Reference : EUV spectroscopy of the Venus dayglow with UVIS on Cassini
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/100141
EUV spectroscopy of the Venus dayglow with UVIS on Cassini
English
Gérard, Jean-Claude mailto [Institut d'Astrophysique et Géophysique, Université de Liège, B5c 17, allée du 6 août, B-4000 Liège, Belgium]
Hubert, Benoît mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)]
Gustin, Jacques mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)]
Shematovich, V. I. [Institute of Astronomy of the Russian Academy of Sciences, 48 Pyatnitskaya St. 119017, Moscow, Russia]
Bisikalo, D. [Institute of Astronomy of the Russian Academy of Sciences, 48 Pyatnitskaya St. 119017, Moscow, Russia]
Gladstone, G. R. [Southwest Research Institute, 6220 Culebra Road, P.O. Drawer 28510, San Antonio, Texas 78228-0510, USA]
Esposito, L. W. [LASP, University of Colorado, 392 UCB Boulder, Colorado 80309-0392, USA]
1-Jan-2011
Icarus: International Journal of Solar System Studies
Academic Press
211
70-80
Yes (verified by ORBi)
International
0019-1035
San Diego
CA
[en] Venus atmosphere ; dayglow ; extreme ultraviolet
[en] We analyze EUV spatially-resolved dayglow spectra obtained at 0.37 nm resolution by the UVIS instrument during the Cassini flyby of Venus on 24 June 1999, a period of high solar activity level. Emissions from OI, OII, NI, CI and CII and CO have been identified and their disc average intensity has been determined. They are generally somewhat brighter than those determined from the observations made with the HUT spectrograph at a lower activity level, We present the brightness distribution along the foot track of the UVIS slit of the OII 83.4 nm, OI 98.9 nm, Lyman-ß + OI 102.5 nm and NI 120.0 nm multiplets, and the CO C-X and B-X Hopfield-Birge bands. We make a detailed comparison of the intensities of the 834 nm, 989 nm, 120.0 nm multiplets and CO B-X band measured along the slit foot track on the disc with those predicted by an airglow model previously used to analyze Venus and Mars ultraviolet spectra. This model includes the treatment of multiple scattering for the optically thick OI, OII and NI multiplets. It is found that the observed intensity of the OII emission at 83.4 nm is higher than predicted by the model. An increase of the O[SUP]+[/SUP] ion density relative to the densities usually measured by Pioneer Venus brings the observations and the modeled values into better agreement. The calculated intensity variation of the CO B-X emission along the track of the UVIS slit is in fair agreement with the observations. The intensity of the OI 98.9 nm emission is well predicted by the model if resonance scattering of solar radiation by O atoms is included as a source. The calculated brightness of the NI 120 nm multiplet is larger than observed by a factor of ˜2-3 if photons from all sources encounter multiple scattering. The discrepancy reduces to 30-80% if the photon electron impact and photodissociation of N[SUB]2[/SUB] sources of N([SUP]4[/SUP]S) atoms are considered as optically thin. Overall, we find that the O, N[SUB]2[/SUB] and CO densities from the empirical VTS3 model provide satisfactory agreement between the calculated and the observed EUV airglow emissions.
Researchers ; Professionals
http://hdl.handle.net/2268/100141
10.1016/j.icarus.2010.09.020
http://adsabs.harvard.edu/abs/2011Icar..211...70G

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