Article (Scientific journals)
The brightness of the CO Cameron bands in the martian discrete aurora: A study based on revised cross sections
Gérard, Jean-Claude; Soret, Lauriane; Hubert, Benoît et al.
2023In Icarus, 402, p. 115602
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Keywords :
Space and Planetary Science; Mars aurora ultraviolet cross section Cameron bands efficiency electrons
Abstract :
[en] We analyze the consequences of the new laboratory measurements of the emissions cross sections of the Cameron bands excited by electron impact on CO2 and CO in the Mars aurora. We use Monte Carlo simulations to investigate the importance of these changes and their dependence on the initial electron energy. The Mars Climate Database (MCD) is used as an input for the temperature and neutral density profiles. Auroral density profiles of O2+, CO+2 and electrons in the aurora are calculated for a range of precipitating electron energies. The total nadir brightness of the Cameron bands is reduced by a factor of 4.5 at 150 eV and 5.1 at 700 eV relative to calculations made with the previously recommended cross section. The relative contributions to the production of the Cameron bands by electron collisions with CO2 and CO are examined. It varies with the CO/CO2 density ratio near the emission peak that depends on the neutral model and season. Dissociative recombination of CO+2 ions provides a contribution between 10% and 45% at the altitude of maximum production of the a 3Π state. The efficiency of the nadir brightness of the Cameron bands is 2.5–3.6 kilorayleighs per incident electron energy flux of 1 mW m-2, with a small dependence on the initial electron energy. Model simulations predict that the intensity ratio of the Cameron bands to the CO+2 UV doublet (UVD) depends on the electron initial energy. It varies from 2.0 at 500 eV to 5.3 at 50 eV, for both Ls = 90° and 225°.
Research center :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Gérard, Jean-Claude  ;  Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Soret, Lauriane  ;  Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Hubert, Benoît  ;  Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Neary, L.
Daerden, F.
Language :
English
Title :
The brightness of the CO Cameron bands in the martian discrete aurora: A study based on revised cross sections
Publication date :
May 2023
Journal title :
Icarus
ISSN :
0019-1035
eISSN :
1090-2643
Publisher :
Elsevier BV
Volume :
402
Pages :
115602
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
BELSPO - Belgian Federal Science Policy Office [BE]
Available on ORBi :
since 26 May 2023

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