Diane Feuillet
Forskare
An old, metal-rich accreted stellar component in the Milky Way stellar disk
Författare
Summary, in English
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.
Avdelning/ar
- Astronomi - Har omorganiserats
Publiceringsår
2022
Språk
Engelska
Publikation/Tidskrift/Serie
Astrophysical Journal
Volym
934
Issue
1
Dokumenttyp
Artikel i tidskrift
Förlag
American Astronomical Society
Ämne
- Astronomy, Astrophysics and Cosmology
Aktiv
Published
ISBN/ISSN/Övrigt
- ISSN: 0004-637X