A star winked out of his eyes. Could it be a ‘failed supernova’?

Some massive stars can go out with a bang, not a bang.

A star that blinked out of view may be a “failed supernova,” a stellar explosion that died down instead of fully exploding, a new study reports. If true, the failed supernova would mark the birth of a black hole.

At the end of their lives, massive stars explode in dazzling explosions known as supernovae, initiated when the star’s core collapses. But sometimes, scientists suspect, there isn’t enough noise for a full explosion, resulting in a star that goes out without fireworks.

No one has ever definitively detected a failed supernova. But now, there is a new candidate. Visible light from the star, a prominent supergiant in the neighboring Andromeda galaxy, dimmed dramatically starting in 2016, disappearing completely by 2023, MIT astrophysicist Kishalay De and colleagues report in a paper submitted Oct. 18 at arXiv.org.

“It’s what you expect [from a failed supernova]. You have something there that is bright and shiny and looks like a massive star, and then it disappears,” says astrophysicist Morgan Fraser, who was not involved in the research.

But the discovery is not yet final. “There are a lot of other things … that can look a bit similar and fool you,” says Fraser, of University College Dublin. For example, dust clouds can cover stars, dimming them (SN: 16.6.21).

Another puzzle: Scientists expect to see some turbulence from a failed supernova, as the star’s outer layers must be inflated. But De and colleagues saw no visible light show. To explain this, the researchers suggest that the star had previously been stripped of part of its outer hydrogen envelope. De declined to comment as the study has not yet been peer-reviewed.

Finally catching a supernova failure would be an astronomical victory. “Right now, it’s the only possible way to actually see a black hole forming,” says Ohio State University astrophysicist Christopher Kochanek.

Kochanek and colleagues previously reported a possible failed supernova (SN: 20.9.16). But scientists are still working to rule out other possible explanations for it. Follow-up observations with the James Webb Space Telescope, or JWST, showed an infrared glow, Kochanek and colleagues reported on February 20. Astrophysical Journal. This infrared light can be emitted by leftover matter falling into a newly formed black hole. Or it could be due to something more mundane than a failed supernova, such as two stars merging and giving rise to a cloud of dust.

Likewise, some infrared glow continued from the newly found extinct star, even as the visible light disappeared. This leaves it in a similar limbo as to whether it is a failed supernova or not. “With the rare observations we have … it’s very difficult to tell the difference,” says astrophysicist Griffin Hosseinzadeh of the University of California, San Diego, who was not involved in the research.

Additional data from JWST may help determine the origin of both of the supposed failed supernovae. Scientists can also look for X-rays, which can be produced if there is a black hole swallowing matter.

Understanding the death throes of stars is important for determining how galaxies obtain their populations of black holes and neutron stars—the ultradense remnants left behind by successful supernovae.SN: 22/2/24). And the collapse of stars is also important for how the chemical elements formed in stars are dispersed throughout the cosmos.

Eventually, scientists hope to be able to predict a star’s ultimate fate. “What we would like to know is, as a function of the mass of the star when it is born, will it be a supernova and make a neutron star, or will it be a failure and make a black hole?” ” says astrophysicist Stanford Woosley of the University of California, Santa Cruz, who was not involved in the research. “The whole idea of ​​black hole birth, and what it looks like and what different masses of stars produce, those are critical issues.”