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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2509.22203 |
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| _version_ | 1866912821224144896 |
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| author | Huang, K. -Y. Méndez-Robayo, E. Viti, S. -G, Mario -A. Higuera |
| author_facet | Huang, K. -Y. Méndez-Robayo, E. Viti, S. -G, Mario -A. Higuera |
| contents | Context. Recent Monte Carlo simulations and laboratory studies of interstellar ices have proposed an alternative pathway involving the radical-molecule H-atom abstraction reaction in the overall mechanism of methanol (CH3OH) formation in dark molecular clouds. Aims. A computational study was conducted to investigate the contribution of the radical-molecule H-atom abstraction route in CH3OH formation in interstellar ices, both in non-shocked and shocked environments, and to examine how the physical conditions of the interstellar medium (ISM) affect the overall CH3OH synthesis pathway. Methods. A set of chemical models were ran using the gas-grain chemical code UCLCHEM to systematically explore methanol synthesis in various physical scenarios, including non-shock and low- and high-velocity C-shocks. Results. This work demonstrated for the first time that, under non-shock and shocked-influenced environments, the primary reaction leading to the formation of methanol in the inner layers of interstellar ices is indeed the radical-molecule H-atom abstraction route. However, such route is dependent on the gas kinetic temperature (Tk), gas volume density (nH2 ), velocity of the C-shock wave (vshock), and cosmic ray ionisation rate (ζ). Furthermore, gaseous formaldehyde may trace C-type shocks and serve to differentiate methanol formation pathways in low-velocity C-shocked environments, as its abundance varies more significantly than that of CH3OH with the inclusion of the H-atom abstraction reaction in UCLCHEM. The H2CO/CH3OH ratio thus represents a potential diagnostic tool for this purpose. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_22203 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Investigating solid-state CH3OH formation with chemical modelling Huang, K. -Y. Méndez-Robayo, E. Viti, S. -G, Mario -A. Higuera Astrophysics of Galaxies Context. Recent Monte Carlo simulations and laboratory studies of interstellar ices have proposed an alternative pathway involving the radical-molecule H-atom abstraction reaction in the overall mechanism of methanol (CH3OH) formation in dark molecular clouds. Aims. A computational study was conducted to investigate the contribution of the radical-molecule H-atom abstraction route in CH3OH formation in interstellar ices, both in non-shocked and shocked environments, and to examine how the physical conditions of the interstellar medium (ISM) affect the overall CH3OH synthesis pathway. Methods. A set of chemical models were ran using the gas-grain chemical code UCLCHEM to systematically explore methanol synthesis in various physical scenarios, including non-shock and low- and high-velocity C-shocks. Results. This work demonstrated for the first time that, under non-shock and shocked-influenced environments, the primary reaction leading to the formation of methanol in the inner layers of interstellar ices is indeed the radical-molecule H-atom abstraction route. However, such route is dependent on the gas kinetic temperature (Tk), gas volume density (nH2 ), velocity of the C-shock wave (vshock), and cosmic ray ionisation rate (ζ). Furthermore, gaseous formaldehyde may trace C-type shocks and serve to differentiate methanol formation pathways in low-velocity C-shocked environments, as its abundance varies more significantly than that of CH3OH with the inclusion of the H-atom abstraction reaction in UCLCHEM. The H2CO/CH3OH ratio thus represents a potential diagnostic tool for this purpose. |
| title | Investigating solid-state CH3OH formation with chemical modelling |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2509.22203 |