Explosive thermonuclear processes on white dwarfs and neutron stars produce novae and bursters

• Material from an ordinary star in a close binary can fall onto the surface of the companion white dwarf or neutron star to produce a surface layer in which thermonuclear reactions can explosively ignite

• Explosive hydrogen fusion may occur in the surface layer of a companion white dwarf, producing the sudden increase in luminosity that we call a nova

• The peak luminosity of a nova is only 10–4 of that observed in a supernova

• Explosive helium fusion may occur in the surface layer of a companion neutron star

• This produces a sudden increase in X-ray radiation, which we call a burster