A Formation-Stage Bottleneck for Exomoons around Close-in Rocky Planets
Abstract
Massive moons around rocky exoplanets are expected outcomes of giant impacts, yet no exomoon has been securely confirmed. We address this problem using meshless finite-mass simulations of giant impacts between differentiated rocky planets that include stellar tidal and Coriolis forces in a local co-rotating frame for orbital periods of 1--300 days, and compare these simulations with otherwise identical collisions in isolation. We find that stellar perturbations impose a severe formation-stage bottleneck on moon-forming disks. Ultra-short-period impacts leave essentially no surviving circumplanetary disk, whereas 10-day systems retain only strongly depleted, radially truncated, and dynamically compact disks. High impact velocities, expected for close-in planets, are devastating for disk generation, while retrograde impacts can slightly compensate for disk mass depletion. These results show that stellar perturbations can suppress exomoon formation around close-in rocky planets, reshaping expectations for the demographics of exomoons.
Related
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BibTeX
@misc{bi2026formationstage,
title = {{A Formation-Stage Bottleneck for Exomoons around Close-in Rocky Planets}},
author = {Rongxi Bi and Hongping Deng and Christian Reinhardt and Shangfei Liu and Yun Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.04512},
eprint = {2608.04512},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.04512},
}
RIS
TY - UNPB
TI - A Formation-Stage Bottleneck for Exomoons around Close-in Rocky Planets
AU - Rongxi Bi
AU - Hongping Deng
AU - Christian Reinhardt
AU - Shangfei Liu
AU - Yun Liu
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2608.04512
UR - https://arxiv.org/abs/2608.04512
AB - Massive moons around rocky exoplanets are expected outcomes of giant impacts, yet no exomoon has been securely confirmed. We address this problem using meshless finite-mass simulations of giant impacts between differentiated rocky planets that include stellar tidal and Coriolis forces in a local co-rotating frame for orbital periods of 1--300 days, and compare these simulations with otherwise identical collisions in isolation. We find that stellar perturbations impose a severe formation-stage bottleneck on moon-forming disks. Ultra-short-period impacts leave essentially no surviving circumplanetary disk, whereas 10-day systems retain only strongly depleted, radially truncated, and dynamically compact disks. High impact velocities, expected for close-in planets, are devastating for disk generation, while retrograde impacts can slightly compensate for disk mass depletion. These results show that stellar perturbations can suppress exomoon formation around close-in rocky planets, reshaping expectations for the demographics of exomoons.
ER -