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Updated: Jul 28, 2026

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight
Published on: October 11, 2016
The infrared spectrum of comet Bradfield (1987s) and the silicate emission feature
M S Hanner1, R L Newburn, R D Gehrz
1Jet Propulsion Laboratory, USA.
Abstract:
Infrared (1-20 micrometers) observations of comet Bradfield (1987s) from three observatories are reported. Silicate emission is prominent in all the data, from heliocentric distance r=0.87 to 1.45 AU. A CVF spectrum at r=1.45 AU shows a peak at 11.3 micrometers identified as crystalline olivine; the spectral shape is similar to that in Halley. Dust optical properties are similar to those of the grains in Halley's jets. Dust production rate near perihelion was approximately 10(6) g s-1 and varied in proportion to (r-2). We suggest that some differences in grain properties among comets could result from differences in the thermal history of the nuclear surface and the relative fraction of the dust particles originating in the subsurface icy layer versus the devolatilized mantle.
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