Speaker
Description
The assembly history of our Galaxy is encoded in the chemodynamical properties of its stellar populations. In this talk, I will present our work on 88,959 K-giant stars selected from three years of data from the DESI Milky Way Survey (MWS) to characterize our Galaxy’s distant stellar halo. Running HDBSCAN, a density-based clustering algorithm on integrals of motion (Energy, Lz, L⊥) and velocity (Vr, VΦ, Vz) , we identified some of the most prominent structures in the stellar halo, such as the Gaia Sausage/Enceladus (GSE), Sagittarius, Aleph, Cetus-Palca stream and the Orphan-Chenab stream. We also explored how distance uncertainties affect this substructure finding approach.
Furthermore, we studied the metallicity distribution (MDF) of the prograde and retrograde stars with high angular momentum that are not assigned to structures by HDBSCAN (the bulk stellar halo), and found they show a similar bimodal distribution, which do not resemble those of Sagittarius or GSE. In contrast, the MDF of the stars in the bulk halo with lower angular momentum appeared similar to that of the GSE. Based on these results, we discuss different GSE accretion scenarios, as well as future directions for characterizing smaller and fainter stellar halo structures to improve our understanding of the Milky Way's evolutionary history.
| Participate the oral/poster presentation award competition | No |
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