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High-temperature measurements of VUV-absorption cross sections of CO2 and their application to exoplanets

hal.structure.identifierSSE 2013
dc.contributor.authorVENOT, O.
hal.structure.identifierLaboratoire Interuniversitaire des Systèmes Atmosphériques [LISA (UMR_7583)]
dc.contributor.authorFRAY, Nicolas
hal.structure.identifierLaboratoire Interuniversitaire des Systèmes Atmosphériques [LISA (UMR_7583)]
dc.contributor.authorBÉNILAN, Yves
hal.structure.identifierLaboratoire Interuniversitaire des Systèmes Atmosphériques [LISA (UMR_7583)]
dc.contributor.authorGAZEAU, Marie-Claire
hal.structure.identifierSSE 2013
dc.contributor.authorHÉBRARD, Eric
dc.contributor.authorLARCHER, Gwenaelle
dc.contributor.authorSCHWELL, Martin
hal.structure.identifierSSE 2013
dc.contributor.authorDOBRIJEVIC, M.
hal.structure.identifierSSE 2013
dc.contributor.authorSELSIS, Franck
dc.date.created2013-02-12
dc.date.issued2013
dc.identifier.issn0004-6361
dc.description.abstractEnUV absorption cross sections are an essential ingredient of photochemical atmosphere models. Exoplanet searches have unveiled a large population of short-period objects with hot atmospheres, very different from what we find in our solar system. Transiting exoplanets whose atmospheres can now be studied by transit spectroscopy receive extremely strong UV fluxes and have typical temperatures ranging from 400 to 2500 K. At these temperatures, UV photolysis cross section data are severely lacking. Aims. Our goal is to provide high-temperature absorption cross sections and their temperature dependency for important atmospheric compounds. This study is dedicated to CO2, which is observed and photodissociated in exoplanet atmospheres. We also investigate the influence of these new data on the photochemistry of some exoplanets. We performed these measurements for the 115 - 200 nm range at 300, 410, 480, and 550 K. In the 195 - 230 nm range, we worked at seven temperatures between 465 and 800 K. We implemented the measured cross section into a 1D photochemical model. For wavelengths > 170 nm, the wavelength dependence of ln(cross-section_CO2(wavelength, T)x1/Qv(T)) can be parametrized with a linear law. Thus, we can interpolate cross-section_CO2(wavelength, T) at any temperature between 300 and 800 K. Within the studied range of temperature, the CO2 cross section can vary by more than two orders of magnitude. This, in particular, makes the absorption of CO2 significant up to wavelengths as high as 230 nm. The absorption cross section of CO2 is very sensitive to temperature. The model predicts that accounting for this temperature dependency of CO2 cross section can affect the computed abundances of NH3, CO2, and CO by one order of magnitude in the atmospheres of hot Jupiter and hot Neptune. This effect will be more important in hot CO2-dominated atmospheres.
dc.language.isoen
dc.publisherEDP Sciences
dc.title.enHigh-temperature measurements of VUV-absorption cross sections of CO2 and their application to exoplanets
dc.typeArticle de revue
dc.identifier.doi10.1051/0004-6361/201220945
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Planétologie et astrophysique de la terre [astro-ph.EP]
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Planétologie et astrophysique de la terre [astro-ph.EP]
dc.identifier.arxiv1302.2432
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.pageid.A131
bordeaux.volume551
bordeaux.peerReviewedoui
hal.identifierhal-00824850
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00824850v1
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