a variable star that undergoes a cataclysmic eruption, observed as a sudden large increase in brightness with a subsequent decline over months or years; it is a close binary system with one component a white dwarfCompare supernova
Word Origin for nova
C19: New Latin nova (stella) new (star), from Latin novus new
A white dwarf star that suddenly and temporarily becomes extremely bright as a result of the explosion at its surface of material accreted from an expanding companion star. The material, mostly hydrogen and helium, is attracted by the white dwarf's gravity and accumulates under growing pressure and heat until nuclear fusion is ignited. Unlike a supernova, a nova is not blown apart by the explosion and gradually returns to its original brightness over a period of weeks to years. Because of their sudden appearance where no star had been previously visible, novae were long thought to be new stars. Since 1925, novae have been classified as variable stars. Compare supernova.