'Death Star' Aimed at Earth

An anonymous reader writes "A spectacular, rotating binary star system is a ticking time bomb, ready to throw out a searing beam of high-energy gamma rays that could lead to a major extinction event — and Earth may be right in the line of fire. Australian science magazine Cosmos Magazine reports: 'Though the risk may be remote, there is evidence that gamma ray bursts have swept over the planet at various points in Earth's history with a devastating effect on life. A 2005 study showed that a gamma-ray burst originating within 6,500 light years of Earth could be enough to strip away the ozone layer and cause a mass extinction. Researchers led by Adrian Melott at the University of Kansas in Lawrence, U.S., suggest that such an event may have been responsible for a mass extinction 443 million years ago, in the late Ordovician period, which wiped out 60 per cent of life and cooled the planet.'"

Comments

Thanks guys

[NIckGorton]

Further research would be required to determine if we are exactly in line with the axis of the system - but even if we are, we probably still have hundreds of thousands of years to come up with a solution, said Tuthill. Thanks for putting that at the end of TFA. Now I need to go change my shorts.

Re:Thanks guys

[KwKSilver]

Not only that, but the star is 8000 light years distant, and the danger-zone was cited as 6500 light years. Even allowing for a 10% error in both figures...

Re:Thanks guys

[Cecil]

Nope. The light, radiowaves, whatever we might use to detect this disturbance would also travel at the speed of light. Put simply, information cannot travel faster than the speed of light. Outside of science fiction, and pending further discoveries in physics, there is absolutely no way to realistically know anything beyond the speed of light, everything we see or detect has already happened. The speed of light is a harsh mistress indeed.

The only thing we can do is rely on predictions based on our existing knowledge of physics that a light-speed event will soon begin, or continue. But we will never be able to know for certain that it's happened until it's upon us. By analogy, we know the sun will continue shining its light at us because we know that even in the worst case scenario, a collapse of its internal fusion reactions would take millions of years and we could see signs that such an event was happening, such as seeing that its hydrogen fuel supplies were about to run out. However, if there is some previously unknown method of collapse that is instantaneous and the sun looked entirely normal until it happened, then it would be entirely possible that the sun has already shut down and in 1 to 8 minutes we are about to realize that today is definitely not a good day.

The Bad Astronomer has covered this on his blog.

[jdoss]

Right here.

Re:Atmosphere? What atmosphere?

[SatanicPuppy]

Nah, polarity flips have been happening for a long time; if we lost our atmosphere every time, this planet would LOOK like mars...Anyway, Mars has no atmosphere because it's too small, not because it doesn't have a liquid core with the attendant magnetic field. Losing the magnetic field (which may or may not happen during a flip...Geologic data isn't precise enough to tell) could cause some problems with regards to the solar wind, but complete loss of atmosphere is extremely unlikely.

The average period between pole flips is about 250,000 years, so that will give you a pretty good idea of how often it happens, and how unlikely it is that atmospheric loss follows. For the curious, it's been about 800,000 years since the last flip, so we're due one.

Earth cooked, news at 11...

[southpolesammy]

So let me see if I've got this right...

If a GRB hits us in the next 10 years, the Earth is cooked and we're screwed. Game over.

If a GRB hits us in the next 100 years, the Earth is cooked, and although I'm gone, life on Earth is still screwed. Game over.

If a GRB hits us in the next 1000 years, the Earth is still cooked, I'm long gone as are the vast majority of my descendants, but maybe mankind (assuming we live that long) will have found the means to leave the planet and preserve itself. However, life on Earth is still screwed. Game over.

Ditto for 10k years, 100k, etc. Basically, there's very little we can do to save the Earth, and next to nothing we can do collectively to save ourselves, except for a few lucky individuals. Thus, the long term goal shouldn't be figuring out how to protect the Earth, but rather we should be figuring out how to preserve our legacy. Fighting against Mother Nature has proven time and time again to be futile.

I wouldn't worry overmuch

[secPM_MS]

While such Wolf-Rayet doubles, or the LBV in Eta Carniae are definitely pre-supernovae, it is unlikely that they are likely gamma ray burst sources. GRB's have a very strong preference for low metallicity environments, almost certainly because higher metal levels cause them to loose too much mass angular momentum. In this region of the galaxy, the metal levels is too high to have a high unlikelihood of GRB's. Also note that for the GRB to propagate into space, the star must first have blown off its envelope, or the GRB is absorbed in the stellar atmosphere and simply adds to the explosion energy (this is probably quite common).

Re:I asked GOD

[lowededwookie]

Actually you're wrong. The word day is used in many contexts in the Bible. The creative days mentioned in the Bible are not literal 24 hour days. In context they refer to periods. There are also scriptures in both Old and New Testaments that say "a thousand years are but as a day in God's eyes" so at bare minimum the creative days would be 6000 years. But what people fail to realise is that there are two creative periods. Genesis 1:1 says "In the beginning God created the heavens and the earth" but from Genesis 1:2 onwards it talks about creative days on Earth and in the original Hebrew the language indicated it was from the perspective of someone standing on the earth looking up so the creation of the sun, moon, and stars would have seemed to have just happened as a dark cloud was removed thus unveiling the luminaries. The problem with those decrying the Bible is that most of them have never read it so they know stuff all about it. For all the mocking if people read it they'd realise it is a fascinating book with prophecies which have been so accurate that in many cases it's been accused of being written after the fact which is wrong considering that Daniel had the book of Isaiah before the fall of Babylon and Isaiah had written not only that Babylon will fall but who and how (Isaiah 45:1-25) which is the only prophecy to mention a person by name and was written 200 years before the event. Archeology backs up most of the Bible so it's not just a book to be taken on faith.

Re:OH NOES

[stjobe]

I'd expect that there is at least some sort of indication that the star is nearing the end of its life.

We can try to figure out what it's burning. The star can burn hydrogen and helium happily for millions and millions of years, but when it runs out of that it's gonna start on carbon, which might last it a thousand years or so, and then it's on to neon for a couple of years, and then oxygen for a few months before finally burning silicon for a few hours before the big show.

In a stars lifetime, the collapse and supernova event may be nearly 'instant', but 10,000 years is nothing when compared to the overall lifetime of a star.

I fear that you are mistaken. The collapse and supernova event is for all intents and purposes instant even in our timeframe. The core collapses in as little as a quarter of a second, the core bounce is over in a millisecond and the explosion lasts for about ten seconds. Quote Wikipedia (emphasis mine):

When the core's size exceeds the Chandrasekhar limit, degeneracy pressure can no longer support it, and catastrophic collapse ensues. The outer part of the core reaches velocities of up to 70,000 km/s (23% of the speed of light) as it collapses toward the center of the star. The rapidly shrinking core heats up, producing high-energy gamma rays that decompose iron nuclei into helium nuclei and free neutrons (via photodisintegration). As the core's density increases, it becomes energetically favorable for electrons and protons to merge (via inverse beta decay), producing neutrons and elementary particles called neutrinos. Because neutrinos rarely interact with normal matter they can escape from the core, carrying away energy and further accelerating the collapse, which proceeds over a timescale of milliseconds. As the core detaches from the outer layers of the star, some of these neutrinos are absorbed by the star's outer layers, beginning the supernova explosion.

So no, a star doesn't just randomly explode, but when it's time to go it goes. And if it's not too small, it's going to go with a really interesting lightshow.

I would imagine that a supernova is similar. Instantaneous from the 'point-of-view' of a star, but aeons to a human.

No, a supernova is most certainly a very brief event. The remnants of that event might linger on for "aeons", but the event itself is surprisingly quick even for a distant observer. Wikipedia again: "A supernova causes a burst of radiation that may briefly outshine its entire host galaxy before fading from view over several weeks or months."