Some stars implode instead of going supernova

[selden]

While perusing the CosmoQuest forum this morning I came across a Universe Today article about a star which seems to have imploded to become a black hole instead of going supernova.

It isn't obvious to me at what stellar mass this starts to become more likely. This particular example (the only one discovered so far, although there probably are many others) seems to have been about 25 solar masses. However, I suspect Betelgeuse (at 7.7 solar masses) is well under that limit.

[stevebowers]

This might be something to do with whether the star is singular or not. An exploding star in a binary system might be perturbed enough to collapse unevenly, so that the collapsing shells don't fall smoothly into a central point; any hint of turbulence and the collapse could become a bounce.

[iancampbell]

I seem to remember reading that there was a very early era (when there was almost nothing except hydrogen and helium) in which many of the stars formed were huge - greater than 200 solar masses - and that such enormous stars implode at the end of their lives instead of going supernova.

Apparently, this only happened very early because the physics of star formation and collapse of the clouds that go on to form stars was different with no "metals" to speak of. For example, the carbon cycle in hot stars would have been impossible; also, relatively small gas clouds (going on to form stars of current main sequence size) would find it difficult to actually collapse, because one of the processes by which such clouds lose energy involves heavier elements - mostly in the form of dust - which also would not be present.

I've seen a few interesting speculations about the different physics of really high-metallicity stars; say 25%, with the Sun at 1.3%. This won't happen naturally for many billions of years, but it might well happen artificially in OA.