Outgassing of icy bodies in the Solar System - II. Heat transport in dry, porous surface dust layers

TL;DR

This paper introduces a new heat conductivity model for porous dust layers in vacuum, validated by experiments, highlighting the importance of radiative heat transfer and its implications for cometary activity modeling.

Contribution

A novel heat transfer model for porous dust layers distinguishing between single particles and aggregates, validated with laboratory experiments including radiative heat transfer.

Findings

Model predictions agree with experimental data when including radiative transfer.

Radiation significantly influences heat transport in porous dust layers.

Implications for modeling cometary activity are discussed.

Abstract

In this work, we present a new model for the heat conductivity of porous dust layers in vacuum, based on an existing solution of the heat transfer equation of single spheres in contact. This model is capable of distinguishing between two different types of dust layers: dust layers composed of single particles (simple model) and dust layers consisting of individual aggregates (complex model). Additionally, we describe laboratory experiments, which were used to measure the heat conductivity of porous dust layers, in order to test the model. We found that the model predictions are in an excellent agreement with the experimental results, if we include radiative heat transport in the model. This implies that radiation plays an important role for the heat transport in porous materials. Furthermore, the influence of this new model on the Hertz factor are demonstrated and the implications of this new model on the modeling of cometary activity are discussed. Finally, the limitations of this new model are critically reviewed.