Dayglow and auroral emissions of Uranus in H2 FUV bands

Barthélemy, Mathieu; Lamy, Laurent; Menager, H.; Schulik, Matthäus; Bernard, D.; Abgrall, H.; Roueff, E.; Cessateur, Gaël; Prangé, Renée; Lilensten, Jean

doi:10.1016/j.icarus.2014.05.035

Cited by 11 publications

(20 citation statements)

References 37 publications

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“…The conclusions from Barthélemy et al (2014) are accurate only if the confidence in the solar UV fluxes is good. Since the solar reflected component represents 90% of the signal, the error on the solar flux becomes critical: an error of 1% on the flux can give rise to an error of at least 10% on the estimation of the airglow and precipitation contributions, which contribute to planetary upper atmosphere and auroral processes.…”

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

“…Interpretations of the recorded spectra between 130 and 170 nm have been made, giving an estimation of the precipitating electron flux (Barthélemy et al 2014) during the auroral event.…”

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

“…In order to interpret these dominant contributions, Barthélemy et al (2014) used albedo data from Yelle et al (1989) deduced from Voyager data, and solar flux data from the TIMED-SEE instrument. They considered no uncertainties on the solar flux, and thus deduced both a new albedo of the planet in the studied spectral range and electron fluxes.…”

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

“…If the solar absolute flux data are less accurate than a few percent, the absolute values deduced from this study are uncertain. This forces the question: Is the detection of the auroral event reported in Barthélemy et al (2014) significant? Studies of the spectral shape of the additional emissions could give interesting additional information.…”

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

“…2 Such is not the case with the solar flux. In Barthélemy et al (2014), the auroral event is detected by an enhancement of 6% of the flux in the spectral region considered. During the period of the observation, the integrated solar flux varies up to about 1%.…”

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

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Sensitivity of upper atmospheric emissions calculations to solar/stellar UV flux

Barthélemy

Cessateur

2014

J. Space Weather Space Clim.

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The solar UV (UltraViolet) flux, especially the EUV (Extreme UltraViolet) and FUV (Far UltraViolet) components, is one of the main energetic inputs for planetary upper atmospheres. It drives various processes such as ionization, or dissociation which give rise to upper atmospheric emissions, especially in the UV and visible. These emissions are one of the main ways to investigate the upper atmospheres of planets. However, the uncertainties in the flux measurement or modeling can lead to biased estimates of fundamental atmospheric parameters, such as concentrations or temperatures in the atmospheres. We explore the various problems that can be identified regarding the uncertainties in solar/stellar UV flux by considering three examples. The worst case appears when the solar reflection component is dominant in the recorded spectrum as is seen for outer solar system measurements from HST (Hubble Space Telescope). We also show that the estimation of some particular line parameters (intensity and shape), especially Lyman a, is crucial, and that both total intensity and line profile are useful. In the case of exoplanets, the problem is quite critical since the UV flux of their parent stars is often very poorly known.

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Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

“…Interpretations of the recorded spectra between 130 and 170 nm have been made, giving an estimation of the precipitating electron flux (Barthélemy et al 2014) during the auroral event.…”

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

Section: Example Of Uranus: Fuv Continuum and Solar Reflectionmentioning

confidence: 99%

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Sensitivity of upper atmospheric emissions calculations to solar/stellar UV flux

Barthélemy

Cessateur

2014

J. Space Weather Space Clim.

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The aurorae of Uranus past equinox

et al. 2017

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The aurorae of Uranus were recently detected in the far ultraviolet with the Hubble Space Telescope (HST) providing a new, so far unique, means to remotely study the asymmetric Uranian magnetosphere from Earth. We analyze here two new HST Uranus campaigns executed in September 2012 and November 2014 with different temporal coverage and under variable solar wind conditions numerically predicted by three different MHD codes. Overall, the HST images taken with the Space Telescope Imaging Spectrograph reveal auroral emissions in three pairs of successive images (one pair acquired in 2012 and two in 2014), hence 6 additional auroral detections in total, including the most intense Uranian aurorae ever seen with HST. The detected emissions occur close the expected arrival of interplanetary shocks. They appear as extended spots at southern latitudes, rotating with the planet. They radiate 5–24 kR and 1.3‐8.8 GW of ultraviolet emission from H2, last for tens of minutes and vary on timescales down to a few seconds. Fitting the 2014 observations with model auroral ovals constrains the longitude of the southern (northern) magnetic pole to 104 ± 26° (284 ± 26°) in the Uranian Longitude System. We suggest that the Uranian near‐equinoctial aurorae are pulsed cusp emissions possibly triggered by large‐scale magnetospheric compressions.

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What characterizes planetary space weather?

Lilensten

Coates

Déhant

et al. 2014

Astron Astrophys Rev

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Space weather has become a mature discipline for the Earth space environment. With increasing efforts in space exploration, it is becoming more and more necessary to understand the space environments of bodies other than Earth. This is the background for an emerging aspect of the space weather discipline: planetary space weather. In this article, we explore what characterizes planetary space weather, using some examples throughout the solar system. We consider energy sources and timescales, the characteristics of solar system objects and interaction processes. We

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Dayglow and auroral emissions of Uranus in H2 FUV bands

Cited by 11 publications

References 37 publications

Sensitivity of upper atmospheric emissions calculations to solar/stellar UV flux

Sensitivity of upper atmospheric emissions calculations to solar/stellar UV flux

The aurorae of Uranus past equinox

What characterizes planetary space weather?

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