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An old, metal-rich accreted stellar component in the Milky Way stellar disk

Feuillet, Diane LU orcid ; Feltzing, Sofia LU orcid ; Sahlholdt, Christian LU and Bensby, Thomas LU orcid (2022) In Astrophysical Journal 934(1).
Abstract
We study the possibility that the Milky Ways' cool stellar disk includes mergers with ancient stars. Galaxies are understood to form in a hierarchical manner, where smaller (proto-)galaxies merge into larger ones. Stars in galaxies, like the Milky Way, contain in their motions and elemental abundance tracers of past events and can be used to disentangle merger remnants from stars that formed in the main galaxy. The merger history of the Milky Way is generally understood to be particularly easy to study in the stellar halo. The advent of the ESA astrometric satellite Gaia has enabled the detection of completely new structures in the halo such as the Gaia-Enceladus-Sausage. However, simulations also show that mergers may be important for the... (More)
We study the possibility that the Milky Ways' cool stellar disk includes mergers with ancient stars. Galaxies are understood to form in a hierarchical manner, where smaller (proto-)galaxies merge into larger ones. Stars in galaxies, like the Milky Way, contain in their motions and elemental abundance tracers of past events and can be used to disentangle merger remnants from stars that formed in the main galaxy. The merger history of the Milky Way is generally understood to be particularly easy to study in the stellar halo. The advent of the ESA astrometric satellite Gaia has enabled the detection of completely new structures in the halo such as the Gaia-Enceladus-Sausage. However, simulations also show that mergers may be important for the build-up of the cool stellar disks. Combining elemental abundances for ∼100 giant branch stars from APOGEE DR17 and astrometric data from Gaia we use elemental abundance ratios to find a hitherto unknown, old stellar component in the cool stellar disk in the Milky Way. We further identify a small sample of RR Lyrae variables with disk kinematics that also show the same chemical signature as the accreted red giant stars in the disk. These stars allow us to date the stars in the accreted component. We find that they are exclusively old. (Less)
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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Astrophysical Journal
volume
934
issue
1
article number
21
publisher
American Astronomical Society
external identifiers
  • scopus:85135110365
ISSN
0004-637X
DOI
10.3847/1538-4357/ac76ba
language
English
LU publication?
yes
id
d82ba9c5-84d7-4b76-8829-38bc1f7b3fbc
date added to LUP
2022-03-03 14:45:42
date last changed
2023-05-10 14:59:04
@article{d82ba9c5-84d7-4b76-8829-38bc1f7b3fbc,
  abstract     = {{We study the possibility that the Milky Ways' cool stellar disk includes mergers with ancient stars. Galaxies are understood to form in a hierarchical manner, where smaller (proto-)galaxies merge into larger ones. Stars in galaxies, like the Milky Way, contain in their motions and elemental abundance tracers of past events and can be used to disentangle merger remnants from stars that formed in the main galaxy. The merger history of the Milky Way is generally understood to be particularly easy to study in the stellar halo. The advent of the ESA astrometric satellite Gaia has enabled the detection of completely new structures in the halo such as the Gaia-Enceladus-Sausage. However, simulations also show that mergers may be important for the build-up of the cool stellar disks. Combining elemental abundances for ∼100 giant branch stars from APOGEE DR17 and astrometric data from Gaia we use elemental abundance ratios to find a hitherto unknown, old stellar component in the cool stellar disk in the Milky Way. We further identify a small sample of RR Lyrae variables with disk kinematics that also show the same chemical signature as the accreted red giant stars in the disk. These stars allow us to date the stars in the accreted component. We find that they are exclusively old.}},
  author       = {{Feuillet, Diane and Feltzing, Sofia and Sahlholdt, Christian and Bensby, Thomas}},
  issn         = {{0004-637X}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{American Astronomical Society}},
  series       = {{Astrophysical Journal}},
  title        = {{An old, metal-rich accreted stellar component in the Milky Way stellar disk}},
  url          = {{http://dx.doi.org/10.3847/1538-4357/ac76ba}},
  doi          = {{10.3847/1538-4357/ac76ba}},
  volume       = {{934}},
  year         = {{2022}},
}