The star winked and disappeared from sight. Is it a “failed supernova”?

Some huge stars may disappear with a bang rather than an explosion.

A star that winks out of sight could be a “failed supernova,” an explosion of stars that gradually faded away without fully exploding, a new study reports. If true, a failed supernova would indicate the birth of a black hole.

At the end of their lives, giant stars undergo a dazzling explosion known as a supernova, which begins when the star’s core collapses. But scientists think there may not be enough energy to cause a complete explosion, resulting in the star disappearing without any fireworks.

No one has definitively detected a failed supernova. But now a new candidate has emerged. Visible light from a supergiant star discovered in the neighboring Andromeda galaxy, faded dramatically It began in 2016 and will disappear completely by 2023, MIT astrophysicist Kishalay De and his colleagues report in a paper submitted to arXiv.org on October 18.

“That’s what you expect [from a failed supernova]. “There’s something bright and shiny that looks like a giant star, and then it disappears,” says astrophysicist Morgan Fraser, who was not involved in the study.

However, this finding is not yet conclusive. “There are many others…that are a bit similar and can be misleading,” says Fraser, of University College Dublin. For example, a cloud of dust can cover a star, making it dark (SN: 21/6/16).

Another mystery: Scientists expect to see some disruption as the star’s outer layers swell from a failed supernova explosion. However, De and his colleagues did not witness any visible light show. To explain that, the researchers suggest that the star had previously been stripped of part of its outer hydrogen envelope. De declined to comment because the study has not yet been peer-reviewed.

If we can conclusively detect the failure of a supernova, it will be an astronomical victory. “Right now, this is the only viable way to actually observe how black holes form,” said Christopher Kochanek, an astrophysicist at Ohio State University.

Kochanek et al. previously reported the possibility of a supernova failure (SN: September 20, 2016). But scientists are still working to rule out other possible explanations for it. In follow-up observations by the James Webb Space Telescope (JWST), infrared glowKochanek et al. reported in a Feb. 20 report. astrophysical journal. That infrared light could be emitted by residual matter falling into the newly formed black hole. Or it could be caused by something more mundane than a failed supernova, such as two stars merging and kicking up a cloud of dust.

Similarly, even though visible light disappeared, some infrared glow remained from newly discovered extinct stars. So whether it’s a failed supernova is similarly in limbo. “Our observations are sparse and it’s very difficult to tell the difference,” says Griffin Hosseinzadeh, an astrophysicist at the University of California, San Diego, who was not involved in the study.

Additional data from JWST could help determine the origins of both of the purported failed supernovae. Scientists can also look for X-rays that can be produced if there is a black hole swallowing matter.

Understanding the death throes of stars is important in determining how galaxies acquire black holes and neutron star populations (the ultra-dense debris left behind by successful supernovae).SN: 2/22/24). And the demise of stars is also important for how chemical elements formed in stars are blown across the universe.

Eventually, scientists hope to be able to predict a star’s ultimate fate. “What we want to know is, as a function of a star’s birth mass, will it go supernova and create a neutron star, or will it fail and create a black hole?” says Stanford Woosley, an astrophysicist at the University of California, Santa Cruz. “The whole idea of ​​the birth of a black hole, what it looks like, what different stellar masses produce, these are important questions.”