Stars tens of times heavier than our Sun don't die as thought before. Computer models show that their core often doesn't ignite a supernova, but quickly collapses into a black hole. Imagine a soufflé: the center suddenly sinks, and almost all the batter falls into the funnel, with just a few drops splashing out. Same for a star: most of its matter falls inward instead of flying away.
In 23 simulations of stellar death, in 18 cases the hole formed before the explosion could blow off the outer layers. This happened for stars 19–60 times heavier than the Sun. We used to think only the most massive stars collapsed this way, but simulations prove otherwise.
The most surprising part: the final mass of the black hole weakly depends on the size of the carbon core. A lighter star can give birth to a heavier hole than a more massive one. Simulations showed: even after collapse, some matter escapes, producing a dim flash. Its light, bending around the hole, turns into a ghostly ring for an observer.
as written by the authors arXiv:2605.01405
Black hole supernovae (BHSNe), the term we use for core-collapse events in which black hole (BH) formation occurs after shock revival but before the explosion is complete, have emerged as a natural outcome of multidimensional simulations as these calculations have been extended to seconds after bounce. Yet they remain one of the least studied outcomes of core collapse. Here, we assess whether they are confined to the most compact and massive progenitors, whose birth rates are low, or whether they arise systematically across a wider range of progenitor structures. We perform 23 long-term axisymmetric core-collapse simulations of progenitors spanning 19.51-60$$\,M_\odot$$ and compactnesses $$0.31 \lesssim \xi_{2.5} \lesssim 0.63$$. We find 18 BHSN outcomes across nearly the full ZAMS mass range considered, corresponding to progenitors with $$0.40 \lesssim \xi_{2.5} \lesssim 0.63$$. BH formation occurs between $$\sim0.7$$ s and $$\sim4.4$$ s after bounce. After BH formation, we continue the evolution with an excision treatment to at least 5000 s. The final explosion energies span $$\sim2\times10^{49}$$-$$3\times10^{51}$$ erg, while the final BH gravitational masses span $$\sim3$$-$$26\,M_\odot$$. We find a clear remnant-mass trend with CO-core mass, but show that the CO core alone is not an adequate proxy for the final BH mass, especially for progenitors at the low- and high-mass ends of the CO-core distribution. Except for the highest CO-core mass models, no single spherical mass coordinate cleanly separates ejecta from remnant material. Finally, a 2D axisymmetric and a 3D model are compared as we discuss differences between the two geometries.
A black hole's mass can reach 26 solar masses — that's like squeezing nine million Earths into an invisible point, around which light wraps into a ring.