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Dec 18, 2014 - 9:34 PM - by pod
Exploding the myth that the dying star Eta Carinae will kill us all.
AS stars go, Eta Carinae is big. It’s old. It’s volatile. And it’s about to blow. So will it really kill us all?
The eyes of astronomers have been on this star for decades. And with good reason: It’s about to go supernova.
This may already have happened: A supercharged mass of subatomic particles could be blasting its way across the gulf of space towards us.
This is what has certain social media sectors alarmed: The enormous flare generated by the collapse of a star more than 100 times bigger than our own could produce a radiation burst powerful enough to kill us all.
As such, Eta Carinae has been dubbed the “Death Star”.
After all, some scientists speculate such a sterilising pulse has already caused at least one mass extinction on Earth. Others say it may be why we are yet to meet aliens: Most may have been killed off by these semi-regular interstellar explosions.
It’s a story of such persistence that it has even prompted the otherwise sedate Scientific American to address the idea.
The simple answer is: It could, but it won’t.
It will, however, produce a spectacular light show.
Cosmic cauldron ... The Carina Nebula is a chaotic region of star formation several thousand light years from Earth. In the central part of the nebula, shown here, dense clouds of gas and dust are lit up by the light of newly born stars. One of these is a true giant — the star Eta Carinae right at the centre of this image.
What is Eta Carinae
It’s an enormous star — 120 times the weight and 240 times the size of our Sun.
“It’s so bright it’s literally tearing itself apart by the strength of its own light and heat,” says Swinburne University astrophysicist Dr Alan Duffy.
“We have no idea how it managed to survive the enormous explosion that flung 10 times the mass of our Sun outwards and we definitely don’t know if the next will be the last.”
You can find roughly where it is by finding the Southern Cross, looking at the closest of its “pointers” — and flipping that position to the cross’ other side. This is a region called the Carinae Nebula.
This dying star is not near: And that’s why we are safe. It is some 7500 light years away.
While the after-effects of such titanic explosions have filled thousands of frames of photos from the likes of the space telescope Hubble, capturing the moment of a star’s death has been much more elusive.
This is why so much telescope time has been devoted to watching Eta Carinae: The convulsions of its death throes are a unique insight into the processes which power our stars.
Eta Carinae is eating itself.
The best fuel has already been burnt, so now less stable substances are roiling around in the star’s core — causing “puffs” of star-stuff to be cast off into the interstellar winds.
How much longer the star will last depends on what it’s “burning” now: If it’s helium, it could last for several hundred thousand years. If its oxygen or carbon, its life can be numbers in years — a century at the most.
But this star is a confused cauldron of action and reaction — complicated even further by a “small” (it’s 30 times bigger than the Sun) companion star in close orbit.
University of California astrophysicist Stan Woosley told Scientific American: “No one knows just what’s going on there … It could die tomorrow or a long time from now.”
And as a specialist in modelling the life cycle of stars, he regards that to be astronomy’s “biggest embarrassment”.
Your standard exploding star is big, bright and brutal.
Gamma-Ray Bursts (GRB) are even bigger. They produce one of the brightest explosions of the known universe.
When a star dies, its depleted core collapses in on itself. In the case of a star that is spinning, this collapse can cause its outer surface to whip around even faster like a figure skater pulling in their arms. Such spinning gas can superheat into a whirling plasma that can approach the speed of light itself.
Once the star’s core begins to collapse... [Read More]