Type Iax supernova

The proposed formation scenario for SN 2012Z is that the original system at the heart of the supernova was a binary pair of large, but otherwise ordinary main sequence stars.

The more massive of the binary stars lost substantial amounts of its hydrogen and helium to its smaller companion, and became a white dwarf.

The newly engorged companion star then evolved into an enlarged stage, whose outer layers engulfed the white dwarf.

The outer hydrogen layers of the overlapping stars were then ejected, leaving behind a still-active helium core and the white dwarf.

[9] This discovery is a milestone in a decades long search by astronomers for such an occurrence; the observation of SN 2012Z was the first time astrophysicists were able to identify a star system that later went to a supernova of this type.