Hydrogen-burning white-dwarf envelope

A hydrogen-burning white-dwarf envelope is a thin nondegenerate surface layer in which accreted or residual hydrogen can undergo nuclear fusion above a degenerate core.

Thin-shell instability is a thermal runaway of nuclear burning in a geometrically thin layer whose pressure is constrained by overlying weight, weakening expansion-driven cooling.

A classical nova is a thermonuclear runaway in hydrogen-rich material accreted onto a white dwarf, producing a sudden luminous outburst and ejecting part of the envelope.