 Kelvin-Helmholtz cooling time

The Kelvin-Helmholtz cooling time estimates how long a self-gravitating body can radiate a reservoir of energy of order its gravitational binding energy. It uses intrinsic luminosity $L_{\mathrm{int}}$, excluding reradiated stellar light. At fixed radius and structure, this reservoir scales as $M^2$; the approximation changes when degeneracy or other internal physics changes the accessible energy.