Journal ArticleDOI
Visible and ultraviolet (800--130 nm) extinction of vapor-condensed silicate, carbon, and silicon carbide smokes and the interstellar extinction curve
TLDR
The extinction curves from 800 to 130 nm (1.25-7.7/micron) of amorphous silicate smokes nominally of olivine and pyroxene composition, carbon smokes, and crystalline SiC smokes are presented as mentioned in this paper.Abstract:
The extinction curves from 800 to 130 nm (1.25-7.7/micron) of amorphous silicate smokes nominally of olivine and pyroxene composition, carbon smokes, and crystalline SiC smokes are presented. The SiC smoke occurred in the low-temperature (beta) cubic structural form. The SiC smoke showed an absorption edge which occurred at significantly longer wavelengths than the calculated extinction profile of the hexagonal SiC form previously used to calculate the interstellar extinction profile. Neither SiC nor amorphous silicates show an extinction band similar to the observed 6.6/micron astronomical extinction band. The infrared absorption peaks for the silicate and SiC samples near 10 microns and 11-13 microns, respectively, were also measured. The ultraviolet to infrared extinction ratio for the amorphous silicate samples is similar to the observed astronomical extinction ratio. The measured extinction ratios for SiC smokes are significantly below the interstellar extinction ratio. The extinction peak of the carbon smokes occurred at 4.0 and 4.25/micron, for samples of mean radii 13 and 6 nm, respectively. The extinction profile is distinctly different from that predicted for graphite grains of the same size, and is similar to that predicted for glassy carbon grains.read more
Citations
More filters
Book ChapterDOI
On the Interpretation of the λ2175Å Feature
TL;DR: The interpretation of the interstellar λ2175 A feature is reviewed in this paper, and various proposed explanations for the feature are examined, and difficulties with each of the proposed interpretations are identified.
Journal ArticleDOI
Synthesis and degradation of nucleic Acid components by formamide and cosmic dust analogues.
Raffaele Saladino,Claudia Crestini,Veronica Neri,John Robert Brucato,Luigi Colangeli,Fabiana Ciciriello,Ernesto Di Mauro,Giovanna Costanzo +7 more
TL;DR: This work shows the unprecedented one‐pot synthesis of a large suite of pyrimidines and purines from formamide in the presence of cosmic‐dust analogues (CDAs) of olivines and investigates the stabilizing effect of CDAs on the intrinsic instability of oligonucleotides in formamide.
Journal ArticleDOI
Analytical electron microscopy of Mg-SiO smokes - A comparison with infrared and XRD studies
TL;DR: In this paper, the microcrystallinity content of unannealed smokes increases with increased annealing for up to 30 hours and the growth of forsterite micro-crystallites in the initially nonstoichiometric smokes may give rise to the contemporaneous growth of the SiO polymorph tridymite and MgO; these react to form enstatite.
Journal ArticleDOI
The absorption efficiency of submicron amorphous carbon particles between 2.5 and 40 μm
TL;DR: In this article, the absorption extinction curves indicate a general λ − 1 fall-off, with small humps at 8, 11 and 12 μm for grains obtained by burning hydrocarbons.
Journal ArticleDOI
Meteoritic evidence that graphite is rare in the interstellar medium
TL;DR: In this paper, a dearth of graphitic carbon was found in meteorites and it was concluded that graphitic material was not a major component of the interstellar dust at the time of the formation of the solar system.
Related Papers (5)
Optical properties of interstellar graphite and silicate grains
Bruce T. Draine,Hyung Mok Lee +1 more