The thermal conductivity of meteorites: New measurements and analysis

    Authors

    C. P. Opeil; G. J. Consolmagno;D. T. Britt

    Comments

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    Abbreviated Journal Title

    Icarus

    Keywords

    Asteroids; Meteorites; Thermal histories; KUIPER-BELT OBJECTS; CHONDRITES; TEMPERATURE; ENCELADUS; EVOLUTION; BODIES; Astronomy & Astrophysics

    Abstract

    We have measured the thermal conductivity at low temperatures (5-300 K) of six meteorites representing a range of compositions, including the ordinary chondrites Cronstad (H5) and Lumpkin (L6), the enstatite chondrite Abee (E4), the carbonaceous chondrites NWA 5515 (CK4 find) and Cold Bokkeveld (CM2), and the iron meteorite Campo del Cielo (IAB find). All measurements were made using a Quantum Design Physical Properties Measurement System, Thermal Transport Option (TTO) on samples cut into regular parallelepipeds of similar to 2-6 mm dimension. The iron meteorite conductivity increases roughly linearly from 15 W m(-1) K(-1) at 100 K to 27 W at 300 K, comparable to typical values for metallic iron. By contrast, the conductivities of all the stony samples except Abee appear to be controlled by the inhomogeneous nature of the meteorite fabric, resulting in values that are much lower than those of pure minerals and which vary only slightly with temperature above 100 K. The L and CK sample conductivities above 100 K are both about 1.5 W K(-1), that of the H is 1.9 W m K(-1), and that of the CM sample is 0.5 W m(-1) K(-1); by contrast the literature value at 300 K for serpentine is 2.5 W m(-1) K(-1) and those of enstatite and olivine range from 4.5 to 5 W m(-1) K(-1) (which is comparable to the Abee value). These measurements are among the first direct measurements of thermal conductivity for meteorites. The results compare well with previous estimates for meteorites, where conductivity was derived from diffusivity measurements and modeled heat capacities; our new values are of a higher precision and cover a wider range of temperatures and meteorite types. If the rocky material that makes up asteroids and provides the dust to comets, Kuiper Belt objects, and icy satellites has the same low thermal conductivities as the ordinary and carbonaceous chondrites measured here, this would significantly change models of their thermal evolution. These values would also lower their thermal inertia, thus affecting the Yarkovsky and YORP evolution of orbits and spin for solid objects; however, in this case the effect would not be as great, as thermal inertia only varies as the square root of the conductivity and, for most asteroids, is controlled by the dusty nature of asteroidal surfaces rather than the conductivity of the material itself. (C) 2010 Elsevier Inc. All rights reserved.

    Journal Title

    Icarus

    Volume

    208

    Issue/Number

    1

    Publication Date

    1-1-2010

    Document Type

    Article

    Language

    English

    First Page

    449

    Last Page

    454

    WOS Identifier

    WOS:000278838200037

    ISSN

    0019-1035

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