Close-up of a star outside our galaxy

The Very Large Telescope of the European Southern Observatory (ESO) located in Chile made it possible to visualize the star WOH G64 located in a neighboring galaxy, 160,000 light years from our solar system.

The image was obtained thanks to the high precision of the telescope’s interferometer, an instrument whose operating mode allows very high resolutions to be obtained.

The photo reveals a star exhaling gas and dust, in the final stages of its existence before it explodes and becomes a bright supernova.

We directly observed an egg-shaped cocoon surrounding the starnotes in a press release the Japanese astrophysicist Keiichi Ohnaka, the main author of the work published in the journal Astronomy & Astrophysics (New window) (in English).

We are delighted with this observation since this cocoon would be linked to the energetic ejection of material from the star occurring just before it transforms into a supernova.

Close-up on WOH G64

To date, astronomers have captured more than two dozen close-up images of stars in our Milky Way, helping to better understand their properties. But detailed observation of a star located outside of it remained extremely difficult due to technical complexity.

The star WOH G64 is located in the Large Magellanic Cloud, the third closest galaxy to ours. With the Milky Way and Andromeda, this cloud is part of the Local Group which brings together 60 galaxies.

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Nicknamed the juggernaut starthis red supergiant type star is approximately 2000 times larger than the Sun. For example, placed in the center of our solar system, it would be so big that it would engulf Mercury, Venus, Earth, Mars and even Jupiter.

Researcher Keiichi Ohnaka and his colleagues have been interested in WOH G64 since 2005. They had succeeded in characterizing certain elements, but had never obtained an image of the star.

To obtain this image, the international research team used the GRAVITY instrument of the telescope’s interferometer. After pairing the recent data with past observations of the star, scientists found that WOH G64 had dimmed in the last decade.

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We found that the star has undergone a significant change over the past ten years, giving us a rare opportunity to observe the life of a star in real timesays German astronomer Gerd Weigelt, from the Max Planck Institute for Radio Astronomy in Bonn, co-author of the study.

Die in a blast

According to some estimates, WOH G64 could explode and become a supernova within the next 10,000 years.

During their final phase of life, red supergiants like WOH G64 shed their outer layers of gas and dust in a process that can last thousands of yearsexplains in the press release astronomer Jacco van Loon, of the Keele University Observatory in the United Kingdom.

This star is certainly one of the most extreme of its kind, and any drastic changes could bring it closer to an explosive end.

Also, the photo shows that the cocoon is stretched. The researchers expected to see a different shape based on previous observations and computer models.

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According to them, this ovoid shape of the cocoon could be explained by the erosion of the star or by the influence of an unknown companion star. Indeed, WOH G64 may form a binary system, but this possibility has not yet been confirmed, due to the opaque clouds of dust that surround it.

It is also possible that the composition (materials) of the layer could be behind the darkening and unexpected shape of the dust cocoon around the star.

As the star gradually becomes less luminous, it will be more and more difficult to take close-up photos of it, even with the most efficient current instruments.

The Very Large Telescope will, however, be equipped by 2026 with the GRAVITY+ instrument, which could make it possible to observe the star further in order to better understand its evolution.

In addition, by 2027, theTHAT will be equipped with another observation tool, the Giant European Telescope, currently under construction in Chile, which will also allow us to zoom in on specific regions with an unprecedented level of detail, giving us an unprecedented close-up view of the stars.