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Beetlejuice: The star continues to behave mysteriously - here's what will happen if it explodes

At the end of 2019, the light of the star dimmed and went from the brightest in the Orion group to the third brightest. Since then it has returned and become even brighter than before

By Albert Zylstra, Professor of Astrophysics, University of Manchester

Betelgeuse dims over time, with an interstellar cloud seen in the last panel. NASA, ESA and E. Wheatley (STScI)
Betelgeuse dims over time, with an interstellar cloud seen in the last panel. NASA, ESA and E. Wheatley (STScI)

The bright red star Beetlejuice (Betelgeuse) located in the Orion constellation has exhibited unexpected behavior.

The star that was also known in ancient times (its name means Beit Aguz in Arabic, and it is also called Beit Aguza in Hebrew) at the end of 2019 and in 2020 it became paler than we have ever seen it - at least in records from more than a century ago. For a short time it became (roughly) paler than Bellatrix, the third brightest star in Orion. This event became known as "The great dimming".

But Beetlejuice has since become bright again. For several days this year, it was the brightest star in Orion—brighter than we've ever seen it. Both events led to speculation Is his death in the form of an imminent explosion. But is there any evidence to support this idea? And how would such an explosion affect us here on Earth?

Stars are, in general, remarkably stable. They shine with the same brightness year after year. But there are exceptions, and some stars - called variable stars - vary in brightness. The most famous is Mira, the "miracle star", which was discovered as a variable star by the German priest David Fabricius In 1596 - this is a pulsating star that expands and contracts regularly.

Algol is another well-known example: it is periodically eclipsed by its companion star. There are about 30 such variable stars visible to the naked eye, although attention is required to distinguish their variations clearly.

Beetlejuice, the seventh brightest star in the sky excluding the Sun, is the brightest of the variable stars. Sometimes Beetlejuice becomes almost as bright as Rigel (the fourth brightest blue star in the constellation), while at other times it is paler. The variation is caused by pulses, similar to Mira's though not as large or regular.

Sometimes, however, a star can be very bright for a short time. This can happen due to a supernova, which is formed when an entire star ends its life in a powerful explosion.

Supernovae can be bright enough to be seen during the day, although this has only happened a few times in the last 1,000 years. A nearby, bright supernova is the kind of event astronomers live for - but few of us will ever get to see. We live in hope.

Mysterious behavior

Although Beetlejuice is a mutable star, the Great Dim in 2021 was extreme. Within months it actually dimmed by about 60%. It eventually turned out to be caused by an interstellar cloud of stars like Beetlejuice constantly spewing gas and dust. A block of gas the size of the star itself, obscured half of the star. Actually, photographs of the star showed whose southern half is missing. Some stars, like Beetlejuice, seem to have weather.

However, we still don't know what caused the sudden brightening - now the star is 50% brighter than usual. But it is not certain that a supernova is indeed close. In stars of this type, a supernova explosion occurs in the core. Brightness changes, on the other hand, are a surface phenomenon.

It is possible that the extreme brightening is actually due to the same dust cloud that caused the dimming, which is now reflecting light from the star towards us and making it appear brighter.

But we can't be sure, and astronomers are getting excited. The mass of Beetlejuice is 15 to 20 times greater than the Sun, and stars with this mass are expected to end their lives in a powerful explosion known as a supernova. Beetlejuice's red color shows that it is Red supergiant, meaning he is already nearing the end of his life.

But that end may still be a million years away. Stars like Beetlejuice can live for more than 10 million years - a very short time for astronomers, but a very long time for anything else.

Even so, scientists continue to run models with some suggesting that a supernova could occur within a few thousand years, while others estimate the timing of this event at 1.5 million years in the future.

There are many mysteries surrounding Beetlejuice. We do not know its exact mass - and even its distance is disputed. It is claimed that the star recently merged with a smaller companion: this explains why it rotates faster than expected as it happens in large stars.

Part The ancient manuscripts The star is referred to as similar to the yellowish Saturn, and not to the reddish Mars. Did the star change color? This could indicate rapid evolution - meaning a supernova may occur sooner rather than later.

Explosion dynamics

If Beetlejuice does explode as a supernova, what will it look like? The star is about 500 light years away from us. After an explosion, we first detect a shower of massless particles called neutrinos, that they will not be harmful to us. After that, the star will brighten rapidly.

After a week or two it will shine about as brightly as the full moon. Beetlejuice's brightness will fade over the next few months, but it will remain visible during daylight hours for six to 12 months. At night it will be possible to see it with the naked eye for another year or two. But after that, we will never see it again – Orion will forever lose its red glow.

Are we in danger? Supernovae produce high-energy particles called cosmic rays, which can pass through Earth's protective magnetic field. But the amounts will be small compared to the other radiation we get for all but the closest supernovae.

A supernova explosion will also produce iron radioactive. In fact, this material is found on Earth's sea floor and on the Moon, apparently formed in a supernova explosion 2 to 3 million years ago. That supernova was maybe 300 light years away from us, closer than Beetlejuice, but far enough away to not harm life on Earth.

A very close supernova, up to 30 light years from Earth, may cause significant problems: Cosmic rays can cause ozone destruction and dangerous UV levels on Earth. It can reduce ozone by half over a period of hundreds to thousands of years: this level is considered capable of causing an extinction event. But such a close supernova would be very rare, and might only happen once every billion years.

After all, Beetlejuice may still be around for a while. And that's good, because it's a fascinating and mysterious planet. We still have a lot to learn about him.

For the article in THE CONVERSATION

More of the topic in Hayadan:

2 תגובות

  1. It doesn't look good this jet flying directly in our direction. In such a situation... the scientists' calculations from a few decades ago greatly underestimate the effect of the radiation (a silent storm of the neutron particles. They will also cause those who hide in the cave to get cancerous tumors/mutations for their offspring, including disabling satellite communication/eliminating every space colony or passenger in a spacecraft for mining raw materials)

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