Milky Way's Metal-Poor Stars display Chemical Transition near the Solar Radius
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arXiv
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866918122638802944 |
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| author | Malhan, Khyati |
| author_facet | Malhan, Khyati |
| contents | The metal-poor stars of a galaxy offer insights into that galaxy's early formation processes and accretion history. Here, we investigate whether the metal-poor stars of our Milky Way galaxy exhibit any characteristic trends in Galactocentric distance versus chemical abundances -- i.e. in the space of $r_{\rm GC}$ vs. [Fe/H] and $r_{\rm GC}$ vs. [X/Fe] -- and if yes, then what is their implication for Galaxy formation. We combine the datasets of APOGEE DR17 and $\textit{Gaia}$ DR3, where the former provides stellar abundances and the latter provides stellar parallaxes. We analyze bright ($G<13$) and metal-poor ([Fe/H]$<-1.2$) stars located far from the disk ($|z|\geq1$ kpc), and explore a total of $19$ abundances. We find that $9$ different abundances exhibit a drastic transition in their distribution near the Solar radius $r_{\rm GC}=8$ kpc. This trend is very unlikely to be related to radial migration, as our metal-poor sample does not contain any disk star. We also analyze the Gaia-Sausage/Enceladus stars, which is a dominant metal-poor population of the Galaxy, and find that it alone cannot account for this trend. This suggests that the Milky Way's metal-poor populations inside and outside the Solar radius likely originated from distinct chemical enrichment scenarios and formation processes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_08360 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Milky Way's Metal-Poor Stars display Chemical Transition near the Solar Radius Malhan, Khyati Astrophysics of Galaxies The metal-poor stars of a galaxy offer insights into that galaxy's early formation processes and accretion history. Here, we investigate whether the metal-poor stars of our Milky Way galaxy exhibit any characteristic trends in Galactocentric distance versus chemical abundances -- i.e. in the space of $r_{\rm GC}$ vs. [Fe/H] and $r_{\rm GC}$ vs. [X/Fe] -- and if yes, then what is their implication for Galaxy formation. We combine the datasets of APOGEE DR17 and $\textit{Gaia}$ DR3, where the former provides stellar abundances and the latter provides stellar parallaxes. We analyze bright ($G<13$) and metal-poor ([Fe/H]$<-1.2$) stars located far from the disk ($|z|\geq1$ kpc), and explore a total of $19$ abundances. We find that $9$ different abundances exhibit a drastic transition in their distribution near the Solar radius $r_{\rm GC}=8$ kpc. This trend is very unlikely to be related to radial migration, as our metal-poor sample does not contain any disk star. We also analyze the Gaia-Sausage/Enceladus stars, which is a dominant metal-poor population of the Galaxy, and find that it alone cannot account for this trend. This suggests that the Milky Way's metal-poor populations inside and outside the Solar radius likely originated from distinct chemical enrichment scenarios and formation processes. |
| title | Milky Way's Metal-Poor Stars display Chemical Transition near the Solar Radius |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2508.08360 |