# Convergent Migration Renders TRAPPIST-1 Long-lived

## TL;DR

This paper demonstrates that the TRAPPIST-1 planetary system's long-term stability is best explained by convergent disk migration leading to resonant configurations, supported by extensive simulations and a publicly available database.

## Contribution

It shows that resonant configurations from disk migration are stable over tens of millions of years, unlike most inferred configurations, indicating migration's role in system formation.

## Key findings

- Most inferred configurations are unstable on short timescales.
- Resonant configurations from disk migration are stable over at least 50 Myr.
- The study provides a database of initial conditions and reproducible simulations.

## Abstract

TRAPPIST-1 is a late M-dwarf orbited by seven Earth-sized planets with orbital period ratios near a chain of mean motion resonances. Due to uncertain system parameters, most orbital configurations drawn from the inferred posterior distribution are unstable on short timescales of $\sim$ 0.5 Myr, even when including the eccentricity damping effect of tides. By contrast, we show that most physically plausible resonant configurations generated through disk migration are stable even without tidal dissipation on timescales of at least 50 Myr ($10^{10}$ orbits), an increase of at least two orders of magnitude. This result, together with the remarkable chain of period ratios in the system, provide strong evidence for convergent migration naturally emplacing the system near an equilibrium configuration forced by the resonant chain. We provide an openly available database of physically plausible initial conditions for TRAPPIST-1 generated through parametrized planet-disk interactions, as well as bit-by-bit reproducible N-body integrations over $10^9-10^{10}$ orbits.