Star Gone Without a Bang
By: Kathleen Guo
A star has seemingly vanished into thin air. The star in question is a burning crystal blue. Stars usually finish their life in a powerful and radiant explosion—a supernova—and leave behind a newly formed black hole, but this one disappeared without a trace.
Andrew Allen, a doctoral student in astrophysics at Trinity College Dublin, checked and rechecked the data. The star was too far away to be directly observed by telescopes, so astronomers look for the distinct signatures that these luminous blue stars imprint on the light coming from their home galaxy. However, those traces have vanished. Observations revealed no evidence of a supernova.
Allan and his colleges predict that the star might have simply skipped over the supernova and went straight into collapsing into a black hole.
“If indeed the star turned into a black hole with no supernova at all, then it’s a case of ‘gone without a bang’ that astronomers have been searching for for a while now,” said Iair Arcavi, an astronomer at Tel Aviv University.
Astronomers have theorized that a star could go out like this. In 2015, a star by the name of N6946-BH1 had also undergone a similar disappearance. It was twenty-five times bigger than our sun, which should’ve left an extremely violent and bright supernova. Instead, it fizzed out and left behind only a black hole.
Allae hopes that that’s what happened here, but the researchers do not yet know for sure. They have not ruled out slightly less dramatic possibilities. One explanation lies within the nature of these extremely bright stars. Blue stars are prone to dramatic shifts in brightness. It might’ve just dipped in brightness after an especially luminous period. Another explanation might simply be that the star is not a star at all. A different team of astronomers in their own study proposed this idea and according to them, the telescopes have been observing the light of a long-lived supernova interacting with the cosmic material around it. These distant interactions could be mistaken for the fluctuations of brightness in a star.
To investigate this mystery further, astronomers will need to collect more observations of the distant galaxy. Allen says that the astronomers will soon deploy the Hubble space telescope to take a look.
Perhaps there really is a different kind of star death, not the ones we’re already familiar with. Which brings up more questions: why do some stars explode in a vibrant array of colors, while some simply fade away into the background? Is there another element at play in the cause of star death rather than the size and luminosity? A few years ago, a team of researchers led by Arcavi came upon a star that had exploded over and over again instead of fading into the darkness after a single blast. As the textbooks say, stars are supposed to die once, they aren’t supposed to remain after their supernova. Then again, they’re also not supposed to quietly wither away into nothingness.