Detection of the actinide Th in an r-process-enhanced star with accretion origin
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arXiv
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| Auteurs principaux: | , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866911843666100224 |
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| author | Qianfan, Xing Gang, Zhao Wako, Aoki Haining, Li Jingkun, Zhao Tadafumi, Matsuno Takuma, Suda |
| author_facet | Qianfan, Xing Gang, Zhao Wako, Aoki Haining, Li Jingkun, Zhao Tadafumi, Matsuno Takuma, Suda |
| contents | The thorium and six second-peak r-process element (56<Z<72) abundances are determined for the alpha-poor star LAMOST J1124+4535 based on a high-resolution spectrum obtained with the High Dispersion Spectrograph (HDS) on the Subaru telescope. The age of J1124+4535 is 11.3$\pm$4.4 Gyr using thorium and other r-process element abundances. J1124+4535 is confirmed to be a Galactic halo metal-poor ([Fe/H] = -1.27$\pm$0.1) star with extreme r-process element over-abundance ([Eu/Fe] = 1.13$\pm$0.08) and alpha element deficiency ([Mg/Fe] = -0.31$\pm$0.09) by the LAMOST-Subaru project. Along with the sub-solar alpha to iron ratios (e.g. [Mg/Fe], [Si/Fe], [Ca/Fe]), the relatively low abundances of Na, Cr, Ni and Zn in J1124+4535 show significant departure from the general trends of the Galactic halo but are in good agreement with those of dwarf galaxies. The chemical abundances and kinematics of J1124+4535 suggest it was formed in the late stage of star formation in a dwarf galaxy which has been disrupted by the Milky Way (MW). The star formation of its progenitor dwarf galaxy lasted more than 2 Gyr and has been affected by a rare r-process event before the occurrence of accretion event. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_11069 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Detection of the actinide Th in an r-process-enhanced star with accretion origin Qianfan, Xing Gang, Zhao Wako, Aoki Haining, Li Jingkun, Zhao Tadafumi, Matsuno Takuma, Suda Astrophysics of Galaxies Solar and Stellar Astrophysics The thorium and six second-peak r-process element (56<Z<72) abundances are determined for the alpha-poor star LAMOST J1124+4535 based on a high-resolution spectrum obtained with the High Dispersion Spectrograph (HDS) on the Subaru telescope. The age of J1124+4535 is 11.3$\pm$4.4 Gyr using thorium and other r-process element abundances. J1124+4535 is confirmed to be a Galactic halo metal-poor ([Fe/H] = -1.27$\pm$0.1) star with extreme r-process element over-abundance ([Eu/Fe] = 1.13$\pm$0.08) and alpha element deficiency ([Mg/Fe] = -0.31$\pm$0.09) by the LAMOST-Subaru project. Along with the sub-solar alpha to iron ratios (e.g. [Mg/Fe], [Si/Fe], [Ca/Fe]), the relatively low abundances of Na, Cr, Ni and Zn in J1124+4535 show significant departure from the general trends of the Galactic halo but are in good agreement with those of dwarf galaxies. The chemical abundances and kinematics of J1124+4535 suggest it was formed in the late stage of star formation in a dwarf galaxy which has been disrupted by the Milky Way (MW). The star formation of its progenitor dwarf galaxy lasted more than 2 Gyr and has been affected by a rare r-process event before the occurrence of accretion event. |
| title | Detection of the actinide Th in an r-process-enhanced star with accretion origin |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2404.11069 |