Cataclysmic variable binary star. Computer illustration of a cataclysmic variable binary star system. A red dwarf (left) is seen in mutual orbit with a white dwarf (right). An accretion disc of material pulled from the red dwarf can be seen around the white dwarf. At the point where the trail of material meets the disc is a hot spot of compressed glowing gas. Systems such as this produce novae, outbursts which suddenly increase the apparent brightness of the system many times. These occur as some gas in the disc explodes on the surface of the white dwarf. Many such novae recur regularly.