The star also appears to be smaller and probably not yet to explode.

That is what researchers from the Australian National University, after taking another look at the star. “The actual size of Betelgeuse has always been a bit of a mystery,” says researcher László Molnár. For example, previous estimates stated that if you placed the star in the heart of our solar system, it would reach the orbit of Jupiter. But the star doesn’t seem to be that big. Observations and models by Molnár and colleagues suggest that it is about a third smaller. “With a radius that is 750 times larger than the radius of our sun.”

Distance
As soon as the size of the still large star was known, the researchers could continue calculating and also accurately determine its distance from the Earth. It again results in a surprise. “Our results show that Betelgeuse is about 530 light years away,” says Molnár. And that makes the star about 25 percent closer to the earth than expected!

You may now be shifting uncomfortably back and forth in your chair. Because isn’t Betelgeuse that dying star about to explode? Yes. But even at a distance of 530 light years, we have little to fear from this, the researchers emphasize.

Explosion
Moreover, according to the Australian study, it does not appear that Betelgeuse will give up in the short term. “Right now, the star is burning helium in its core,” says researcher Meridith Joyce. “Which means that it is far from exploding. The explosion could take around 100,000 years. ”

Speculations
To be honest, it is a bit disappointing. All the more so because at the end of last year there was still a lot of speculation that the star could explode at any moment: a real spectacle that you should be able to see clearly from Earth thanks to its close proximity to the star. Possibly even in broad daylight! The speculations were motivated by the star’s brightness suddenly began to wane a year ago. Was this the beginning of the end? “Betelgeuse is normally one of the brightest stars in the sky, but we’ve seen its brightness diminish twice since the end of 2019,” said Joyce. “That led to speculation that the star is about to explode.”

Pulseren
We now know that the first decrease in brightness was caused through huge dust clouds between the earth and Betelgeuse. The dust blocked the star’s light, making it less bright. However, that mystery had only just been solved when the star’s brightness declined again in the summer of 2020. Astronomers could not directly identify this decrease. Reason for Molnár and colleagues to dive in. They used models to map the star’s activity, hoping to find an explanation for the decrease in brightness. Successfully. “We found that the second – smaller – decrease in brightness is probably due to the star’s pulsing.” By mapping the activities in the star, the researchers were also able to determine that Betelgeuse does not seem to explode in the short term. And also make a more accurate estimate of the size of the star and its distance from the Earth.

Although it is expected that it will take some time before Betelgeuse explodes, researchers are continuing to keep a close eye on the red giant. “It’s really special when a star explodes,” says Joyce. “And this is the closest candidate. Betelgeuse offers us the unique opportunity to study what happens to a star before it explodes. ”