From Interstellar Dust to Comets: Infrared Emission from Comet Hale-Bopp (C/1995 O1)

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Abstract
The 3-20 μm IR thermal emission spectrum of comet Hale-Bopp (C/1995 O1) at a heliocentric distance of rh=1.15 AU has been calculated using fluffy aggregates of silicate core-organic refractory mantle interstellar dust as the comet dust model. The principal dust properties, similar to those obtained for other comets, provide good fits to the observation. Our results are significantly different from the general opinion that Hale-Bopp is rich in submicron grains. The mean grain masses derived here are 2-3 orders of magnitude higher than those estimated from the empirical superheat method or from the IR emission modeling, both of which use compact silicate/carbon particles. It has been shown that the IR emission alone cannot give a reliable dust production rate. We have also modeled the crystalline silicate emission spectrum.