For the first time, astronomers have observed the complete collapse of a massive star directly into a black hole, without the typical accompanying supernova explosion. This rare event provides the clearest picture yet of how massive stars transform into black holes—a cosmic process previously understood largely through theory rather than direct observation.
The research, published in the journal Science, combines over a decade of archival data with recent observations from various ground and space-based telescopes. The findings open a new chapter in understanding the origins of black holes.
A Giant Star That Simply “Disappeared”
The star at the center of this discovery, designated M31-2014-DS1, is located approximately 2.5 million light-years from Earth in the Andromeda Galaxy—the Milky Way’s closest galactic neighbor.
From 2005 to 2023, researchers analyzed data from NASA’s NEOWISE project and other telescopes. They identified an unusual pattern:
- In 2014, the star’s infrared light began to increase.
- By 2016, the star had dramatically dimmed within less than a year.
- Between 2022 and 2023, the star had practically vanished in visible light and near-infrared—its brightness reduced to one ten-thousandth of its original level.
Currently, only a faint signal remains detectable in mid-infrared light, with a brightness about one-tenth of its initial state.
“This star used to be one of the brightest in Andromeda, and then it was just…gone,” said Kishalay De, the lead researcher of the study from the Flatiron Institute. He likened the event to what would happen if the star Betelgeuse in our own sky suddenly disappeared, causing considerable excitement in the astronomical community.
From these dramatic changes in light, the researchers concluded that the star’s core had collapsed and transformed into a black hole.
Why No Supernova?
Generally, stars generate energy by fusing hydrogen into helium in their cores. This reaction creates outward pressure that balances the inward pull of gravity.
However, when a star with a mass 10 times or greater than our Sun runs out of fuel, this balance collapses. Gravity takes over, and the core collapses to form an incredibly dense neutron star.
In many cases, the release of particles called neutrinos triggers a powerful shockwave that blasts away the star’s outer layers in a spectacular supernova explosion. However, in certain instances—such as with M31-2014-DS1—that shockwave fails to expel the material.
much of the star’s material falls back into the center, forming a black hole.
“We’ve known for almost 50 years that black holes exist,” De stated. “But we’re still in the early stages of understanding which stars turn into black holes and how that process happens.”
The Hidden Role of Convection
A key finding of this study is the role of convection, the movement of gas caused by extreme temperature differences within the star.
The star’s core is incredibly hot, while its outer layers are much cooler. This difference creates turbulent, up-and-down gas movement.
As the core collapses, the outer layers are still moving rapidly due to this convection. Theoretical models suggest that this movement prevents all the material from immediately falling into the black hole. Instead, the inner layers form an orbit around the black hole, the outer layers are slowly pushed outward, and the ejected material cools and forms cosmic dust.
This discovery offers a unique opportunity to refine our understanding of stellar evolution and the formation of black holes. While supernovae are dramatic events that signal the death of massive stars, this observation demonstrates that some stars can quietly slip into oblivion, leaving behind a black hole without a grand finale. Further research, utilizing advanced telescopes like the James Webb Space Telescope, will be crucial to unraveling the mysteries surrounding these “failed supernovae” and the black holes they create.