The Sun Will Become an Enormous Dusty Nebula When It Finally Dies

Monday, 07 May 2018 - 6:40PM
Space
Sun
Monday, 07 May 2018 - 6:40PM
The Sun Will Become an Enormous Dusty Nebula When It Finally Dies
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NASA, ESA, and the Hubble Heritage (STScI / AURA)- ESA / Hubble Collaboration
It's hard to imagine that we'll worry about the sun toward the end of its life. Since it has at least 5 billion years left, there's a good chance that humanity will either be dead or interstellar by that time.

But a new study from a group of international researchers, led by Albert Zijlstra from the University of Manchester, gives a pretty good idea of what will happen to the sun when it finally dies. It doesn't involve a star-sized grim reaper, instead focusing on the large planetary nebula - a large ring of interstellar gas and dust - that our dying sun will turn into. 

The big concern about our sun was whether it would be luminous when it finally collapses into dust, which requires a certain amount of mass that the sun may not contain, and glowing is an important part of being a visible planetary nebula. To determine the answer with some more certainty, the researchers used a data-driven model to predict the life cycles of stars.



This model could also predict how luminous a star's envelope (which it expels upon death) would be, and it determined that even a low-mass star like our sun will heat up extremely quickly when it dies. This is precisely what needs to happen for a bright and visible planetary nebula to form.

Most stars in our universe, regardless of type, will turn into a nebula at the end of its life, but about 10 percent of stars can face various other fates. Astrophysicists had never managed to conclusively prove that our sun would fall into the 90 percent until now, partly because old models weren't accurate - even though scientists could find examples of low-mass stars becoming bright nebulae, the models suggested a star had to have a large mass.

So this new model solves a lot of contradictions regarding stellar deaths. According to Zijlstra, who said the following in a press release from the University of Manchester:

Opening quote
"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 the star's mass. This reveals the star's core, which by this point in the star's life is running out of fuel, eventually turning off and before finally dying.

It is only then the hot core makes the ejected envelope shine brightly for around 10,000 years – a brief period in astronomy. This is what makes the planetary nebula visible. Some are so bright that they can be seen from extremely large distances measuring tens of millions of light years, where the star itself would have been much too faint to see."
Closing quote


The sun is still toward the lower end of stars that can become a nebula, and if it were even slightly smaller, it might not produce a visible nebula. But going off this new model, the sun will still be bright once it's gone.

Again, this is several billion years down the line. So don't worry about the sun going crazy anytime soon; we're not expecting any surprises when NASA sends a probe to examine it later this year.
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