Detection of the Actinide Th in an r-process-enhanced Star with Accretion Origin
The thorium and six second-peak r -process element (56 ≤ Z ≤ 72) abundances are determined for the α -poor star LAMOST J1124+4535 based on a high-resolution spectrum obtained with the High Dispersion Spectrograph on the Subaru Telescope. The age of J1124+4535 is 11.3 ± 4.4 Gyr using thorium and othe...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad2fa4 |
| _version_ | 1797216219867119616 |
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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 |
| author_sort | Qianfan Xing |
| collection | DOAJ |
| description | The thorium and six second-peak r -process element (56 ≤ Z ≤ 72) abundances are determined for the α -poor star LAMOST J1124+4535 based on a high-resolution spectrum obtained with the High Dispersion Spectrograph on the Subaru Telescope. The age of J1124+4535 is 11.3 ± 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 ± 0.1) star with extreme r -process element overabundance ([Eu/Fe] = 1.13 ± 0.08) and α element deficiency ([Mg/Fe] = −0.31 ± 0.09) by the LAMOST-Subaru project. Along with the subsolar α- 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 a 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 that has been disrupted by the Milky Way. 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. |
| first_indexed | 2024-04-24T11:42:29Z |
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| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-04-24T11:42:29Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj.art-39601ba6a6504ee894c9926e32f9ec4c2024-04-09T18:15:19ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-0196517910.3847/1538-4357/ad2fa4Detection of the Actinide Th in an r-process-enhanced Star with Accretion OriginQianfan Xing0https://orcid.org/0000-0003-0663-3100Gang Zhao1https://orcid.org/0000-0002-8980-945XWako Aoki2https://orcid.org/0000-0002-8975-6829Haining Li3https://orcid.org/0000-0002-0389-9264Jingkun Zhao4https://orcid.org/0000-0003-2868-8276Tadafumi Matsuno5https://orcid.org/0000-0002-8077-4617Takuma Suda6https://orcid.org/0000-0002-4318-8715Key Lab of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences (CAS) A20 Datun Road, Chaoyang, Beijing 100101, People's Republic of China ; qfxing@nao.cas.cn, gzhao@nao.cas.cnKey Lab of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences (CAS) A20 Datun Road, Chaoyang, Beijing 100101, People's Republic of China ; qfxing@nao.cas.cn, gzhao@nao.cas.cn; School of Astronomy and Space Science, University of Chinese Academy of Sciences , No.19(A) Yuquan Road, Shijingshan District, Beijing 100049, People's Republic of ChinaNational Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Astronomical Science Program, Graduate Institute for Advanced Studies, SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanKey Lab of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences (CAS) A20 Datun Road, Chaoyang, Beijing 100101, People's Republic of China ; qfxing@nao.cas.cn, gzhao@nao.cas.cnKey Lab of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences (CAS) A20 Datun Road, Chaoyang, Beijing 100101, People's Republic of China ; qfxing@nao.cas.cn, gzhao@nao.cas.cnNational Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Astronomical Science Program, Graduate Institute for Advanced Studies, SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Astronomisches Rechen-Institut , Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, 69120 Heidelberg, GermanyDepartment of Liberal Arts, Tokyo University of Technology , Nishi Kamata 5-23-22, Ota-ku, Tokyo 144-8535, Japan; Research Center for the Early Universe, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, JapanThe thorium and six second-peak r -process element (56 ≤ Z ≤ 72) abundances are determined for the α -poor star LAMOST J1124+4535 based on a high-resolution spectrum obtained with the High Dispersion Spectrograph on the Subaru Telescope. The age of J1124+4535 is 11.3 ± 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 ± 0.1) star with extreme r -process element overabundance ([Eu/Fe] = 1.13 ± 0.08) and α element deficiency ([Mg/Fe] = −0.31 ± 0.09) by the LAMOST-Subaru project. Along with the subsolar α- 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 a 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 that has been disrupted by the Milky Way. 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.https://doi.org/10.3847/1538-4357/ad2fa4Milky Way stellar haloStellar abundancesGalaxy mergers |
| spellingShingle | Qianfan Xing Gang Zhao Wako Aoki Haining Li Jingkun Zhao Tadafumi Matsuno Takuma Suda Detection of the Actinide Th in an r-process-enhanced Star with Accretion Origin The Astrophysical Journal Milky Way stellar halo Stellar abundances Galaxy mergers |
| title | Detection of the Actinide Th in an r-process-enhanced Star with Accretion Origin |
| title_full | Detection of the Actinide Th in an r-process-enhanced Star with Accretion Origin |
| title_fullStr | Detection of the Actinide Th in an r-process-enhanced Star with Accretion Origin |
| title_full_unstemmed | Detection of the Actinide Th in an r-process-enhanced Star with Accretion Origin |
| title_short | Detection of the Actinide Th in an r-process-enhanced Star with Accretion Origin |
| title_sort | detection of the actinide th in an r process enhanced star with accretion origin |
| topic | Milky Way stellar halo Stellar abundances Galaxy mergers |
| url | https://doi.org/10.3847/1538-4357/ad2fa4 |
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