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 ksol as a function of the filling factor of dust aggregates φ. The results reveal that ksol is approximately proportional to φ2, 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.
- Comets: general
- Radiative transfer