Stability analysis of single planet systems and their habitable zones

TL;DR

This paper investigates the dynamical stability of single-planet systems with potential habitable zones, comparing numerical and analytical stability boundaries, and identifies systems capable of supporting terrestrial planets.

Contribution

It introduces a new analytical parameter for stability boundaries, reveals the fractal nature of these boundaries, and provides a catalog of systems that can host habitable terrestrial planets.

Findings

Analytical stability boundary diverges from Hill boundary.

Actual stability boundary is fractal, requiring a second parameter.

Several known systems can support terrestrial planets in their habitable zones.

Abstract

We study the dynamical stability of planetary systems consisting of one hypothetical terrestrial mass planet ($1 $ or $10 \mearth$) and one massive planet ($10 \mearth - 10 \mjup$). We consider masses and orbits that cover the range of observed planetary system architectures (including non-zero initial eccentricities), determine the stability limit through N-body simulations, and compare it to the analytic Hill stability boundary. We show that for given masses and orbits of a two planet system, a single parameter, which can be calculated analytically, describes the Lagrange stability boundary (no ejections or exchanges) but which diverges significantly from the Hill stability boundary. However, we do find that the actual boundary is fractal, and therefore we also identify a second parameter which demarcates the transition from stable to unstable evolution. We show the portions of the habitable zones of $\rho$ CrB, HD 164922, GJ 674, and HD 7924 which can support a terrestrial planet. These analyses clarify the stability boundaries in exoplanetary systems and demonstrate that, for most exoplanetary systems, numerical simulations of the stability of potentially habitable planets are only necessary over a narrow region of parameter space. Finally we also identify and provide a catalog of known systems which can host terrestrial planets in their habitable zones.