Gas-phase Molecules in Protoplanetary Nebulae with the 21 μm Emission Feature II. Carbon monosulfide
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arXiv
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| Autori principali: | , , , , , , , , , |
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| Natura: | Preprint |
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2025
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| author | Qiu, Jian-Jie Zhang, Yong Lu, Deng-Rong Chang, Zheng-Xue Zhang, Jiang-Shui Li, Xiao-Hu Tang, Xin-Di Qiu, Yisheng Nakashima, Jun-ichi Jia, Lan-Wei |
| author_facet | Qiu, Jian-Jie Zhang, Yong Lu, Deng-Rong Chang, Zheng-Xue Zhang, Jiang-Shui Li, Xiao-Hu Tang, Xin-Di Qiu, Yisheng Nakashima, Jun-ichi Jia, Lan-Wei |
| contents | The carrier of the 21 $μ$m emission feature discovered in a handful of protoplanetary nebulae (PPNe) is one of the most intriguing enigmas in circumstellar chemistry. Investigating the gas-phase molecules in PPNe could yield important hints for understanding the 21 $μ$m feature. In this paper, we report observations of the CS $J = 5 \to 4$ line at 245 GHz and the CO $J = 1 \to 0$ line at 115 GHz toward seven PPNe exhibiting the 21 $μ$m feature. We find that CS is extremely scarce in these PPNe and the CS line is only detected in one source, IRAS Z02229+6208. Based on the assumption of local thermal equilibrium and negligible optical depth, we derive that the CS column densities and fractional abundances relative to H$_{2}$ are $N$(CS) < 9.1 ${\times}$ 10$^{13}$cm$^{-2}$ and $f$(CS) < 8.1 ${\times}$ 10$^{-7}$. A comparison of the CS abundances across different circumstellar envelopes reveals that the variations in CS abundance are complex, depending not only on the evolutionary stages but also on the properties of individual objects. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_13629 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Gas-phase Molecules in Protoplanetary Nebulae with the 21 μm Emission Feature II. Carbon monosulfide Qiu, Jian-Jie Zhang, Yong Lu, Deng-Rong Chang, Zheng-Xue Zhang, Jiang-Shui Li, Xiao-Hu Tang, Xin-Di Qiu, Yisheng Nakashima, Jun-ichi Jia, Lan-Wei Astrophysics of Galaxies Solar and Stellar Astrophysics Chemical Physics The carrier of the 21 $μ$m emission feature discovered in a handful of protoplanetary nebulae (PPNe) is one of the most intriguing enigmas in circumstellar chemistry. Investigating the gas-phase molecules in PPNe could yield important hints for understanding the 21 $μ$m feature. In this paper, we report observations of the CS $J = 5 \to 4$ line at 245 GHz and the CO $J = 1 \to 0$ line at 115 GHz toward seven PPNe exhibiting the 21 $μ$m feature. We find that CS is extremely scarce in these PPNe and the CS line is only detected in one source, IRAS Z02229+6208. Based on the assumption of local thermal equilibrium and negligible optical depth, we derive that the CS column densities and fractional abundances relative to H$_{2}$ are $N$(CS) < 9.1 ${\times}$ 10$^{13}$cm$^{-2}$ and $f$(CS) < 8.1 ${\times}$ 10$^{-7}$. A comparison of the CS abundances across different circumstellar envelopes reveals that the variations in CS abundance are complex, depending not only on the evolutionary stages but also on the properties of individual objects. |
| title | Gas-phase Molecules in Protoplanetary Nebulae with the 21 μm Emission Feature II. Carbon monosulfide |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics Chemical Physics |
| url | https://arxiv.org/abs/2508.13629 |