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It is reasonable to assume that the structure of a planet and the interiordistribution of its components are determined by its formation history. We thusfollow the growth of a planet from a small embryo through its subsequentevolution. We estimate the accretion rate range based on a protoplanetary diskmodel at a large enough distance from the central star, for water ice to be amajor component. We assume the accreted material to be a mixture of silicaterock and ice, with no H-He envelope, as the accretion timescale is much longerthan the time required for the nebular gas to dissipate. We adopt a thermalevolution model that includes accretional heating, radioactive energy release,and separation of ice and rock. Taking the Safronov parameter and theice-to-rock ratio as free parameters, we compute growth and evolutionarysequences for different parameter combinations, for 4.6 Gyr.  We find the final structure to depend significantly on both parameters. Lowinitial ice to rock ratios and high accretion rates, each resulting inincreased heating rate, lead to the formation of extended rocky cores, whilethe opposite conditions leave the composition almost unchanged and result inrelatively low internal temperatures. When rocky cores form, the ice-rich outermantles still contain rock mixed with the ice. We find that a considerablefraction of the ice evaporates upon accretion, depending on parameters, andassume it is lost, thus the final surface composition and bulk density of theplanet do not necessarily reflect the protoplanetary disk composition.

The Effect of Accretion Rate and Composition on the Structure of Ice-rich Super-Earths