Abundances of Jupiter's trace hydrocarbons from Voyager and Cassini

Nixon, C. A.; Achterberg, R. K.; Romani, P. N.; Allen, Mark; Zhang, X.; Teanby, N. A.; Irwin, Patrick; Flasar, F. M.

doi:10.1016/j.pss.2010.05.008

Cited by 55 publications

(97 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Once produced, C 2 H 6 is chemically stable for timescales longer than a Jupiter year (e.g. , Figure 12 of Nixon et al 2010) and so would be expected to become longitudinally well-mixed, which our results also indicate. The magnitude of uncertainties on retrieved hydrocarbon concentrations in the southern auroral region prevented us from making any assessment of how their concentrations are modified by the southern auroral region.…”

Section: Discussionsupporting

confidence: 63%

“…(Simon-Miller et al, 2006;Nixon et al, 2007Nixon et al, , 2010. We note that Jupiter's subsolar latitude and distance from the Sun changed from 3.3…”

Section: Radiance Differencesmentioning

confidence: 85%

“…• N retrieved in Fletcher et al (2009) and Nixon et al (2010). However, alternative temperature profiles are also tested in performing retrievals.…”

Section: Radiative Transfer Modellingmentioning

confidence: 99%

See 2 more Smart Citations

Jupiter’s auroral-related stratospheric heating and chemistry II: Analysis of IRTF-TEXES spectra measured in December 2014

Sinclair

Orton

Greathouse

et al. 2018

Icarus

Self Cite

View full text Add to dashboard Cite

We present a retrieval analysis of TEXES (Texas Echelon Cross Echelle Spectrograph (Lacy et al., 2002)) spectra of Jupiter's high latitudes obtained on NASA's Infrared Telescope Facility on December 10-11th 2014. The vertical temperature profile and vertical profiles of C 2 H 2 , C 2 H 4 and C 2 H 6 were retrieved at both high-northern and high-southern latitudes and results were compared in 'quiescent' regions and regions known to be affected by Jupiter's aurora in order to highlight how auroral processes modify the thermal structure and hydrocarbon chemistry of the stratosphere. In qualitative agreement with Sinclair et al. (2017a), we find temperatures in auroral regions to be elevated with respect to quiescent regions at two discrete pressures levels at approximately 1 mbar and 0.01 mbar. For example, in comparing retrieved temperatures at 70• N, 60• W (a representative quiescent region) and 70• N, 180• W (centred on the northern auroral oval), temperatures increase by 19.0 ± 4.2 K at 0.98 mbar, 20.8 ± 3.9 K at 0.01 mbar but only by 8.3 ± 4.9 K at the intermediate level of 0.1 mbar. We conclude that elevated temperatures at 0.01 mbar result from heating by joule resistance of the atmosphere and the energy imparted by electron and ion precipitation. However, temperatures at 1 mbar are considered to result either from heating by shortwave radiation of aurorally-produced haze particulates or precipitation of higher energy population of charged particles. Our former conclusion would be consistent with results of auroral-chemistry models, that predict the highest number densities of aurorally-produced haze particles at this pressure level (Wong et al., 2000(Wong et al., , 2003. C 2 H 2 and C 2 H 4 exhibit enrichments but C 2 H 6 remains constant within uncertainty when comparing retrieved concentrations in the northern auroral region with quiescent longitudes in the same latitude band. At 1 mbar, C 2 H 2 increases from 278.4 ± 40.3 ppbv at 70• N, 60• W to 564.4 ± 72.0 ppbv at 70• N, 180• W and at 0.01 mbar, over the same longitude range at 70• N, C 2 H 4 increases from 0.669 ± 0.129 ppmv to 6.509 ± 0.811 ppmv. However, we note that non-LTE (local thermodynamic equilibrium) emission may affect the cores of the strongest C 2 H 2 and C 2 H 4 lines on the northern auroral region, which may be a possible source of error in our derived concentrations. We retrieved concentrations of C 2 H 6 at 1 mbar of 9.03 ± 0.98 ppmv at 70• N, 60• W and 7.66 ± 0.70 ppmv at 70• N, 180• W. Thus, C 2 H 6 's concentration appears constant (within uncertainty) as a function of longitude at 70• N.

show abstract

Section: Discussionsupporting

confidence: 63%

“…(Simon-Miller et al, 2006;Nixon et al, 2007Nixon et al, , 2010. We note that Jupiter's subsolar latitude and distance from the Sun changed from 3.3…”

Section: Radiance Differencesmentioning

confidence: 85%

See 1 more Smart Citation

Jupiter’s auroral-related stratospheric heating and chemistry II: Analysis of IRTF-TEXES spectra measured in December 2014

Sinclair

Orton

Greathouse

et al. 2018

Icarus

Self Cite

View full text Add to dashboard Cite

show abstract

“…Simon-Miller et al (2006) compared Voyager-IRIS and Cassini-CIRS spectra but focused their analysis on the tropospheric to lower stratospheric pressure ranges. and Nixon et al (2010) used Cassini-CIRS and Voyager-IRIS zonally-averaged data to determine meridional variations in stratospheric temperature, C 2 H 2 and C 2 H 6 but avoided using spectra covering the auroral regions such that quiescent and auroral conditions were not averaged together. Kunde et al (1996) presented comparisons of observed and synthetic Cassini-CIRS spectra and used radiance contrasts between non-auroral and auroral regions to calculate the power emitted from auroral-related hotspots.…”

Section: Introductionmentioning

confidence: 99%

Jupiter’s auroral-related stratospheric heating and chemistry I: Analysis of Voyager-IRIS and Cassini-CIRS spectra

Sinclair

Orton

Greathouse

et al. 2017

Icarus

Self Cite

107

View full text Add to dashboard Cite

Auroral processes are evident in Jupiter's polar atmosphere over a large range in wavelength (X-ray to radio). In particular, previous observations in the mid-infrared (5 to 15 µm) have shown enhanced emission from CH 4 , C 2 H 2 and C 2 H 4 and further stratospheric hydrocarbon species in spatial regions coincident with auroral processes observed at other wavelengths. These regions, described as auroral-related hotspots, observed at approximately 160• W to 200• W (System III) at high-northern latitudes and 330• W to 80• W at high-southern latitudes, indicate that auroral processes modify the thermal structure and composition of the neutral atmosphere. However, previous studies have struggled to differentiate whether the aforementioned enhanced emission is a result of either temperature changes and/or changes in the concentration of the emitting species. We attempt to address this degeneracy in this work by performing a retrieval analysis of Voyager 1-IRIS spectra (acquired in 1979) and Cassini-CIRS spectra (acquired in 2000/2001) of Jupiter. Retrievals of the vertical temperature profile in Cassini-CIRS spectra covering the auroral-related hotspots indicate the presence of two discrete vertical regions of heating at the 1-mbar level and at pressures of 10-µbar and lower. For example, in Cassini-CIRS 2.5 cm −1 'MIRMAP' spectra at 70• N (planetographic) 180• W (centred on the auroral oval), we find temperatures at the 1-mbar level and 10-µbar levels are enhanced by 15.3 ± 5.2 K and 29.6 ± 15.0 K respectively, in comparison to results at 70• N, 60• W in the same dataset. High temperatures at 10-µbar and lower pressures were considered indicative of joule heating, ion and/or electron precipitation, ion-drag and energy released form exothermic ion-chemistry. However, we conclude that the heating at the 1-mbar level is the result of either a layer of aurorally-produced haze particles, which are heated by incident sunlight and/or adiabatic heating by downwelling within the auroral hot-spot region. The former mechanism would be consistent with the vertical profiles of polycyclic aromatic hydrocarbons (PAHs) and haze particles predicted in auroral-chemistry models (Wong et al., 2000(Wong et al., , 2003. Retrievals of C 2 H 2 and C 2 H 6 were also performed and indicate C 2 H 2 is enriched but C 2 H 6 is depleted in auroral regions relative to quiescent regions. For example, using CIRS ∆ν = 2.5 cm −1 spectra, we determined that C 2 H 2 at 0.98 mbar increases by 175.3 ± 89.3 ppbv while C 2 H 6 at 4.7 mbar decreases by 0.86 ± 0.59 ppmv in comparing results at 70• N, 180• W and 70• N, 60• W. These results represent a mean of values retrieved from different initial assumptions and thus we believe they are robust. We believe these contrasts in C 2 H 2 and C 2 H 6 between auroral and quiescent regions can be explained by a coupling of auroral-driven chemistry and horizontal advection. Ion-neutral and electron recombination chemistry in the auroral region enriches all C 2 hydrocarbons but in particular, the unsaturated ...

show abstract

“…In principle, clouds and hazes can be the result of condensation chemistry or be photochemically produced. The solar system giant planets are likely dominated by photochemical stratospheric hydrocarbon hazes (Nixon et al 2010) produced in a similar way to tholins in the atmosphere of Titan (Khare et al 1984). The strong UV flux on the upper atmosphere of hot Jupiter exoplanets may generally enhance photochemically generated hydrocarbon species.…”

Section: Introductionmentioning

confidence: 99%

Transmission spectral properties of clouds for hot Jupiter exoplanets

Wakeford

Sing

2015

A&A

189

205

View full text Add to dashboard Cite

Clouds play an important role in the atmospheres of planetary bodies. It is expected that, like all the planetary bodies in our solar system, exoplanet atmospheres will also have substantial cloud coverage, and evidence is mounting for clouds in a number of hot Jupiters. To better characterise planetary atmospheres, we need to consider the effects these clouds will have on the observed broadband transmission spectra. Here we examine the expected cloud condensate species for hot Jupiter exoplanets and the effects of various grain sizes and distributions on the resulting transmission spectra from the optical to infrared, which can be used as a broad framework when interpreting exoplanet spectra. We note that significant infrared absorption features appear in the computed transmission spectrum, the result of vibrational modes between the key species in each condensate, which can potentially be very constraining. While it may be hard to differentiate between individual condensates in the broad transmission spectra, it may be possible to discern different vibrational bonds, which can distinguish between cloud formation scenarios, such as condensate clouds or photochemically generated species. Vibrational mode features are shown to be prominent when the clouds are composed of small sub-micron sized particles and can be associated with an accompanying optical scattering slope. These infrared features have potential implications for future exoplanetary atmosphere studies conducted with JWST, where such vibrational modes distinguishing condensate species can be probed at longer wavelengths.

show abstract

Abundances of Jupiter's trace hydrocarbons from Voyager and Cassini

Cited by 55 publications

References 38 publications

Jupiter’s auroral-related stratospheric heating and chemistry II: Analysis of IRTF-TEXES spectra measured in December 2014

Jupiter’s auroral-related stratospheric heating and chemistry II: Analysis of IRTF-TEXES spectra measured in December 2014

Jupiter’s auroral-related stratospheric heating and chemistry I: Analysis of Voyager-IRIS and Cassini-CIRS spectra

Transmission spectral properties of clouds for hot Jupiter exoplanets

Contact Info

Product

Resources

About