Disk dispersal freezes overstable resonant librations
Abstract
Context. Convergent migration in a gaseous protoplanetary disk can capture a planet pair into mean-motion resonance. Eccentricity damping can subsequently make the resonant libration overstable and drive the pair out of resonance. Most studies of this process, however, assume a static disk. Aims. We examine how the decay of disk torques during dispersal changes this outcome and whether it can freeze an overstable libration before the pair escapes. Methods. We describe disk dispersal by allowing the migration and eccentricity-damping timescales to increase exponentially on a local timescale τd. Integrating the time-dependent growth rate predicts τd,crit∝τe,0. We test this scaling with direct N-body integrations and relate τd to the time taken by a photoevaporative cavity edge to cross the local torque-producing region. Results. The simulations recover a linear boundary, τd,crit≃ Sτe,0, with S≃3 over the explored parameter range. In a fiducial minimum-mass solar nebula, faster propagation of the cavity edge shortens the local dispersal time. The ratio τd/τd,crit also decreases with orbital radius, so both effects favour resonant survival. Conclusions. When local disk dispersal is sufficiently rapid, the libration amplitude can freeze and the planet pair can remain in resonance instead of escaping through overstability. Late disk evolution can therefore alter the outcome of resonant overstability.
Related
- Migration and eccentricity damping timescales in overstable resonant planetary systems: hydrodynamic and N-body simulations
- The dispersal law of young star clusters: free expansion -- A Gaia/eROSITA census of Orion and Sco--Cen
- Bridging magnetothermal winds and photoevaporation to model discs dispersal
- Quantifying the decline in CO(2-1) intensity around PHANGS-HST star clusters: Constraints on molecular gas dispersal, stellar feedback, and cluster formation efficiency
- The Galactic disk structure revealed by Gaia XP spectra
BibTeX
@misc{lin2026disk,
title = {{Disk dispersal freezes overstable resonant librations}},
author = {Linghong Lin and Beibei Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.04897},
eprint = {2609.04897},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.04897},
}
RIS
TY - UNPB
TI - Disk dispersal freezes overstable resonant librations
AU - Linghong Lin
AU - Beibei Liu
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2609.04897
UR - https://arxiv.org/abs/2609.04897
AB - Context. Convergent migration in a gaseous protoplanetary disk can capture a planet pair into mean-motion resonance. Eccentricity damping can subsequently make the resonant libration overstable and drive the pair out of resonance. Most studies of this process, however, assume a static disk. Aims. We examine how the decay of disk torques during dispersal changes this outcome and whether it can freeze an overstable libration before the pair escapes. Methods. We describe disk dispersal by allowing the migration and eccentricity-damping timescales to increase exponentially on a local timescale τ_d. Integrating the time-dependent growth rate predicts τ_d,crit∝τ_e,0. We test this scaling with direct N-body integrations and relate τ_d to the time taken by a photoevaporative cavity edge to cross the local torque-producing region. Results. The simulations recover a linear boundary, τ_d,crit≃ Sτ_e,0, with S≃3 over the explored parameter range. In a fiducial minimum-mass solar nebula, faster propagation of the cavity edge shortens the local dispersal time. The ratio τ_d/τ_d,crit also decreases with orbital radius, so both effects favour resonant survival. Conclusions. When local disk dispersal is sufficiently rapid, the libration amplitude can freeze and the planet pair can remain in resonance instead of escaping through overstability. Late disk evolution can therefore alter the outcome of resonant overstability.
ER -