Scientists take first detailed image of a star outside our galaxy

Scientists from the European Southern Observatory (ESO) have managed to take a detailed image of a star in a galaxy other than our Milky Way, a first that will allow them to better study this star at the end of its life. 160,000 light years away, the star WOH G64 is located in the Large Magellanic Cloud, a small satellite galaxy of ours.

Nicknamed by astronomers the “Colossal Star”, it is approximately 2,000 times larger than our Sun and is classified among the red supergiants, one of the last stages in the evolution of massive stars before their explosion as a supernova. Closer to us in the Milky Way, the star Betelgeuse in the constellation Orion also belongs to the category of red supergiants and, as such, is closely watched by astrophysicists.

“We discovered an egg-shaped cocoon that closely surrounds the star”details in an ESO press release, published on Thursday, November 21, Keiichi Ohnaka, astrophysicist at the Andrés Bello University of Chile. “The ovoid shape in the center represents the material ejected by the central star and still surrounding it. We can also see another oval ring surrounding this ovoid shape. “Although additional observations are needed to definitively confirm this, we believe that this ring is also formed by material ejected from the star.”he explained to Agence France-Presse.

The scientists had “clues” that the star’s surroundings were not spherical, but no images had been taken until now. “With this image we will be able to create a better computer model of the star and study how it expels material before disappearing”explains the researcher, who led a study on these observations, published Thursday in the journal Astronomy and Astrophysics.

This elongated cocoon, a sign that the star “It ejects more material in some directions than in others”It could be a consequence of its interaction with another star, according to Ohnaka. “Although we have not yet found a second star, such a companion could exist and would still be difficult to detect if it is much fainter than the main star.”says.

“The life of a star in real time”

Mr. Ohnaka’s team has long been interested in this giant star. In 2005 and 2007, these astronomers used the interferometer on ESO’s Very Large Telescope (VLTI) in Chile to learn more about its characteristics. But at that time, the interferometer only combined light from two of the VLT’s astronomical telescopes. To obtain the image published on Thursday, astronomers had to wait for the development of the Gravity instrument, which captures light from four telescopes, creating very detailed cosmic images.

Comparing these new results with previous observations, they found that WOH G64 had become dimmer over the past decade. She has “It has undergone significant changes in the last ten years, giving us a unique opportunity to observe the life of a star in real time.”says Gerd Weigelt, co-author of the study cited in the press release and professor of astronomy at the Max Planck Institute in Bonn, Germany.

In their final stages of life, before exploding as a supernova, red supergiants lose their outer layers of gas and dust, in a process that can last hundreds of thousands of years. Scientists who observed WOH G64 believe that ejected material could be responsible for its dimming and that this could mean that the star has entered a new phase of its life cycle.

“Or it could return to its previous state after a while, although we don’t know how long that could take.” Precisely for this reason we believe that it is important to follow this star by observing it with different telescopes and instruments.”Ohnaka emphasizes.

As the star dims, it becomes increasingly difficult to take more close-up images, even with VLTI. But planned upgrades to the telescope’s instruments could soon change this.