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Physicists calculate when the last supernova will occur



Physicists calculate when the last supernova will occur

An artist̵

7;s notion of a dark brown dwarf that may resemble black dwarfs that are expected to form in the future. Image provider: NASA / JPL-Caltech

The end of the universe as we know it will not be accompanied by an explosion. Most stars will slowly melt as their temperature decreases to zero.

Theoretical physicist Matt Caplan said: “It would be a somewhat sad, lonely and chilly place, adding that no one would be by to see this long breakup happen during distant future. Most believe it will all be dark when the universe ends. “It’s called ‘thermal death’, where the universe will be mostly about,” said Caplan, who envisioned a slightly different picture when calculating how some of these dead stars might change according to the eons. black holes and burned stars.

The punctuation mark in the dark could be the sound of silent fireworks – remnant explosions of stars were never expected to explode. New theoretical work by Caplan, an assistant professor of physics at Illinois State University, discovered that many white dwarfs could explode in supernovas in the distant future, long after everything else in the universe. Pillars die and be quiet.

In the present universe, the catastrophic deaths of large stars in supernova explosions occur when internal nuclear reactions produce iron in the core. Iron cannot be burned by stars – it accumulates as a poison, causing the star’s collapse to create a supernova. But smaller stars tend to die with a slightly higher dignity, shrink and become white dwarfs by the end of their lives.

“Stars with a mass about 10 times the mass of the sun don’t have the gravity or the density to make iron in their cores the way large stars do, so they can’t explode in one,” Caplan said. the supernova right now ”. “As white dwarfs cool down in the next few trillion years, they will fade, eventually solidifying and becoming ‘black dwarf’ stars that no longer shine.” Like today’s white dwarfs, they will be made up mainly of light elements such as carbon and oxygen and will be the size of the earth but contain masses comparable to that of the sun, and their insides are compressed with The density is millions of times greater than anything on earth.

But just because they are cold doesn’t mean nuclear reactions stop. “Stars shine through fusion – they are hot enough to smash small nuclei together to create larger nuclei, releasing energy. White dwarfs are ash, they are burned out.” But fusion can still happen due to quantum tunneling, only Caplan says: “Fusion happens, even at zero, it only takes a very long time.” He notes that this is the key to turning a black dwarf into iron and activating a supernova.

Caplan’s new work, approved for publication by Royal Astronomical Society monthly announcement, calculate how long these nuclear reactions produce iron and how much iron different sized black dwarfs need to explode. He calls his theoretical explosions “black dwarf supernovae” and calculates that the first will happen in about 10 to 1100 years. “Over the years, it’s been like saying the word ‘trillion’ almost a hundred times. If you write it down, it will take up almost a page. It’s worth thinking about in the future.”

Of course, not all black dwarfs will explode. “Only the most massive black dwarfs, about 1.2 to 1.4 times the mass of the sun, will blow away.” However, that means that up to 1% of all stars in existence today, about a billion trillion stars, can die this way. As for the rest, they will remain black dwarfs. “Even with very slow nuclear reactions, our sun still doesn’t have enough mass to explode in a supernova, even in the far future. You can turn the entire sun into a supernova. It still won’t explode. ”

Caplan calculates that the heaviest black dwarfs will explode first, then gradually smaller stars, until there are no more to explode after about 10.32000 years At that time, the universe can truly be dead and silent. “It’s hard to imagine that whatever happens after that, the black dwarf supernova could be the last interesting thing to happen in the universe. They could be the last supernova ever.” By the time the first black dwarfs explode, the universe will be unrecognizable. “The galaxies will scatter, the black holes will evaporate, and the expansion of the universe will pull all the rest so far apart that it is never possible to see any other objects explode. Even light won’t be able to physically travel that far. ”

Though he will never see one, Caplan remains unaffected. “I became a physicist for a reason. I wanted to think about the big questions – why is the universe here, and how will it end?” When asked what next big question, Caplan said, “Maybe we’ll try to simulate some of the black dwarf supernovae. If we can’t see them in the sky then at least we can see. them on the computer. ”


The specter of ancient explosions inhabits the stars today


Provided by Illinois State University



Quote: Physicists calculate when the last supernova will occur (2020, August 13) retrieved August 13, 2020 from https://phys.org/news/2020-08- physicists-supernova.html

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