Formation of Close-in Super-Earths by Giant Impacts: Effects of Initial Eccentricities and Inclinations of Protoplanets

Abstract

Recent observations have revealed the eccentricity and inclination distributions of close-in super-Earths. These distributions have the potential to constrain their formation processes. In the in-situ formation scenario, the eccentricities and inclinations of planets are determined by gravitational scattering and collisions between protoplanets on the giant impact stage. We investigate the effect of the initial eccentricities and inclinations of protoplanets on the formation of close-in super-Earths. We perform $N$-body simulations of protoplanets in gas-free disks, changing the initial eccentricities and inclinations systematically. We find that while the eccentricities of protoplanets are well relaxed through their evolution, the inclinations are not. When the initial inclinations are small, they are not generally pumped up since scattering is less effective and collisions occur immediately after orbital crossing. On the other hand, when the initial inclinations are large, they tend to be kept large since collisional damping is less effective. Not only the resultant inclinations of planets, but also their number, eccentricities, angular momentum deficit, and orbital separations are affected by the initial inclinations of protoplanets.

arXiv commentAccepted for publication in AJ

References in corpus (24)

• Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
• Architecture of Kepler's Multi-transiting Systems: II. New investigations with twice as many candidates
• The Minimum-Mass Extrasolar Nebula: In-Situ Formation of Close-In Super-Earths
• The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets
• Eccentricity from transit photometry: small planets in Kepler multi-planet systems have low eccentricities
• Migration then assembly: Formation of Neptune mass planets inside 1 AU
• Planetary Candidates Observed by Kepler VI: Planet Sample from Q1-Q16 (47 Months)
• Testing In Situ Assembly with the Kepler Planet Candidate Sample
• Densities and Eccentricities of 139 Kepler Planets from Transit Time Variations
• Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis
• Toward a Deterministic Model of Planetary Formation VI: Dynamical Interaction and Coagulation of Multiple Rocky Embryos and Super-Earth Systems around Solar Type Stars
• Post-Oligarchic Evolution of Protoplanetary Embryos and the Stability of Planetary Systems
• Merging Criteria for Giant Impacts of Protoplanets
• Formation of Terrestrial Planets from Protoplanets under a Realistic Accretion Condition
• Formation of close in Super-Earths \& Mini-Neptunes: Required Disk Masses \& Their Implications
• A reassessment of the in situ formation of close-in super-Earths
• Disk-planets interactions and the diversity of period ratios in Kepler's multi-planetary systems
• Correlations between compositions and orbits established by the giant impact era of planet formation
• The Orbital Stability of Planets Trapped in the First-Order Mean-Motion Resonances
• The statistical mechanics of planet orbits
• Warm Debris Disks Produced by Giant Impacts During Terrestrial Planet Formation
• The Kepler Dichotomy in Planetary Disks: Linking Kepler Observables to Simulations of Late-Stage Planet Formation
• Suppression of type I migration by disk winds
• Eccentricity Evolution Through Accretion of Protoplanets

Cited by in corpus (20)

• Architectures of Compact Super-Earth Systems Shaped by Instabilities
• HD219666b: A hot-Neptune from TESS Sector 1
• Survival of non-coplanar, closely-packed planetary systems after a close encounter
• Formation of compact systems of super-Earths via dynamical instabilities and giant impacts
• In situ formation of hot Jupiters with companion super-Earths
• The dynamical evolution of transiting planetary systems including a realistic collision prescription
• Collisional Fragmentation is Not a Barrier to Close-in Planet Formation
• Radial migration of gap-opening planets in protoplanetary disks. II. The case of a planet pair
• The origins of nearly coplanar, non-resonant systems of close-in super-Earths
• On the Orbital Spacing Pattern of Kepler Multiple Planet Systems
• Ejection of close-in super-Earths around low-mass stars in the giant impact stage
• Size evolution of close-in super-Earths through giant impacts and photoevaporation
• On the Degree of Dynamical Packing in the Kepler Multi-planet Systems
• On the origin of the eccentricity dichotomy displayed by compact super-Earths: dynamical heating by cold giants
• Orbital stability of compact three-planet systems, II: Post-instability impact behaviour
• Orbital Evolution of Close-in Super-Earths Driven by Atmospheric Escape
• Multiverse Predictions for Habitability: Planetary Characteristics
• Dynamical Instability of Multi-planet Systems and Free-floating Planets
• Evidence for a Non-Dichotomous Solution to the Kepler Dichotomy: Mutual Inclinations of Kepler Planetary Systems from Transit Duration Variations
• Super-earths and mini-neptunes follow different orbital period-eccentricity relations