Astronomers have directly observed a massive star in the Andromeda Galaxy collapse into a black hole without exploding as a supernova. The star, known as M31-2014-DS1, vanished over several years, leaving behind glowing debris detectable in infrared light. This event provides detailed insights into stellar black hole formation.
In a rare cosmic event, scientists tracked the demise of M31-2014-DS1, a luminous star located 2.5 million light-years away in the Andromeda Galaxy. Using data from NASA's NEOWISE mission and other telescopes spanning 2005 to 2023, researchers noted the star brightening in infrared light starting in 2014. By 2016, its brightness plummeted sharply within less than a year. From 2022 to 2023, it had faded to just one-ten-thousandth of its previous brightness in visible and near-infrared wavelengths, becoming nearly invisible, while glowing at about one-tenth intensity in mid-infrared light.
The observations, detailed in a study published on February 12, 2026, in Science, indicate the star's core collapsed under gravity, forming a black hole without the expected supernova explosion. Instead, convection in the star's outer layers—driven by temperature differences—pushed material outward gradually. This process expelled most of the envelope, with only about 1% falling back to feed the black hole over decades, creating a lingering infrared glow from dust-shrouded debris.
Lead author Kishalay De, an associate research scientist at the Simons Foundation's Flatiron Institute, described the significance: "This is just the beginning of the story... it's going to continue to fade very slowly. And this may end up being a benchmark for understanding how stellar black holes form in the universe." He compared the disappearance to if Betelgeuse vanished suddenly, noting the star was once among Andromeda's most luminous.
Co-author Andrea Antoni explained the convection's role: "the accretion rate... is much slower than if the star imploded directly in. This convective material has angular momentum, so it circularizes around the black hole." The findings also align with a prior case, NGC 6946-BH1, suggesting failed supernovae quietly produce black holes more commonly than previously thought. De added, "We've known for almost 50 years now that black holes exist, yet we are barely scratching the surface of understanding which stars turn into black holes and how they do it."
This event refines models of massive stars' ends, where nuclear fusion fails, gravity dominates, and outcomes vary between explosions and quiet collapses.