Main-sequence Empire

An empire on the verge of collapse, named after a main-sequence star. When a main-sequence star has burned through its hydrogen, it switches to helium and bloats into a red giant, though it's essentially being hollowed out inside. Eventually, because it has lost the mass that could sustain its volume, it collapses. If it was an average-sized star, into a white dwarf, or a black hole if above average. Its sapped of all its strength but its military, and now its burning that. Like a red giant, its imperial swelling is a sign of decay, not health. And its unsustainable. Collapse is inevitable. Possibly, given its size, into a black hole, which will suck the whole world in after it.