WOH G64 is an enormous star located about 160,000 light-years away in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way. This remarkable object was recently captured in unprecedented detail by the Very Large Telescope Interferometer (VLTI) at the European Southern Observatory (ESO), revealing new insights into the star’s dramatic final stages before it explodes as a supernova. The newly gathered data has provided astronomers with a clearer image of WOH G64, a red supergiant roughly 2,000 times the size of our Sun.
Keiichi Ohnaka, an astrophysicist at Universidad Andrés Bello in Chile, led the team responsible for the breakthrough. According to Ohnaka, the team has successfully zoomed in on a dying star beyond our own galaxy for the first time. The star is surrounded by an intriguing egg-shaped cocoon of gas and dust, a structure that has fascinated scientists and may be linked to the star’s violent ejection of material. The observations were published in the scientific journal Astronomy & Astrophysics, highlighting this unique discovery.
Stars like WOH G64 are extremely rare and challenging to study. Astronomers have previously managed to capture detailed images of stars within the Milky Way, but observing stars in other galaxies has remained elusive due to their distance. WOH G64, known as a “behemoth star” due to its immense size, presents a rare opportunity to study the final life stages of a massive star. The ESO’s VLTI, situated in Chile’s Atacama Desert, had been previously used by Ohnaka’s team to gather data about this particular star in 2005 and 2007. Despite extensive studies over the years, a clear image of WOH G64 was still out of reach.
The breakthrough came with the development of GRAVITY, a second-generation instrument for the VLTI, which allowed the team to capture detailed images of the star. This tool, which uses a technique called interferometry to combine the light from multiple telescopes, provided a level of sharpness never achieved before. Comparing the new data to earlier observations revealed an unexpected change: WOH G64 had dimmed significantly over the past decade, indicating a crucial transformation in its final stages. Gerd Weigelt, a professor at the Max Planck Institute for Radio Astronomy, noted that this phenomenon provides a rare chance to observe a star’s evolution in real-time.
The shedding of gas and dust by red supergiants like WOH G64 is a well-documented phase of stellar death. These massive stars lose their outer layers over thousands of years, eventually exposing their cores, which will later collapse in a supernova explosion. However, the egg-shaped cocoon surrounding WOH G64 raised new questions. The shape and dimming of the star were unexpected based on previous models, suggesting that the dying star’s activity might be more complex than initially believed. The unusual shape of the cocoon might be due to the star’s shedding process or potentially the influence of an unseen companion star, which could be altering the surrounding material.
Jacco van Loon, director of Keele Observatory in the United Kingdom and a co-author of the study, emphasized that WOH G64 is one of the most extreme red supergiants known. Its unpredictability is part of what makes it so fascinating to astronomers, who are eager to observe any sudden changes that might precede its explosive end. These changes could offer valuable clues about the life cycles of massive stars and their eventual fate.
The ability to observe such a distant and enormous star in such detail is a testament to the advances in modern astronomy. Yet, as WOH G64 continues to fade, capturing new images grows increasingly difficult, even with the VLTI’s capabilities. Future improvements in observational technology, including the planned upgrades like GRAVITY+, hold promise for astronomers to continue tracking this star’s progression. Enhancements in the precision of ESO’s instruments could provide critical data to understand what happens as stars of this size approach their violent ends.
For now, WOH G64 remains a stellar puzzle, and further observations will be crucial in unraveling the mechanisms at play in its dying stages. The dramatic transformation observed by Ohnaka’s team underscores the complexity of stellar evolution and the many mysteries that remain as astronomers continue to peer into the depths of space. The discovery not only advances our understanding of stars beyond our galaxy but also serves as a poignant reminder of the dynamic and ever-changing nature of the cosmos.
Source: ESO