Astronomers take first close-up photo of a star outside our galaxy

Image shows dying star in its final stages before becoming a supernova

The star WOH G64 was taken by the Gravity instrument on the European Southern Observatory telescope. Photo: ESO/K. Ohnaka et al

The first close-up photograph of a star outside the Milky Way has been taken by astronomers.

The WOH G64 star is 160,000 light years from Earth and the new image shows it in the last stages before becoming a supernova.

“For the first time, we have succeeded in taking a zoomed-in image of a dying star in a galaxy outside our own Milky Way,” said astrophysicist and lead author Keiichi Ohnaka.

The photograph shows a bright oval at the centre and a dusty cocoon shrouding the star. The fainter elliptical ring seen around it could be the inner rim of a dusty torus but the team behind the work published in Astronomy and Astrophysics on Thursday said more observations were needed to confirm that.

“We discovered an egg-shaped cocoon closely surrounding the star,” said Prof Ohnaka of Universidad Andres Bello in Chile. "We are excited because this may be related to the drastic ejection of material from the dying star before a supernova explosion."

The team believes the cocoon’s egg shape could be explained by either the star emitting gas or the influence of an as-yet undiscovered companion star.

The star is part of the Large Magellanic Cloud, one of the small galaxies that orbits the Milky Way.

It was photographed by the European Southern Observatory’s so-called very large telescope interferometer and the new observations reveal a star puffing out gas and dust.

Astronomers have taken more than 20 close-up images of stars inside the Milky Way but this was a step further in complexity and the team had to wait until the technology was available. In 2005 and again in 2007, the team had used telescopes in the Atacama Desert, Chile to learn about the star but a photograph was not possible until a new imaging system called Gravity was developed.

“This star is one of the most extreme of its kind and any drastic change may bring it closer to an explosive end,” said co-author Jacco van Loon, from the Keele University in the UK.

In the final life stages, "red supergiant" stars such as the one photographed shed outer layers of gas and dust in a process that can last thousands of years.

Astronomers have known about this star for decades and called it the "behemoth star". With a size about 2,000 times that of the Sun, WOH G64 is classified as a red supergiant.