In an unprecedented advance in the astronomya group of scientists managed to capture the first detailed image of a star outside the Milky Way. It is about WOH G64a red supergiant located 160,000 light years from Earth, in the Large Magellanic Clouda satellite galaxy.
This star stands out for its colossal size, approximately 2,000 times the radius of the Sunand its advanced evolutionary stage, which places it in the last moments of its life before becoming a supernova.
Despite its immense size, observations were challenging due to its remoteness and the complexity of studying stars in other galaxies. The findings were published in the magazine Astronomy & Astrophysics.
The achievement was possible thanks to Very Large Telescope Interferometer (VLTI) from the European Southern Observatory (ESO), located in the Atacama Desert, Chile. This system combines light collected by several individual telescopes and creates a “virtual telescope” with great resolution.
The key instrument in this process was GRAVITYa second-generation tool designed to study extremely faint and distant objects. In observations made in December 2020, it made it possible to reconstruct a high-resolution image of the star in the near-infrared spectrum.
This level of precision overcomes previous limitations, allowing it to detail structures that would otherwise remain hidden.
The observations revealed that WOH G64 is surrounded by a egg-shaped gas and dust envelopean unexpected feature compared to previous models that suggested a more uniform shape. According to the astrophysicist from the National University Andrés Bello of Chile, Keiichi Ohnakain a statement from ESO, this envelope could be related to the massive loss of material that occurs in the final stages of red supergiant stars.
The elongation could indicate the presence of bipolar flowsa phenomenon associated with gravitational collapse or interactions between binary stars. Alternatively, it is suggested that a undetected stellar companion could be altering the distribution of material in the environment. These findings highlight the complexity of the dynamic processes that occur in the last stages of these cosmic bodies.
Additionally, the data showed that the star became noticeably dimmer over the past decade. Researchers like Gerd Weigelt from the Max Planck Institute, co-author of the study, suggest that this could be due to the accumulation of dust in the surrounding envelope, which blocks some of the emitted light. This change offers a rare opportunity to observe in real time how massive stars go through their final stages before exploding as supernovae.
The phase of massive mass loss that WOH G64 experiences is crucial to understanding the evolution of massive stars. These red supergiants expel enormous amounts of material, which eventually enrich the interstellar medium and they play an essential role in the formation of new stars and planets.
The WOH G64 case is especially interesting due to its size and extreme features. Being some three times larger than Betelgeusewhich has an estimated radius in 764 times that of the Sun and is one of the brightest in the night sky, its evolution may provide unprecedented information about how the most massive stars end their life cycle.
The WOH G64 image represents just the beginning of what will be possible with future technologies. The next instrument GRAVITY+an upgrade to the current system, promises to improve the ability to capture even more detailed images of distant, faint stars. This will allow not only to continue the study of the large star, but also to explore similar systems in other neighboring galaxies.
These advances not only help unravel the mysteries of individual stars like WOH G64, but also open the door to a broader understanding of the stellar evolution and the cosmic processes that shape the universe.
