A ringworld makes more sense from the point of view of zero structural load and stress if it's built to the right diameter and 'orbits' at the right distance. Of course, there would need to be some spin to create gravity, which will keep the structure stable too.

A 20 year long time lapse video put together from images taken by the Hubble Space Telescope shows the shock front from a supernova moving through space.
phys.org/news/2023-09-edge-supernova-hubble-time-lapse-movie.html

I had to watch the video in this article twice to see that the rather beautiful wispy gas does actually move in the video's end sequence!
That's how far travelling at half a million mph takes you in 20 years.

The same thing that makes it glow.
It's a shock wave caused by expanding material from the supernova ramming into the surrounding interstellar medium (ISM).

The ISM is a hard vacuum by our standards. But even a few atoms per cubic metre add up over cubic lightyears!

Climate change due to a comet impact on Syria 12,800 years ago may have kick started the human population resorting to agriculture rather than their previous hunter gatherer lifestyle.

phys.org/news/2023-10-prehistoric-cosmic-airburst-advent-agriculture.html

"In this general region, there was a change from more humid conditions that were forested and with diverse sources of food for hunter-gatherers, to drier, cooler conditions when they could no longer subsist only as hunter-gatherers," said Earth scientist James Kennett, a professor emeritus of UC Santa Barbara . The settlement at Abu Hureyra is famous among archaeologists for its evidence of the earliest known transition from foraging to farming. "The villagers started to cultivate barley, wheat and legumes," he noted. "This is what the evidence clearly shows."

Initial analysis of the asteroid dust and rocks returned to NASA by the OSIRIS-REx mission shows it to be heaving with carbon and water.
Both are essential for life as we know it on Earth.
This supports the theory that life on Earth, and the oceans themselves, originated from materials delivered by the extended asteroid bombardment known to have happened early on in its history.

www.sciencealert.com/first-look-at-pristine-asteroid-dust-reveals-abundance-of-water-and-carbon