nova


novasearch for term

An explosive increase in stellar brightness by a factor of one hundred thousand to one million. Most novas occur in closely bound binary star systems in which one member is a white dwarf. The white dwarf draws material (mostly hydrogen) that lies outside the companion star's Roche lobe from the companion star. As hydrogen falls onto the white dwarf, the surface temperature and pressure increase until the hydrogen shell suddenly explodes in runaway thermonuclear reaction. Most of the material falls back onto the white dwarf. This is a recurring process that can continue as long as a steady stream of hydrogen flows to the white dwarf.