Cataclysmic variable binary star. Artwork showing a nova formation stage in a cataclysmic variable binary star system. A red dwarf (upper right) is seen in mutual orbit with a white dwarf (lower left). An accretion disc (orange) 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 (white) of compressed glowing gas. Systems such as this produce novae, outbursts which suddenly increase the apparent brightness of the star many times. These occur as some gas in the disc explodes on the surface of the white dwarf. Many such novae recur regularly.