WOH G64: A Rare Hypergiant Star Approaches Supernova

WOH G64, one of the largest known stars in the universe, has undergone a significant transformation that may indicate an impending supernova. Research led by Gonzalo Muñoz-Sanchez at the National Observatory of Athens, published in *Nature Astronomy*, reveals that WOH G64 has transitioned from a red supergiant to a rare yellow hypergiant. This change, first observed in 2014, suggests the star is shedding its outer layers and heating up as it nears the end of its life cycle.

This planet has changed color, shrank after losing layers, and could now explode: a star with more than 1,500 times the radius of the Sun has intrigued astronomers since 2014 and could become a supernZME Science

Discovered in the 1970s within the Large Magellanic Cloud, a dwarf galaxy orbiting the Milky Way, WOH G64 is notable for its immense size, measuring over 1,500 times the radius of the Sun. Despite being less than 5 million years old, WOH G64 is on a fast track to a dramatic demise, contrasting sharply with the Sun's lifespan of approximately 4.6 billion years.

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The transformation of WOH G64 has been documented in detail, particularly with images captured by the Very Large Telescope Interferometer in 2024, which revealed a dusty cocoon surrounding the star. This observation supports the hypothesis that WOH G64 is losing mass as it evolves. The study suggests that a significant portion of the star's surface was ejected in 2014, potentially due to interactions with a companion star, confirmed through spectral analysis.

This planet has changed color, shrank after losing layers, and could now explode: a star with more than 1,500 times the radius of the Sun has intrigued astronomers since 2014 and could become a supern

The transition from a red supergiant to a yellow hypergiant is theorized to occur when massive stars rapidly evolve from burning hydrogen to helium, leading to the loss of outer layers and core contraction. The current phase of WOH G64 may also be linked to a "superwind" phase, characterized by strong internal pulsations as the star's core fuel is depleted.

This planet has changed color, shrank after losing layers, and could now explode: a star with more than 1,500 times the radius of the Sun has intrigued astronomers since 2014 and could become a supern

The eventual explosion of WOH G64 as a supernova is anticipated, although predicting the exact timing remains challenging. The ongoing observation of this star provides a unique opportunity for astronomers to witness the final stages of a massive star's life cycle in real time. Such an event could enhance our understanding of stellar evolution and the mechanisms behind supernova explosions.

This planet has changed color, shrank after losing layers, and could now explode: a star with more than 1,500 times the radius of the Sun has intrigued astronomers since 2014 and could become a supern

While the findings regarding WOH G64's transformation are groundbreaking, some critics argue that the predictions surrounding its imminent explosion are speculative. The complexities of stellar evolution and the variability in individual star lifespans make precise forecasting difficult.

This planet has changed color, shrank after losing layers, and could now explode: a star with more than 1,500 times the radius of the Sun has intrigued astronomers since 2014 and could become a supern

• “If we are lucky, we will see the death of WOH G64 in our lifetimes – not only providing an incredible intergalactic spectacle but also helping scientists complete the puzzle of this fascinating star.” — Sara Webb, Lecturer, Centre for Astrophysics and Supercomputing, Swinburne University of Technology.

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The study of WOH G64 exemplifies the dynamic nature of stellar life cycles and the potential for significant astronomical events that can enhance our understanding of the universe.

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