PX282 - E5f - post AGB

planetary nebulae form from the ejected material
the hot C and O core is exposed, which is called a white dwarf
it has a radius $\sim R_{\oplus}$ and a mass $≃ 0.6 M_{⊙}$
past a certain mass, they collapse
this is called the chandrashekhar limit, $M_{C S L} \approx 1.4 M_{⊙}$