Long-Term Stability of Tightly Packed Multi-Planet Systems in Prograde, Coplanar, Circumstellar Orbits within the $\alpha$ Centauri AB System

Abstract

We perform long-term simulations, up to ten billion years, of closely-spaced configurations of 2 -- 6 planets, each as massive as the Earth, traveling on nested orbits about either stellar component in $\alpha$ Centauri AB. The innermost planet initially orbits at either the inner edge of its star's empirical habitable zone (HZ) or the inner edge of its star's conservative HZ. Although individual planets on low inclination, low eccentricity, orbits can survive throughout the habitable zones of both stars, perturbations from the companion star require that the minimum spacing of planets in multi-planet systems within the habitable zones of each star must be significantly larger than the spacing of similar multi-planet systems orbiting single stars in order to be long-lived. The binary companion induces a forced eccentricity upon the orbits of planets in orbit around either star. Planets on appropriately-phased circumstellar orbits with initial eccentricities equal to their forced eccentricities can survive on more closely spaced orbits than those with initially circular orbits, although the required spacing remains higher than for planets orbiting single stars. A total of up to nine planets on nested prograde orbits can survive for the current age of the system within the empirical HZs of the two stars, with five of these orbiting $\alpha$ Centauri B and four orbiting $\alpha$ Centauri A.

24 pages, 15 figures, 6 tables; accepted for publication in Astronomical Journal

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Cited by in corpus (19)

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• Imaging low-mass planets within the habitable zone of α Centauri
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• The chemical composition of $\alpha$ Cen AB revisited
• Searching for Planets Orbiting Alpha Centauri A with the James Webb Space Telescope
• Orbital stability of compact three-planet systems, I: Dependence of system lifetimes on initial orbital separations and longitudes
• Stable lifetime of compact, evenly-spaced planetary systems with non-equal masses
• A Pluto--Charon Sonata: Dynamical Limits on the Masses of the Small Satellites
• Exomoons in Systems with a Strong Perturber: Applications to $\alpha$ Cen AB
• Europium as a lodestar: diagnosis of radiogenic heat production in terrestrial exoplanets
• Obliquity Evolution of Circumstellar Planets in Sun-like Stellar Binaries
• Evolution of $\alpha$ Centauri B's protoplanetary disc
• Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of $\alpha$ Cen A. I. Observations, Orbital and Physical Properties, and Exozodi Upper Limits
• Dynamical Fates of S-Type Planetary Systems in Embedded Cluster Environments
• Moon-packing around an Earth-mass Planet
• Orbital stability of compact three-planet systems III. The role of three-body resonances
• Simulations of astrometric planet detection in Alpha Centauri by intensity interferometry
• Orbital Stability of Closely-Spaced Four-planet Systems