SCALING THE EARTH: A SENSITIVITY ANALYSIS OF TERRESTRIAL EXOPLANETARY INTERIOR MODELS

• Published in: The Astrophysical journal 2016-03, Vol.819 (1), p.32
• Main Authors: Unterborn, C. T., Dismukes, E. E., Panero, W. R.
• Format: Article
• Language: English
• Subjects: Earth; Extrasolar planets; Mathematical models; Perturbation methods; planets and satellites: fundamental parameters; planets and satellites: interiors; planets and satellites: terrestrial planets; Sensitivity analysis; Silicates; Silicon; Terrestrial planets
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/819/1/32

ABSTRACT An exoplanet's structure and composition are first-order controls of the planet's habitability. We explore which aspects of bulk terrestrial planet composition and interior structure affect the chief observables of an exoplanet: its mass and radius. We apply these perturbations to the Earth, the planet we know best. Using the mineral physics toolkit BurnMan to self-consistently calculate mass-radius models, we find that the core radius, the presence of light elements in the core, and an upper mantle consisting of low-pressure silicates have the largest effects on the final calculated mass at a given radius, none of which are included in current mass-radius models. We expand these results to provide a self-consistent grid of compositionally as well as structurally constrained terrestrial mass-radius models for quantifying the likelihood of exoplanets being "Earth-like." We further apply this grid to Kepler-36b, finding that it is only ∼20% likely to be structurally similar to the Earth with Si/Fe = 0.9 compared with the Earth's Si/Fe = 1 and the Sun's Si/Fe = 1.19.