Clathration of Volatiles in the Solar Nebula and Implications for the Origin of Titan's Atmosphere

Mousis, O.; Lunine, Jonathan I.; Thomas, C.; Pasek, Matthew A.; Marboeuf, U.; Alibert, Yann; Ballenegger, V.; Cordier, Daniel; Ellinger, Y.; Pauzat, F.; Picaud, Sylvain

doi:10.1088/0004-637x/691/2/1780

Cited by 75 publications

(60 citation statements)

References 56 publications

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“…7,52 On the other hand, in order to interpret the Ar deficiency in the atmosphere of Titan, it has been proposed that the satellite was formed from icy planetesimals initially produced in the solar nebula and that were partially devolatilized at a temperature not exceeding ∼ 50 K during their migration within Saturn's subnebula. 13 In this case, because Ar is poorly trapped in clathrates formed above ∼ 50 K in the nebula, only tiny amounts of this compound would have been incorporated in the building blocks of the forming Titan, in agreement with the observations. In particular, our nominal model predicts that this noble gas would remain essentially trapped in CH 4 -dominated clathrate 3 , and subsequently in the satellite, with Ar/CH 4 of 2.7 × 10 −5 (see Fig.…”

Section: The Argon Deficiency In Titansupporting

confidence: 82%

“…Thus, clathrates may have been accreted in comets, in the forming giant planets and in their surrounding satellite systems. 4,[12][13][14][17][18][19][20][21][22][23][24] During the twentieth century, many theoretical and experimental studies allowed This approach, used today in the industry and in science, has saved substantial experimental efforts for the determination of i) the equilibrium pressure of a clathrate formed from various mixtures and ii) the mole fraction of the different species trapped in the clathrate from a given fluid phase.…”

Section: Introductionmentioning

confidence: 99%

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Volatile inventories in clathrate hydrates formed in the primordial nebula

et al. 2010

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Examination of ambient thermodynamic conditions suggest that clathrate hydrates could exist in the martian permafrost, on the surface and in the interior of Titan, as well as in other icy satellites. Clathrate hydrates probably formed in a significant fraction of planetesimals in the solar system. Thus, these crystalline solids may have been accreted in comets, in the forming giant planets and in their surrounding satellite systems. In this work, we use a statistical thermodynamic model to investigate the composition of clathrate hydrates that may have formed in the primordial nebula. In our approach, we consider the formation sequence of the different ices occurring during the cooling of the nebula, a reasonable idealization of the process by which volatiles are trapped in planetesimals. We then determine the fractional occupancies of guests in each clathrate hydrate formed at given temperature. The major ingredient of our model is the description of the guest-clathrate hydrate interaction by a spherically averaged Kihara potential with a nominal set of parameters, most of which being fitted on experimental equilibrium data. Our model allows us to find that Kr, Ar and N 2 can be efficiently encaged in clathrate hydrates formed at temperatures higher than ∼ 48.5 K in the primitive nebula, instead of forming pure condensates below 30 K. However, we find at the same time that the determination of the relative abundances of guest species incorporated in these clathrate hydrates strongly depends on the choice of the parameters of the Kihara potential and also on the adopted size of cages. Indeed, testing different potential parameters, we have noted that even minor dispersions between the different existing sets can lead to non-negligible variations in the determination of the volatiles trapped in clathrate hydrates formed in the primordial nebula. However, these variations are not found to be strong enough to reverse the relative abundances between the different volatiles in the clathrate hydrates themselves. On the other hand, if contraction or expansion of the cages due to temperature variations are imposed in our model, the Ar and Kr mole fractions can be modified up to several orders of magnitude in clathrate hydrates. Moreover, mole fractions of other molecules such as N 2 or CO are also subject to strong changes with the variation of the size of the cages. Our results may affect the predictions of the composition of the planetesimals formed in the outer solar system. In particular, the volatile abundances calculated in the giant planets atmospheres should be altered because these quantities are proportional to the mass of accreted and vaporized icy planetesimals. For similar reasons, the estimates of the volatile budgets accreted by icy satellites and comets may also be altered by our calculations. For instance, under some conditions, our calculations predict that the abundance of argon in the atmosphere of Titan should be higher than the value measured by Huygens. Moreover, the Ar abundance in comets...

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Section: The Argon Deficiency In Titansupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Volatile inventories in clathrate hydrates formed in the primordial nebula

et al. 2010

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“…The CO ice is not condensed in the Saturnian sub-nebula. As a consequence, the satellitesimals formed in the disk could be depleted of this ice as suggested by Mousis et al (2008). This would explain the deficiency of CO observed in Titan's atmosphere (Alibert & Mousis, 2007).…”

Section: The Disk Evolution and Chemistrymentioning

confidence: 85%

From Gas to Satellitesimals: Disk Formation and Evolution

2010

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The subject of satellite formation is strictly linked to the one of planetary formation. Giant planets strongly shape the evolution of the circum-planetary disks during their formation and thus, indirectly, influence the initial conditions for the processes governing satellite formation. In order to fully understand the present features of the satellite systems of the giant planets, we need to take into account their formation environments and histories and the role of the different physical parameters. In particular, the pressure and temperature profiles in the circum-planetary nebulae shaped their chemical gradients by allowing the condensation of ices and noble gases. These chemical gradients, in turn, set the composition of the satellitesimals, which represent the building blocks of the present regular satellites.

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“…In addition to water ice, the model takes into account the solid phases of CO, CO 2 , CH 4 , and H 2 S. These molecules are among the most abundant volatile species (production rates relative to water greater than 1%) observed in cometary nuclei (Bockelée-Morvan et al 2004) and are susceptible to form clathrates at low-pressure conditions (Lunine & Stevenson 1985). Other molecules such as H 2 CO, CH 3 OH, and NH 3 , which are also abundant in comets, have not been considered in this study because there are no experimental data concerning the equilibrium of H 2 CO and CH 3 OH clathrates (Fray & Schmitt 2009;Marboeuf et al 2008;Mousis et al 2009), while NH 3 does not form clathrates (Lunine & Stevenson 1985). Table 1 gives the X/H 2 O (J X ) mole fractions relative to water (with X = CO, CO 2 , CH 4 or H 2 S) of the volatiles initially present in the nucleus, either condensed in the porous network (first number), or trapped in the amorphous matrix (second number, in parenthesis).…”

Section: Thermodynamic Parameters and Initial Compositionmentioning

confidence: 99%

On the stability of clathrate hydrates in comets 67P/Churyumov-Gerasimenko and 46P/Wirtanen

Marboeuf

Mousis

Petit

et al. 2010

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Context. For several years, Jupiter-family comets have been the targets of spacecraft missions whose aims are to determine the comets' composition, structure, and physical properties. The Rosetta mission is currently flying towards comet 67P/Churyumov Gerasimenko for a rendezvous in August 2014 and comet 46P/Wirtanen is considered for a rendezvous in 2021 with the PriME (Primitive Material Explorer) mission, which is currently proposed to NASA. Aims. Here we investigate the stability conditions of clathrate hydrates within the comets 67P/Churyumov-Gerasimenko and 46P/Wirtanen by considering an initial mixture of amorphous H 2 O with CO, CO 2 , CH 4 , and H 2 S in the nuclei. Methods. We use a one-dimensional nucleus model, which considers an initially homogeneous sphere composed of a predefined porous mixture of ices and dust in specified proportions and describes heat transmission, gas diffusion, sublimation/recondensation of volatiles within the nucleus, water ice phase transition, dust release, and mantle formation. Results. We show that stability conditions of multiple guest clathrates are permanently reached in the subsurface of both comets, and in a broader manner in the subsurface of all short period comets. The thickness of the stability zone of the clathrate slightly oscillates with time as a function of the heliocentric distance, but never vanishes. When comets approach perihelion, our calculations suggest that clathrate layers, which are located closer to the nucleus surface, may destabilize before amorphous ice is tranformed into crystalline ice.

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Clathration of Volatiles in the Solar Nebula and Implications for the Origin of Titan's Atmosphere

Cited by 75 publications

References 56 publications

Volatile inventories in clathrate hydrates formed in the primordial nebula

Volatile inventories in clathrate hydrates formed in the primordial nebula

From Gas to Satellitesimals: Disk Formation and Evolution

On the stability of clathrate hydrates in comets 67P/Churyumov-Gerasimenko and 46P/Wirtanen

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