Thermal conductivity of porous aggregates

Context. The thermal conductivity of highly porous dust aggregates is a key parameter for many subjects in planetary science; it is not yet fully understood, however. Aims. We investigate the thermal conductivity of fluffy dust aggregates with filling factors lower than 10 -1 . Methods. We determined the temperature structure and heat flux of the porous dust aggregates calculated through 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 sol as a function of the filling factor of dust aggregates φ . The results reveal that k sol is approximately proportional to φ 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.