Cataclysmic or explosive variable stars are those that undergo a dramatic change in their properties . This group include novae and supernovae . A binary star system that include a nearby white dwarf can produce certain types of these spectacular stellar explosions , including the nova and a Type 1a supernova . The explosion is created when the white dwarf accretes hydrogen from the companion star , building up mass until the hydrogen undergoes fusion . Some novae are also recurrent , having periodic outbursts of moderate amplitude .