What is so "cataclysmic" about these variables?
Cataclysmic, or explosive, variables actually undergo an explosive
reaction. A cataclysmic variable system consists of a white dwarf star
and a normal star. The stars are so close together that gas flows from
the normal star onto the dwarf where it swirls into a disk. When this
disk of gas collapses onto the white dwarf, it releases large amounts of
Meanwhile, on the surface of the white dwarf, hydrogen is accumulating.
it undergoes thermonuclear fusion. This is seen as an explosion. Cataclysmic
variables are generally divided into three categories, depending on the
intensity of this explosion. After the explosion, the white dwarf
begins collecting more hydrogen and the process starts again.