On the origin of the eccentricity dichotomy displayed by compact super-Earths: dynamical heating by cold giants

Abstract

Approximately half of the planets discovered by NASA's Kepler mission are in systems where just a single planet transits its host star, and the remaining planets are observed to be in multi-planet systems. Recent analyses have reported a dichotomy in the eccentricity distribution displayed by systems where a single planet transits compared with that displayed by the multi-planet systems. Using $N$-body simulations, we examine the hypothesis that this dichotomy has arisen because inner systems of super-Earths are frequently accompanied by outer systems of giant planets that can become dynamically unstable and perturb the inner systems. Our initial conditions are constructed using a subset of the known Kepler five-planet systems as templates for the inner systems, and systems of outer giant planets with masses between those of Neptune and Saturn that are centred on orbital radii $2\le a_{\mathrm{p}}\le 10$ au. The parameters of the outer systems are chosen so that they are always below an assumed radial velocity detection threshold of 3 ms${}^{-1}$. The results show an inverse relation between the mean eccentricities and the multiplicites of the systems. Performing synthetic transit observation of the final systems reveals dichotomies in both the eccentricity and multiplicity distributions that are close to being in agreement with the Kepler data. Hence, understanding the observed orbital and physical properties of the compact systems of super-Earths discovered by Kepler may require holistic modelling that couples the dynamics of both inner and outer systems of planets during and after the epoch of formation.

arXiv comment19 pages, 24 figures, accepted to MNRAS

References in corpus (52)

• The false positive rate of Kepler and the occurrence of planets
• Planetary Candidates Observed by Kepler, III: Analysis of the First 16 Months of Data
• Characteristics of planetary candidates observed by Kepler, II: Analysis of the first four months of data
• Dynamical Outcomes of Planet-Planet Scattering
• Prevalence of Earth-size planets orbiting Sun-like stars
• Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
• Dynamical Origin of Extrasolar Planet Eccentricity Distribution
• Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets
• Origins of Eccentric Extrasolar Planets: Testing the Planet-Planet Scattering Model
• Planetary Candidates Observed by Kepler. VIII. A Fully Automated Catalog With Measured Completeness and Reliability Based on Data Release 25
• Collisions between Gravity-Dominated Bodies: 2. The Diversity of Impact Outcomes during the End Stage of Planet Formation
• Collisions Between Gravity-Dominated Bodies: 1. Outcome Regimes and Scaling Laws
• Tidal Evolution of Close-in Extra-Solar Planets
• Breaking the Chains: Hot Super-Earth systems from migration and disruption of compact resonant chains
• The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets
• Migration then assembly: Formation of Neptune mass planets inside 1 AU
• Planetary Candidates Observed by Kepler VI: Planet Sample from Q1-Q16 (47 Months)
• About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of their Intrinsic Architecture
• The orbital eccentricity of small planet systems
• Densities and Eccentricities of 139 Kepler Planets from Transit Time Variations
• Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis
• Planetary Candidates Observed by Kepler. VII. The First Fully Uniform Catalog Based on The Entire 48 Month Dataset (Q1-Q17 DR24)
• Planetary Candidates Observed by Kepler IV: Planet Sample From Q1-Q8 (22 Months)
• An ancient extrasolar system with five sub-Earth-size planets
• Transit Timing Observations from Kepler: VII. Confirmation of 27 planets in 13 multiplanet systems via Transit Timing Variations and orbital stability
• Planetary Candidates Observed by Kepler V: Planet Sample from Q1-Q12 (36 Months)
• The Super Earth-Cold Jupiter Relations
• AMD-stability and the classification of planetary systems
• The destruction of inner planetary systems during high-eccentricity migration of gas giants
• Can planetary instability explain the Kepler dichotomy?
• Scattering outcomes of close-in planets: constraints on planet migration
• Transit Timing Variation of Near-Resonance Planetary Pairs. II. Confirmation of 30 planets in 15 Multiple Planet Systems
• Kepler-68: Three Planets, One With a Density Between That of Earth and Ice Giants
• The effects of external planets on inner systems: multiplicities, inclinations, and pathways to eccentric warm Jupiters
• Effects of Dynamical Evolution of Giant Planets on Survival of Terrestrial Planets
• CKS VIII: Eccentricities of Kepler Planets and Tentative Evidence of a High Metallicity Preference for Small Eccentric Planets
• The Kepler Dichotomy in Planetary Disks: Linking Kepler Observables to Simulations of Late-Stage Planet Formation
• Hiding Planets Behind a Big Friend: Mutual Inclinations of Multi-Planet Systems with External Companions
• Effects of Unseen Additional Planetary Perturbers on Compact Extrasolar Planetary Systems
• Eccentricities and Inclinations of Multi-Planet Systems with External Perturbers
• In-Situ Scattering of Warm Jupiters and Implications for Dynamical Histories
• Dynamically hot Super-Earths from outer giant planet scattering
• Chemical Diversity of Super-Earths As a Consequence of Formation
• Perturbation of Compact Planetary Systems by Distant Giant Planets
• Mutual Orbital Inclinations Between Cold Jupiters and Inner Super-Earths
• Dynamical instability and its implications for planetary system architecture
• Forming Diverse Super-Earth Systems in Situ
• Formation of compact systems of super-Earths via dynamical instabilities and giant impacts
• Formation of Close-in Super-Earths by Giant Impacts: Effects of Initial Eccentricities and Inclinations of Protoplanets
• A Search for Lost Planets in the Kepler Multi-planet Systems and the Discovery of the Long-period, Neptune-sized Exoplanet Kepler-150 f
• Secular evolution of close in planets: the effects of general relativity
• Kepler Object of Interest Network III. Kepler-82f: A new non-transiting $21 M_\bigoplus$ planet from photodynamical modelling

Cited by in corpus (6)

• The HD 137496 system: A dense, hot super-Mercury and a cold Jupiter
• Planetary Orbit Eccentricity Trends (POET). I. The Eccentricity-Metallicity Trend for Small Planets Revealed by the LAMOST-Gaia-Kepler Sample
• Period Ratio Sculpting Near Second-Order Mean-Motion Resonances
• The New Generation Planetary Population Synthesis (NGPPS) VIII. Impact of host star metallicity on planet occurrence rates, orbital periods, eccentricities, and radius valley morphology
• Effects of Outer Giant Planets on In Situ Formation of Inner Super-Earths
• TOI-1438: A rare system with two short-period sub-Neptunes and a tentative long-period Jupiter-like planet orbiting a K0V star