[metalman]

not an astro anything, but the easy question is how does the sun switch off it's light output so suddenly as to cause a perfect garavitational collapse presumably it has to be a large metal rich star and exist without too much local gas or a companion star one thing is clear at this point is that the variety of stelar and galactic variability is much larger than what was predicted even a few decades ago, though the idea of a star just neatly removing itself from this universe when it's done, is very strange indeed

[madaxe_again]

It doesn’t necessarily switch anything off or collapse - it’s possible for a star of the right mass and density to simply end up with a core that is held up only by degeneracy pressure, and the core slowly shrinks as it cools until it lies within its schwarzschild radius, and the rest of the star is either quietly consumed by this relatively slow process, or just escapes as though nothing much happened. Which from the outside looks like the star just turning off.

[MoonGhost]

It cannot just escape without a push as the gravity is still the same?

[saltcured]

I assume they meant until all the mass collapses across the threshold, the remaining shell of the star outside is still radiating energy and a "solar" wind, which is particles escaping. So some is escaping away while some is slipping under.