Snapped up and close, a dying star outside the Milky Way

Santiago, Chile

Astronomers have captured the first close-up shot of a star outside our galaxy. This star is in the end stages of its life and is gearing up to explode as a supernova. WOH G64 was discovered in the 1970s and has been under constant observation since then. It is among the largest stars on record and is also extremely luminous. It is one of the most massive red supergiants (RSGs) as well.

The star lives in the Large Magellanic Cloud (LMC), which is the Milky Way’s largest satellite galaxy. The images were captured by the European Southern Observatory's Very Large Telescope Interferometer. Getting such an up-close look at the star is a major accomplishment for the scientists who have been watching the star.

“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,” lead author Keiichi Ohnaka, an astrophysicist from Universidad Andrés Bello in Chile, said.

WOH G64 is a whopping 160,000 light-years away and 2,000 times larger than the Sun.

The images were published in the journal Astronomy and Astrophysics. The study, titled “Imaging the innermost circumstellar environment of the red supergiant WOH G64 in the Large Magellanic Cloud", gives a detailed account of the star.

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The star is dying

The images show a cocoon of dust around the star, which the authors say is evidence that it’s convulsed and shed some of its outer layers.

“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.”

The study authors call WOH G64 "the most extreme of its kind", one that is inching towards an explosion.

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

“Significant mass loss in the red supergiant (RSG) phase is of great importance for the evolution of massive stars before they end their life in a supernova (SN) explosion,” the researchers wrote in the paper.

"These massive stars forge heavy elements through nucleosynthesis then spread them out into their surroundings when they explode. These heavy elements make rocky planets possible," they add.

Such stars can also "trigger the birth of new stars", and so, the authors say, "Better images of stars approaching their explosive ends help astronomers understand them better."