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

Feltzing, Sofia; Feuillet, Diane (2023-08-20). The Metal-weak Milky Way Stellar Disk Hidden in the Gaia–Sausage–Enceladus Debris : The APOGEE DR17 View. Astronomical Journal, 953, (2)
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| Published | English
Authors:
Feltzing, Sofia ; Feuillet, Diane
Department:
Lund Observatory - Has been reorganised
Department of Geology
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 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.

ISSN:
0004-6256
LUP-ID:
2379a565-90bc-4741-8362-9e9fafe96359 | Link: https://lup.lub.lu.se/record/2379a565-90bc-4741-8362-9e9fafe96359 | Statistics

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