Two Empirical Regimes of the Planetary Mass-Radius Relation

Abstract

Today, with the large number of detected exoplanets and improved measurements, we can reach the next step of planetary characterization. Classifying different populations of planets is not only important for our understanding of the demographics of various planetary types in the galaxy, but also for our understanding of planet formation. We explore the nature of two regimes in the planetary mass-radius (M-R) relation. We suggest that the transition between the two regimes of "small" and "large" planets, occurs at a mass of 124 \pm 7, M_Earth and a radius of 12.1 \pm 0.5, R_Earth. Furthermore, the M-R relation is R \propto M^{0.55\pm 0.02} and R \propto M^{0.01\pm0.02} for small and large planets, respectively. We suggest that the location of the breakpoint is linked to the onset of electron degeneracy in hydrogen, and therefore, to the planetary bulk composition. Specifically, it is the characteristic minimal mass of a planet which consists of mostly hydrogen and helium, and therefore its M-R relation is determined by the equation of state of these materials. We compare the M-R relation from observational data with the one derived by population synthesis calculations and show that there is a good qualitative agreement between the two samples.

accepted for publication in A&A

References in corpus (9)

• The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters
• Probabilistic Forecasting of the Masses and Radii of Other Worlds
• Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation
• The Mass of KOI-94d and a Relation for Planet Radius, Mass, and Incident Flux
• Formation of Jupiter using opacities based on detailed grain physics
• Global Models of Planet Formation and Evolution
• Occurrence and core-envelope structure of 1--4x Earth-size planets around Sun-like stars
• The opacity of grains in protoplanetary atmospheres
• Grain opacity and the bulk composition of extrasolar planets. I. Results from scaling the ISM opacity

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