Carbon isotope chemistry in protoplanetary disks: Effects of C/O ratios
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866909162965827584 |
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| author | Lee, Seokho Nomura, Hideko Furuya, Kenji |
| author_facet | Lee, Seokho Nomura, Hideko Furuya, Kenji |
| contents | Carbon isotope fractionation of CO has been reported in the disk around TW Hya,where elemental carbon is more abundant than elemental oxygen ([C/O]$_{\rm elem}$> 1). We investigated the effects of the [C/O]$_{\rm elem}$ ratio on carbon fractionation using astrochemical models that incorporate isotope-selective photodissociation and isotope-exchange reactions. The $^{12}$CO/$^{13}$CO ratio could be lower than the elemental carbon isotope ratio due to isotope exchange reactions when the [C/O]$_{\rm elem}$ ratio exceeds unity. The observed $^{12}$CO/$^{13}$CO and H$^{12}$CN/H$^{13}$CN ratios around TW Hya could be reproduced when the [C/O]$_{\rm elem}$ ratio is 2~5. In the vicinity of the lower boundary of the warm molecular layer, the formation of ices leads to the gas phase [C/O]$_{\rm elem}$ ratio approaching unity, irrespective of the total (gas + ice) [C/O]$_{\rm elem}$ ratio. This phenomenon reduces the variation in the $^{12}$CO/$^{13}$CO ratio across different [C/O]$_{\rm elem}$ ratios. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_01635 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Carbon isotope chemistry in protoplanetary disks: Effects of C/O ratios Lee, Seokho Nomura, Hideko Furuya, Kenji Astrophysics of Galaxies Earth and Planetary Astrophysics Carbon isotope fractionation of CO has been reported in the disk around TW Hya,where elemental carbon is more abundant than elemental oxygen ([C/O]$_{\rm elem}$> 1). We investigated the effects of the [C/O]$_{\rm elem}$ ratio on carbon fractionation using astrochemical models that incorporate isotope-selective photodissociation and isotope-exchange reactions. The $^{12}$CO/$^{13}$CO ratio could be lower than the elemental carbon isotope ratio due to isotope exchange reactions when the [C/O]$_{\rm elem}$ ratio exceeds unity. The observed $^{12}$CO/$^{13}$CO and H$^{12}$CN/H$^{13}$CN ratios around TW Hya could be reproduced when the [C/O]$_{\rm elem}$ ratio is 2~5. In the vicinity of the lower boundary of the warm molecular layer, the formation of ices leads to the gas phase [C/O]$_{\rm elem}$ ratio approaching unity, irrespective of the total (gas + ice) [C/O]$_{\rm elem}$ ratio. This phenomenon reduces the variation in the $^{12}$CO/$^{13}$CO ratio across different [C/O]$_{\rm elem}$ ratios. |
| title | Carbon isotope chemistry in protoplanetary disks: Effects of C/O ratios |
| topic | Astrophysics of Galaxies Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2404.01635 |