Astronomers have documented the disappearance of a massive star in the neighboring Andromeda galaxy, concluding that it collapsed directly into a black hole without the typical fiery explosion of a supernova. This rare observation provides one of the most direct views yet of a star's quiet death and the birth of a new black hole.
The star, located approximately 2.5 million light-years from Earth, was about 13 times the mass of our sun. Its vanishing act challenges long-held theories about how black holes are formed, suggesting they may be more common than previously believed.
Key Takeaways
- A star named M31-2014-DS1 in the Andromeda galaxy has disappeared from view.
- Scientists believe the star, 13 times the mass of the sun, collapsed into a black hole.
- The event occurred without a supernova, a process known as a 'quiet collapse'.
- This discovery could change our understanding of how many black holes exist in the universe.
A Cosmic Disappearance
The mystery began when astronomers, led by Kishalay De of Columbia University, analyzed archival data. They noticed that a star, designated M31-2014-DS1, had undergone a strange transformation. Before its disappearance, it shone with the intensity of 100,000 suns, making it one of the brighter stars in Andromeda.
Around 2014, the star experienced a significant brightening in infrared light. However, by 2016, it began to fade dramatically. Follow-up observations in 2023 using powerful instruments, including the Keck Observatory in Hawaii and the Hubble Space Telescope, confirmed the star was gone.
"I remember the moment when we pointed the telescope towards this star — except the star was not there at all," De recalled. "Stars that are this bright, this massive, do not just randomly disappear into darkness."
By 2023, the star's brightness had plummeted to about one ten-thousandth of its original luminosity, effectively vanishing from sight in visible light.
Challenging Old Theories
The prevailing theory of black hole formation involves a supernova, a cataclysmic explosion that occurs when a massive star runs out of fuel. The explosion blasts the star's outer layers into space, leaving behind a dense core that can collapse into a black hole or a neutron star.
The case of M31-2014-DS1 presents a different scenario. Its relatively modest mass—just 13 times that of our sun—and the lack of any explosive signature point to a direct collapse.
Rethinking Stellar Death
Traditionally, stars below 20 solar masses were not considered prime candidates for collapsing into black holes without a supernova. This event suggests the threshold may be much lower. "Ten years ago, if someone said a 13 solar-mass star would turn into a black hole, nobody would believe that," De explained.
This "quiet collapse" suggests that the star's core was so dense that it imploded under its own gravity in a matter of hours, swallowing itself before an explosion could occur. This finding implies that the universe might be populated with many more black holes than astronomers can account for with supernova-based models alone.
What Happens Next?
Although the star itself is gone, astronomers can still detect the aftermath of its collapse. A faint glow in infrared light remains, produced by dust and gas from the star's outer layers that are now swirling around the newly formed black hole.
This material is moving too quickly to fall directly in. Instead, it has formed a rotating disk that will slowly feed the black hole over time, similar to water circling a drain.
Future Observations
Scientists plan to continue monitoring the site with advanced telescopes like the James Webb Space Telescope (JWST). They predict the infrared signal will steadily fade over the next few decades as more material is consumed by the black hole. Recent data from JWST has already confirmed that the black hole is heavily shrouded in the star's leftover material.
Researchers also used NASA's Chandra X-ray Observatory to search for high-energy radiation from the area. No X-rays were detected, which was expected. The dense cloud of gas and dust currently surrounding the black hole is likely blocking any X-rays from escaping. As this material clears over time, future observations may finally detect the tell-tale X-ray signature of a black hole feeding.
A New Way to Find Black Holes
This discovery provides a new template for astronomers searching for the birth of black holes. Instead of monitoring countless stars in the hope of catching one as it vanishes, they can now look for a specific signature: a sudden, bright flare-up in infrared light followed by a rapid fade.
This method could help identify other stars on the brink of a quiet collapse, offering more opportunities to witness these fundamental cosmic events.
"This is essentially as close as we can get to seeing the death of a massive star," De stated. The research, published in the journal Science, not only documents a star's end but also opens a new chapter in understanding the life cycle of stars and the formation of the universe's most enigmatic objects.