Betelgeuse looks a lot stranger than we thought, and physics shouldn't allow it

If you're a long-time Astram viewer, you'll already know that Beetle Juu is no ordinary star. Beetlejuice is a super red giant in the Orion constellation that is just 650 light years from the solar system, making it the second largest star and the tenth brightest. in the sky without counting the Sun a few years ago Beetlejuice made the news when the bright supergiant seemed to be receiving indications that it could be about to explode in a supernova but that was not the only surprise that Beetlejuice had in store for astronomers' measurements. of the Elmer telescope array have detected that Beetlejuice is spinning at an astonishing rate, approximately once every 20 years.

Well, that may sound a little disappointing, but for a star the size of Beetle Juu this means that the surface is spinning at a speed of 18,000 kmph or about 5 km/second, which is 10 times faster than our own speed at the Earth's surface and, for a massive supergiant star, almost breaks the laws of

physics

. I'm Alex Molan and you're watching astram join. me today as we delve into the unusual surface of beesel juice and the secrets behind its seemingly impossible rotation speed, let's start with the basics, there are a couple of different ways to measure the rotation of objects in the night sky if the object is lo large enough like the sun, moon, or even a planet in our solar system, it's easy enough to point a telescope at it and watch its features move in real time for reference.

The Moon's angular diameter is about half a degree and you can probably make out its features. with your own eyes Jupiter's angular diameter is hundredths of a degree, but its features are still clearly visible through a telescope. So what about Beetle Juice, the supergiant star just 650 light years away for all its size? Beetlejuice is still far enough from Earth. that its angular diameter is 1,000 times smaller than that of Jupiter, making it appear totally blurry even to our most powerful telescopes. Fortunately, there is another way to tell if a star like Beetle Juu is spinning. It's less direct than just taking a good look at it, but it's a clever way.

Technique that is based on a simple effect that you may have already heard of. Doppler shift. The same effect is also responsible for the change in the pitch of a siren when an ambulance passes by. When the ambulance approaches you, the siren sounds at a higher pitch due to sound waves. It hits you with a higher frequency than if the ambulance was stopped, but as soon as the ambulance starts to move away from you, the effect inverts the sound waves hitting you with a lower frequency and the siren sounds at a lower pitch, which What you probably won't notice is that the Doppler shift affects the light waves bouncing off the ambulance just as it affects the sound waves coming from its siren.

The higher frequency light as the ambulance approaches makes it appear slightly bluer and as soon as it starts to move away from you the effect changes and it

looks

slightly redder, the only reason this visual effect is not obvious It's because the speed of light is a million times faster than the speed of sound, so it would take a much faster ambulance for us to really notice the optical Doppler shift we experience. There may not be ambulances here on Earth flying at 5 km/second, but those kinds of speeds are fair game in space, which brings us back to Beetle juu, when a star spins, half of its surface shrinks. will move towards us and at the same time as the other half moves away, this creates a gradient of colors emitted by the star that we can observe with our telescopes even if the star is too blurry for us to make out any of its distinguishing features by looking at which side. is bluer and which one. side is redder we can infer the direction of rotation and by measuring how different the bluer frequencies are from the redder ones we can calculate the rotation speed of the stars.

This was the technique used by astronomers to analyze the data collected by Alma and conclude that the beetle juice surface was spinning at 5 km/s - that's all well and good, except that the known

physics

of the spin of stars predicts that 5 km /s is too big a speed for a red supergiant like Beetle Juice. Let's take our sun as an example of its rotation. The speed is similar at about 2 k/s, but it is also 1,000 times smaller and about 10 times lighter than Beetle Juu if our Sun were to expand to the size of Beetle Juu, which would envelop the entire inner solar system and almost reach Jupiter's orbit in the In this process, its speed would decrease to only 2 m/s to conserve angular momentum in the same way that a spinning ice skater decelerates when she extends her arms and if the sun became 10 times heavier. to even out the mass of beetle juice. its speed would drop to 0.2 m/s, so the bigger and heavier a star is, the slower we expect it to spin, and yet Beetle Juice seems to defy all those expectations.

What's happening here, one possible explanation is that although Beetle Juice didn't do it. By starting with this angular momentum, it gained it through a process known as stellar cannibalism, unsurprisingly. Stellar cannibalism is exactly what we call it when one star eats another star, usually its companion in a binary orbit, in more scientific terms, the star's gravity. it moves the gas away from its companion layer by layer until only the inner core remains; That gas carries most of the companion star's angular momentum, so the first star ends up not only growing but also spinning faster than nature would normally

allow

, but is this really the story of How Beetle Got to Spin Juice or is there something even more mysterious going on beneath the surface?

A team of researchers collaborating in Europe and China have recently suggested that Be Ju's seemingly ridiculous rotation speed could simply be a giant optical illusion to see how it's possible, we think. Back to what the Alma team actually measured with their state-of-the-art telescope array, although their images of the juu beetle were blurry, they were still able to make out that half of the star emits slightly redder frequencies of light than normal. while the other half emits slightly bluer frequencies, the obvious explanation for this 50/50 split is that the star is rotating with one half moving towards us and the other half moving away from us at the same time, the green arrow in the image Beetle Juu. is meant to represent the axis of this rotation, but what if that wasn't the only explanation for the color gradient detected by Alma?

Simulations of Beetle Juice have revealed that its surface is a chaotic, turbulent place that constantly bubbles under its own heat like water bubbling in an oven. Each of these bubbles is enormous and spreads outward at deadly speeds. A single bubble can be 100 million kilometers in diameter and cover a large fraction of Beetle Juice's surface. If one of these bubbles were headed your way, not even today's most powerful spaceship could save it. From its lightning speed of up to 30 km/second, your only hope would be for the bubble to burst and violently crash to the surface before it reaches you as the gas bubbles all over Beetle Juice rise and fall, its surface becoming a mosaic of regions that move towards or away from us as observers on Earth, in turn, the Doppler shift causes the light emitted from these regions to shift blue or red in a recent paper that Rose questions all the previous explanations about beetle juices. rotation, the international team of researchers proposed that Beetle Juice might not be spinning rapidly at all;

Instead, Elma's observations could be detecting a range of light frequencies coming from Beetle Juice due to turbulence on its surface, so astronomers may have been misinterpreting those changes in frequency as a rotation effect, but it has provided Paying close attention to the physics, you may have noticed that there is still a loose end with this alternative explanation: a rotating star should produce a smooth gradient of light frequencies ranging from bluer-than-expected light to one edge. to get higher-than-expected light on the other, meanwhile, a turbulent star should produce a random mosaic of colors with bluer spots where the bubbles rise and redder spots where the bubbles fall back down, how could astronomers of Alma having confused one with the other, if astronomers observed a smooth gradient of colors coming from Beetle juu,

shouldn

't the mosaic explanation in an ideal world already be ruled out?

That would be true, the gradients would correspond to rotation and the patches would correspond to Bubbles, but remember that Beetle Juice is so far away that the image captured by Alma is far from ideal and is blurrier than a high definition photograph when running simulations of Beetle Juice's surface to account for the limited resolution of the observations, they predict that the redshift and blueshift bubbling spots will be easily mistaken for a rotational gradient about 90% of the time, this means that Even if the Elma astronomers did nothing wrong in their analysis, Beel Juice's boiling surface may have fooled them into thinking it's spinning much faster than it is.

In reality, this also means that astronomers are now pursuing a key goal: higher-resolution studies of Beetle Juice that could more accurately differentiate the two scenarios. The good news is that there are already better images of Beetle Juu taken with the same telescope but with a longer exposure. Sometimes the bad news for those of us who are more impatient is that it will probably take a couple of years to properly analyze those answers are coming although for now I'm curious where you would place your bets is Beetlejuice It really spins at 5 km/second after being eaten to its companion star or the new claim that this rotation speed is nothing more than an optical illusion will be justified.

Let me know what you think in the comments below on Astram, one of my favorite parts of the job. is being able to research and learn everything about the different topics that eventually become videos. The universe is so full of interesting facts. I love learning about some new idea or discovery and yet, outside of my work in astronomy, I haven't had as much time to spend learning as I would like, which is why I was so impressed with Imprint, the sponsor of today's video, Imprint is an app that creates short lessons with which you can easily develop a daily learning habit.

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