Astronomers have taken an incredible picture of the surface of another star, revealing its appearance in stunning detail and showing a remarkable feature in the process.
The star that was snapped is an aging red giant called π1 Gruis. It is located 530 light-years from Earth, making this image all the more impressive. We’ve never seen another star as clear as this before.
The image was taken by an international team of astronomers using the Very Large Telescope (VLT), operated by the ESO. An instrument called PIONIER on the telescope made the image possible, letting them see the star in greater detail than ever before. A paper on the findings is published in Nature.
"We have already taken a few other images of stars, but never any as detailed as this one," Claudia Paladini from the European Southern Observatory (ESO), the study's lead author, told IFLScience.
Its diameter is 700 times larger than our Sun and it's several thousand times brighter, believed to be a snapshot of what will happen to our Sun in about 5 billion years.
This is the first time we’ve seen granulation patterns on another star in the form of huge convective cells – or bubbles – on the star’s surface. Each cell seen in the image is about 120 million kilometers (75 million miles) across, or a quarter the size of the star. That’s more than the distance from our Sun to Venus. The cells on our Sun measure a puny 1,500 kilometers (930 miles) across by comparison.
π1 Gruis is only 1.5 times the mass of our Sun despite being much larger in size. It has a much lower surface gravity as a result, giving rise to these large convective cells, or granules. It's one of a pair of stars, the other being π2 Gruis.
This isn’t the first time we’ve seen a star in such detail – Antares was imaged back in August 2017 just as impressively. But this is the first time we’ve really seen this sort of detail on such a variable star.
It’s thought that π1 Gruis ran out of hydrogen about 20,000 years ago, heating up to 100 million degrees as it ceased the early stages of nuclear fusion. This caused it to fuse helium into heavier atoms like carbon and oxygen, creating a hot core that expelled its outer layers and ballooning it into its huge size today. We’ve previously found material from this shell 0.9 light-years from the star.
And now we've seen what the star looks like in all its glory, a possible glimpse into the future when our Sun undergoes the same fate.
"A few billions of year ago it probably looked as our Solar System looks today. The stars had its planets around, perhaps life," said Paladini.
"It's a look into the future by imaging something that happened in the past."