Two Hubble Space Telescope images are overlain onto an artist impression of the internal structure of a super-AGB star. The super-AGB star is a red giant star, with a compact core surrounded by nuclear burning helium and hydrogen shells and a large convective mantle. It is not clear how it comes to an end: it may leave a neon-rich white dwarf illuminating a Planetary Nebula (top picture), or explode as a supernova as shown in the bottom picture of a supernova remnant.