Astronomers have recently achieved a monumental breakthrough by capturing the first close-up image of a star located beyond our own Milky Way galaxy. This momentous photograph features the massive star, WOH G64, during an extraordinary phase as it nears the end of its life. The image conveys a vivid depiction of the star expelling gas and dust, an essential precursor to its impending explosion as a supernova.
WOH G64 is positioned approximately 160,000 light-years away from Earth, residing within the Large Magellanic Cloud, a smaller galaxy that orbits the Milky Way. The image was taken using the Very Large Telescope Interferometer, which is situated in Chile’s Atacama Desert. This unprecedented visual representation, along with a decade’s worth of observational data on WOH G64, has afforded astronomers a unique perspective on the violent lifecycle of this star. A study was released detailing these observations in the journal Astronomy & Astrophysics.
Keiichi Ohnaka, an astrophysicist from Andrés Bello National University in Chile and lead author of the study, expressed excitement over the discovery. With this image, researchers noted an egg-shaped cocoon surrounding WOH G64, a feature that may hint at significant material being ejected by the star in its final stages. This finding is especially important in understanding the fate of massive stars nearing the end of their stellar life cycles.
Describing WOH G64 as a “behemoth star,” scientists highlight that it is a red supergiant approximately 2,000 times the size of our solar system’s sun. During their concluding phases, red supergiants shed their outer layers of gas and dust gradually over potentially thousands of years. WOH G64 was initially discovered in 1981, and subsequent observations indicated that it was among the most luminous and extreme examples of its category.
Study coauthor Jacco van Loon, from Keele University in the UK, emphasized the significance of tracking this star since the 1990s. His investigations began while he was a student at the European Southern Observatory. Van Loon had measured the rate at which WOH G64 was ejecting material and concluded it was unlikely to maintain such high levels of ejection indefinitely.
Throughout the years of observation, van Loon noted fluctuations in the star’s brightness, which suggested an ongoing transformation from a massive red supergiant to a hotter, smaller star. Ohnaka’s team employed the Very Large Telescope Interferometer to conduct studies in 2005 and 2007 but had to wait until advancements were made in telescope technology before they could successfully capture detailed images of WOH G64.
Comparing new observations from the telescope with earlier data revealed that the star’s luminosity has dimmed considerably. Gerd Weigelt, an astronomy professor from the Max Planck Institute for Radio Astronomy in Bonn, Germany, remarked on this significant change over the past decade, urging that this phenomenon provides a rare glimpse into the evolution of a star in real time.
The gas and dust released by WOH G64 has likely played a pivotal role in its recent dimming and the unusual shape of the cocoon that now surrounds it, according to the researchers. There is also speculation that a nearby, unseen companion star may influence the formation and dynamics of this dust cocoon.
WOH G64 stands as one of the largest and most luminous stars in the Large Magellanic Cloud. If it were to occupy the same space as our sun, its reach would extend far beyond the orbit of Jupiter. If WOH G64 ultimately goes supernova, its explosion would be visible to the naked eye from Earth. Edward Guinan, an astronomy professor at Villanova University, underscored the significance of the recent capture of this moment. He praised the impressive capabilities of the VLTI/Gravity instrument, which was used to reveal the complex gas and dust torus around the star.
It is worth noting that the light captured in the latest image took an astonishing 160,000 years to reach our planet. Upon its birth, WOH G64 was likely between 25 and 40 times the mass of the sun—massive stars like it ultimately collapse under gravitational pressure, leading to the creation of black holes. While scientists anticipate that it will explode as a supernova in the future, determining the precise timing of this event remains an insurmountable challenge.
Van Loon mentioned that while it is impossible to predict when a red supergiant will explode, history offers insights. The surprise supernova in 1987 within the same galaxy was previously thought to be a blue supergiant, which Hubble Space Telescope observations later clarified had once been a red supergiant. This comparison may suggest that WOH G64 is currently undergoing a similar metamorphosis, potentially taking thousands of years before it might finally explode.
It is essential to recognize that blue supergiant stars—notably some of
