Results 261 to 270 of about 27,054 (290)
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Primitive Grain Clumps and Organic Compounds in Carbonaceous Chondrites
Nature, 1976WE show here that the physical conditions in prestellar molecular clouds favour the condensation of complex organic polymers, including amino acids, within a matrix of smaller refractory particles. Such composite grain clumps with dimensions exceeding 1 µm could be expelled along with gaseous material in protostellar cocoons, causing the widespread ...
F. Hoyle, N.C. Wickramasinghe
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Carbonaceous grain processing in space and in the laboratory
Advances in Space Research, 1999Laboratory simulations of carbonaceous grain processing which occurs in space are fundamental to outline an evolutionary pathway for these particles. We consider the UV spectral changes induced in hydrogenated carbon grains by thermal annealing, UV irradiation and ion bombardment.
V. MENNELLA +6 more
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Hydrogenation of PAH molecules through interaction with hydrogenated carbonaceous grains
Phys. Chem. Chem. Phys., 2014Carbonaceous materials contribute to a significant proportion of the interstellar dust inventory. Reactions on such grain surfaces are thought to play important roles in interstellar chemical networks. Of particular importance are reactions involving hydrogen atoms, and pathways to the formation of the most abundant molecular species, H2.
Thrower, John D. +4 more
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Low-temperature condensation of carbonaceous dust grains from PAHs
Proceedings of the International Astronomical Union, 2019AbstractInterstellar carbon has been detected in both gas-phase molecules and solid particles. The goal of this study is to identify the link between these two phases of cosmic carbon. Here we report preliminary results on the low temperature formation of carbonaceous dust grains from gas-phase aromatic hydrocarbon precursors.
Lisseth Gavilan Marin +7 more
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GRAIN SIZE AND PETROGRAPHY OF C2 AND C3 CARBONACEOUS CHONDRITES
Meteoritics, 1978Grain size frequency distributions of the ≥ 0.1 mm size fractions have been measured for 19 C2 and C3 carbonaceous chondrites (7 CM2, 5 CO3, 6 CV3 and 1 CV2). The grain size frequency distribution curves and summary statistics are remarkably similar for the CM2 and CO3 meteorites, with ranges of median grain size from 2.36φ to 2.67φ and graphic mean ...
Trude V.V. King, Elbert A. King
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Experimental study of laboratory-synthesized carbonaceous grains and astrophysical implications
AIP Conference Proceedings, 1994We present here the most recent results obtained in the laboratory from various kinds of carbon‐based submicron grains. The joint use of VUV, IR and Raman spectroscopy allows to characterize them and to determine their structural and spectral properties. We compare our results with similiar data obtained by various authors on other kinds of carbonacous
L. Colangeli +6 more
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Infrared spectra of carbonaceous chondrites and the composition of intertellar grains
Astrophysics and Space Science, 1975Infrared spectra (7–40 μ) of the carbonaceous chondrites, Cold Bokkeveld, Murray, and Orgueil are compared with phyllosilicate minerals and interstellar grain spectra. Similarities in the position and shape of the silicate feature near 9.8 μ suggest that similar silicate minerals are present in primitive meteorites and the interstellar dust.
A. Zaikowski, R. F. Knacke
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Measurements of molecular hydrogen formation on carbonaceous grains
1999Measurements of molecular hydrogen formation on an amorphous carbon sample have been carried out under astrophysically relevant conditions, i.e., using low fluxes of cold (similar to 200 K) hydrogen-isotope beams, sample temperature be tween 5 K and 20 K.
PIRRONELLO, Valerio +3 more
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A quenched carbonaceous composite (QCC) grain model for the interstellar 220 NM extinction hump
Astrophysics and Space Science, 1986The dependence of the wavelength of peak absorption of dust grains on the grain size is investigated analytically by using an oscillator model for the absorption band. The peak wavelength of a weak absorption band is much less sensitive to the grain size than that of a strong band.
T. Onaka +4 more
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