Bold claim: A star 1,540 times the size of our Sun is transforming right before our eyes, and this change could foreshadow a spectacular end—perhaps a supernova that births a black hole.
Astronomers have observed one of the universe’s most colossal stars undergo a dramatic transformation into a rare type of stellar object. The event, centered on WOH G64 (also known as IRAS 04553–6825) in the Large Magellanic Cloud, sits about 163,000 light-years away. This behemoth is roughly 1,540 solar radii, over 28 solar masses, and shines with about 282,000 times the Sun’s brightness. Since its discovery in the 1970s, it has appeared as a red supergiant wrapped in a dusty torus.
In 2014, however, the star’s appearance shifted. A team led by Gonzalo Muñoz-Sanchez of the National Observatory of Athens noted a change in color paired with a rise in surface temperature. Their analysis suggested a red supergiant transitioning into a rare yellow hypergiant—a possible real-time glimpse of a star “dying.”
“Stars with initial masses between about 23 and 30 solar masses that evolve into red supergiants remain uncertain in their fate,” Muñoz-Sanchez explained to Space.com. “It’s unclear whether such stars end in a supernova, collapse into a black hole, or pass through a yellow hypergiant phase first. WOH G64 could hold the answer.”
What makes this finding especially striking is that the temperature shift occurred over roughly a year, occurring without the violent upheavals we often associate with rapid stellar change.
Beyond the star’s transformation, the researchers uncovered that WOH G64 is not alone: it resides in a binary system, which could influence its evolution in important ways. Binary interactions might strip away outer material, drive up temperatures, or alter the star’s life path altogether. In a scenario where mass transfer occurs, the envelope of the red supergiant could be partially shed, exposing the companion and nudging the system toward a yellow hypergiant phase. Alternatively, the transition might stem from intrinsic, eruptive processes within the star itself, with a prolonged eruption followed by a quiescent return to yellow temperatures.
Both possibilities are exceptionally rare, and witnessing either unfold on human timescales is nearly unprecedented. Ongoing observations are crucial to determine whether binary dynamics or internal stellar mechanisms dominate in WOH G64’s evolution.
Recent data also hint that other extreme red supergiants could harbor binary companions, complicating the broader question of how these massive stars die, the role binaries play in shaping their fates, and how their deaths manifest as supernovae or other endpoints.
If interactions in the binary system are significant, the stars could even merge. If not, the primary star may approach core collapse, potentially ending as a supernova or directly forming a black hole. In scientific terms, WOH G64 appears to be highly evolved, and a core-collapse event could occur within a timescale ranging from hundreds to a few thousand years—though it remains extraordinarily unlikely to happen within our lifetimes.
A Nature article published February 23 reports these findings. The research adds a fresh piece to the puzzle of how the most massive stars live and die, and what we can expect when they do finally end their lives.
Robert Leais is a science journalist based in the U.K. His work has appeared in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek, ZME Science, and more. He writes about science communication for Elsevier and the European Journal of Physics. You can follow him on Twitter @sciencef1rst.
Would you agree that binary interactions could be the dominant factor in accelerating a red supergiant’s transition to a yellow hypergiant, or do intrinsic stellar processes seem more plausible to you? Share your thoughts in the comments.
