Abstract
view Abstract Citations (30) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Effect of Grain Mantles and Grain Shape upon the 9.7 and 18 Micron Silicate Features O'Donnell, James E. Abstract Absorption and polarization cross sections are calculated for spheroidal silicate grains in the wavelength regime 7-22 microns in order to investigate the effect of changes in grain composition upon the 9.7 micron and 18 micron bands. The addition of mantles is found to be incompatible with 9.7 micron absorption data unless the mantles are relatively thin and transparent. Comparison with polarization data for BN and AFGL 2591 suggests an additional absorbing component is present, possibly as inclusions within the silicate grains, in order to account for the relatively strong short-wavelength wing seen in the 9.7 micron band toward both objects. The high 18 micron polarization observed toward BN (R18/10 = 0.75) cannot be reproduced by the addition of a mantle or by varying the grain shape and implies silicates with a stronger 18 micron band than has been previously assumed in interstellar grain models. Publication: The Astrophysical Journal Pub Date: December 1994 DOI: 10.1086/174993 Bibcode: 1994ApJ...437..262O Keywords: Absorption Cross Sections; Astronomical Models; Cosmic Dust; Infrared Astronomy; Interstellar Extinction; Interstellar Matter; Polarization (Waves); Silicates; Cross Sections; Mathematical Models; Spheroids; Astronomy; ISM: DUST; EXTINCTION; ISM: INDIVIDUAL NAME: BECKLIN-NEUGEBAUER; POLARIZATION full text sources ADS | data products SIMBAD (2)
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