Scaling the Earth: A Sensitivity Analysis of Terrestrial Exoplanetary Interior Models
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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2016
- DOI:
- 10.3847/0004-637X/819/1/32
- arXiv:
- arXiv:1510.07582
- Bibcode:
- 2016ApJ...819...32U
- Keywords:
-
- Earth;
- planets and satellites: fundamental parameters;
- planets and satellites: interiors;
- planets and satellites: terrestrial planets;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 8 pages, 8 figures, 2 tables