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| Hauptverfasser: | , , , |
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| Format: | Preprint |
| Veröffentlicht: |
2025
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| Online-Zugang: | https://arxiv.org/abs/2508.12873 |
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| _version_ | 1866911110015221760 |
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| author | Bowesman, Charles A. Yurchenko, Sergei N. Al-Refaie, Ahmed Tennyson, Jonathan |
| author_facet | Bowesman, Charles A. Yurchenko, Sergei N. Al-Refaie, Ahmed Tennyson, Jonathan |
| contents | The TIRAMISU code, a new program for computing on-the-fly non-LTE molecular spectra and opacities for solving self-consistent radiative transfer problems in exoplanet atmospheres, is presented. The ultra-hot Jupiter KELT-20 b is used as a case study to identify the wavelength regions at which non-LTE effects may be detectable. It is shown that upper atmospheric OH in vibrational non-LTE should be observable primarily via hot bands in the mid-infrared and enhanced photodissociation in the visible. Varying the abundance of OH in non-LTE demonstrates a non-linear relationship between the abundance and the strength of non-LTE effects. Using recent calculations of the photodissociation probabilities of OH it is shown that non-LTE effects can increase the total photodissociation rate by two orders of magnitude in the upper atmosphere, which is likely to have a significant impact on atmospheric and chemical modelling. Increases and reductions in the molecular opacities under non-LTE conditions may lead to the mischaracterisation of molecular abundances in retrievals that only consider opacities computed under LTE. Collisional data requirements to support future non-LTE modelling for a variety of exoplanet atmospheres and across a wide range of wavelengths are discussed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_12873 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | TIRAMISU: Non-LTE radiative transfer for molecules in exoplanet atmospheres Bowesman, Charles A. Yurchenko, Sergei N. Al-Refaie, Ahmed Tennyson, Jonathan Earth and Planetary Astrophysics The TIRAMISU code, a new program for computing on-the-fly non-LTE molecular spectra and opacities for solving self-consistent radiative transfer problems in exoplanet atmospheres, is presented. The ultra-hot Jupiter KELT-20 b is used as a case study to identify the wavelength regions at which non-LTE effects may be detectable. It is shown that upper atmospheric OH in vibrational non-LTE should be observable primarily via hot bands in the mid-infrared and enhanced photodissociation in the visible. Varying the abundance of OH in non-LTE demonstrates a non-linear relationship between the abundance and the strength of non-LTE effects. Using recent calculations of the photodissociation probabilities of OH it is shown that non-LTE effects can increase the total photodissociation rate by two orders of magnitude in the upper atmosphere, which is likely to have a significant impact on atmospheric and chemical modelling. Increases and reductions in the molecular opacities under non-LTE conditions may lead to the mischaracterisation of molecular abundances in retrievals that only consider opacities computed under LTE. Collisional data requirements to support future non-LTE modelling for a variety of exoplanet atmospheres and across a wide range of wavelengths are discussed. |
| title | TIRAMISU: Non-LTE radiative transfer for molecules in exoplanet atmospheres |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2508.12873 |