By BlueShift and AFP | 2024-11-22

Scientists have taken the first ever close-up image of a star outside of the Milky Way, capturing a blurry shot of a dying behemoth 2,000 times bigger than the Sun.

Roughly 160,000 light-years from Earth, the red supergiant WOH G64 sits in the Large Magellanic Cloud, a satellite galaxy that orbits the Milky Way.

The image was captured by a team of researchers using a new instrument of the ESO's Very Large Telescope Interferometer (VLTI) in Chile.

"For the first time, we have succeeded in taking a zoomed-in image of a dying star," Keiichi Ohnaka, an astrophysicist at Chile's Andres Bello National University, said in a statement November 21.

The image shows the bright if blurry yellow star enclosed inside an oval outline.

"We discovered an egg-shaped cocoon closely surrounding the star," Ohnaka said.

"We are excited because this may be related to the drastic ejection of material from the dying star before a supernova explosion," added the lead author of a study published in the journal Astronomy & Astrophysics last month.

'Witness a star's life in real time'

Astronomers have known about WOH G64 for decades, and Ohnaka's team has been watching the star for some time.

In 2005 and 2007 they used the VLTI, which combined the light from two telescopes, to learn more about the star.

But capturing an image remained out of reach until GRAVITY, one of the VLTI's second-generation instruments, recently came online.

GRAVITY combines the light of four VLT telescopes, each assisted by adaptive optics.

It provides imaging with four-milliarcsecond resolution, and can measure the positions and movements of stars and other celestial objects with a precision of a few ten microarcseconds, according to the ESO.

When Ohnaka's team compared all their observations, the astronomers were surprised to find that WOH G64 had dimmed over the last decade.

"The star has been experiencing a significant change in the last 10 years, providing us with a rare opportunity to witness a star's life in real time," said study co-author Gerd Weigelt of Germany's Max Planck Institute for Radio Astronomy.

'An explosive end'

Study co-author Jacco van Loon of Keele University in the United Kingdom has been studying WOH G64 since the 1990s.

"This star is one of the most extreme of its kind, and any drastic change may bring it closer to an explosive end," he said.

In their final life stages, red supergiants shed their outer layers of gas and dust in a process that can last thousands of years.

It could be this expelled material that is making the star appear dimmer, the scientists said.

This could also explain the strange shape of the dust cocoon that surrounds the star.

Another explanation for the egg-shaped cocoon could be that there is another star hidden somewhere inside that has not yet been discovered.

As the star becomes fainter, taking other close-up pictures will become increasingly difficult, the ESO statement said.

Soon GRAVITY+ -- which combines improvements of the GRAVITY instrument with infrastructure upgrades for the VLTI -- promises to change this.

"Similar follow-up observations with ESO instruments will be important for understanding what is going on in the star," Ohnaka said.