A giant star in the neighboring Andromeda galaxy has simply faded from view, leaving behind the telltale signs of a newborn black hole instead of the violent fireworks of a supernova. The star was about 13 times more massive than the Sun and its light dimmed by a factor of roughly 10,000, a quiet ending that challenges what we thought we knew about how the heaviest stars die. Astronomers now see this silent collapse as some of the clearest evidence yet that massive stars can skip the explosion entirely and collapse straight into darkness.
By tracking the star’s slow brightening and sudden disappearance over several years, multiple observatories have stitched together a rare, almost cinematic view of a black hole forming in real time. The object, labeled M31-2014-DS1, sits about 2.5 m light-years away in Andromeda, close enough for telescopes to watch its final act in remarkable detail and to measure how much of its mass fell inward instead of being blasted into space.
The star that went missing in Andromeda
Astronomers first identified M31-2014-DS1 as a supergiant that started out about 13 times the mass of the Sun and shone so brightly that it was visible across the 2.5 m distance to Andromeda. For years it behaved like an ordinary massive star, radiating steadily in optical and infrared light and fitting neatly into models of how such giants evolve. That apparent normalcy makes its vanishing act all the more striking, because nothing in its early behavior hinted at such a quiet, catastrophic end.
The key twist came when long-term monitoring revealed that the star’s brightness did not end in a sudden flash but in a slow fade that accelerated into a plunge. Observations show that by the time astronomers realized what was happening, the light from this once-dominant beacon had dropped by a factor of 10,000, effectively erasing it from direct view. Detailed analysis of this fading pattern, combined with follow-up checks for any lingering stellar remnant, instead pointed to the formation of a compact object that matches the expected signature of a newly formed black hole in Andromeda.
Watching a black hole form in real time
What sets this case apart is how thoroughly astronomers were able to follow the transformation from living star to invisible remnant. A coordinated campaign of optical and infrared telescopes traced the light curve as M31-2014-DS1 brightened slightly, then dimmed, then almost vanished, providing what researchers describe as direct evidence that a massive star can collapse into a black hole without a traditional supernova. Follow-up work captured the surrounding region in high resolution and found no surviving star that could explain the missing light, strengthening the case that the core had imploded instead of exploding.
Those conclusions are backed by a detailed study that tracked the object’s changing brightness and the subtle glow from material around it, which pointed to a compact, extremely dense remnant at the same location as the vanished star. That analysis, reported as astronomers “caught in the act” of watching a vanishing star turn into a black hole, has been described in depth through careful follow-up imaging. Taken together, the data provide one of the strongest observational links yet between a specific massive star and the black hole it appears to have left behind.
NASA’s early clues and the Andromeda connection
The story of this disappearing star actually begins years before the final fade, when a NASA telescope picked up a subtle brightening in Andromeda. In 2014, an infrared survey recorded how the light from a massive star in that galaxy gradually grew stronger, a sign that something unusual was happening deep in its core. That early signal, which later discussions on NASA infrared data linked to M31-2014-DS1, gave astronomers a rare chance to keep the star under close watch as it approached its end.
Because Andromeda is our nearest large galactic neighbor, its stars are close enough for telescopes to resolve individual giants like M31-2014-DS1 and to track their changes over time. That proximity allowed teams to combine space-based infrared measurements with ground-based optical spectra, building a timeline that connects the 2014 brightening to the later collapse. The result is a uniquely detailed portrait of a star in Andromeda that did not explode but instead seems to have slipped quietly into a black hole.
Evidence for a “failed supernova”
The most striking aspect of M31-2014-DS1’s death is what astronomers did not see. When a massive star reaches the end of its life, we usually expect a brilliant supernova, a blast of light and energy that can briefly outshine an entire galaxy. In this case, the expected fireworks never arrived. Instead, the light curve flattened and then plunged, with no sign of the sharp, energetic spike that would mark a normal explosion. That missing flash is a central reason researchers interpret this event as a “failed supernova,” in which the star’s core collapses directly into a black hole and most of the outer layers fall in after it.
Detailed modeling suggests that about 98% of the star’s mass collapsed inward, creating a black hole of roughly 6.5 solar masses and leaving very little material to power an outward blast. That estimate comes from work that examined how much light and kinetic energy would be needed to eject the star’s outer layers, then compared it with what was actually observed in the aftermath. One analysis, which describes how 98% of the fell inward to create a 6.5 solar mass black hole, fits neatly with the faint, lingering glow that telescopes still detect from the region.
How telescopes pinned down M31-2014-DS1
Pinning this event on a specific star required precise, repeated observations of the same patch of sky. Astronomers used large ground-based facilities to track the supergiant labeled M31-2014-DS1, measuring its spectrum and brightness over several years to confirm that it was indeed about 13 times the mass of the Sun. As the star faded, those same instruments kept returning to the coordinates, looking for any sign that a surviving companion or a dust-obscured star might be hiding in the glare. Instead, the data showed a near-total disappearance consistent with a collapse into a compact object.
One key program, described through the object designated M31-2014-DS1, used high-resolution spectroscopy to confirm that the star was a supergiant in Andromeda and to track the sharp decline in its brightness. Those observations, combined with space-based imaging, ruled out the possibility that the star had simply dimmed behind a dust cloud or merged with a neighbor. Instead, the pattern of fading light and the lack of any surviving stellar source pointed strongly to a direct collapse scenario.
