![Evolution of impact-generated debris for the high-velocity impact cases. Rows correspond to different impact scenarios with varying orbital periods (Porb) and impact velocities (vimp), as labeled. Columns show snapshots at 0.35, 2.65, 14.69, and 18.05 hr after impact. Particles are shown in a midplane slice with |z| < 0.1 R⊕, and colors indicate material origin and composition. In the 2.65 and 14.69 hr snapshots, particles are additionally highlighted according to their final fate, identifying those incorporated into the disk and those that later escaped from the system.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/A-Formation.png?fit=1200%2C673&ssl=1)
[astro-ph.EP] 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.
Rongxi Bi, Hongping Deng, Christian Reinhardt, Shangfei Liu, Yun Liu
Comments: 18 pages, 7 figures, 4 tables; submitted to The Astrophysical Journal Letters
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2608.04512 [astro-ph.EP] (or arXiv:2608.04512v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2608.04512
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Submission history
From: Rongxi Bi
[v1] Wed, 5 Aug 2026 06:48:35 UTC (22,118 KB)
https://arxiv.org/abs/2608.04512
Astrobiology, exoplanet,
