Results 251 to 260 of about 381,696 (284)

Stability of amorphous circumstellar silicate grains

Astronomische Nachrichten, 1986
AbstractBerechnungen innerhalb der klassischen Nukleationstheorie zeigen, daß Mg2SiO4‐Staubteilchen mit Radien von etwa 0,1 μm, die sich mit hoher Wahrscheinlichkeit im zirkumstellaren Raum um Sterne späten Spektraltyps bilden, bei etwa 750 K auskondensieren müssen, um amorph zu bleiben.
Th. Henning, J. Svatoš
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Photoelectron yield of silicate and graphite grains

Journal of the Optical Society of America B, 1995
The photoelectric yields of small silicate and graphite grains are calculated as a function of incident photon wavelength for the purpose of modeling interstellar grains. The large surface-to-volume ratio of a small grain is expected to result in an increased photoelectric yield when compared with a bulk sample of the same material.
J. L. Ballester, Y. Shi, E. Dwek
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Infrared spectra of silicate grains

Astronomische Nachrichten, 1971
AbstractThe observed 10 μm emission is interpreted as due to Si‐O‐stretching vibrations of the SiO4‐tetrahedrons of circumstellar silicate grains.
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Carbon and silicate grains in the laboratory as analogues of cosmic dust

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2001
Carbon and silicate grains are the two main components of cosmic dust. There is increasing spectroscopic evidence that their composition varies according to the cosmic environment and the experienced processing. Irradiation from ultraviolet photons and cosmic rays, as well as chemical interactions with the interstellar gas play a crucial role for grain
V, Mennella, J R, Brucato, L, Colangeli
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Thermal Processing of Formamide Ices on Silicate Grain Analogue

The Journal of Physical Chemistry A, 2014
Fourier transform-infrared spectroscopy (FT-IR) and temperature programmed desorption (TPD) have been used to examine the thermal processing of three isotopes of pure formamide ice (HCONH2, DCONH2, and HCOND2) adsorbed on a SiO2 interstellar grain analogue.
Dawley, M. Michele, Pirim, Claire, Orlando, Thomas   +2 more
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The search for trace elements in stardust silicate grains

2022
Isotopically anomalous dust grains that formed in the outflows of evolved stars and in the ejecta of stellar explosions are a minor, but important component of primitive Solar System materials. These grains carry records of stellar nucleosynthesis and evolution, circumstellar grain formation, and stars contributing material to the nascent Solar System.
Leitner, Jan, Hoppe, Peter, Trieloff, Mario   +2 more
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Infrared Extinction Cross Sections of Silicate Grains

Publications of the Astronomical Society of the Pacific, 1973
Extinction cross sections for plagioclase and pyroxene silicate particles have been calculated for frequencies between 10 and 1400 cm-1. Results are compared to infrared observations of grains.
Roger F. Knacke, R. Kevin Thomson
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Penetration and corrosion of magnesia grain by silicate slags

British Ceramic Transactions, 2000
AbstractPenetration and corrosion resistance of high purity sintered and fused magnesia grain by model EAF (CaO/SiO2 = 1·38) and BOF ‘late’ slags (CaO/SiO2 = 3·29) at 1600 and 1700°C were investigated by SEM, EDS, and XRD analysis. Thermodynamic calculations were performed to assist interpretation of the reaction processes involved.
S. Zhang, H. Sarpoolaky, N.J. Marriott, W.E. Lee   +3 more
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Silicate Grains in Space: Laboratory Results

1988
Since their discovery in the spectra of some strong IR sources (Stein et al., 1969; Woolf and Ney, 1969; Forrest et al., 1979), the bands at around 10 µm and 20 µm have been respectively attributed to typical Si-O stretching and O-Si-0 bending modes in the SiO4 tetrahedra of the silicate structure. The presence of silicate grains around “O” stars ([O]/[
F. Leucci, L. Colangeli, E. Bussoletti, W. Krätchmer   +3 more
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Optical properties of circumstellar silicate grains

Astrophysics and Space Science, 1991
The optical properties of circumstellar silicate dust grains around oxygen-rich giant stars are investigated with close attention to infrared observations of OH/IR stars. The optical constants are deduced from available astronomical and laboratory data.
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