Where Do Hot Jupiters Come From? Revisiting Tidal Disruption and Ejection in High-Eccentricity Migration
Abstract
The origin of hot Jupiters remains a key open question. In the high-eccentricity migration scenario, traditional coreless models predict a strict tidal exclusion zone within tidal radii , in which giant planets are either fully disrupted or ejected. We revisit this limit using three-dimensional hydrodynamic simulations of giant planets with realistic dense cores (10 - 20 ). We find that even a few-percent-mass core fundamentally changes the outcome: \textbf{no total disruptions} occur within the previously suggested destruction zone (). For deep encounters () planets suffer severe envelope stripping and are either progressively downsized to dense remnants or ejected after a few close encounters, possibly contributing to the free-floating planet population. In the intermediate regime (--), planets experience significant partial mass loss over repeated encounters. For wider encounters (), mass loss is minimal, allowing the planets gradually circularize into hot Jupiters. Furthermore, we show that for highly eccentric orbits (), the change in specific orbital energy depends primarily on periastron distance rather than semi-major axis . This enables us to extrapolate our fixed- results across a broad (, ) parameter space and identify a well-defined tidal ejection zone whose sharp boundaries converge asymptotically. Our results highlight the crucial role of planetary internal structure in high-eccentricity migration and suggest that the survival and transformation of core-bearing giant planets are far more common than previously thought.
Keywords
Cite
@article{arxiv.2605.14433,
title = {Where Do Hot Jupiters Come From? Revisiting Tidal Disruption and Ejection in High-Eccentricity Migration},
author = {Qianli Fan and Shang-Fei Liu},
journal= {arXiv preprint arXiv:2605.14433},
year = {2026}
}
Comments
17 pages, 6 figures, accepted for publication in The Astrophysical Journal Letters