Size evolution of close-in super-Earths through giant impacts and photoevaporation

Abstract

The Kepler transit survey with follow-up spectroscopic observations has discovered numerous super-Earth sized planets and revealed intriguing features of their sizes, orbital periods, and their relations between adjacent planets. For the first time, we investigate the size evolution of planets via both giant impacts and photoevaporation to compare with these observed features. We calculate the size of a protoplanet, which is the sum of its core and envelope sizes, by analytical models. $N$-body simulations are performed to evolve planet sizes during the giant impact phase with envelope stripping via impact shocks. We consider the initial radial profile of the core mass and the initial envelope mass fractions as parameters. Inner planets can lose their whole envelopes via giant impacts, while outer planets can keep their initial envelopes since they do not experience giant impacts. Photoevaporation is simulated to evolve planet sizes afterward. Our results suggest that the period-radius distribution of the observed planets would be reproduced if we perform simulations in which the initial radial profile of the core mass follows a wide range of power-law distributions and the initial envelope mass fractions are $\sim 0.1$. Moreover, our model shows that the adjacent planetary pairs have similar sizes and regular spacings, with slight differences from detailed observational results such as the radius gap.

arXiv commentaccepted for publication in ApJ

References in corpus (55)

• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Kepler planets: a tale of evaporation
• Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
• The evaporation valley in the Kepler planets
• Atmospheric Escape from Hot Jupiters
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• Internal Structure of Massive Terrestrial Planets
• The California Kepler Survey VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap
• An asteroseismic view of the radius valley: stripped cores, not born rocky
• The Role of Core Mass in Controlling Evaporation: the Kepler Radius Distribution and the Kepler-36 Density Dichotomy
• Core-powered mass loss and the radius distribution of small exoplanets
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• Roche lobe effects on the atmospheric loss of "Hot Jupiters"
• Building the Terrestrial Planets: Constrained Accretion in the Inner Solar System
• 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: 1. Outcome Regimes and Scaling Laws
• Collisions between Gravity-Dominated Bodies: 2. The Diversity of Impact Outcomes during the End Stage of Planet Formation
• Sculpting the Valley in the Radius Distribution of Small Exoplanets as a by-product of Planet Formation: The Core-Powered Mass-Loss Mechanism
• The California-Kepler Survey V. Peas in a Pod: Planets in a Kepler Multi-planet System are Similar in Size and Regularly Spaced
• The California-Kepler Survey. I. High Resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets
• Revised Radii of Kepler Stars and Planets Using Gaia Data Release 2
• Super-Earth Atmospheres: Self-Consistent Gas Accretion and Retention
• Formation and Structure of Low Density Exo-Neptunes
• Composition and fate of short-period super-Earths: The case of CoRoT-7b
• Toward a Deterministic Model of Planetary Formation VI: Dynamical Interaction and Coagulation of Multiple Rocky Embryos and Super-Earth Systems around Solar Type Stars
• Atmospheres of low-mass planets: the "boil-off"
• In-situ Accretion of Hydrogen-Rich Atmospheres on Short-Period Super-Earths: Implications for the Kepler-11 Planets
• Atmospheric Mass Loss During Planet Formation: The Importance of Planetesimal Impacts
• The Gaia-Kepler Stellar Properties Catalog. II. Planet Radius Demographics as a Function of Stellar Mass and Age
• N-body simulations of planetary accretion around M dwarf stars
• The Frequency of Giant impacts on Earth-like Worlds
• Stealing the Gas: Giant Impacts and the Large Diversity in Exoplanet Densities
• A Metallicity Recipe for Rocky Planets
• Giant Impact: An Efficient Mechanism for the Devolatilization of Super-Earths
• Formation of close-in super-Earths in evolving protoplanetary disks due to disk winds
• Exoplanets around Low-mass Stars Unveiled by K2
• Condition for Capture into First-order Mean Motion Resonances and Application to Constraints on Origin of Resonant Systems
• Accretion and Evolution of ~2.5 Earth-mass Planets with Voluminous H/He Envelopes
• Atmospheric mass loss due to giant impacts: the importance of the thermal component for hydrogen-helium envelopes
• The Kepler Dichotomy in Planetary Disks: Linking Kepler Observables to Simulations of Late-Stage Planet Formation
• The Kepler Peas in a Pod Pattern is Astrophysical
• On the patterns observed in Kepler multi-planet systems
• Atmospheric Erosion by Giant Impacts onto Terrestrial Planets
• Atmospheric Erosion by Giant Impacts onto Terrestrial Planets: A Scaling Law for any Speed, Angle, Mass, and Density
• Atmosphere loss in planet-planet collisions
• Eccentricity Evolution Through Accretion of Protoplanets
• Do the TRAPPIST-1 Planets Have Hydrogen-rich Atmospheres?
• Optically Thin Core Accretion: How Planets Get Their Gas in Nearly Gas-Free Disks
• Peas in a Pod? Radius correlations in Kepler multi-planet systems
• Impact of photoevaporative mass loss on masses and radii of water-rich sub/super-Earths
• Unified simulations of planetary formation and atmospheric evolution: Effects of pebble accretion, giant impacts, and stellar irradiations on super-Earth formation
• Formation of Close-in Super-Earths by Giant Impacts: Effects of Initial Eccentricities and Inclinations of Protoplanets
• CKS IX: Revisiting the Minimum-Mass Extrasolar Nebula with Precise Stellar Parameters
• Unified simulations of planetary formation and atmospheric evolution II: Rapid disk clearing by photoevaporation yields low-mass super-Earth atmospheres
• Ejection of close-in super-Earths around low-mass stars in the giant impact stage

Cited by in corpus (7)

• A fading radius valley towards M-dwarfs, a persistent density valley across stellar types
• Homogeneous search for helium in the atmosphere of 11 gas giant exoplanets with SPIRou
• The K2-3 system revisited: testing photoevaporation and core-powered mass loss with three small planets spanning the radius valley
• Shallower radius valley around low-mass hosts: Evidence for icy planets, collisions or high-energy radiation scatter
• Formation of super-Earths and mini-Neptunes from rings of planetesimals
• Revising core powered mass loss: A critical assessment of the "energy limited" argument
• Retention of primordial atmospheres through giant impacts