Results 231 to 240 of about 2,942 (252)

On the origin of isolated olivine grains in type 2 carbonaceous chondrites

Earth and Planetary Science Letters, 1978
Two possibilities exist for the origin of aggregates and isolated grains in C2 meteorites: (1) high-temperature phases that condensed directly from a solar nebular gas accumulated as aggregates and single grains on the parent bodies of carbonaceous chondrites and remained unaltered since, or (2) all high-temperature phases in these meteorites are now ...
Lawrence Grossman, Edward Olsen
exaly   +2 more sources

Carbonaceous grain processing in space and in the laboratory

Advances in Space Research, 1999
Laboratory 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, L. COLANGELI, J. R. BRUCATO, E. EPIFANI, E. PALOMBA, PALUMBO, Pasquale, ROTUNDI, Alessandra   +6 more
openaire   +3 more sources

Primitive Grain Clumps and Organic Compounds in Carbonaceous Chondrites

Nature, 1976
WE 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
openaire   +1 more source

Hydrogenation of PAH molecules through interaction with hydrogenated carbonaceous grains

Phys. Chem. Chem. Phys., 2014
Carbonaceous 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.; id_orcid 0000-0003-0974-8077, Friis, Emil E., Skov, Anders L., Jørgensen, Bjarke, Hornekær, Liv   +4 more
openaire   +3 more sources

GRAIN SIZE AND PETROGRAPHY OF C2 AND C3 CARBONACEOUS CHONDRITES

Meteoritics, 1978
Grain 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
openaire   +1 more source

Experimental study of laboratory-synthesized carbonaceous grains and astrophysical implications

AIP Conference Proceedings, 1994
We 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, V. Mennella, E. Bussoletti, G. Monaco, P. Merluzzi, P. Palumbo, A. Rotundi   +6 more
openaire   +1 more source

Low-temperature condensation of carbonaceous dust grains from PAHs

Proceedings of the International Astronomical Union, 2019
AbstractInterstellar 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, Salma Bejaoui, Gregory Gate, Michael Haggmark, Nathan Svadlenak, Mattanjah de Vries, Ella Sciamma-O’Brien, Farid Salama   +7 more
openaire   +1 more source

Measurements of molecular hydrogen formation on carbonaceous grains

1999
Measurements 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, Liu C, Roser JE, Vidali G.   +3 more
openaire   +1 more source

Carbonaceous Agents Produce Magnesium Grain Refinement

Chemical & Engineering News Archive, 1952
openaire   +1 more source

Origin and Evolution of Carbonaceous Presolar Grains in Stellar Environments

2006
Thomas J. Bernatowicz, Thomas K. Croat, Tyrone L. Daulton   +2 more
openaire   +1 more source