Sublimation-driven fragmentation of icy dust aggregates in main-belt comets
- 1School of Aeronautics and Astronautics, Shenzhen Campus of Sun Yat-sen University
- 2National Key Laboratory of Space Environment Interaction With Matters, Lanzhou Institute of Physics
- 3State Key Laboratory of Atmospheric Environment and Extreme Meteorology, Institute of Atmospheric Physics, Chinese Academy of Sciences
Abstract
Context. The post-release fragmentation behavior of dust from main-belt comets (MBCs) significantly alters the particle size distribution and number density, thereby affecting the accuracy of dust impact risk assessments for spacecraft. Aims. We aim to construct a coupled thermophysical and mechanical model for porous MBCs’ dust to evaluate their structural stability and investigate the physical mechanisms of sublimation-driven disintegration. Methods. We constructed a refined thermophysical model for porous MBCs’ dust by integrating the ballistic particle-cluster aggregation algorithm with a hybrid radiative-transfer strategy and solving the coupled energy–mass balance equations using the finite element method. By comparing the sublimation-induced internal pore pressure with the effective tensile strength of the hierarchical aggregate structure, a critical failure criterion was established to evaluate the mechanism of dust fragmentation. Results. Numerical simulations reveal strict size selectivity for sublimation-driven fragmentation. At a heliocentric distance of 1.69 AU, sublimation-driven fragmentation is confined to a narrow size range approximately bounded by 50 and 70 mm if the secondary aggregate size is 1/5 of the macroscopic aggregate size. Furthermore, increasing heliocentric distance generally suppresses sublimation-induced internal pressure buildup, while both the bulk porosity and secondary aggregate size significantly influence gas transport, tensile-strength thresholds, and the resulting fragmentation outcome. Conclusions. Sublimation-driven fragmentation is identified as the hierarchical disintegration of millimeter- and centimeter-sized aggregates at low stress thresholds. Since the predicted critical sizes significantly exceed sizes of typical tail dust grains, we conclude that this mechanism is a near-surface phenomenon occurring prior to dust entrainment, rather than a process occurring within the comet tail.
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BibTeX
@article{yujie2026sublimationdriven,
title = {{Sublimation-driven fragmentation of icy dust aggregates in main-belt comets}},
author = {Zhao Yujie and Guo Wenqi and Wang Yusen and Huang Junhai and Zhu Boyang and Li Cunhui and Liu Ranran and Liu Xiaodong},
journal = {Astronomy \& Astrophysics},
year = {2026},
month = oct,
doi = {10.1051/0004-6361/202659698},
url = {https://doi.org/10.1051/0004-6361/202659698},
note = {CC BY},
}
RIS
TY - JOUR
TI - Sublimation-driven fragmentation of icy dust aggregates in main-belt comets
AU - Zhao Yujie
AU - Guo Wenqi
AU - Wang Yusen
AU - Huang Junhai
AU - Zhu Boyang
AU - Li Cunhui
AU - Liu Ranran
AU - Liu Xiaodong
PY - 2026
DA - 2026/10/24
JO - Astronomy & Astrophysics
DO - 10.1051/0004-6361/202659698
UR - https://doi.org/10.1051/0004-6361/202659698
AB - Context. The post-release fragmentation behavior of dust from main-belt comets (MBCs) significantly alters the particle size distribution and number density, thereby affecting the accuracy of dust impact risk assessments for spacecraft. Aims. We aim to construct a coupled thermophysical and mechanical model for porous MBCs’ dust to evaluate their structural stability and investigate the physical mechanisms of sublimation-driven disintegration. Methods. We constructed a refined thermophysical model for porous MBCs’ dust by integrating the ballistic particle-cluster aggregation algorithm with a hybrid radiative-transfer strategy and solving the coupled energy–mass balance equations using the finite element method. By comparing the sublimation-induced internal pore pressure with the effective tensile strength of the hierarchical aggregate structure, a critical failure criterion was established to evaluate the mechanism of dust fragmentation. Results. Numerical simulations reveal strict size selectivity for sublimation-driven fragmentation. At a heliocentric distance of 1.69 AU, sublimation-driven fragmentation is confined to a narrow size range approximately bounded by 50 and 70 mm if the secondary aggregate size is 1/5 of the macroscopic aggregate size. Furthermore, increasing heliocentric distance generally suppresses sublimation-induced internal pressure buildup, while both the bulk porosity and secondary aggregate size significantly influence gas transport, tensile-strength thresholds, and the resulting fragmentation outcome. Conclusions. Sublimation-driven fragmentation is identified as the hierarchical disintegration of millimeter- and centimeter-sized aggregates at low stress thresholds. Since the predicted critical sizes significantly exceed sizes of typical tail dust grains, we conclude that this mechanism is a near-surface phenomenon occurring prior to dust entrainment, rather than a process occurring within the comet tail.
SN - 0004-6361
SN - 1432-0746
ER -