Dead Planet

A planet which has lost 77% of it's core, most commonly due to pure energy fissures, is considered to be a dead planet. For the most part these planets can still be held together by their own gravity because 77% is thought to be the critical point where the density of a planet has been lowered to the point that pure energy fissures become rare. The rate of this decay is typically accelerated if the planet is orbiting a green dwarf star due to the higher concentration of fissure particles.