A dying star produces an unexploded black hole

Thanks to infrared data, a new Science study confirms the discovery of a dying star that fell directly into a black hole without exploding.

Using infrared data, a new study published in the journal Science reveals the discovery of a star that collapses directly into a black hole when it dies, without exploding.The discovery shows that these processes, so difficult to detect, can happen much more often than the expert.

A scientific team has documented a massive star in the dying Andromeda galaxy that fell straight into a black hole instead of a normal supernova explosion.

These events are difficult to detect because the stars collapse rather than explode along the way.The finding suggests that the formation of black holes through direct collapse may be more common than previously thought, but is usually overlooked.

Therefore, the authors note that this is further evidence that there may be more black holes in the Universe than previously thought.The study was conducted by the Flatiron Institute of the Simons Foundation (USA), details were published in the journal Science.

At the end of their lives, giant stars become unstable and increase in size, causing noticeable changes in their brightness over time that humans can observe.In many cases, these stars die in brilliant supernovae that are very bright and easy to see.

However, not all stars die.It has been thought that some massive stars do not explode.Instead, when the star's core explodes, its outer material falls in and forms a black hole.

The problem is that these "failed supernovae" are difficult to detect because they emit very weak energy signals.Therefore, the only way until now to know that they had occurred was simply because the stars disappeared from view.

In a typical galaxy containing tens of billions of stars, it is very difficult to detect the disappearance of a single star.

In this new paper, the American Foundation team used long-term archived observations from NASA's NEOWISE spacecraft, an infrared space telescope that searches for asteroids and comets.Using this data, they discovered an unusual star object in the Andromeda galaxy that shone briefly, but then steadily faded.

"In a typical galaxy with between tens and hundreds of billions of stars, it is very difficult to see the loss of a star," Kishalay De, a researcher at the Flatiron Institute and first author of the paper, told SINC.

As De explains, the infrared glow associated with the outer envelope ejected by the star during this process is "very faint and requires long-term wide-field infrared monitoring, which is only possible with data from the NEOWISE mission."

The star they discovered, called M31-2014-DS1, grew in infrared light for about two years starting in 2014, but then faded and became invisible in optical light in 2022. Its body is now detected in the mid-infrared, making it ten times brighter than before.

Thus, they discovered that the star did not explode as a supernova at the end of its life, but instead its core collapsed directly into the black hole, slowly shedding the outer layers.

"This suggests that the formation of black holes by direct collapse may be common, but largely overlooked. With our study, we show that infrared observations provide an effective way to identify these processes," say the researchers.

Furthermore, De points out that the mass of the progenitor star, roughly 13 times the mass of the Sun, is below the long-conjectured threshold for black hole formation.

“Esto sugiere que los agujeros negros pueden formarse a partir de un rango de masas estelares mucho más amplio de lo que se pensaba, lo que aumenta significativamente las estimaciones sobre el número de agujeros negros que existen en el universo”, añade.

The results suggest that black holes can form from a much wider range of stellar masses than previously thought.

However, researchers have yet to fully explain why some stars explode as supernovas and others collapse directly into black holes.

"The results show that massive stars with relatively low masses can explode almost completely, challenging traditional assumptions," the researchers say."This probably means that it depends on the fine details of stellar structure and core physics, rather than relying solely on stellar mass, but this will need to be clarified in future studies," he added.

Kishalay De et al.Extinction of massive stars in the Andromeda galaxy due to the formation of a black hole.Science (2026).