A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses

TL;DR

This paper introduces a comprehensive grid model for the mass-radius relationship of solid exoplanets with 0.1 to 100 Earth masses, incorporating detailed layered compositions and equations of state.

Contribution

It provides a new detailed model grid for 3-layer exoplanets, including updated equations of state and tools for quick interior property estimation from mass and radius.

Findings

Contours on mass-radius diagrams help determine planetary properties.

Ternary diagrams illustrate possible layer compositions for given mass-radius data.

The model accounts for various phases of water and iron, improving interior structure predictions.

Abstract

This paper describes a new grid for the mass-radius relation of 3-layer exoplanets within the mass range of 0.1 through 100 Earth Masses. The 3 layers are: Fe (epsilon iron), MgSiO3 (including both the perovskite phase, post-perovskite phase, and its dissociation at ultra-high pressures), and H2O (including Ices Ih, III, V, VI, VII, X, and the superionic phase along the melting curve). We discuss the current state of knowledge about the equations of state (EOS) that influence these calculations and the improvements used in the new grid. For the 2-layer model, we demonstrate the utility of contours on the mass-radius diagrams. Given the mass and radius input, these contours can be used to quickly determine the important physical properties of a planet including its p0 (central pressure), p1/p0 (core-mantle boundary pressure over central pressure), CMF (core mass fraction) or CRF (core radius fraction). For the 3-layer model, a curve segment on the ternary diagram represents all possible relative mass proportions of the 3 layers for a given mass-radius input. These ternary diagrams are tabulated into Table3 with the intent to make comparison to observations easier. How the presence of Fe in the mantle affects the mass-radius relations is also discussed in a separate section. A dynamic and interactive tool to characterize and illustrate the interior structure of exoplanets built upon models in this paper is available on the website: http://www.cfa.harvard.edu/~lzeng