On the Degree of Dynamical Packing in the Kepler Multi-planet Systems
arXiv:2306.12967 · doi:10.1093/mnras/stad1921
Abstract
Current planet formation theories rely on initially compact orbital configurations undergoing a (possibly extended) phase of giant impacts following the dispersal of the dissipative protoplanetary disk. The orbital architectures of observed mature exoplanet systems have likely been strongly sculpted by chaotic dynamics, instabilities, and giant impacts. One possible signature of systems continually reshaped by instabilities and mergers is their dynamical packing. Early Kepler data showed that many multi-planet systems are maximally packed - placing an additional planet between an observed pair would make the system unstable. However, this result relied on placing the inserted planet in the most optimistic configuration for stability (e.g., circular orbits). While this would be appropriate in an ordered and dissipative picture of planet formation (i.e. planets dampen into their most stable configurations), we argue that this best-case scenario for stability is rarely realized due to the strongly chaotic nature of planet formation. Consequently, the degree of dynamical packing in multi-planet systems under a realistic formation model is likely significantly higher than previously realized. We examine the full Kepler multi planet sample through this new lens, showing that ~60-95% of Kepler multi-planet systems are strongly packed and that dynamical packing increases with multiplicity. This may be a signature of dynamical sculpting or of undetected planets, showing that dynamical packing is an important metric that can be incorporated into planet formation modelling or when searching for unseen planets.
15 pages, 4 figures. Accepted for publication in MNRAS
References in corpus (21)
- Array Programming with NumPy
- The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
- Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
- Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis
- A resonant chain of four transiting, sub-Neptune planets
- The Gaia-Kepler Stellar Properties Catalog. II. Planet Radius Demographics as a Function of Stellar Mass and Age
- Kepler Multi-Planet Systems Exhibit Unexpected Intra-system Uniformity in Mass and Radius
- Predicting the long-term stability of compact multiplanet systems
- Accounting for Incompleteness due to Transit Multiplicity in Kepler Planet Occurrence Rates
- A 1.9 Earth radius rocky planet and the discovery of a non-transiting planet in the Kepler-20 system
- The statistical mechanics of planet orbits
- CKS VIII: Eccentricities of Kepler Planets and Tentative Evidence of a High Metallicity Preference for Small Eccentric Planets
- Exoplanet Imitators: A test of stellar activity behavior in radial velocity signals
- The onset of instability in resonant chains
- Revisiting the Long-Period Transiting Planets from Kepler
- Formation of compact systems of super-Earths via dynamical instabilities and giant impacts
- A Criterion for the Stability of Planets in Chains of Resonances
- Fundamental limits from chaos on instability time predictions in compact planetary systems
- Edge-of-the-Multis: Evidence for a Transition in the Outer Architectures of Compact Multi-Planet Systems
- Pairwise Tidal Equilibrium States and the Architecture of Extrasolar Planetary Systems
- Formation of Close-in Super-Earths by Giant Impacts: Effects of Initial Eccentricities and Inclinations of Protoplanets