In 2009, a giant star 25 times more massive than the sun disappeared. OK, it’s not that simple. It went through a period of brilliance, increasing in brightness to millions of suns, as if it were about to explode in a supernova. But then it disappeared instead of exploding. And when astronomers tried to look at the star with the Large Binocular Telescope (LBT), Hubble, and Spitzer Space Telescope, they couldn’t see anything. The star named N6946-BH1 is now considered a failed supernova. The name BH1 comes from the fact that astronomers believe that this star collapsed into a black hole rather than causing a supernova. But that’s just a guess. All we know for sure is that it brightened for a while and then became too dark for our telescopes to see. But that’s changed thanks to the James Webb Space Telescope (JWST).
The new study, published on the preprint server arXiv, analyzes data collected by JWST’s NIRCam and MIRI instruments. It shows a bright infrared source that appears to be a shell of leftover dust surrounding the location of the original star. This is consistent with material being ejected from the star as it rapidly brightens. It could also be infrared light from matter falling into the black hole, although this seems less likely. Surprisingly, the team found not one remaining item, but three. This makes it less likely that the supernova model will fail. Previous observations of N6946-BH1 were a combination of these three sources because the resolution was not high enough to distinguish them. Therefore, a more likely pattern is that the 2009 brightening was caused by an ad hoc merger. What appears to be a giant, bright star is a star system that brightens when two stars merge, then fades.
Although the data favors the merger model, it cannot rule out the failure of the supernova model. And this makes our understanding of supernovae and stellar-mass black holes more complicated. We know from black hole mergers observed by LIGO and other gravitational wave observatories that stellar-mass black holes exist and are relatively common. Therefore, some massive stars will become black holes. But the question remains whether they go supernova first. Regular supernovae may have enough mass left over to become a black hole, but it’s hard to imagine how the most massive stellar black holes could form after supernovae.
N6946-BH1 is located in a galaxy 22 million light-years away, so the fact that JWST can distinguish between multiple sources is very impressive. It also gives astronomers hope that similar stars will be observed in time. With more data, we will be able to distinguish between stellar mergers and true failed supernovae, which will help us understand the final stages of stars as they evolve into black holes. has stellar mass.
source: https://dx.doi.org/10.48550/arxiv.2309.16121