Cessateur, G.G.CessateurKeyser, J. DeJ. DeKeyserMaggiolo, R.R.MaggioloGibbons, A.A.GibbonsGronoff, G.G.GronoffGunell, H.H.GunellDhooghe, F.F.DhoogheLoreau, J.J.LoreauVaeck, N.N.VaeckAltwegg, KathrinKathrinAltwegg0000-0002-2677-8238Bieler, AndréAndréBieler0000-0002-0055-7808Briois, C.C.BrioisCalmonte, Ursina MariaUrsina MariaCalmonte0000-0002-0982-7501Combi, M. R.M. R.CombiFiethe, B.B.FietheFuselier, S. A.S. A.FuselierGombosi, T. I.T. I.GombosiHässig, MyrthaMyrthaHässig0000-0001-9255-3734Le Roy, LénaLénaLe Roy0000-0002-5984-6153Neefs, E.E.NeefsRubin, MartinMartinRubin0000-0001-6549-3318Sémon, ThierryThierrySémon2024-10-252024-10-252016https://boris-portal.unibe.ch/handle/20.500.12422/150912Observations of the green and red-doublet emission lines have previously been realized for several comets. We present here a chemistry-emission coupled model to study the production and loss mechanisms of the O(¹S) and O(¹D) states, which are responsible for the emission lines of interest for comet 67P/Churyumov-Gerasimenko. The recent discovery of O₂ in significant abundance relative to water 3.80 ± 0.85% within the coma of 67P has been taken into consideration for the first time in such models. We evaluate the effect of the presence of O₂ on the green to red-doublet emission intensity ratio, which is traditionally used to assess the CO₂ abundance within cometary atmospheres. Model simulations, solving the continuity equation with transport, show that not taking O₂ into account leads to an underestimation of the CO₂ abundance within 67P, with a relative error of about 25%. This strongly suggests that the green to red-doublet emission intensity ratio alone is not a proper tool for determining the CO₂ abundance, as previously suggested. Indeed, there is no compelling reason why O₂ would not be a common cometary volatile, making revision of earlier assessments regarding the CO₂ abundance in cometary atmospheres necessary. The large uncertainties of the CO₂ photodissociation cross section imply that more studies are required in order to better constrain the O(¹S) and O(¹D) production through this mechanism. Space weather phenomena, such as powerful solar flares, could be used as tools for doing so, providing additional information on a good estimation of the O₂ abundance within cometary atmospheres.en500 - Science::520 - Astronomy500 - Science::530 - Physics600 - Technology::620 - Engineeringarticle10.7892/boris.9721110.1002/2015ja022013