An Etymological Dictionary of Astronomy and Astrophysics

In evolutionary models of → post-asymptotic giant branch stars,
the occurrence of the helium shell burning when the star has reached the → white dwarf cooling track.
This leads to the possibility of a violent → helium shell flash and expansion on a time-scale of ≤ 10 years. The rapid expansion and prompt change in surface composition observed in → Sakurai’s Object are thought to be due to such a very late thermal pulse.

See also: → very; → late; → thermal; → pulse.