Motivated by the trends found in the observed sample of extrasolar planets , this paper determines tidal equilibrium states for forming planetary systems — subject to conservation of angular momentum , constant total mass , and fixed orbital spacing . In the low-mass limit , valid for superearth-class planets with masses of order m _ { p } \sim 10 M _ { \oplus } , previous work showed that energy optimization leads to nearly equal mass planets , with circular orbits confined to a plane . The present treatment generalizes previous results by including the self-gravity of the planetary bodies . For systems with sufficiently large total mass m _ { \scriptstyle T } in planets , the optimized energy state switches over from the case of nearly equal mass planets to a configuration where one planet contains most of the material . This transition occurs for a critical mass threshold of approximately m _ { \scriptstyle T } \raise 1.29 pt \hbox { $ > $ } \kern - 7.5 pt \lower 3.01 pt \hbox { $ \sim% $ } m _ { \scriptstyle C } \sim 40 M _ { \oplus } ( where the value depends on the semimajor axes of the planetary orbits , the stellar mass , and other system properties ) . These considerations of energy optimization apply over a wide range of mass scales , from binary stars to planetary systems to the collection of moons orbiting the giant planets in our solar system .