final helium flash object

A final helium flash object is an evolved star that, in descending the white dwarf cooling track, undergoes a final thermal pulse when its helium shell ignites causing it to expand rapidly to high luminosity and become a born-again planetary nebula. This phase of stellar evolution is extremely short, lasting only a few decades to a few centuries and would rarely be observed. A handful of final helium flash object candidates have been identified, including Sakurai's Object, FG Sagittae, and V605 Aquilae.