Mystery behind massive star suddenly vanishing decoded

The James Webb Space Telescope has helped demystify the strange 2009 observation of a giant star about 25 times more massive than the sun that appeared to disappear from existence.

In 2009, astronomers observed what they believed was a giant star about 25 times more massive than the sun, increasing its brightness to a million suns as if it was about to explode into a supernova, then suddenly fading instead of exploding.

However, later observations using the Hubble and the Spitzer space telescope as well as the Large Binocular Telescope (LBT) could not spot the star N6946-BH1, now considered a failed supernova.

Astronomers suspected that the star – 22 million light-years away – may have collapsed to become a black hole instead of triggering a supernova.

Stars are typically considered to form a black hole only after they go supernova (SN), but this observation of N6946-BH1 hinted that stars may fall short of a supernova and still make a black hole.

“N6946-BH1 is the first plausible candidate for a failed supernova (SN), a peculiar event in which a massive star disappears without the expected bright SN, accompanied by collapse into a black hole (BH),” scientists said.

Researchers suspected this observation may help to explain why we don’t see supernovae from the most massive stars.

However, new observations using instruments aboard the Webb telescope – described in a preprint posted in the arXiv server – point to a bright infrared source that is likely from a dust shell remnant surrounding the original star.

While this could be due to material ejected from the star, researchers say the observation may have also been from material falling into a black hole.

The yet-to-be peer-reviewed research reports not one remnant object in the position of the star, but three, making the failed supernova model less likely.

Researchers now suspect that the 2009 brightening observation was rather likely caused by two stars merging.

The brightening they say may have been due to two stars merging, which then faded.

Researchers say the failed supernova model can still not be completely ruled out.

“At present, the interpretation of N6946-BH1 remains uncertain. The observations match expectations for a stellar merger, but theoretical ambiguity in the failed SN hypothesis makes it hard to dismiss,” scientists wrote in the study.

The findings, however, point to the potential of the Webb telescope to distinguish multiple sources millions of light years away.