The ultraviolet radiation from the star is making the nebula glow. The Butterfly Nebula was one of the bipolar planetary nebulae lying near the galactic core that were discovered to be preferentially aligned to the galactic plane of the Milky Way.see:
SEE: B. Rees and A.A.Zijlstra: "There is strong evidence for cylindrical rotation in the Bulge, with angular momentum perpendicular to the Galactic plane (Howard et al. 2009)". SEE: B. Rees and A.A.Zijlstra: https://arxiv.org/pdf/1307.5711.pdf
Butterfly alignment. perpendicular to the milky way disc explained by the Q-FFF Theory due to the GABHs ( Galaxy Anchor Black Holes) of our galaxy and those of butterfly stars.
Conclusion, NOT all exploded stars have butterfly shapes because they are the result of a new phenomena which is the growing of the original star between two local Herbig Haro Black Holes into new sibling stars expelled just like later planets..
