Silicon carbide and the origin of interstellar carbon grains

Frenklach, Michael; Carmer, C. S.; Feigelson, E. D.

doi:10.1038/339196a0

Cited by 58 publications

(40 citation statements)

References 29 publications

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“…Dust grains produced in Carbonrich asymptotic giant branch stars are abundant in SiC crystallites 18 . Their size can range from few nm in the proximities to the star to some mm.…”

Section: Resultsmentioning

confidence: 99%

“…SiC is produced close to the evolved star as small-sized nanoparticles (typically few nm) and it has been proven that the crystallization rates of SiC grains can be very fast (Emm h À 1 ) at high temperatures 18 . In our experiment, we have used singlecrystal surfaces to simulate the process, and one might think that the surface chemical properties of large extended crystals and nanoparticles could be completely different.…”

Section: Discussionmentioning

confidence: 99%

“…The main current theories invoke either combustion-like [10][11][12] or ultraviolet-driven-acetylenicpolymerization and evaporation processes in most evolved objects [13][14][15][16][17] . However, the efficiency of such processes is still unknown 8,9,18 and during the last 30 years an important amount of work has been performed to determine PAHs origin and physicochemical properties.…”

mentioning

confidence: 99%

“…1. Such SiC grains are formed in the inner regions (1-5 R*, R* stellar radius) of evolved stars by means of gas-phase condensation 14,18 . We show that in space, SiC crystallites possess a significant amount of segregated carbon on their surfaces, primarily organized as graphitic overlayers.…”

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confidence: 99%

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Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

et al. 2014

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Polycyclic aromatic hydrocarbons as well as other organic molecules appear among the most abundant observed species in interstellar space and are key molecules to understanding the prebiotic roots of life. However, their existence and abundance in space remain a puzzle. Here we present a new top-down route to form polycyclic aromatic hydrocarbons in large quantities in space. We show that aromatic species can be efficiently formed on the graphitized surface of the abundant silicon carbide stardust on exposure to atomic hydrogen under pressure and temperature conditions analogous to those of the interstellar medium. To this aim, we mimic the circumstellar environment using ultra-high vacuum chambers and investigate the SiC surface by in situ advanced characterization techniques combined with first-principles molecular dynamics calculations. These results suggest that top-down routes are crucial to astrochemistry to explain the abundance of organic species and to uncover the origin of unidentified infrared emission features from advanced observations.

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“…Dust grains produced in Carbonrich asymptotic giant branch stars are abundant in SiC crystallites 18 . Their size can range from few nm in the proximities to the star to some mm.…”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

et al. 2014

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“…The carbonaceous component of cosmic dust plays an important role in the universe (Henning & Salama 1998). Carbon particles are thought to be primarily formed in the outflow of carbon stars, through a combustion-like process where small carbon chains (e.g., acetylene) form polycyclic aromatic hydrocarbons (PAHs) that nucleate into larger-size PAHs and, ultimately, into nanoparticles (Frenklach et al 1989;Pascoli & Polleux 2000;Jäger et al elsewhere in this volume). According to the model, that was developed to account for the formation of carbonaceous meteoritic materials, nucleation occurs above 2000 K, followed by the growth of amorphous carbon on the condensation nuclei in the 2000-1500 K temperature range.…”

Section: Introductionmentioning

confidence: 99%

Formation and Evolution of Circumstellar and Interstellar PAHs: A Laboratory Study

Contreras

Ricketts

Salama

2011

EAS Publications Series

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Abstract. Studies of dust analogs formed from hydrocarbon (CH4, C2H2, C2H4, C2H6) and PAH precursors have been performed using a new facility that we have developed to simulate interstellar and circumstellar processes. The species formed in a plasma are detected, characterized and monitored in situ with high-sensitivity techniques, which provide both spectroscopic and ion mass information. From these measurements we derive information on the nature, the size and the structure of dust particles, as well as a better understanding of the growth and destruction processes of extraterrestrial dust.

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Experimental and modeling study of shock‐tube oxidation of acetylene

Eiteneer

Frenklach

2003

Int J of Chemical Kinetics

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Nine mixtures of acetylene and oxygen diluted in argon were studied behind reflected shock waves at temperatures of 1150-2132 K and pressures of 0.9-1.9 atm. Initial compositions were varied from very fuel-lean to moderately fuel-rich, covering equivalence ratios of 0.0625-1.66. Two more mixtures with added ethylene were used to boost the sensitivity to reactions of vinyl oxidation. The progress of reaction was monitored by laser absorption of CO molecules. The collected experimental data were subjected to extensive detailed chemical kinetics analysis. The initial kinetic model was assembled based on recent literature data and then optimized using the solution mapping technique. The analysis was extended to include recent experimental observations of Hidaka and co-workers (Combust Flame 1996, 107, 401). The derived model reproduces closely both sets of experimental data, the result obtained by modifying nine rate coefficients and three enthalpies of formation of intermediate species. The identified parameter tradeoffs and justification for the changes are discussed.

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Silicon carbide and the origin of interstellar carbon grains

Cited by 58 publications

References 29 publications

Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

Formation and Evolution of Circumstellar and Interstellar PAHs: A Laboratory Study

Experimental and modeling study of shock‐tube oxidation of acetylene

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