Astronomers may have witnessed a rare cosmic phenomenon: the quiet death of a massive star that vanished without the expected stellar explosion. The event, known as a “failed supernova,” could signal the birth of a new black hole, as proposed in a recent study led by MIT astrophysicist Kishalay De. Observed in the neighboring Andromeda galaxy, this phenomenon might offer insights into how stars die and collapse, expanding our understanding of the universe’s black hole population.
The ‘Failed Supernova’: A Star That Died Without a Bang
Stars typically end their lives with a supernova, a powerful explosion triggered when a massive star’s core collapses under its own gravity. But scientists theorize that not all stars die with such explosive grandeur. Sometimes, a star may lack the necessary energy for a full-blown explosion, leading to what’s termed a “failed supernova.” Rather than detonating, the star dims and seemingly fades from existence, leaving a black hole in its place.
This event, if confirmed, would represent one of the first observed cases of a failed supernova. According to De’s team, the star — a supergiant — began to dim in 2016 and disappeared entirely by 2023. The findings, published on October 18 in arXiv.org, indicate that the star’s visible light faded without a significant light show, a departure from what astronomers expect during a typical supernova event.
“It’s what you expect from a failed supernova,” says astrophysicist Morgan Fraser from University College Dublin, who was not involved in the study. “You have something bright and massive that suddenly disappears.”
The Complexities of Confirming a Failed Supernova
While the dramatic dimming of the star suggests a failed supernova, the discovery remains inconclusive. Stellar death, even under typical circumstances, is a complex process that doesn’t always follow predictable patterns. Other phenomena, such as thick clouds of dust enveloping a star, could create a similar dimming effect. “There’s a lot of other things that can look a little bit similar and mislead you,” adds Fraser.
Adding to the mystery, scientists expected some visible changes from the failed supernova, such as the release of the star’s outer layers, but none were detected. This lack of visible disturbance may suggest that the star had already shed part of its outer hydrogen envelope before it dimmed out, which could help explain the absence of any detectable light flare.
Past Observations and the Role of JWST
Failed supernovas have been a topic of interest for astronomers seeking to understand the life cycle of massive stars. Christopher Kochanek, an astrophysicist at Ohio State University, previously reported another suspected failed supernova in 2016. Follow-up observations using the James Webb Space Telescope (JWST) detected infrared light around the area where the star vanished, which could indicate residual matter falling into a newly formed black hole.
This recent candidate in Andromeda has shown similar infrared signals despite the absence of visible light, hinting at the possibility of another failed supernova. However, the sparse data makes it challenging to differentiate between a failed supernova and other events, such as a merger between two stars.
“Additional observations with JWST could provide the necessary insights to confirm or rule out this failed supernova,” says Griffin Hosseinzadeh, an astrophysicist from the University of California, San Diego.
The Importance of Studying Stellar Death
Understanding how stars end their lives is critical to determining how galaxies populate with black holes and neutron stars — dense remnants formed by the explosive death of stars. While most supernovas distribute elements like carbon and oxygen into space, helping seed future stars and planets, failed supernovas might end up trapping these elements, transforming into black holes without leaving behind the typical elemental legacy.
Failed supernovas could provide a unique way to observe black hole formation directly. As Kochanek notes, “For the moment, it’s the only feasible way of actually seeing a black hole being formed.” The concept of a black hole “birth” is largely theoretical, and witnessing it in real-time would add a crucial piece to the puzzle of stellar evolution.
The Chicken-and-Egg Question of Galaxies and Black Holes
Failed supernovas are also valuable for exploring one of the most debated questions in astrophysics: Did black holes form first and attract gas and stars to create galaxies, or did galaxies form first, leading to the development of black holes at their centers? This question goes to the core of our understanding of the universe’s structure, where massive galaxies often harbor supermassive black holes.
The study of smaller stellar-mass black holes, like those that might result from failed supernovas, could offer insights into the early stages of this cosmic development. Observing failed supernovas in action, especially in nearby galaxies like Andromeda, might reveal whether black holes can form without typical supernova explosions.
A Future in Stellar Predictions
Scientists aim to predict the fate of stars based on their initial mass, temperature, and elemental composition. As astrophysicist Stanford Woosley of the University of California, Santa Cruz, explains, “What we’d like to know is, as a function of the mass of the star when it’s born, is it going to be a supernova and make a neutron star, or is it going to be a failure and make a black hole?”
Woosley’s question gets to the heart of the matter: the conditions that determine a star’s final fate. Stars born with sufficient mass and a favorable composition may end as neutron stars, while others lacking these attributes could quietly transition into black holes. Understanding these dynamics has implications for black hole populations, as well as for galactic chemical enrichment and elemental distribution.
Could We See More Failed Supernovas?
The more data collected, the closer scientists get to identifying true failed supernovas. While the Andromeda candidate remains unconfirmed, upcoming observations from JWST and other telescopes could eventually provide conclusive evidence. By studying stars with similar characteristics, astronomers may discover patterns that distinguish failed supernovas from other stellar events.
The Andromeda star, with its sudden disappearance and remaining infrared glow, could represent the latest step toward that discovery. “There’s more to be explored,” says Hosseinzadeh. “Failed supernovas are rare, but with our advanced tools, we’re finally able to catch them.”
As researchers continue observing these cosmic events, they gain valuable insights into black hole formation and the evolution of galaxies. Each star that winks out of existence offers a clue to understanding the full picture of stellar life cycles and the cosmic forces shaping our universe.
A Star’s Quiet Exit Marks a New Chapter in Astrophysics
The potential failed supernova in Andromeda underscores the mysteries that still linger around star death. For astronomers, a star that quietly disappears could offer as much knowledge as a star that explodes, revealing alternative pathways to black hole formation and galaxy evolution. With cutting-edge instruments like JWST on hand, astrophysics is poised to delve deeper into these quiet cosmic events. The Andromeda event may be just one instance, but it holds the promise of unraveling the processes that govern the life, death, and rebirth of stars across the universe.
