Composition and chemistry of Titan's stratosphere

Bézard, Bruno

doi:10.1098/rsta.2008.0186

Cited by 24 publications

(16 citation statements)

References 40 publications

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“…Table 10.5 ). This latter value is 1/14 of the gas phase mass production rate of C 2 H 6 , as Bézard (2009) concluded from an empirical analysis of Cassini and Huygens data. But Atreya et al (2006) argued that this ratio may be as large as ½, based on Wilson and Atreya (2004) whose gas phase production rates are systematically lower than Yung et al (1984) and Lavvas et al (2008) .…”

Section: Sources Sinks and Photochemistry Of Atmospheric Compositionmentioning

confidence: 72%

“…Bézard 2009). This is consistent with subsidence in the winter polar vortex, bringing air rich in photochemical compounds from their formation region in the upper atmosphere down to the stratosphere (see Sections 10.6 and 10.7 and Chapter 13).…”

Section: Minor Constituents -N-bearing Species and Nitrilesmentioning

confidence: 99%

“…10.8 , 10.10 ), (3) the stratospheric CH 4 mole fraction is 0.0141 from GCMS (Niemann et al 2005) , and (4) the thermospheric CH 4 mole fraction obtained by INMS at the lowest altitudes sampled is slightly lower than the stratospheric value ) and indicative of CH 4 destruction. Bézard (2009) inferred the mass production rates of C 2 H 6 and haze from CIRS derived C 2 H 6 and DISR derived haze profi les under the assumption that diffusive transport dominates below their respective formation regions. He obtained a production ratio of 15 times more C 2 H 6 than haze.…”

Section: Sources Sinks and Photochemistry Of Atmospheric Compositionmentioning

confidence: 99%

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Atmospheric Structure and Composition

Strobel

Atreya

Bézard

et al. 2009

Titan From Cassini-Huygens

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Section: Sources Sinks and Photochemistry Of Atmospheric Compositionmentioning

confidence: 72%

Section: Minor Constituents -N-bearing Species and Nitrilesmentioning

confidence: 99%

Section: Sources Sinks and Photochemistry Of Atmospheric Compositionmentioning

confidence: 99%

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Atmospheric Structure and Composition

Strobel

Atreya

Bézard

et al. 2009

Titan From Cassini-Huygens

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“…Di-acetylene and tri-acetylene have been detected in the upper stratosphere by CIRS limb observations (Bezard 2009). However, the vertical abundance profiles of di-and triacetylene in Titan's atmosphere show a rapid decrease with altitude.…”

Section: Search For C 2 H 2 On Titan With Near-infrared Spectroscopymentioning

confidence: 99%

Acetylene on Titan’s Surface

Singh

McCord

Combe

et al. 2016

ApJ

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Titan's atmosphere is opaque in the near-infrared due to gaseous absorptions, mainly by methane, and scattering by aerosols, except in a few "transparency windows." Thus, the composition of Titan's surface remains difficult to access from space and is still poorly constrained. Photochemical models suggest that most of the organic compounds formed in the atmosphere are heavy enough to condense and build up at the surface in liquid and solid states over geological timescales. Acetylene (C 2 H 2 ) net production in the atmosphere is predicted to be larger than any other compound and C 2 H 2 has been speculated to exist on the surface of Titan. C 2 H 2 was detected as a trace gas sublimated/evaporated from the surface using the Gas Chromatograph Mass Spectrometer after the landing of the Huygens probe. Here we show evidence of C 2 H 2 on the surface of Titan by detecting absorption bands at 1.55 and 4.93 μm using the Cassini Visual and Infrared Mapping Spectrometer at three different equatorial areas-Tui Regio, eastern Shangri La, and Fensal-Aztlan/Quivira. We found that C 2 H 2 is preferentially detected in lowalbedo areas, such as sand dunes and near the Huygens landing site. The specific location of the C 2 H 2 detections suggests that C 2 H 2 is mobilized by surface processes, such as surface weathering by liquids through dissolution/ evaporation processes.

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“…The paper by Bézard (2009) describes our current knowledge of chemistry in Titan's stratosphere, which ultimately leads to the formation of large hydrocarbon molecules and haze particles. In practice, it is difficult to measure directly stratospheric winds on Titan, but Teanby et al (2009) show that monitoring stratospheric composition will also, with our knowledge of the relevant chemical processes, allow us to deduce stratospheric winds due to their role in redistributing constituents globally.…”

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confidence: 99%

Preface

Mueller-Wodarg

Yelle

2008

Phil. Trans. R. Soc. A.

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Saturn's largest Moon, Titan, is among the most fascinating worlds in our Solar System, hosting a substantial atmosphere rich in complex chemistry, a diverse and weathered surface and a highly variable outer space environment driven primarily by Saturn's dynamic magnetosphere. While measurements by the Voyager spacecraft during their flybys in the early 1980s provided the first opportunity to study Titan in more detail, a true revolution in our knowledge of this enigmatic body had to await the arrival of the Cassini/Huygens spacecraft into orbit around Saturn in 2004. This international mission has given and continues to provide the most detailed measurements to date of the Titan system. A particular highlight was the successful landing of the Huygens probe on Titan's surface on 14 January 2005, which carried out ground-breaking in situ measurements of both the atmosphere and surface. The Cassini orbiter continues to measure Titan's surface, atmosphere and space environment both in situ and by remote sensing during periodic flybys of Titan, and our hope is to gain a first-level understanding of how this complex and closely coupled system works before the end of the mission. The exploration of a body as diverse as Titan, its history, geology, meteorology, chemistry, upper atmosphere, exosphere as well as plasma and magnetic environment requires expertise from many different scientific communities. What the case of Titan shows particularly well is that all of these processes and regions are intimately coupled and need the different communities to work closely together. To foster this communication and obtain an overview of the status of our knowledge of Titan's atmosphere and its space environment towards the end of the Cassini/Huygens primary mission (2004)(2005)(2006)(2007)(2008), we organized a scientific Discussion Meeting at the Royal Society in London on 3-4 December 2007.The 14 invited talks at this event were given by scientists from Europe and the USA and form the basis for this issue. One overarching question the Cassini/Huygens mission is trying to answer is that of the origin of Titan and its atmosphere, a topic explored in the papers by Owen & Niemann (2009) and Tobie et al. (2009). With a surface pressure 1.6 times that on the Earth and the main constituent being molecular nitrogen, many parallels have been drawn between the atmospheres of the Earth and Titan, and the comparison of their atmospheres is featured in several papers of this issue. For instance, the study by Tokano (2009) highlights important differences between Titan and the Earth as far as wind direction and seasonal variation in the lowest atmospheric layer, the troposphere, are concerned. Flasar & Achterberg's (2009) paper extends discussions of winds into Titan's stratosphere and points out the strong coupling between temperatures, winds and composition there. This strong coupling is also reproduced by the latest general circulation models of Titan's stratosphere, as discussed by

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Composition and chemistry of Titan's stratosphere

Cited by 24 publications

References 40 publications

Atmospheric Structure and Composition

Atmospheric Structure and Composition

Acetylene on Titan’s Surface

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