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Apparently Betelgeuse is about to go Supernova

Unable to read that because it wants to disable ad blocking. Are they saying Betelgeuse nova'ed six hundred plus years ago so we'll see it soon, or are they saying it's about to nova now and it'll be visible here in six hundred plus years?

I'm sure it'll be pretty but possibly not worth waiting around for.
 
TragicMonkey said:
Unable to read that because it wants to disable ad blocking. Are they saying Betelgeuse nova'ed six hundred plus years ago so we'll see it soon, or are they saying it's about to nova now and it'll be visible here in six hundred plus years?

I'm sure it'll be pretty but possibly not worth waiting around for.
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Fair call quite interesting though
 
Actually, it probably isn't. According to some recent models, it as a whole may be younger than we previously thought, being actually the merger of two smaller stars. So it may have a few million more years left.
 
I guess if some neutrino detectors detect heaps of neutrinos then heaps of telescopes will turn their attention to this star no matter what the cause of the neutrinos is.
 
TragicMonkey said:
Unable to read that because it wants to disable ad blocking. Are they saying Betelgeuse nova'ed six hundred plus years ago so we'll see it soon, or are they saying it's about to nova now and it'll be visible here in six hundred plus years?

I'm sure it'll be pretty but possibly not worth waiting around for.
Click to expand...

IF Betelgeuse actually were "about to go supernova", it would really mean it happened already and we're about to observe it.
 
One thing about red giants is that although their radius and volume is much bigger, the actual mass is not so much.

So, Wikipedia gives the mass of Betelgeuse as 11.6+5.0/−3.9 M☉ but its radius is 900 times bigger than our sun and its volume is 700 million times larger, so it's much less dense on average. I wonder if the mass is relatively uniformly distributed or if it's much denser at the center than near its surface?
 
Puppycow said:
One thing about red giants is that although their radius and volume is much bigger, the actual mass is not so much.

So, Wikipedia gives the mass of Betelgeuse as 11.6+5.0/−3.9 M☉ but its radius is 900 times bigger than our sun and its volume is 700 million times larger, so it's much less dense on average. I wonder if the mass is relatively uniformly distributed or if it's much denser at the center than near its surface?
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On the surface there is nothing compressing the material. However deeper down there is all the mass above that to compress the material. It is also far more likely to be made of the heavier elements. Hence the density difference increases the older and the heavier the star is.
 
If mass were evenly distributed, you wouldn't get fusion in the core. You actually need the pressure and temperature there for fusion.
 
That said, on the topic of more mass but less density, it helps to remember that all the photons coming from the centre exert radiation pressure on the plasma above. Photons don't have mass, but have momentum anyway, so when a photon coming from below is absorbed by a charged particle above, conservation of momentum still applies, so that particle is shoved upwards. When it's re-emitted, it's in a random direction, which means half the time it's backwards, so the particle is nudged even more upwards. (And the layers below that absorb it get pushed a bit downwards.)

So basically the star is so big because it produces a lot of energy, i.e., a lot of photons, which keep pushing its outer layers outwards. While gravity is doing its best to keep them back. Basically it's like when you throw a ball upwards. If you throw it with more energy, it goes higher. Except here the ball is a particle in the plasma that makes up the star.

When fusion stops, there's nothing more pushing upwards, and the star starts to collapse fast. If the resulting extra pressure and heat (as potential energy gets converted into kinetic energy) are enough to start fusing the next set of elements, the star restarts basically. If it already went as high as it can go (either not big enough, or it already fused up to iron and nickel), then not. And if it's big enough, its outer layers can go kablooie.
 
When you consider the huge volume - out past the orbit of Mars in our solar system, and the relatively low mass - only about twelve times the mass of our Sun, then the outer parts of Betelgeuse are an extremely good vacuum.
 
The article in the OP doesn't seem to be suggesting an immanent supernova. From the link in the OP:
There's no scientific reason to believe that Betelgeuse is in any more danger of going supernova today than at any random day over the next ~100,000 years or so, but many of us — including a great many professional and amateur astronomers — are hoping to witness the first naked-eye supernova in our galaxy since 1604.
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lomiller said:
The article in the OP doesn't seem to be suggesting an immanent supernova. From the link in the OP:
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Please remember in astronomy 100,000 years is soon. If it will explode in the next 100,000 years then the probability of it exploding in the next 20 years is one in 5,000. People have bought tatts tickets with worse odds than that.
 
ceptimus said:
When you consider the huge volume - out past the orbit of Mars in our solar system, and the relatively low mass - only about twelve times the mass of our Sun, then the outer parts of Betelgeuse are an extremely good vacuum.
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On average Betelgeuse is five decimal orders of magnitude less dense than Earth's atmosphere. But pretty much the out parts of any atmosphere are going to be near vacuum.

HansMustermann said:
In terms of density? Absolutely. In terms of pressure? Eh, maybe not so much.
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What distinction are you making here? Density and pressure would be related.
 
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