Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357
We report on the chemical composition of the very metal-poor (VMP; [Fe/H] = −2.9) star LAMOST J1645+4357, which was identified as a red giant having peculiar abundance ratios by Li et al. The standard abundance analysis is carried out for this object and the well-studied metal-poor star HD 122563, w...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acf1f8 |
| _version_ | 1797686003357450240 |
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| author | Wako Aoki Haining Li Nozomu Tominaga Tadafumi Matsuno Satoshi Honda Gang Zhao |
| author_facet | Wako Aoki Haining Li Nozomu Tominaga Tadafumi Matsuno Satoshi Honda Gang Zhao |
| author_sort | Wako Aoki |
| collection | DOAJ |
| description | We report on the chemical composition of the very metal-poor (VMP; [Fe/H] = −2.9) star LAMOST J1645+4357, which was identified as a red giant having peculiar abundance ratios by Li et al. The standard abundance analysis is carried out for this object and the well-studied metal-poor star HD 122563, which has similar atmospheric parameters. LAMOST J1645+4357 has a remarkable abundance set, highlighted by these features: (1) nitrogen is significantly enhanced ([N/Fe] = +1.4), and the total abundance of C and N is also very high ([(C+N)/Fe] = +0.9); (2) α -elements are overabundant with respect to iron, as generally found in VMP stars; (3) Ti, Sc, Co, and Zn are significantly deficient; (4) Cr and Mn are enhanced compared to most of VMP stars; and (5) Sr and Ba are deficient, and the Sr/Ba ratio ([Sr/Ba] = −1.0) is significantly lower than the value expected for the r -process. The overall abundance pattern of this object from C to Zn is well reproduced by a faint supernova model assuming spherical explosion, except for the excess of Cr and Mn, which requires enhancement of incomplete Si burning or small contributions from a Type Ia or pair-instability supernova. There remains, however, a question as to why the abundance pattern of this star is so unique among VMP stars. |
| first_indexed | 2024-03-12T00:59:23Z |
| format | Article |
| id | doaj.art-a312dacad539445fad7b2d427bd35145 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T00:59:23Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-a312dacad539445fad7b2d427bd351452023-09-14T09:49:19ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195512810.3847/1538-4357/acf1f8Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357Wako Aoki0https://orcid.org/0000-0002-8975-6829Haining Li1https://orcid.org/0000-0002-0389-9264Nozomu Tominaga2Tadafumi Matsuno3https://orcid.org/0000-0002-8077-4617Satoshi Honda4https://orcid.org/0000-0001-6653-8741Gang Zhao5https://orcid.org/0000-0002-8980-945XNational Astronomical Observatory of Japan, National Institutes of Natural Sciences , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan ; aoki.wako@nao.ac.jp; 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 , A20 Datun Road, Chaoyang, Beijing 100012, People’s Republic of ChinaNational Astronomical Observatory of Japan, National Institutes of Natural Sciences , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan ; aoki.wako@nao.ac.jp; Astronomical Science Program, Graduate Institute for Advanced Studies , SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Department of Physics, Faculty of Science and Engineering, Konan University , 8-9-1 Okamoto, Kobe, Hyogo 658-8501, JapanKapteyn Astronomical Institute, University of Groningen , Landleven 12, 9747 AD Groningen, The NetherlandsNishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo , 407-2, Nishigaichi, Sayo-cho, Sayo, Hyogo 679-5313, JapanKey Lab of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences , A20 Datun Road, Chaoyang, Beijing 100012, People’s Republic of ChinaWe report on the chemical composition of the very metal-poor (VMP; [Fe/H] = −2.9) star LAMOST J1645+4357, which was identified as a red giant having peculiar abundance ratios by Li et al. The standard abundance analysis is carried out for this object and the well-studied metal-poor star HD 122563, which has similar atmospheric parameters. LAMOST J1645+4357 has a remarkable abundance set, highlighted by these features: (1) nitrogen is significantly enhanced ([N/Fe] = +1.4), and the total abundance of C and N is also very high ([(C+N)/Fe] = +0.9); (2) α -elements are overabundant with respect to iron, as generally found in VMP stars; (3) Ti, Sc, Co, and Zn are significantly deficient; (4) Cr and Mn are enhanced compared to most of VMP stars; and (5) Sr and Ba are deficient, and the Sr/Ba ratio ([Sr/Ba] = −1.0) is significantly lower than the value expected for the r -process. The overall abundance pattern of this object from C to Zn is well reproduced by a faint supernova model assuming spherical explosion, except for the excess of Cr and Mn, which requires enhancement of incomplete Si burning or small contributions from a Type Ia or pair-instability supernova. There remains, however, a question as to why the abundance pattern of this star is so unique among VMP stars.https://doi.org/10.3847/1538-4357/acf1f8Stellar abundancesNucleosynthesisPopulation II stars |
| spellingShingle | Wako Aoki Haining Li Nozomu Tominaga Tadafumi Matsuno Satoshi Honda Gang Zhao Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357 The Astrophysical Journal Stellar abundances Nucleosynthesis Population II stars |
| title | Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357 |
| title_full | Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357 |
| title_fullStr | Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357 |
| title_full_unstemmed | Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357 |
| title_short | Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357 |
| title_sort | unique chemical composition of the very metal poor star lamost j1645 4357 |
| topic | Stellar abundances Nucleosynthesis Population II stars |
| url | https://doi.org/10.3847/1538-4357/acf1f8 |
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