Compositional imprints in density-distance-time: a rocky composition for close-in low-mass exoplanets from the location of the valley of evaporation

Abstract

We use an end-to-end model of planet formation, thermodynamic evolution, and atmospheric escape to investigate how the statistical imprints of evaporation depend on the bulk composition of planetary cores (rocky vs. icy). We find that the population-wide imprints like the location of the "evaporation valley" in the distance-radius plane and the corresponding bimodal radius distribution clearly differ depending on the bulk composition of the cores. Comparison with the observed position of the valley (Fulton et al. 2017) suggests that close-in low-mass Kepler planets have a predominately Earth-like rocky composition. Combined with the excess of period ratios outside of MMR, this suggests that low-mass Kepler planets formed inside of the water iceline, but still undergoing orbital migration. The core radius becomes visible for planets losing all primordial H/He. For planets in this "triangle of evaporation" in the distance-radius plane, the degeneracy in compositions is reduced. In the observed diagram, we identify a trend to more volatile-rich compositions with increasing radius (R/R_Earth<1.6 rocky; 1.6-3.0 ices and/or H/He; >3: H/He). The mass-density diagram contains important information about formation and evolution. Its characteristic broken V-shape reveals the transitions from solid planets to low-mass core-dominated planets with H/He and finally to gas-dominated giants. Evaporation causes density and orbital distance to be anti-correlated for low-mass planets, in contrast to giants, where closer-in planets are less dense, likely due to inflation. The temporal evolution of the statistical properties reported here will be of interest for the PLATO 2.0 mission which will observe the temporal dimension.

24 pages, 12 figures. Accepted in ApJ. Minor changes relative to v1

References in corpus (39)

• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Mass-Radius Relationships for Solid Exoplanets
• Most 1.6 Earth-Radius Planets are not Rocky
• The evaporation valley in the Kepler planets
• Atmospheric Escape from Hot Jupiters
• One or more bound planets per Milky Way star from microlensing observations
• On the radiative equilibrium of irradiated planetary atmospheres
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• An asteroseismic view of the radius valley: stripped cores, not born rocky
• 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"
• Detection of Carbon Monoxide and Water Absorption Lines in an Exoplanet Atmosphere
• The imprint of exoplanet formation history on observable present-day spectra of hot Jupiters
• Migration and the formation of systems of hot super-Earths and Neptunes
• Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation
• Make Super-Earths, Not Jupiters: Accreting Nebular Gas onto Solid Cores at 0.1 AU and Beyond
• The Extreme Ultraviolet and X-Ray Sun in Time: High-Energy Evolutionary Tracks of a Solar-Like Star
• Radius and Structure models for the First Super-Earth Planet
• The Mass of Kepler-93b and The Composition of Terrestrial Planets
• Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres
• A Spectrum of an Extrasolar Planet
• A generalized bayesian inference method for constraining the interiors of super Earths and sub-Neptunes
• Atmospheric Mass Loss During Planet Formation: The Importance of Planetesimal Impacts
• Hydrodynamics of Embedded Planets' First Atmospheres. II. A Rapid Recycling of Atmospheric Gas
• Bayesian Analysis of Hot Jupiter Radius Anomalies: Evidence for Ohmic Dissipation?
• On the Absorption and Redistribution of Energy in Irradiated Planets
• Planet formation with envelope enrichment: new insights on planetary diversity
• Global Models of Planet Formation and Evolution
• An Atmospheric Structure Equation for Grain Growth
• A reassessment of the in situ formation of close-in super-Earths
• An Analytic Radiative-Convective Model for Planetary Atmospheres
• Analytical Models of Exoplanetary Atmospheres. II. Radiative Transfer via the Two-stream Approximation
• A 1.9 Earth radius rocky planet and the discovery of a non-transiting planet in the Kepler-20 system
• Grain opacity and the bulk composition of extrasolar planets. I. Results from scaling the ISM opacity
• Bayesian analysis of interiors of HD 219134b, Kepler-10b, Kepler-93b, CoRoT-7b, 55 Cnc e, and HD 97658b using stellar abundance proxies
• Convection and Mixing in Giant Planet Evolution
• Spin-Orbit angle distribution and the origin of (mis)aligned hot Jupiters
• The unstable CO2 feedback cycle on ocean planets

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