What will our sun look like after it dies? Scientists have predicted what the last days of our Solar System will look like, and when it will happen. And we men will not see around the curtain of the Sun.
Previously, astronomers thought the Sun would erupt into a planetary cloud – a bright bubble of gas and cosmic dust – until evidence suggested it should be a smidge heavier.
An international team of astronomers flipped again in 2018 and found that the planet nebula is indeed the most likely solar corpse.
The Sun was born about 4.6 billion years ago – the estimated age of other objects in the Solar System that formed around the same time. From observations of other stars, astronomers predict that the end of their lives will be reached in another 10 billion years.
There are other things that will come along the way, of course. About 5 billion years ago, the Sun turned into a red giant. The center of the star will shrink, but its outer layers will expand to orbit Mars, sinking our planet in the process. If it is still there.
One thing is certain: We won’t be around that time. In fact, humanity only has about 1 billion years left until we find this rock far away. This means that the Sun increases in brightness by about 10 percent every billion years.
That doesn’t sound like much, but that increasing brightness will end life on Earth. Our oceans will disappear, and the surface will become too warm for water to form. We will be about as kaput as possible.
This is what follows the red giant that proved difficult to hang. Some previous studies have found that in order to form a bright planetary nebula, the initial star must have been up to twice the mass of the Sun.
However, a 2018 study used calculations to determine that, like 90 percent of other stars, our Sun is 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 – known as its envelope – into space. The envelope can be as much as half of the star’s mass. This reveals the star’s core, which at this point in the star’s life is running. It eventually runs out of fuel, and before it finally dies, explained astrophysicist Albert Zijlstra from the University of Manchester in the UK, one of the authors of the paper.
“Then finally the hot core causes the ejected envelope to shine for about 10,000 years – a short time in astronomy. This is what makes the planetary nebulae visible. Some are so bright that they can be seen from great distances measuring ten. million light-years, where the star itself would have been much fainter to see”.
The data model that the team created actually predicts the life cycle of different types of stars, such as the brightness of planetary nebulae associated with different star masses.
Planetary nebulae are relatively common throughout the universe, with famous ones including the Helix Nebula, the Cat’s Eye Nebula, the Ring Nebula, and the Bubble Nebula.
The planets are called nebulae, not because they have anything in them, but because, when they were first discovered by William Herschel in the late 18th century, they looked like planets through the telescopes of the time.
Almost 30 years ago, astronomers noticed something special: The brightest planetary nebula in other galaxies, all of them have about the same brightness. This means that, theoretically at least, by looking at the nebulae of planets in other galaxies, astronomers can calculate how far away they are.
The data showed this to be true, but the models contradicted it, which has plagued scientists ever since its discovery.
“Old and low-mass stars make nebula planets much fainter than young, massive stars. This has become a source of conflict over the past 25 years,” Zijlstra said.
“The data said you could get a clear planetary nebula from a low-mass star like the Sun, the models said it couldn’t, less than twice the mass of the Sun would give a planet nebula too faint to see.”
In the 2018 models, we solved this problem by showing that the Sun is near the lower mass limit for a star that can produce a visible cloud.
Even a star with a mass less than 1.1 times that of the Sun will not produce a visible nebula. However, stars larger up to 3 times heavier than the Sun make the clouds brighter.
For the rest of the stars are interposed, the predicted brightness being the nearest to the observed.
“It turned out well,” 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 difficult to measure in space, we also found out what the Sun is going to do when it dies!”
The research was published in a journal Nature Astronomy.
An earlier version of this article was published in May 2018.
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