Semiclassical Estimates of Pressure-induced Line Widths for Infrared Absorption in Hot (Exo)planetary Atmospheres
Because of elevated temperatures and high fluxes of stellar radiation irreproducible in laboratory conditions, molecules and molecular ions found or expected in exoplanetary atmospheres are generally poorly characterized from the viewpoint of their spectroscopic line-shape parameters; in many cases,...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4365/ad9b19 |
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| author | Jeanna Buldyreva Kathleen Stehlin Sergei N. Yurchenko Elizabeth R. Guest Jonathan Tennyson |
| author_facet | Jeanna Buldyreva Kathleen Stehlin Sergei N. Yurchenko Elizabeth R. Guest Jonathan Tennyson |
| author_sort | Jeanna Buldyreva |
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| description | Because of elevated temperatures and high fluxes of stellar radiation irreproducible in laboratory conditions, molecules and molecular ions found or expected in exoplanetary atmospheres are generally poorly characterized from the viewpoint of their spectroscopic line-shape parameters; in many cases, there are no data at all. Advanced theoretical approaches (classical, semiclassical, and quantum mechanical), without mentioning their high computational cost, are also impracticable due to the lack of potential energy surfaces. To fill this gap of crucially missing line-broadening parameters, we provide estimated values issued from a simple rotationally independent semiclassical expression. Only the index related to the leading long-range interaction term, molecular masses and kinetic diameters, as well as temperature are used as input parameters. A wide range of absorbers and perturbation by He, Ar, H _2 , N _2 , O _2 , CO, NO, CO _2 , H _2 O, CH _4 , and NH _3 as well as self-perturbation are considered. The explicit temperature dependence T ^−0.5 allows calculations to be limited to the single reference temperature of 296 K; for other temperatures a simple scaling can be used. The full set of line-broadening coefficients obtained with various possible values of kinetic diameters is provided by the new Collisional Line-broadening Parameters database, which is specifically designed for this purpose. “Midvalue” (or more recent) kinetic diameters are retained to create one-value line-broadening data required to populate the ExoMol database. A way to generate rotationally dependent line widths is proposed. |
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| institution | Kabale University |
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| language | English |
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| spelling | doaj-art-457c294cf00a42889560e74fb657d9532025-01-09T06:51:50ZengIOP PublishingThe Astrophysical Journal Supplement Series0067-00492025-01-0127612310.3847/1538-4365/ad9b19Semiclassical Estimates of Pressure-induced Line Widths for Infrared Absorption in Hot (Exo)planetary AtmospheresJeanna Buldyreva0Kathleen Stehlin1Sergei N. Yurchenko2https://orcid.org/0000-0001-9286-9501Elizabeth R. Guest3Jonathan Tennyson4https://orcid.org/0000-0002-4994-5238Institut UTINAM, UMR 6213 CNRS, Université de Franche-Comté , 16 Route de Gray, Besançon cedex, 25030, France ; jeanna.buldyreva@univ-fcomte.frInstitut UTINAM, UMR 6213 CNRS, Université de Franche-Comté , 16 Route de Gray, Besançon cedex, 25030, France ; jeanna.buldyreva@univ-fcomte.frDepartment of Physics and Astronomy, University College London , Gower Street, London, WC1E 6BT, UK ; s.yurchenko@ucl.ac.ukDepartment of Physics and Astronomy, University College London , Gower Street, London, WC1E 6BT, UK ; s.yurchenko@ucl.ac.ukDepartment of Physics and Astronomy, University College London , Gower Street, London, WC1E 6BT, UK ; s.yurchenko@ucl.ac.ukBecause of elevated temperatures and high fluxes of stellar radiation irreproducible in laboratory conditions, molecules and molecular ions found or expected in exoplanetary atmospheres are generally poorly characterized from the viewpoint of their spectroscopic line-shape parameters; in many cases, there are no data at all. Advanced theoretical approaches (classical, semiclassical, and quantum mechanical), without mentioning their high computational cost, are also impracticable due to the lack of potential energy surfaces. To fill this gap of crucially missing line-broadening parameters, we provide estimated values issued from a simple rotationally independent semiclassical expression. Only the index related to the leading long-range interaction term, molecular masses and kinetic diameters, as well as temperature are used as input parameters. A wide range of absorbers and perturbation by He, Ar, H _2 , N _2 , O _2 , CO, NO, CO _2 , H _2 O, CH _4 , and NH _3 as well as self-perturbation are considered. The explicit temperature dependence T ^−0.5 allows calculations to be limited to the single reference temperature of 296 K; for other temperatures a simple scaling can be used. The full set of line-broadening coefficients obtained with various possible values of kinetic diameters is provided by the new Collisional Line-broadening Parameters database, which is specifically designed for this purpose. “Midvalue” (or more recent) kinetic diameters are retained to create one-value line-broadening data required to populate the ExoMol database. A way to generate rotationally dependent line widths is proposed.https://doi.org/10.3847/1538-4365/ad9b19Molecular dataMolecular spectroscopyCollisional broadeningExoplanet atmospheresStellar atmospheric opacity |
| spellingShingle | Jeanna Buldyreva Kathleen Stehlin Sergei N. Yurchenko Elizabeth R. Guest Jonathan Tennyson Semiclassical Estimates of Pressure-induced Line Widths for Infrared Absorption in Hot (Exo)planetary Atmospheres The Astrophysical Journal Supplement Series Molecular data Molecular spectroscopy Collisional broadening Exoplanet atmospheres Stellar atmospheric opacity |
| title | Semiclassical Estimates of Pressure-induced Line Widths for Infrared Absorption in Hot (Exo)planetary Atmospheres |
| title_full | Semiclassical Estimates of Pressure-induced Line Widths for Infrared Absorption in Hot (Exo)planetary Atmospheres |
| title_fullStr | Semiclassical Estimates of Pressure-induced Line Widths for Infrared Absorption in Hot (Exo)planetary Atmospheres |
| title_full_unstemmed | Semiclassical Estimates of Pressure-induced Line Widths for Infrared Absorption in Hot (Exo)planetary Atmospheres |
| title_short | Semiclassical Estimates of Pressure-induced Line Widths for Infrared Absorption in Hot (Exo)planetary Atmospheres |
| title_sort | semiclassical estimates of pressure induced line widths for infrared absorption in hot exo planetary atmospheres |
| topic | Molecular data Molecular spectroscopy Collisional broadening Exoplanet atmospheres Stellar atmospheric opacity |
| url | https://doi.org/10.3847/1538-4365/ad9b19 |
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