warp) of the Galactic disk or tidal
debris of a disrupted Milky Way (MW) satellite galaxy. Our
exploration shows that GASS is indeed made of stars from a dwarf
spheroidal (dSph) galaxy, although we still can not rule out the
possibility that GASS was dynamically created out of a previously
formed outer MW disk. And whereas the TriAnd Star Cloud has been
assumed to come from the tidal disruption of the same accreted MW
satellite as the GASS/Monoceros Ring, our comparison of the
abundance patterns in GASS and TriAnd M giants suggests that the
TriAnd Star Cloud is likely an independent halo substructure
unrelated to GASS/Monoceros Ring. Furthermore, our findings also
suggest that the MW may have accreted other satellites in
addition to the on-going, well-known Sagittarius (Sgr) dwarf
galaxy. |
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