The ejecta of classical novae

Classical novae are interacting binary stars in which a thermonuclear runaway in material accreted onto a white dwarf from a companion red dwarf results in the ejection of around 10(-4) M-circle dot at hundreds to thousands of kilometres per second. Recent Hubble Space Telescope and MERLIN imaging of the expanding ejecta from several classical novae are presented. In general the ejecta are clumpy but often display coherent structures, most notably equatorial rings of enhanced emission encircling prolate ellipsoidal shells. Physical mechanisms (including the common envelope phase and anisotropic irradiation of the shell) which may result in the generation of these structures are discussed.