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; Neary, L.; Daerden, Frank

doi:10.1016/j.icarus.2023.115602

Cited by 4 publications

(2 citation statements)

References 60 publications

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“…The initial energy of the monoenergetic electrons is varied between 20 and 1,000 eV, depending on the simulations. This energy range corresponds to that determined by previous studies for the discrete aurora (Gérard et al., 2023; Soret et al., 2016, 2021; Xu et al., 2022). The effects of the crustal magnetic field are considered in this model.…”

Section: Model Of Fuv Emissionssupporting

confidence: 87%

Quantifying the Electron Energy of Mars Aurorae Through the Oxygen Emission Brightness Ratio at 130.4 and 135.6 nm

Soret,

Hubert,

Gérard

et al. 2024

JGR Planets

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Mars discrete aurorae are caused by accelerated electrons precipitating into the atmosphere and interacting with species such as atomic oxygen. However, the energy of the electrons causing these aurorae remains currently unclear: no simultaneous and concurrent measurements of electron analyzers and spectrometers have been performed so far, preventing from assessing the exact energy of the downgoing auroral electrons. Several auroral emissions have been observed so far on Mars, among which are two oxygen emissions in the far ultraviolet at 130.4 and 135.6 nm. In this study, we simulate the vertical distribution of these auroral oxygen emissions with an electron transport calculation coupled with a radiative transfer model to account for the optical thickness of the atmosphere for the 130.4‐nm triplet. We show that the brightness ratio of these oxygen emissions is independent of the downward electron energy flux and only slightly depends on the atomic oxygen atmospheric composition. In contrast, the brightness ratio is strongly related to the initial energy of the auroral electrons. Measuring the brightness ratio is therefore a unique tool to remotely estimate the energy of the electrons causing the Mars discrete aurorae. We compare our model results with observations from the Emirates Mars Ultraviolet Spectrometer on board the Emirates Mars Mission and find that electrons with typical energies of 250–300 eV are compatible with the observed ratio of 5.

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Section: Model Of Fuv Emissionssupporting

confidence: 87%

Quantifying the Electron Energy of Mars Aurorae Through the Oxygen Emission Brightness Ratio at 130.4 and 135.6 nm

Soret,

Hubert,

Gérard

et al. 2024

JGR Planets

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“…The Mars Atmosphere and Volatile EvolutioN (MAVEN) Imaging Ultraviolet Spectrograph (IUVS) has expanded our understanding with over 400 detections of discrete aurora (278 detections in limb mode and 126 detections in nadir mode), revealing different behaviors within and outside Mars' strong crustal magnetic field region or “mini–magnetosphere” in the southern hemisphere which is near 177°E and 52°S (Bowers et al., 2023; Fang et al., 2022; Girazian et al., 2022; Johnston et al., 2023; Schneider et al., 2021; Soret et al., 2021). Both MEx (Mars Express) and MAVEN observations of discrete aurorae are mainly focused on mid ultraviolet (MUV) emissions, such as CO Cameron bands (190–270 nm),

{\text{CO}}_{2}^{+}

UV doublet (at 288–289 nm), and the oxygen forbidden emission (at 297.2 nm) due to their higher brightness (Gérard et al., 2015, 2023; Schneider et al., 2018; Soret et al., 2021).…”

Section: Nightside Aurora On Marsmentioning

confidence: 99%

EMM EMUS Observations of FUV Aurora on Mars: Dependence on Magnetic Topology, Local Time, and Season

Chirakkil,

Lillis,

Deighan

et al. 2024

JGR Planets

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We present a comprehensive study of the nightside aurora phenomenon on Mars, utilizing observations from EMUS onboard Emirates Mars Mission. The oxygen emission at 130.4 nm is by far the brightest FUV auroral emission line observed at Mars. Our statistical analysis reveals geographic, solar zenith angle, local time, and seasonal dependencies of auroral occurrence. Higher occurrence of aurora is observed in regions of open magnetic topology, where crustal magnetic fields are either very weak or both strong and vertical. Aurora occurs more frequently closer to the terminator and is more likely on the dusk side than on the dawn side of the night hemisphere. A pronounced auroral feature appears close to midnight local times in the southern hemisphere, consistent with the spot of energetic electron fluxes previously identified in the Mars Global Surveyor data. This auroral spot is more frequent after midnight than before. Additionally, some regions on Mars are “aurora voids” where essentially no aurora occurs. Aurora exhibits a seasonal dependence, with a major enhancement near perihelion. Non–crustal field aurora additionally shows a secondary enhancement near Ls 30°. This seasonal variability is a combination of the variability in ionospheric photoelectrons and thermospheric atomic oxygen abundance. Auroral occurrence also shows an increase with the rise of Solar Cycle 25. The brightest auroral pixels are observed during space weather events such as Coronal Mass Ejections and Stream Interaction Regions. These observations not only shed light on where and when Martian aurora occurs, but also add to our understanding of Mars' magnetic environment and its interaction with the heliosphere.

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Magnetically controlled ionosphere of Mars: A model analysis with the vertical plasma drift effects

Majeed,

Bougher,

Withers

et al. 2024

Icarus

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The brightness of the CO Cameron bands in the martian discrete aurora: A study based on revised cross sections

Cited by 4 publications

References 60 publications

Quantifying the Electron Energy of Mars Aurorae Through the Oxygen Emission Brightness Ratio at 130.4 and 135.6 nm

Quantifying the Electron Energy of Mars Aurorae Through the Oxygen Emission Brightness Ratio at 130.4 and 135.6 nm

EMM EMUS Observations of FUV Aurora on Mars: Dependence on Magnetic Topology, Local Time, and Season

Magnetically controlled ionosphere of Mars: A model analysis with the vertical plasma drift effects

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