Wouldn’t it be nice to know when a giant star is about to die in a catastrophic supernova explosion? A team of astronomers did just that. If you see a red giant star surrounded by a thick envelope of material, watch out – the star will likely explode within a few years.
When a massive star approaches the end of its life, it goes through several violent phases. Deep in the star’s core, it turns from fusing hydrogen to fusing heavier elements, starting with helium and then moving on to carbon, oxygen, magnesium and silicon. At the end of the streak, the star eventually forms the iron in its core. As iron drains energy rather than releases it, this means the star’s end, and in less than twelve minutes, it turns inside out in a brilliant explosion called Supernova.
But despite all the buzz in the hearts of stars, from the outside it’s hard to say exactly what’s going on. Certainly, towards the end of their lives, these giant stars swell to extreme sizes. It also gets brighter – up to tens of thousands of times brighter than the sun. But because the surfaces of stars are so puffy, the outside temperatures actually drop, making it look as if they were red giants.
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The most famous example of such a star near the station is Betelgeuse. If it is placed inside Solar Systemthis star – which is only 11 times the mass of the sun – will extend into its orbit Jupiter. It will turn into a supernova any day now, but “any day” for an astronomer might be a million years away. Although we know that these types of stars will eventually explode in a supernova, there is no way to get a more accurate estimate than that. Or, at least, that was the case.
Now, a team of astronomers has developed a way to detect supernovae that are likely to explode within a few years. They reported their results in a paper Posted in arXiv . prepress database It was accepted for publication in the Journal of Monthly Notices of the Royal Astronomical Society.
They specifically studied a few dozen of a unique type of supernova known as Type II-P supernovae. Unlike other supernovae, these explosions remain bright long after the initial explosion.
In some examples, astronomers looked at old catalogs and found pictures of stars before they exploded, and they all appear to be giant red giants like Betelgeuse. This is a clear indication that these types of stars are supernova candidates, ready to explode at any moment.
The stars that produce these types of supernovae are believed to have dense envelopes of surrounding material before they explode. These shrouds are denser than measured around Betelgeuse. It is the heating of that material from the initial shock wave that causes the brightness to persist; Simply put, there are more things around you to keep glowing well after the first sign of an explosion.
This dense shroud also causes this type of supernova to be visible more quickly than its more exposed cousins. When the explosion initially occurs, the shock wave collides with the material surrounding the star, causing the shock wave to lose its force as it passes. While the energies of a supernova are initially sufficient to emit high-energy radiation, such as X-rays and gamma rays, after mixing the shock wave with surrounding matter, the emitted radiation is of optical wavelengths.
So it seems that these dense shrouds of material around stars It’s also a boon that a supernova is about to happen.
But how long does it take to form this shroud? The researchers studied two models. In one model, the star unleashed high-speed winds from its surface, slowly separating parts of it and spreading it around to make the shroud over decades. In the second model, the star experienced a violent explosion before the supernova that sent out gas up to a tenth of its weight sun block In orbit in less than a year.
The researchers then modeled how all of this material would affect our images of the star. Either way, once the star builds its shroud, it will be deeply obscured in a way that our current imaging technology can detect.
Since we have direct images of some pre-supernova stars taken less than 10 years before they exploded, the astronomers concluded that the slow and steady model wouldn’t work. Otherwise, the star would be obscured.
All of this means that once a giant star builds a thick shroud of material around itself, it will likely transform into a supernova within a few years. So, if you’ve been traveling across the universe and encountered exactly this scenario, consider yourself a forewarning.
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