The ring is not a product of the supernova. It's pre-existing material, that is being energized by impact of the supernova ejecta (it took a few months for it t

The ring is not a product of the supernova. It's pre-existing material, that is being energized by impact of the supernova ejecta (it took a few months for it to start brightening). There are actually three rings, a smaller one around the previous star's equator, and two larger ones above and below. The hourglass-like figure is actually quite common, produced by the star rotaton.