Astronomers have found a way to predict the explosions of dying stars

(ORDO NEWS) — Of course, it would be great to know when a giant star is about to die in a catastrophic supernova explosion. A team of astronomers managed to do just that.

How a star dies

As a massive star nears the end of its life, it goes through several turbulent phases. Deep in its core, there is a transition from the fusion of hydrogen to the fusion of heavy elements, starting with helium and moving on to carbon, oxygen, magnesium and silicon.

At the end of the chain, the star finally forms iron in its core. Since the iron sucks energy instead of releasing it, it spells the end for the star, and in less than a dozen minutes it actually turns inside out in a fantastic explosion called a supernova.

But behind all the fuss that goes on in the heart of a star, it’s hard to tell from the outside what exactly is going on. Of course, at the end of their lives, these giant stars swell to extreme sizes.

They also become extraordinarily bright, up to tens of thousands of times brighter than the Sun. But because the surface of stars is so stretched out, their outer temperature actually drops, making them look like red giants.

The most famous example of such a supernova is Betelgeuse. If it were within our solar system, this star, which is only 11 times as massive as the Sun, would stretch out to the orbit of Jupiter.

It could go supernova any day now, but “any day” in astronomy means in a million years. Although we know that such stars finally explode in supernovae, there is no way to get a better estimate than this. Or at least it used to be.

Evidence of the beginning of the death of a star

Now a team of astronomers has developed a way to detect supernovae that are likely to erupt within a few years.

They specifically studied several dozen unique types of supernovae known as Type II-P supernovae. Unlike others, these explosions remain bright for a long time after the initial flash.

In a few examples, astronomers looked through old catalogs and found images of stars before they exploded, all of which appear to be red supergiants like Betelgeuse. This is clear evidence that such stars are supernova candidates ready to explode at any moment.

It is believed that the stars leading to such supernovae have dense material shells surrounding them before the explosion. These shells are orders of magnitude denser than those measured around Betelgeuse.

It is the heating of this material from the initial shock wave that delays the brightness; it’s just that there’s more material around that continues to glow after the first signs of an explosion.

Astronomers have found a way to predict the explosions of dying stars 1
Red giant

This dense shell also causes this type of supernova to become visible faster than their more open relatives. When the explosion first occurs, the shock wave hits the matter around the star, causing the shock wave to lose steam as it passes through it.

While the energy from the supernova is initially sufficient to release high-energy radiation such as X-rays and gamma rays, once the shock wave and surrounding material mix, it becomes visible at optical wavelengths.

So it seems that these dense material shells around the stars are also a sign that a supernova is about to happen.

Star cocoon

But how long does it take to form this material veil? The researchers studied two models. In one, the star was blowing high-speed winds from its surface that slowly pulled pieces of itself apart and carried them around, creating savannahs for decades.

In the second model, the star experienced a powerful pre-eternal explosion, which in less than a year sent a gas with a mass of one tenth the mass of the Sun into orbit.

The researchers then simulated how all this material would affect our images of the star. In any case, once the dawn had built its savannah, it would have been heavily obscured in such a way that our current imaging technology could detect it.

Because we have direct images of some supernovae taken less than 10 years before they erupted, astronomers have concluded that the slow-permanent model won’t work. Otherwise, the star would be dimmed.

All this means that as soon as a supergiant star creates a thick material shell around itself, it is likely to go supernova within a few years.


Contact us: [email protected]

Our Standards, Terms of Use: Standard Terms And Conditions.