The composition of dust in Jupiter-family comets inferred from infrared spectroscopy

    Authors

    M. S. Kelley;D. H. Wooden

    Abbreviated Journal Title

    Planet Space Sci.

    Keywords

    Comets; Spectra: infrared; Comets: dust; PROTOPLANETARY ACCRETION DISKS; PRIMORDIAL SOLAR NEBULA; SPITZER-SPACE-TELESCOPE; DEEP IMPACT; HALE-BOPP; OPTICAL-PROPERTIES; LIGHT-SCATTERING; SILICATE FEATURE; CRYSTALLINE SILICATES; SPECTRAL; OBSERVATIONS; Astronomy & Astrophysics

    Abstract

    We review the composition of Jupiter-family comet (JFC) dust as inferred from infrared spectroscopy. We find that JFCs have 10 mu m silicate emission features with fluxes roughly 20-25% over the dust continuum (emission strength 1.20-1.25), similar to the weakest silicate features in Oort Cloud (OC) comets. We discuss the grain properties that alter the silicate emission feature (composition, size, and structure/shape), and emphasize that thermal emission from the comet nucleus can have significant influence on the derived silicate emission strength. Recent evidence suggests that grain porosity is the is different between JFCs and OC comets, but more observations and models of silicates in JFCs are needed to determine if a consistent set of grain parameters can explain their weak silicate emission features. Models of 8 m telescope and Spitzer Space Telescope observations have shown that JFCs have crystalline silicates with abundances similar to or less than those found in OC comets, although the crystalline silicate mineralogy of comets 9P/Tempel and C/1995 O1 (Hale-Bopp) differ from each other in Mg and Fe content. The heterogeneity of comet nuclei can also be assessed with mid-infrared spectroscopy, and we review the evidence for heterogeneous dust properties in the nucleus of comet 9P/Tempel. Models of dust formation, mixing in the solar nebula, and comet formation must be able to explain the observed range of Mg and Fe content and the heterogeneity of comet 9P/Tempel, although more work is needed in order to understand to what extent do comets 9P/Tempel and Hale-Bopp, represent comets as a whole. (C) 2008 Elsevier Ltd. All rights reserved.

    Journal Title

    Planetary and Space Science

    Volume

    57

    Issue/Number

    10

    Publication Date

    1-1-2009

    Document Type

    Article

    Language

    English

    First Page

    1133

    Last Page

    1145

    WOS Identifier

    WOS:000269035900005

    ISSN

    0032-0633

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