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Communication Dans Un Congrès Année : 2021

Modeling of SEP induced auroral emission: Contribution of MeV protons

Résumé

Simultaneous observations with the Solar Energetic Particle (SEP) and the Imaging Ultraviolet Spectrograph (IUVS) instruments on board the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft discovered a new type of Martian aurora, diffuse aurora, that spans across the nightside of Mars due to the interaction of solar energetic particles (SEPs) with the Martian atmosphere [Schneider et al., 2015, 2018]. It is unclear whether the origin of diffuse aurora is electron or proton precipitations. This study aims to model the SEP induced diffuse auroral emission by both electrons and protons to explain the observed diffuse auroral emission profiles. We have developed a Monte Carlo model to calculate the limb intensity profile of the CO2+ ultraviolet doublet (UVD) due to precipitation of energetic electrons and protons with energy ranges from 100 eV to 100 keV and from 100 eV to 5 MeV, respectively, using electron and proton fluxes observed by MAVEN during the December 2014 SEP event and the September 2017 SEP event. Our results showed that proton-induced CO2+ UVD emission is brighter and narrower with respect to the altitude profile and has a lower peak altitude than electron-induced CO2+UVD emission. The calculated peak altitudes of the CO2+ UVD limb profiles are 76 km and 56 km in the SEP events that occurred during December 2014 and September 2017, respectively, which are in good agreement with the IUVS observations. We have succeeded in reproducing the peak altitudes and shapes of the observed CO2+ UVD limb profiles using the SEP fluxes observed by MAVEN. This was possible by taking into account the contribution of protons with energy up to MeV, indicating that both energetic electrons and protons contribute to producing the observed MAVEN/IUVS diffuse aurora.
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Dates et versions

insu-04469208 , version 1 (20-02-2024)

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Y. Nakamura, N. Terada, François Leblanc, Ali Rahmati, H. Nakagawa, et al.. Modeling of SEP induced auroral emission: Contribution of MeV protons. American Geophysical Union, Fall Meeting 2021, Dec 2021, New Orleans, United States. pp.id. P44B-06. ⟨insu-04469208⟩
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