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Title: Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation

We apply hydrodynamic evaporation models to different synthetic planet populations that were obtained from a planet formation code based on the core-accretion paradigm. We investigated the evolution of the planet populations using several evaporation models, which are distinguished by the driving force of the escape flow (X-ray or EUV), the heating efficiency in energy-limited evaporation regimes, or both. Although the mass distribution of the planet populations is barely affected by evaporation, the radius distribution clearly shows a break at approximately 2 R {sub ⊕}. We find that evaporation can lead to a bimodal distribution of planetary sizes and to an 'evaporation valley' running diagonally downward in the orbital distance—planetary radius plane, separating bare cores from low-mass planets that have kept some primordial H/He. Furthermore, this bimodal distribution is related to the initial characteristics of the planetary populations because low-mass planetary cores can only accrete small primordial H/He envelopes and their envelope masses are proportional to their core masses. We also find that the population-wide effect of evaporation is not sensitive to the heating efficiency of energy-limited description. However, in two extreme cases, namely without evaporation or with a 100% heating efficiency in an evaporation model, the final size distributions showmore » significant differences; these two scenarios can be ruled out from the size distribution of Kepler candidates.« less
Authors:
;  [1] ; ; ;  [2] ;  [3]
  1. Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)
  2. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
  3. Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d'Azur, F-06300 Nice (France)
Publication Date:
OSTI Identifier:
22370293
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; DISTANCE; EFFICIENCY; EVAPORATION; EVAPORATION MODEL; EXTREME ULTRAVIOLET RADIATION; HEATING; HYDRODYNAMIC MODEL; MASS; MASS DISTRIBUTION; PLANETS; SATELLITE ATMOSPHERES; SATELLITES; STAR EVOLUTION; X RADIATION