Low-temperature thermal properties of iron meteorites

1Christopher S. Noyes,2Guy. J. Consolmagno,2Robert J. Macke,3,4Daniel T. Britt,1Cyril P. Opeil
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13895]
1Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts, 02467 USA
2Vatican Observatory, Vatican City, V-00120 Vatican City State
3Department of Physics, University of Central Florida, 4111 Libra Dr, Orlando, Florida, 32816 USA
4Center of Lunar and Asteroid Surface Science, 12354 Research Pkwy, Suite 214, Orlando, Florida, 32826 USA
Published by arrangement with John Wiley & Sons

We have measured the thermal conductivity and specific heat capacity of subsamples from four iron meteorites with nickel concentrations between 5% and 8% (Agoudal, Canyon Diablo, Muonionalusta, and Sikhote-Alin) at temperatures between 5 and 300 K. From these, we have calculated their thermal diffusivity and thermal inertia values across this temperature range. For comparison, we also measured subsamples from two L chondrites (NWA 11038 and NWA 11344) at the same time, using the same methods. The thermal diffusivity results of the irons show a relatively constant value for T > 100 K with a characteristic low-temperature maxima at ∼5 K for the iron meteorites; by contrast, the diffusivities of the L chondrites fell by a factor of two over this range and reached low-temperature maxima at ∼20 K. Thermal inertia values show a crossover behavior, with a strong increase in thermal inertia as temperatures drop below 55 K and a less dramatic change at higher temperatures. Our new diffusivity and inertia values cover a wider range of temperatures than previous literature data for iron meteorites. They also provide a useful ground truth in understanding remotely sensed thermal inertias of potentially metal-rich asteroids, including 16 Psyche, target of the NASA Psyche mission.


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