AUTHORS:

Kossacki K.J.

ABSTRACT:

The aim of the work is to analyze limitations of the applicability of equations for the rate of outgassing of the nuclei of comets. I presented the results of experiments performed using large samples composed of agglomerates of radii up to few centimeters. In this respect the present work is the continuation of the paper Kossacki et al. (2023) about the outgassing of mixtures of millimeter sized agglomerates. The ratio between the radii of agglomerates and the radii of smallest grains present in agglomerates was previously about 10 and now is about 100. The measured changes of masses of the samples during experiments were compared with the results of calculations based on the structures of the samples and the recorded temperatures. Considered were two different mathematical models. One requires knowledge of the porosity, but not of the granulation of material (Kossacki 2021), while the second assumes knowledge of the radii of the smallest grains and of the agglomerates, as well as of the vapor pressure in pores between agglomerates (Kossacki et al. 2023). It was found that: (1) both models can reproduce the results of experiments and (2) the gas pressure in pores normalized to the pressure of phase equilibrium exhibits strong dependence on the temperature and weak dependence on the sizes of agglomerates. Based on the presented results I recommend to use equations which do not include the vapor pressure in pores.

ICARUS, 2025, vol. 435, art. 116541, doi: 10.1016/j.icarus.2025.116541