Hydrogen-ionization disk instability
= Hydrogen-ionization disk instability
Partial <hydrogen> <ionization> changes disk cooling and permits cold and hot stable thermal branches separated by unstable equilibria. A <dwarf nova> can cycle between a cold matter-storing disk and a hot, rapidly accreting disk. The cycle is described by the evolution of local <surface density> and <temperature>, coupled to <viscous evolution of an accretion disk>.