For the first time, scientists have captured a zoomed-in photo of a star outside of our Milky Way galaxy. The image revealed surprising details about WOH G64, a giant star that is probably dying, researchers report November 21 in Astronomy & Astrophysics.
The star, which is about 1,500 times the size of our sun, sits 160,000 light-years away from Earth. It lives inside the Large Magellanic Cloud, a small galaxy that orbits the Milky Way.
Until now, WOH G64 seemed almost impossible to photograph clearly — it would have required a telescope bigger than 100 meters across. Instead, astronomers combined information from four 1.8-meter telescopes to piece together the image. And it’s giving them a rare view of what happens at the end of a star’s life.
“This star, WOH G64, gives us a very real opportunity to investigate what a star is doing, supposedly, just before a supernova explosion,” says Keiichi Ohnaka, an astronomer at the Universidad Andrés Bello in Santiago, Chile. “‘Just before’ in an astronomical sense. Not today or next week or next year.”
It could be 10,000 to 100,000 years before WOH G64 explodes into a supernova, if it does at all. But the clues that hint of the star’s demise are promising. The star was surrounded by a hazy egg-shaped cocoon, which Ohnaka theorizes could be made of the material that stars emit when they’re dying, like gas and dust particles.
But the main hint that the star is dying comes from just how faded it appeared in the image, especially compared with older records of the star’s brightness. Ohnaka thinks the star started ejecting more and more material over the past decade, causing it to dim. Dimming periods can be temporary for some stars, but others never bounce back (SN: 11/29/20).
“At first, we wanted to take another close-up,” says Ohnaka. But it didn’t quite work. The star was too faint. “So, we started monitoring it to see when it comes back…. But maybe, more interestingly, it might not come back. It may just get fainter and fainter.”
