Investigating the Lower Limit of Metallicity for the Galactic Thin Disk
We explore the metal-poor regime of the Galactic disk on the distribution of stars in the [ α /M]– V _ϕ plane, to identify the most metal-poor thin disk (MPTnD) stars belonging to the low- α sequence. Chemical abundances and velocities of sample stars are either taken or derived from APOGEE DR17 and...
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| Language: | English |
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9c38 |
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| author | Guozhen Hu Zhengyi Shao Erbil Gügercinoǧlu Wenyuan Cui |
| author_facet | Guozhen Hu Zhengyi Shao Erbil Gügercinoǧlu Wenyuan Cui |
| author_sort | Guozhen Hu |
| collection | DOAJ |
| description | We explore the metal-poor regime of the Galactic disk on the distribution of stars in the [ α /M]– V _ϕ plane, to identify the most metal-poor thin disk (MPTnD) stars belonging to the low- α sequence. Chemical abundances and velocities of sample stars are either taken or derived from APOGEE DR17 and Gaia DR3 catalogs. We find the existence of a well-separated extension of the kinematically thin disk stars in the metallicity range of −1.2 < [M/H] < −0.8 dex. Based on two-by-two distributions of [Mg/Mn], [Al/Fe] and [C+N/Fe], we further confirmed 56 high-possibility metal-poor thin disk (HP-MPTnD) giant stars and suggested the lower metallicity limit of the thin disk below −0.95 dex. A comparative analysis of the HP-MPTnD sample with other Galactic components revealed its chemo-dynamical similarities with canonical thin disk stars. These low- α metal-poor stars are predominantly located in the outer disk region and formed in the early stage of the formation of thin disk. Their existence provides compelling support for the two-infall model of the Milky Way's disk formation. Moreover, these stars impose observational constraints on the timing and metallicity of the second gas infall event. |
| format | Article |
| id | doaj-art-522198bc38ba454c91f5e7a5e53fba51 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-522198bc38ba454c91f5e7a5e53fba512025-01-17T08:25:54ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0197915910.3847/1538-4357/ad9c38Investigating the Lower Limit of Metallicity for the Galactic Thin DiskGuozhen Hu0https://orcid.org/0000-0003-1828-5318Zhengyi Shao1https://orcid.org/0000-0001-8611-2465Erbil Gügercinoǧlu2Wenyuan Cui3https://orcid.org/0000-0003-1359-9908Department of Physics, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China; Physics Postdoctoral Research Station at Hebei Normal University , Shijiazhuang 050024, People’s Republic of China; Shanghai Astronomical Observatory , Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s Republic of China ; zyshao@shao.ac.cnShanghai Astronomical Observatory , Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s Republic of China ; zyshao@shao.ac.cn; Key Lab for Astrophysics , Shanghai 200234, People’s Republic of ChinaNational Astronomical Observatories , Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, People’s Republic of ChinaDepartment of Physics, Hebei Normal University , Shijiazhuang 050024, People’s Republic of ChinaWe explore the metal-poor regime of the Galactic disk on the distribution of stars in the [ α /M]– V _ϕ plane, to identify the most metal-poor thin disk (MPTnD) stars belonging to the low- α sequence. Chemical abundances and velocities of sample stars are either taken or derived from APOGEE DR17 and Gaia DR3 catalogs. We find the existence of a well-separated extension of the kinematically thin disk stars in the metallicity range of −1.2 < [M/H] < −0.8 dex. Based on two-by-two distributions of [Mg/Mn], [Al/Fe] and [C+N/Fe], we further confirmed 56 high-possibility metal-poor thin disk (HP-MPTnD) giant stars and suggested the lower metallicity limit of the thin disk below −0.95 dex. A comparative analysis of the HP-MPTnD sample with other Galactic components revealed its chemo-dynamical similarities with canonical thin disk stars. These low- α metal-poor stars are predominantly located in the outer disk region and formed in the early stage of the formation of thin disk. Their existence provides compelling support for the two-infall model of the Milky Way's disk formation. Moreover, these stars impose observational constraints on the timing and metallicity of the second gas infall event.https://doi.org/10.3847/1538-4357/ad9c38Galaxy abundancesGalaxy disksGalaxy formationGalaxy kinematicsGalaxy dynamicsGalaxy stellar content |
| spellingShingle | Guozhen Hu Zhengyi Shao Erbil Gügercinoǧlu Wenyuan Cui Investigating the Lower Limit of Metallicity for the Galactic Thin Disk The Astrophysical Journal Galaxy abundances Galaxy disks Galaxy formation Galaxy kinematics Galaxy dynamics Galaxy stellar content |
| title | Investigating the Lower Limit of Metallicity for the Galactic Thin Disk |
| title_full | Investigating the Lower Limit of Metallicity for the Galactic Thin Disk |
| title_fullStr | Investigating the Lower Limit of Metallicity for the Galactic Thin Disk |
| title_full_unstemmed | Investigating the Lower Limit of Metallicity for the Galactic Thin Disk |
| title_short | Investigating the Lower Limit of Metallicity for the Galactic Thin Disk |
| title_sort | investigating the lower limit of metallicity for the galactic thin disk |
| topic | Galaxy abundances Galaxy disks Galaxy formation Galaxy kinematics Galaxy dynamics Galaxy stellar content |
| url | https://doi.org/10.3847/1538-4357/ad9c38 |
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