A nova remnant is made up of the material either left behind by a sudden explosive fusion eruption by classical novae, or from multiple ejections by recurrent novae. Over their short lifetimes, this novae shell shows expansion velocities are around 1000 km/s, whose faint nebulosity usually are illuminated by their progenitor stars via light echos as observed with the spherical shell of Nova Persei 1901 or the energies remaining in the expanding bubbles like T Pyxidis.
As most novae require a close binary system, with a white dwarf and main sequence, sub-giant; or the merging of two red dwarfs; so probably all novae remnants must be associated with binaries. This theortically means these nebulae shapes might be affected by their central progenitor stars and the amount of matter ejected by novae. Shapes of these novae nebulae is of much interest to modern astrophysicists.
Nova remnants when compared to supernova remnants or planetary nebulae generate much less both in energy and mass. They can be observed for perhaps a few centuries. Examples of novae displaying nebula shells or remnants include: GK Per, RR Pic, DQ Her, FH Ser, V476 Cyg, V1974 Cyg, HR Del and V1500 Cyg. Notably, more novae remnants have been found with the new novae, due to improve imaging technology like CCD and at other wavelengths.
^Liimets, T.; Corradi, R.L.M.; Santander-García, M.; Villaver, E.; Rodríguez-Gil, P.; Verro, K.; Kolka, I. (2014). "A Dynamical Study of the Nova Remnant of GK Persei / Stella Novae: Past and Future Decades.". ASP Conference Series, Proceedings of a conference held 4–8 February 2013 at the Pavilion Clock Tower, Cape Town, South Africa. Edited by P.A. Woudt and V.A.R.M. Ribeiro, 2014. 490: 109–115. arXiv:1310.4488. Bibcode:2014ASPC..490..109L. doi:10.1086/109995.