Titan’s atmosphere from ISO mid-infrared spectroscopy

Coustenis, A.; Salama, A.; Schulz, B.; Ott, Stephan; Lellouch, E.; Encrenaz, Thérèse; Gautier, D.; Feuchtgruber, H.

doi:10.1016/s0019-1035(02)00028-3

Cited by 315 publications

(226 citation statements)

References 42 publications

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“…The similar H 2 O fluxes per unit area into the four giant planets and Titan (Feuchtgruber et al 1997;Coustenis et al 1998;Moses et al 2000), combined with the rather constant dust flux (∼3×10 −18 g cm −2 s −1 ) measured in interplanetary space beyond 5 AU (Landgraf et al 2002) have been regarded as evidence that micrometeoroids -interplanetary (IDPs) or interstellar -are the dominant source (Moses et al 2000). Along with the evidence that the H 2 O present in Jupiter's atmosphere results from the Shoemaker-Levy 9 1994 impact -and that CO in Jupiter, Saturn, and Neptune Cavalié et al 2010;Lellouch et al 2005) also result from ancient cometary impacts -our inference that Enceladus is a quantitatively viable source of Saturn's water clearly shifts the paradigm towards local or sporadic sources playing a more important role.…”

Section: Discussion and Implications For The Source Of Water In Saturmentioning

confidence: 80%

“…Emission lines due to water vapor in the far-infrared spectrum (λ > 30 μm) of the giant planets and Titan, first discovered by ISO (Feuchtgruber et al 1997;Coustenis et al 1998) prove the existence of an external supply of water to these reducing atmospheres. At Saturn and Jupiter, spectrally resolved observations of the fundamental 1 10 -1 01 line of ortho-H 2 O at 557 GHz (538 μm), obtained by SWAS in September 1999 (Bergin et al 2000), indicated a ∼10% contrast emission with ∼20 km s −1 width.…”

Section: Observations and Initial Interpretationmentioning

confidence: 99%

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Direct detection of the Enceladus water torus withHerschel

Hartogh

Lellouch

Moreno

et al. 2011

A&A

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Cryovolcanic activity near the south pole of Saturn's moon Enceladus produces plumes of H 2 O-dominated gases and ice particles, which escape and populate a torus-shaped cloud. Using submillimeter spectroscopy with Herschel, we report the direct detection of the Enceladus water vapor torus in four rotational lines of water at 557, 987, 1113, and 1670 GHz, and probe its physical conditions and structure. We determine line-of-sight H 2 O column densities of ∼4 × 10 13 cm −2 near the equatorial plane, with a ∼50 000 km vertical scale height. The water torus appears to be rotationally cold (e.g. an excitation temperature of 16 K is measured for the 1113 GHz line) but dynamically excited, with non-Keplerian dispersion velocities of ∼2 km s −1 , and appears to be largely shaped by molecular collisions. From estimates of the influx rates of torus material into Saturn and Titan, we infer that Enceladus' activity is likely to be the ultimate source of water in the upper atmosphere of Saturn, but not in Titan's.

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Section: Discussion and Implications For The Source Of Water In Saturmentioning

confidence: 80%

Section: Observations and Initial Interpretationmentioning

confidence: 99%

Direct detection of the Enceladus water torus withHerschel

Hartogh

Lellouch

Moreno

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…These species are also of importance for astronomical studies: Benzene has been detected in the north polar auroral region of Jupiter [364] and in the stratospheres of Jupiter and Saturn [365] as well as in Titan's atmosphere [366]. The need for laboratory spectroscopic data to study organic chemistry in planetary atmospheres was highlighted in Refs.…”

Section: Aromatic Speciesmentioning

confidence: 99%

The HITRAN2012 molecular spectroscopic database

Rothman

Gordon

Babikov

et al. 2013

Journal of Quantitative Spectroscopy and Radiative Transfer

3,006

1,794

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“…Trace amounts of ethane, ethylene, and acetylene have been detected within the atmospheres of these planets as well (Cruikshank 1998). Observations of Titan with ISO by Coustenis et al (2003) also revealed the presence of a few percent of methane, as well as minor traces of associated hydrocarbons including ethane (C 2 H 6 ), ethylene (C 2 H 4 ), acetylene (C 2 H 2 ), propane (C 3 H 8 ), allene ( H 2 CCCH 2 ), methylacetylene (CH 3 CCH ), diacetylene ( HCCCCH ), and benzene (C 6 H 6 ). Infrared studies of outer solar system icy bodies like Pluto with the United Kingdom Infrared Telescope ( UKIRT) verified from the position of the methane band that methane molecules are not only embedded in solid nitrogen ( N 2 ) dominated ices but also as islands of solid methane ( Douté et al 1999).…”

Section: Introductionmentioning

confidence: 94%

“…Coustenis et al (2003) have analyzed the atmosphere of Saturn's moon Titan using ISO and found that not only are methane, ethane, ethylene, and acetylene present, but also more complex hydrocarbons such as propane, propyne, benzene, allene, and diacetylene. Most modeling of Titan is focused on attempting to recreate these molecules from gas-phase processes initiated by UV irradiation (e.g., Tran et al 2005); however, it is clear that the surface is known to be bombarded by energetic ions, photons and electrons that are capable of producing more complex molecules in the solid state.…”

Section: Astrophysical Implicationsmentioning

confidence: 99%

Laboratory Studies on the Irradiation of Methane in Interstellar, Cometary, and Solar System Ices

Bennett

Jamieson

Osamura

et al. 2006

ApJ

156

168

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Pure methane ices (CH 4 ) were irradiated at 10 K with energetic electrons to mimic the energy transfer processes that occur in the track of the trajectories of MeV cosmic-ray particles. The experiments were monitored via an FTIR spectrometer (solid state) and a quadrupole mass spectrometer (gas phase). Combined with electronic structure calculations, this paper focuses on the identification of CH x (x ¼ 1Y4) and C 2 H x (x ¼ 2Y6) species and also investigates their formation pathways quantitatively. The primary reaction step is determined to be the cleavage of a carbonhydrogen bond of the methane molecule to form a methyl radical (CH 3 ) plus a hydrogen atom. Hydrogen atoms recombined to form molecular hydrogen, the sole species detected in the gas phase during the irradiation exposure. In the matrix two neighboring methyl radicals can recombine to form an internally excited ethane molecule (C 2 H 6 ), which either can be stabilized by the surrounding matrix or was found to decompose unimolecularly to the ethyl radical (C 2 H 5 ) plus atomic hydrogen and then to the ethylene molecule (C 2 H 4 ) plus molecular hydrogen. The initially synthesized ethane, ethyl, and ethylene molecules can be radiolyzed subsequently by the impinging electrons to yield the vinyl radical (C 2 H 3 ) and acetylene (C 2 H 2 ) as degradation products. Upon warming the ice sample after the irradiation, the new species are released into the gas phase, simulating the sublimation processes interstellar ices undergo during the hot core phase or comets approaching perihelion. Our investigations also aid the understanding of the synthesis of hydrocarbons likely to be formed in the aerosol particles and organic haze layers of hydrocarbon-rich atmospheres of planets and their moons such as Titan.

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Titan’s atmosphere from ISO mid-infrared spectroscopy

Cited by 315 publications

References 42 publications

Direct detection of the Enceladus water torus withHerschel

Direct detection of the Enceladus water torus withHerschel

The HITRAN2012 molecular spectroscopic database

Laboratory Studies on the Irradiation of Methane in Interstellar, Cometary, and Solar System Ices

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