Variation in the H[FORMULA][F][SUP]+[/SUP][INF]3[/INF][/F][/FORMULA] Emission of Uranus

Lam, H. A.; Miller, Steven D.; Joseph, R. D.; Geballe, T. R.; Trafton, Laurence M.; Tennyson, Jonathan; Ballester, G. E.

doi:10.1086/310424

Cited by 32 publications

(17 citation statements)

References 10 publications

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“…As expected, the spectrum shows a few strong emission lines, especially at 4.684 and 4.875 µm, belonging to the H 3 + ν 2 fundamental band centered at 4 µm, originating from the upper stratosphere. Other lines of this band have been previously detected (Trafton et al 1993(Trafton et al , 1999Lam et al 1997;Encrenaz et al 2003). Unexpectedly, the spectrum also exhibits a series of emission lines which, as shown in Fig.…”

Section: Observationssupporting

confidence: 61%

First detection of CO in Uranus

Encrenaz

Lellouch

Drossart

et al. 2003

A&A

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Abstract. The spectrum of Uranus has been recorded in Oct.-Nov. 2002, between 4.6 and 5.0 µm, using the ISAAC imaging spectrometer at the VLT-UT1 (ANTU) 8-m telescope of ESO. The spectral resolving power was 1500. In addition to a few strong H 3 + emission lines, the spectrum of Uranus distinctly shows the emission lines of the CO(1-0) band from R7 to P8. The relative intensity distribution of the observed CO emission is not compatible with a thermal distribution, for any value of the rotational temperature. The most likely emission mechanism is fluorescence, and a good fit is obtained assuming a constant CO mixing ratio of 3× 10 −8 at the tropopause and above. The tropospheric continuum of Uranus is also detected beween 4.7 and 5.0 µm. The observed continuum can be fitted assuming reflected sunlight above a cloud level at 3.1 bars, presumably attributed to H 2 S. Upper limits of 2 × 10 −8 and 1 × 10 −6 are inferred for the CO and PH 3 tropospheric mixing ratios above this level. The low CO tropospheric upper limit might suggest that the CO vertical distribution is not uniform.

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Section: Observationssupporting

confidence: 61%

First detection of CO in Uranus

Encrenaz

Lellouch

Drossart

et al. 2003

A&A

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“…Of all the ionic species predicted to be present on the Ice Giants, only H + 3 has been detected, and only on Uranus [37,69,71,72,76,199,[202][203][204]. Observations of H + 3 have provided a useful probe of thermospheric conditions on Uranus.…”

Section: Chemistry Of the Thermosphere And Ionospherementioning

confidence: 99%

Atmospheric chemistry on Uranus and Neptune

Moses

Cavalié

Fletcher

et al. 2020

Phil. Trans. R. Soc. A.

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Comparatively little is known about atmospheric chemistry on Uranus and Neptune, because remote spectral observations of these cold, distant ‘Ice Giants’ are challenging, and each planet has only been visited by a single spacecraft during brief flybys in the 1980s. Thermochemical equilibrium is expected to control the composition in the deeper, hotter regions of the atmosphere on both planets, but disequilibrium chemical processes such as transport-induced quenching and photochemistry alter the composition in the upper atmospheric regions that can be probed remotely. Surprising disparities in the abundance of disequilibrium chemical products between the two planets point to significant differences in atmospheric transport. The atmospheric composition of Uranus and Neptune can provide critical clues for unravelling details of planet formation and evolution, but only if it is fully understood how and why atmospheric constituents vary in a three-dimensional sense and how material coming in from outside the planet affects observed abundances. Future mission planning should take into account the key outstanding questions that remain unanswered about atmospheric chemistry on Uranus and Neptune, particularly those questions that pertain to planet formation and evolution, and those that address the complex, coupled atmospheric processes that operate on Ice Giants within our solar system and beyond. This article is part of a discussion meeting issue ‘Future exploration of ice giant systems’.

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“…[4] Since Voyager 2, two attempts have been made to re-observe Uranus' Far-UV (FUV) aurorae with the Hubble Space Telescope (HST), once in 1998 with the Space Telescope Imaging Spectrograph (STIS, program 7439, PI: G. Ballester) and again in 2005 with the Advanced Camera for Surveys (ACS, program 10502, PI: J. Clarke), but without reporting any positive detection. In parallel, long-term ground-based observations at near-IR (NIR) wavelengths revealed variations in the thermospheric emission of the H 3 + molecule, part of which ($20%) was attributed to auroral precipitations [Lam et al, 1997;Trafton et al, 1999;Melin et al, 2011]. As a result, our knowledge of the magnetosphere remains essentially based on the few hours of observations acquired 26 years ago.…”

Section: Introductionmentioning

confidence: 99%

Earth‐based detection of Uranus' aurorae

Lamy

Prangé

Hansen

et al. 2012

Geophysical Research Letters

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[1] This study is based on multi-planet multi-wavelength observations of planetary aurorae throughout the heliosphere, acquired along the propagation path of a series of consecutive interplanetary shocks. The underlying motivation to track the shocks was to increase the probability of detection of auroral emissions at Uranus. Despite several Earth-based attempts in the past few years, at Far-UV (FUV) and Near-IR (NIR) wavelengths, such emissions have never been unambiguously reobserved since their discovery by Voyager 2 in 1986. Here, we present a campaign of FUV observations of Uranus obtained in November 2011 with the Hubble Space Telescope (HST) during active solar wind conditions. We positively identify auroral signatures in several of these HST measurements, together with some obtained in 1998, representing the first images of Uranus' aurorae. We analyze their characteristics and discuss the implications for the asymmetric Uranian magnetosphere and its highly variable interaction with the solar wind flow from near-solstice (1986) to near-equinox (2011) configurations.

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Variation in the H[FORMULA][F][SUP]+[/SUP][INF]3[/INF][/F][/FORMULA] Emission of Uranus

Cited by 32 publications

References 10 publications

First detection of CO in Uranus

First detection of CO in Uranus

Atmospheric chemistry on Uranus and Neptune

Earth‐based detection of Uranus' aurorae

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