Stability of Condensed Hydrocarbons in the Solar Nebula

Zolotov, M. Yu.; Shock, Everett L.

doi:10.1006/icar.2001.6589

Cited by 23 publications

(19 citation statements)

References 86 publications

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“…1000 K, the exact temperature depending on the pressure, the thermodynamically preferred states of carbon and oxygen atoms are in the molecules CH 4 and H 2 O rather than CO (see, e.g., Burrows &Sharp 1999 andZolotov &Shock 2001). At a sufficiently low temperature, water and ice droplets form, while CH 4 remains in the gas phase until the temperature drops significantly below 100 K (Boogert et al 1998).…”

Section: Discussionmentioning

confidence: 99%

“…At a sufficiently low temperature, water and ice droplets form, while CH 4 remains in the gas phase until the temperature drops significantly below 100 K (Boogert et al 1998). The disk's approach to this thermodynamically predicted state in a sufficiently short time can be facilitated by Fischer-Tropsch (FT) catalysis on the surface of iron grains at phases when the material was warmer than 400 K, as has been suggested to explain the presence of carbonaceous material in meteorites (see, e.g., Kress &Tielens 2001 andZolotov &Shock 2001). Alternatively, gas-phase chemistry may be important (Morgan et al 1991).…”

Section: Discussionmentioning

confidence: 99%

“…The usual view is that most of the carbonaceous material was incorporated as carbon-rich compounds from the interstellar medium and then further processed (Ehrenfreund & Charnley 2000;Kerridge 1999). However, a contrary view is that even in the oxygen-rich solar nebula, Fischer-Tropsch catalysis on the surface of metal grains at T 1 400 K was an important route for the synthesis of carbon-rich molecules (Kress & Tielens 2001;Zolotov & Shock 2001). Alternatively, gas-phase synthesis of such molecules may be important (Morgan et al 1991).…”

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confidence: 99%

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Polycyclic Aromatic Hydrocarbons Orbiting HD 233517, an Evolved Oxygen-rich Red Giant

Jura

Bohac

Sargent

et al. 2006

ApJ

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We report spectra obtained with the Spitzer Space Telescope in the l p 5-35 mm range of HD 233517, an evolved K2 III giant with circumstellar dust. For l 1 13 mm, the flux is a smooth continuum that varies approximately as . For l ! 13 mm, although the star is oxygen-rich, PAH features produced by carbon-rich Ϫ5/3 n species at 6.3, 8.2, 11.3, and 12.7 mm are detected along with likely broad silicate emission near 20 mm. These results can be explained if there is a passive, flared disk orbiting HD 233517. Our data support the hypothesis that organic molecules in orbiting disks may be synthesized in situ as well as having been incorporated from the interstellar medium.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Polycyclic Aromatic Hydrocarbons Orbiting HD 233517, an Evolved Oxygen-rich Red Giant

Jura

Bohac

Sargent

et al. 2006

ApJ

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“…equilibrium, and hydrocarbons can coexist with water vapour in a metastable state (Zolotov & Shock 2001). Reactions between hydrocarbons and atomic H occur with significant rates such that all hydrocarbons with more than three carbon atoms are degraded to small hydrocarbons with 1 or 2 carbon atoms, mainly CH 4 and C 2 H 2 , before they disappear at temperatures above ∼1200 K by oxidation to CO.…”

Section: A2 Oxidation Of Sootmentioning

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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“…This radiation-induced lattice damage represents an accumulation of latent energy because atomic displacement defects in solids typically store about 1 eV each (Devanathan et al 1998). Since a Frenkel pair in graphite represents approximately 2.7 eV, or 4.3× 10 −19 J, displacing more than 1% of the atoms in carbonaceous materials (Zolotov and Shock 2001), including nanocrystalline carbon and polyaromatic graphite precursors, can create a stored energy density of approximately 2 MJ kg −1 , while comparable defect densities in oxide and silicate phases can store approximately 0.1 MJ kg −1 (Kurath 1957). If 9P/Tempel-1's interior contains carbonaceous materials (Ewels et al 2003) and grains of oxides or silicates such as enstatite or olivine with high densities of frozen in radiation damage, energy released from shockheated grains or dust could augment the kinetic energy of the Deep Impact probe.…”

Section: Introductionmentioning

confidence: 99%

Xenomict energy in cold solids in space

Seitz¹,

Raymond

Kissel

et al. 2006

Naturwissenschaften

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Minerals on earth whose crystalline order has been reduced by radioactive decay of contained atoms are termed "metamict." They are rare and few because in most crystalline solids, atoms and vacancies are relatively mobile at terrestrial temperatures, and radiation damage tends to be self-annealing. This is not the case in the extreme cold of deep space. Below roughly 100 K, reduced vacancy mobility allows cosmic ray and solar wind induced lattice defects to endure and accumulate for eons, reaching energy densities of up to MJ kg −1 in some materials. We examine the possible effects of the release of energy stored in cold deep-space materials when solid-state defects recombine upon warming due to impacts, gravitational infall, or perihelion. Dimensional analysis suggests energetic defect recombination in radiation-damaged "xenomict" solids in comets, and planetesimals may, in some circumstances, raise internal temperatures enough to melt ice and volatilize frozen gases. We speculate that this may account for some cometary outbursts and Deep Impact experiment results. Calorimetric experiments on appropriately irradiated natural and synthetic materials are needed to further quantify these mechanisms.

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Stability of Condensed Hydrocarbons in the Solar Nebula

Cited by 23 publications

References 86 publications

Polycyclic Aromatic Hydrocarbons Orbiting HD 233517, an Evolved Oxygen-rich Red Giant

Polycyclic Aromatic Hydrocarbons Orbiting HD 233517, an Evolved Oxygen-rich Red Giant

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

Xenomict energy in cold solids in space

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