Absorptive properties of silicate core-mantle grains

Abstract

view Abstract Citations (167) References (49) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Absorptive properties of silicate core-mantle grains. Aannestad, P. A. Abstract Absorption and extinction efficiencies for silicate and silicate core-ice mantle grains are presented for olivine-type particles in the wavelength range .07 micron to 1 mm, for fused quartz-type particles in the range .056 micron to 1 mm, and for lunar silicate-type particles in the range 1 micron to 1 mm. Comparison with the observed near-infrared absorption spectrum in the BN object shows that no single type of these particles can adequately account for the observed 9.8 micron feature, and that a mixture of various types of silicates may be required. Fits to the relative strengths of the observed ice and silicate features give mantle-to-core volume ratios from 0.3 to 1.3. The emission efficiency at wavelengths above 100 microns is found to be sensitive to the presence of an ice mantle with the silicate grains in inverse proportion to the square of the wavelength, while the core-mantle grains follow an inverse cube law. Upper limits to the enhancement of the far-infrared emissivity due to impurities are deduced, and it is found that only core-mantle grains can reasonably account for the observed far-infrared luminosities of many H II regions. Publication: The Astrophysical Journal Pub Date: August 1975 DOI: 10.1086/153757 Bibcode: 1975ApJ...200...30A Keywords: Absorption Spectra; Cosmic Dust; Infrared Astronomy; Interstellar Extinction; Silicates; Far Infrared Radiation; H Ii Regions; Interstellar Matter; Lunar Dust; Olivine; Astrophysics full text sources ADS |