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The Metal-weak Milky Way Stellar Disk Hidden in the Gaia–Sausage–Enceladus Debris : The APOGEE DR17 View

Feltzing, Sofia LU orcid and Feuillet, Diane LU orcid (2023) In Astronomical Journal 953(2).
Abstract

We have for the first time identified the early stellar disk in the Milky Way by using a combination of elemental abundances and kinematics. Using data from APOGEE DR17 and Gaia we select stars in the Mg–Mn–Al–Fe plane with elemental abundances indicative of an accreted origin and find stars with both halo-like and disk-like kinematics. The stars with halo-like kinematics lie along a lower sequence in [Mg/Fe], while the stars with disklike kinematics lie along a higher sequence. Combined with astroseismic observations, we determine that the stars with halo-like kinematics are old, 9–11 Gyr, and that the more evolved stellar disk is about 1–2 Gyr younger. We show that the in situ fraction of stars on deeply bound orbits is not small, in... (More)

We have for the first time identified the early stellar disk in the Milky Way by using a combination of elemental abundances and kinematics. Using data from APOGEE DR17 and Gaia we select stars in the Mg–Mn–Al–Fe plane with elemental abundances indicative of an accreted origin and find stars with both halo-like and disk-like kinematics. The stars with halo-like kinematics lie along a lower sequence in [Mg/Fe], while the stars with disklike kinematics lie along a higher sequence. Combined with astroseismic observations, we determine that the stars with halo-like kinematics are old, 9–11 Gyr, and that the more evolved stellar disk is about 1–2 Gyr younger. We show that the in situ fraction of stars on deeply bound orbits is not small, in fact the inner Galaxy likely harbors a genuine in situ population together with an accreted one. In addition, we show that the selection of the Gaia–Sausage–Enceladus in the En−Lz plane is not very robust. In fact, radically different selection criteria give almost identical elemental abundance signatures for the accreted stars.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Astronomical Journal
volume
953
issue
2
article number
143
publisher
IOP Publishing
external identifiers
  • scopus:85176406845
ISSN
0004-6256
DOI
10.3847/1538-4357/ace185
language
English
LU publication?
yes
id
2379a565-90bc-4741-8362-9e9fafe96359
date added to LUP
2023-12-14 13:20:01
date last changed
2024-04-13 05:16:45
@article{2379a565-90bc-4741-8362-9e9fafe96359,
  abstract     = {{<p>We have for the first time identified the early stellar disk in the Milky Way by using a combination of elemental abundances and kinematics. Using data from APOGEE DR17 and Gaia we select stars in the Mg–Mn–Al–Fe plane with elemental abundances indicative of an accreted origin and find stars with both halo-like and disk-like kinematics. The stars with halo-like kinematics lie along a lower sequence in [Mg/Fe], while the stars with disklike kinematics lie along a higher sequence. Combined with astroseismic observations, we determine that the stars with halo-like kinematics are old, 9–11 Gyr, and that the more evolved stellar disk is about 1–2 Gyr younger. We show that the in situ fraction of stars on deeply bound orbits is not small, in fact the inner Galaxy likely harbors a genuine in situ population together with an accreted one. In addition, we show that the selection of the Gaia–Sausage–Enceladus in the E<sub>n</sub>−L<sub>z</sub> plane is not very robust. In fact, radically different selection criteria give almost identical elemental abundance signatures for the accreted stars.</p>}},
  author       = {{Feltzing, Sofia and Feuillet, Diane}},
  issn         = {{0004-6256}},
  language     = {{eng}},
  month        = {{08}},
  number       = {{2}},
  publisher    = {{IOP Publishing}},
  series       = {{Astronomical Journal}},
  title        = {{The Metal-weak Milky Way Stellar Disk Hidden in the Gaia–Sausage–Enceladus Debris : The APOGEE DR17 View}},
  url          = {{http://dx.doi.org/10.3847/1538-4357/ace185}},
  doi          = {{10.3847/1538-4357/ace185}},
  volume       = {{953}},
  year         = {{2023}},
}