Thermal conductivity of porous aggregates

Abstract

$Context.$ The thermal conductivity of highly porous dust aggregates is a key parameter for many subjects in planetary science; however, it is not yet fully understood. $Aims.$ In this study, we investigate the thermal conductivity of fluffy dust aggregates with filling factors of less than $10^{-1}$. $Methods.$ We determine the temperature structure and heat flux of the porous dust aggregates calculated by $N$-body simulations of static compression in the periodic boundary condition. $Results.$ We derive an empirical formula for the thermal conductivity through the solid network $k_{\mathrm{sol}}$ as a function of the filling factor of dust aggregates $\varphi$. The results reveal that $k_{\mathrm{sol}}$ is approximately proportional to ${\varphi }^2$, and the thermal conductivity through the solid network is significantly lower than previously assumed. In light of these findings, we must reconsider the thermal histories of small planetary bodies.

arXiv comment4 pages, 4 figures. Accepted for publication in Astronomy & Astrophysics

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• Thermal inertias of pebble-pile comet 67P/Churyumov-Gerasimenko
• Cometary surface dust layers built out of millimetre-scale aggregates: dependence of modelled cometary gas production on the layer transport properties
• Heat transfer in granular media with weakly interacting particles
• Geometrical structure and thermal conductivity of dust aggregates formed via ballistic cluster-cluster aggregation
• Photophoresis in the circumjovian disk and its impact on the orbital configuration of the Galilean satellites
• Interpebble contact radius in a comet nucleus
• Interparticle normal force in highly porous granular matter during compression