2014ApJ...795...65J -
Astrophys. J., 795, 65 (2014/November-1)
Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation.
JIN S., MORDASINI C., PARMENTIER V., VAN BOEKEL R., HENNING T. and JI J.
Abstract (from CDS):
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⊕. 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 show significant differences; these two scenarios can be ruled out from the size distribution of Kepler candidates.
Abstract Copyright:
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Journal keyword(s):
planets and satellites: atmospheres - planets and satellites: interiors - planets and satellites: physical evolution
Simbad objects:
3
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