In Alistair Reynold's House of Suns, there is the concept of creating a 'stardam' to prevent unstable stars from destroying nearby systems when they blow up. It says:
A billion or so years later, we began to collect them. We scour space for the occluding signatures of orphaned, starless ringworlds. We fix pushers to their dark sides and launch them across the galaxy at miserable, snail-like fractions of light. It must be done with care, lest the structures shatter into a trillion twinkling fragments. Ringworlds are immensely strong, but they are not indestructible. What they are is shiny. In fact, there is nothing shinier in the known universe. That mirrored inner surface reflects everything, including neutrinos that would happily sail through fifty light-years of solid lead.
To dam a star, to enclose it completely, would require the construction of a Dyson shell. Humans can shroud a star with a swarm of bodies, a Dyson cloud, but we cannot forge a sphere. Instead we approximate one by surrounding a star with thousands of ringworlds, all of similar size but with no two having exactly the same diameter. We make a discus and then start tilting, until each ringworld is encircling the star at a unique angle. The light of the star rams through the narrowing gaps as the ringworlds tighten into their final orientation. Shutters close on a fierce, deadly lantern.
Then suddenly there is no star, just a dark sphere. Inside that shell, the energies of the dying star are held in reflected fury, allowed to bounce back and forth between those flawless reflecting surfaces until, photon by photon, they gradually leak out into space at a harmless intensity.
It takes an unthinkably long time. Should the stardam collapse before most of that pent-up energy has been allowed to dissipate, the results would be more disastrous than the explosion the dam was designed to contain.
My questions are:
The discus would be made of thousands of 'ringworlds' arranged in concentric circles of decreasing diameter (from the outermost part of the discus). If each 'ringworld' is raised by a unique angle on the same side (let's say top-left), all they can cover is the 'top left' and 'bottom-right' part of the potential sphere around the sun. A full half still remains uncovered. Also, can a few thousand 'ringworlds' really cover a supergiant star? An illustration available on the net would be really helpful.
How can a closed sphere prevent the star from exploding? Won't the entire thing burst open as soon as enough pressure builds, like a bomb inside a metal sphere?