EXOPLANET INTERIOR MODELS FOR A RANGE OF HOST STAR COMPOSITIONS

Self-compression models of both hypothetical and detected exoplanets were created to determine properties such as the interior layering and surface gravity. These models operate under the assumptions that (1) the relative Fe, Mg, and Si abundances of the planet is equivalent to that of its host star (i.e., that planetary bulk chemistry is “chondritic”), (2) the temperature profile of the planet will be Earth-like, and (3) the planet will consist of four or five isochemical layers: an upper (olivine/pyroxene dominated), lower (perovskite dominated), and basal transitional (post-perovskite dominated) mantle, a liquid iron core, and possibly a stishovite/enstatite transition mantle layer in low Mg/Si systems. Host star Mg/Si ratio (0.93-1.74) sets the upper mantle mineralogy (olivine/pyroxene/stishovite), with oxygen added to complete these minerals. Stellar Fe/Si (0.2-1.2) was used to determine the core mass percentage (CMP from 10-40%) of the planet. This study created models of one Earth-mass (1 M_E) hypothetical exoplanets as well as of five detected exoplanets from the Centauri system, Mu Arae, CoRoT-7, Kepler-10, and Kepler-93. For 45 other stellar systems, 1-M_E planets ranged in radii range from 6294 to 6731 km (±11 km) and in surface gravity from 8.79 to 10.05 m/s²(±0.03 m/s²) . For 1-M_E planets, planet radius depends on the core mass percentage according to R= -16.8km (CMP) + 6957km (±11km).