Betelgeuse, Betelgeuse, Betelgeuse!

Dimming update?

Back at the end of December, I posted that the red supergiant Betelgeuse, in the constellation of Orion, was dimming visibly. It used to be one of the brightest stars in the sky, and now it’s not even in the top 20. Yes, it’s less than half as bright as it was just over a year ago.

Red supergiant stars such as Betelgeuse normally end their lives in supernovas, which would be seriously cool to see. We’d be quite safe here, at a good enough distance, but we’d be able to see the explosion as it happened during the day, and it’d be months before it dimmed.

There are other possible explanations for what we’re seeing. One theory that might be quite feasible is that a large and dense gas cloud has passed in front of the star. This sort of thing does happen, and would explain the phenomenon quite well.

Since the star’s dimming has been in the news, more and more people have been watching it. Most recent reports suggest that the rate at which it’s dimming has slowed. Maybe it’s going to return to a more normal brightness again. Whatever's going on, we’re still very much in the “who knows” area.

Shape?

Image: ESO/M. Montargès et al.

At about the same time as the talk of Betelgeuse dimming, ESO scientists working at the beautifully-named “Very Large Telescope” in Chile made some observations of the star. One of the instruments at the VLT can actually resolve near (or large) stars as a disk, rather than a point of light.

The latest pictures show something that I’m having trouble believing. The star has gone out of round. Not just a little – it looks like a jellybean. Whaaa...?

Check out the attached photo from the VLT.

Pronunciation?

Finally, how do you pronounce “Betelgeuse”? There’s a lot of discussion about this, and some people insist on “bet-el-zherrz”, which I find faintly amusing. My rule is that you pronounce it in any way you please, as long as the person you’re talking to understands what you’re on about.