The composition of planets is largely determined by the chemical and dynamical evolution of the disk during planetesimal formation and growth .
To predict the diversity of exoplanet compositions , previous works modeled planetesimal composition as the equilibrium chemical composition of a protoplanetary disk at a single time .
However , planetesimals form over an extended period of time , during which , elements sequentially condense out of the gas as the disk cools and are accreted onto planetesimals .
To account for the evolution of the disk during planetesimal formation , we couple models of disk chemistry and dynamics with a prescription for planetesimal formation .
We then follow the growth of these planetesimals into terrestrial planets with N-body simulations of late stage planet formation to evaluate the effect of sequential condensation on the bulk composition of planets .
We find that our model produces results similar to those of earlier models for disks with C/O ratios close to the solar value ( 0.54 ) .
However , in disks with C/O ratios greater than 0.8 , carbon rich planetesimals form throughout a much larger radial range of the disk .
Furthermore , our model produces carbon rich planetesimals in disks with C/O ratios as low as \sim 0.65 , which is not possible in the static equilibrium chemistry case .
These results suggest that ( 1 ) there may be a large population of short period carbon rich planets around moderately carbon enhanced stars ( 0.65 < C/O < 0.8 ) and ( 2 ) carbon rich planets can form throughout the terrestrial planet region around carbon rich stars ( C/O > 0.8 ) .