Astronomers have made a fascinating discovery. They’re watching a massive star named WOH G64, over 163,000 light-years away in the Large Magellanic Cloud. This star, about 1,540 times larger than our sun, is changing in a dramatic way. It might be heading toward a powerful supernova explosion and the birth of a black hole. WOH G64 has been known since the 1970s but is recently evolving from a red supergiant to a yellow hypergiant.
In 2014, a team from the National Observatory of Athens, led by Gonzalo Muñoz-Sanchez, observed WOH G64’s color shift and rising temperature. This indicates a significant transformation, suggesting they might be witnessing a star dying right before their eyes. “It’s unusual to see a star change like this so swiftly,” Muñoz-Sanchez said. Typically, rapid changes are tied to violent events, but this transformation was quiet and smooth.
What makes WOH G64 intriguing is its potential fate. Stars like it, with masses between 23 and 30 times that of our sun, can take different paths. Some explode into supernovas, while others collapse directly into black holes. WOH G64 might help answer this age-old question among astrophysicists.
Interestingly, WOH G64 is quite young at just 5 million years, compared to our sun’s 4.6 billion years. Despite its youth, massive stars burn through their fuel quickly, leading to a short life span. But not every red supergiant transforms into a yellow hypergiant; these stages of life are still not fully understood.
Experts estimate that there are only a few dozen confirmed yellow hypergiants, making this transformation exceptionally rare. For a star to shift from red to yellow, it requires a strong stellar wind to strip away its outer layers, but only the most massive stars can generate such outflows.
In a surprising twist, researchers found that WOH G64 isn’t alone; it’s part of a binary system with another star. This connection complicates its transformation. If the main star pulls material from its companion, it could speed up its evolution to the yellow phase. “Binary interactions could be crucial in creating yellow hypergiants,” Muñoz-Sanchez explained.
Some recent studies suggest that other extreme red supergiants might also exist in binary systems. Understanding if a star’s unique traits come from its nature or from interactions with a companion is vital. This knowledge helps astronomers predict the stars’ deaths and the supernovas they leave behind—an area that remains largely unexplored.
WOH G64’s ongoing mass exchange with its companion could lead to a spectacular collision, or it may evolve quietly into a supernova. According to Muñoz-Sanchez, we could see WOH G64 undergo core collapse in the coming hundreds to thousands of years. While experiencing such an event in our lifetime is unlikely, the astronomical community eagerly watches, hoping to understand more about stellar life cycles with insights from WOH G64.
This research was detailed in a paper released in *Nature* on February 23. With this star, scientists not only gain knowledge about its past but also about the universe’s future.
