An artist's concept of a dwarf nova system. The gravitational field of a white dwarf pulls matter off the surface of a companion star into a disk surrounding the white dwarf. The disk occasionally goes into outburst, making the dwarf nova system about 100 times brighter than in quiescence. Radio jets are now believed to be formed during the first few hours of an outburst, during the rapid brightening stage.
A. Beardmore, University of Leicester