Nova remnant

Over their short lifetimes, nova shells show expansion velocities of around 1000 km/s,[1] whose faint nebulosities are usually illuminated by their progenitor stars via light echos as observed with the spherical shell[1] of Nova Persei 1901[2] or the energies remaining in the expanding bubbles like T Pyxidis.

[3] Most novae require a close binary system, with a white dwarf and a main sequence, sub-giant, or red giant star, or the merging of two red dwarfs, so probably all nova remnants must be associated with binaries.

[4] This theoretically means these nebula shapes might be affected by their central progenitor stars and the amount of matter ejected by novae.

[1] The shapes of these nova nebulae are of much interest to modern astrophysicists.

Examples of novae displaying nebula shells or remnants include the following:[1]