Scientists have discovered when and how our sun will die, and it will be epic: ScienceAlert

Scientists have discovered when and how our sun will die, and it will be epic: ScienceAlert

What will our sun look like after it dies? Scientists have made predictions about what the final days of our solar system will look like and when it will happen. And we humans will not be there to see the curtain call of the sun.

Previously, astronomers thought the sun would turn into a planetary nebula — a luminous bubble of gas and cosmic dust — until there was evidence that the sun should be a fraction more massive.

An international team of astronomers turned it around again in 2018 and found that a planetary nebula is indeed the most likely solar.

The sun is about 4.6 billion years old – measured by the age of other objects in the solar system that formed around the same time. Based on observations of other stars, astronomers predict that it will reach the end of its life in about 10 billion years.

Of course, other things happen along the way. In about 5 billion years, the sun will turn into a red giant. The core of the star will shrink, but the outer layers will expand into the orbit of Mars, which is engulfing our planet in the process. If it is already there.

One thing is certain: by then we won’t be here anymore. In fact, humanity has only about 1 billion years to go unless we find a way to get rid of this rock. That’s because the sun is about . increases in brightness 10 percent every billion years.

That doesn’t sound like much, but that increase in brightness will put an end to life on Earth. Our oceans will evaporate and the surface will become too hot to form water. We’ll be as kaput as you can get.

It’s what comes after the red giant that has proved difficult to pin down. several previous studies have found that, in order for a clear form planetary nebulathe first star must have been up to twice as massive as the sun.

However, the 2018 study used computer modeling to determine that our sun, like 90 percent of other stars, is most likely to shrink from a red giant to become a white dwarf and then end up as a planetary nebula.

“When a star dies, it ejects a mass of gas and dust – also called its shell – into space. The shell can be as much as half the mass of the star. This reveals the core of the star, which is on this point in the star’s life runs out of fuel, eventually shutting down and eventually dying,” explained astrophysicist Albert Zijlstra of the University of Manchester in the United Kingdom, one of the authors of the article.

“Only then does the hot core make the ejected shroud shine brightly for about 10,000 years – a short period in astronomy. This is what makes the planetary nebula visible. Some are so bright that they can be seen from extremely long distances of tens of millions of light years, where the star itself would have been far too dim to see.”

The data model the team created actually predicts the life cycles of different types of stars, to calculate the brightness of the planetary nebula associated with different star masses.

Planetary nebulae are relatively common in the observable universe, with famous nebulae such as the Helix Nebula, the Cat’s Eye Nebula, the Ring Nebula, and the Bubble Nebula.

heic0414a1Cat’s Eye Nebula (NASA/ESA)

They are called planetary nebulae, not because they have anything to do with planets, but because, when the first were discovered by William Herschel in the late 18th century, they resembles planets in appearance through the telescopes of that time.

Nearly 30 years ago, astronomers noticed something curious: the brightest planetary nebulae in other galaxies all have about the same brightness level. This means that, at least in theory, by looking at the planetary nebulae in other galaxies, astronomers can calculate how far away they are.

The data showed this to be correct, but the models contradicted it, which has annoyed scientists ever since its discovery.

“Old, low-mass stars should make much fainter planetary nebulae than young, more massive stars. This has become a source of conflict over the past 25 years,” said Zijlstra

“The data said you could get bright planetary nebulae from low mass stars like the sun. The models said that wasn’t possible. Anything less than about twice the mass of the sun would give a planetary nebula that is too dim. to see.”

The 2018 models solved this problem by showing that the Sun has about the lower limit of mass for a star that can produce a visible nebula.

Even a star with a mass less than 1.1 times that of the Sun will not produce a visible nebula. On the other hand, larger stars up to 3 times more massive than the Sun will produce the brighter nebulae.

For all other stars in between, the predicted brightness is very close to what has been observed.

“This is a great result,” says Zijlstra said. “Not only do we now have a way to measure the presence of stars a few billion years old in distant galaxies, which is a range that is remarkably difficult to measure, we’ve even figured out what the sun will do when it dies!”

The research is published in the journal Natural Astronomy.

An earlier version of this article was first published in May 2018.

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