Unveiling Galactic substructures with M Giant stars: A kinematic and chemical study based on LAMOST DR9, Gaia DR3 and APOGEE DR17
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| Autores principales: | , , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866911144887713792 |
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| author | Ding, Longfei Li, Jing Xue, Xiang-Xiang Tian, Hao Yan, Zhengzhou Zhao, Gang |
| author_facet | Ding, Longfei Li, Jing Xue, Xiang-Xiang Tian, Hao Yan, Zhengzhou Zhao, Gang |
| contents | Based on the updated M giant star catalog selected from LAMOST DR9, we iden-tify substructures within the integrals-of-motion space through Friends-of-Friends cluster-ing algorithm. We obtain members belonging to several known substructures: the Sagittarius stream, Galactic Anticenter Substructure (GASS), Gaia-Enceladus-Sausage (GES), Splash, and the high-α disk. Furthermore, we also identify two groups which cannot be clearly asso-ciated with previously known substructures. Our findings confirm the existence of metal-rich constituents within the GES, representing newly formed stars that originated from the metal-enriched gas delivered during the GES merger event and subsequently evolved. Additionally, this study further expands the sample of GASS, high-α disk, and Splash stars. Analysis of these metal-rich M giant stars as members of the GES, Splash, and high-α disk compo-nents supports an evolution scenario for the early Milky Way, as proposed by previous stud-ies. In this scenario, stars initially formed in a high-α primordial disk were dynamically heated by the massive accretion event (GES). This process redistributed stellar orbits, creat-ing the Splash population, while the undisturbed portion of the primordial disk persisted as the present-day high-α disk component. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_07744 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unveiling Galactic substructures with M Giant stars: A kinematic and chemical study based on LAMOST DR9, Gaia DR3 and APOGEE DR17 Ding, Longfei Li, Jing Xue, Xiang-Xiang Tian, Hao Yan, Zhengzhou Zhao, Gang Astrophysics of Galaxies Based on the updated M giant star catalog selected from LAMOST DR9, we iden-tify substructures within the integrals-of-motion space through Friends-of-Friends cluster-ing algorithm. We obtain members belonging to several known substructures: the Sagittarius stream, Galactic Anticenter Substructure (GASS), Gaia-Enceladus-Sausage (GES), Splash, and the high-α disk. Furthermore, we also identify two groups which cannot be clearly asso-ciated with previously known substructures. Our findings confirm the existence of metal-rich constituents within the GES, representing newly formed stars that originated from the metal-enriched gas delivered during the GES merger event and subsequently evolved. Additionally, this study further expands the sample of GASS, high-α disk, and Splash stars. Analysis of these metal-rich M giant stars as members of the GES, Splash, and high-α disk compo-nents supports an evolution scenario for the early Milky Way, as proposed by previous stud-ies. In this scenario, stars initially formed in a high-α primordial disk were dynamically heated by the massive accretion event (GES). This process redistributed stellar orbits, creat-ing the Splash population, while the undisturbed portion of the primordial disk persisted as the present-day high-α disk component. |
| title | Unveiling Galactic substructures with M Giant stars: A kinematic and chemical study based on LAMOST DR9, Gaia DR3 and APOGEE DR17 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2509.07744 |