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Grady, M. M.; Wright, I. P.

doi:10.1023/a:1024645906350

Cited by 83 publications

(25 citation statements)

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“…This does not prove that chondritic methane significantly contributes to the atmospheric budget, but at least it indicates that a chondritic source is not incompatible with the available data. On the opposite, 15 N/ 14 N in chondritic organic matter is much smaller than the value in Titan's atmosphere (Grady & Wright 2003;Niemann et al 2010), which suggests that internal dissociation of chondritic organic matter cannot be a main source for the atmospheric N 2 . The potential contribution of the chondritic organic matter to the atmospheric inventory remains an opened question, which will require further investigations.…”

Section: Resultsmentioning

confidence: 91%

“…Primitive carbonaceous chondrites may represent a good proxy of the rocky phase in Saturn's environments. They provide at least upper limits for volatile content of the rocky phase, CI chondrites being the most volatile-rich ones among the different chondrites (e.g., Grady & Wright 2003). Table 2 presents typical composition CI chondrites in term of C, N, S and noble gas content (e.g., Mazor et al 1970;Black 1972;Pepin 1991;Lodders 2003) and the total mass potentially provided in the rocky phase of Titan, assuming that Titan's rock fraction is 50%.…”

Section: Composition Of the Rocky Phasementioning

confidence: 99%

“…However, carbon and nitrogen in chondrites are not in the form of CH 4 and N 2 , but mainly in the form of insoluble organic matters made of complex macromolecules (e.g., Grady & Wright 2003). Such complex organic matters may partly dissociate into simpler molecules at relatively elevated temperatures, such as CO 2 at temperatures of about ∼500-900 K or CH 4 at temperatures of about 800-900 K at ambient pressure (Okumura & Mimura 2011).…”

Section: Composition Of the Rocky Phasementioning

confidence: 99%

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TITAN'S BULK COMPOSITION CONSTRAINED BYCASSINI-HUYGENS: IMPLICATION FOR INTERNAL OUTGASSING

Tobie

Gautier

Hersant

2012

ApJ

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In the present report, by using a series of data gathered by the Cassini-Huygens mission, we constrain the bulk content of Titan's interior for various gas species (CH 4 , CO 2 , CO, NH 3 , H 2 S, Ar, Ne, Xe), and we show that most of the gas compounds (except H 2 S and Xe) initially incorporated within Titan are likely stored dissolved in the subsurface water ocean. CO 2 is likely to be the most abundant gas species (up to 3% of Titan's total mass), while ammonia should not exceed 1.5 wt%. We predict that only a moderate fraction of CH 4 , CO 2 , and CO should be incorporated in the crust in the form of clathrate hydrates. By contrast, most of the H 2 S and Xe should be incorporated at the base of the subsurface ocean, in the form of heavy clathrate hydrates within the high-pressure ice layer. Moreover, we show that the rocky phase of Titan, assuming a composition similar to CI carbonaceous chondrites, is a likely source for the noble gas isotopes ( 40 Ar, 36 Ar, 22 Ne) that have been detected in the atmosphere. A chondritic core may also potentially contribute to the methane inventory. Our calculations show that a moderate outgassing of methane containing traces of neon and argon from the subsurface ocean would be sufficient to explain the abundance estimated by the Gas Chromatograph Mass Spectrometer. The extraction process, implying partial clathration in the ice layers and exsolvation from the water ocean, may explain why the 22 Ne/ 36 Ar ratio in Titan's atmosphere appears higher than the ratio in carbonaceous chondrites.

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Section: Resultsmentioning

confidence: 91%

Section: Composition Of the Rocky Phasementioning

confidence: 99%

Section: Composition Of the Rocky Phasementioning

confidence: 99%

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TITAN'S BULK COMPOSITION CONSTRAINED BYCASSINI-HUYGENS: IMPLICATION FOR INTERNAL OUTGASSING

Tobie

Gautier

Hersant

2012

ApJ

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“…These studies all find high abundances of carbonaceous material (see the reviews of Wooden 2002Wooden , 2008Ehrenfreund et al 2004). Moreover, carbonaceous chondrites, which are the most pristine meteoritic material, contain some mass-percent of carbonaceous material (Grady & Wright 2003).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution of carbon dust in the early solar nebula and the carbon content of planetesimals

Gail

Trieloff

2017

A&A

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Context. A high fraction of carbon bound in solid carbonaceous material is observed to exist in bodies formed in the cold outskirts of the solar nebula, while bodies in the region of terrestrial planets contain only very small mass fractions of carbon. Most of the solid carbon component is lost and converted into CO during the spiral-in of matter as the Sun accretes matter from the solar nebula. Aims. We study the fate of the carbonaceous material that entered the proto-solar disc by comparing the initial carbon abundance in primitive solar system material and the abundance of residual carbon in planetesimals and planets in the asteroid belt and the terrestrial planet region. Methods. We constructed a model for the composition of the pristine carbonaceous material from observational data on the composition of the dust component in comets and of interplanetary dust particles and from published data on pyrolysis experiments. This material entered the inner parts of the solar nebula during the course of the build-up of the proto-sun by accreting matter from the proto-stellar disc. Based on a one-zone evolution model of the solar nebula, we studied the pyrolysis of the refractory and volatile organic component and the concomitant release of hydrocarbons of high molecular weight under quiescent conditions of disc evolution, while matter migrates into the central parts of the solar nebula. We also studied the decomposition and oxidation of the carbonaceous material during violent flash heating events, which are thought to be responsible for the formation of chondrules. To do this, we calculated pyrolysis and oxidation of the carbonaceous material in temperature spikes that were modeled according to cosmochemical models for the temperature history of chondrules. Results. We find that the complex hydrocarbon components of the carbonaceous material are removed from the disc matter in the temperature range between 250 and 400 K, but the amorphous carbon component survives to temperatures of 1200 K. Without efficient carbon destruction during flash-heating associated with chondrule formation, the carbon abundance of terrestrial planets, except for Mercury, would be of several percent and not as low as it is found in cosmochemical studies. Chondrule formation seems to be a crucial process for the carbon-poor composition of the material of terrestrial planets.

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“…However, recent studies have suggested the possible presence of 12 C enriched carbon in the core by fractionation processes during early accretion and segregation of metallic core [14,15]. Studies on other planetary materials in the solar system, such as howardite-eucrite-diogenite (HED) meteorites, shergottite-nakhlite-chassignite (SNC) meteorites and chondrites suggest that there is a remarkable difference in isotopic composition between these bodies and bulk silicate Earth values, the later being heavier than the former in the order of about 10 to 15 [16][17][18]. Thus, the validity of the assumption that the bulk Earth carbon isotope composition is equivalent to the carbon isotopic composition of silicate mantle is being debated recently [1,14,15].…”

Section: Introductionmentioning

confidence: 99%

High-Pressure and High-Temperature Carbon Isotope Fractionation in the Fe-C System: Implications for Carbon Dynamics in the Deep Earth

Satish-Kumar

2017

The Review of High Pressure Science and Technology

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Cited by 83 publications

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TITAN'S BULK COMPOSITION CONSTRAINED BYCASSINI-HUYGENS: IMPLICATION FOR INTERNAL OUTGASSING

TITAN'S BULK COMPOSITION CONSTRAINED BYCASSINI-HUYGENS: IMPLICATION FOR INTERNAL OUTGASSING

Spatial distribution of carbon dust in the early solar nebula and the carbon content of planetesimals

High-Pressure and High-Temperature Carbon Isotope Fractionation in the Fe-C System: Implications for Carbon Dynamics in the Deep Earth

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