These, I am afraid, are mere irritants. Nothing major. How about an event that would guarantee 100% extinction, with no notice whatsoever until it actually happened? How about something that may have already taken place? Worried?
Meet WR 104. More after the jump.
Pretty isn’t it? This is a picture of WR 104 taken from the Keck infrared telecope. WR 104 is a binary star system, located, it is thought, about 8000 light years out from Earth, towards the center of the Milky Way. Two stars, locked in a graceful dance, one an 0-type star, one possibly a Wolf Rayet type star. Both are super-massive, and both super luminous, and both (if our assumptions about their type and makeup are correct) the kind of stars that die in tremendous super or even maybe hypernovae.
The type 0 star poses no real threat, at that distance it will merely be something bright and pretty to look at in the night sky. The other, though, does not seem quite as appealing – there is the slim chance that this star, when it dies, could generate what is the most powerful event known to exist in the universe – a gamma-ray burst.
As is well postulated, when a star dies the slow breakdown of its material leads to a shrinking and a tremendous increase in density. Finally, when the matter within the star can be reduced down no more, and there is no more nuclear fuel to be spent – the core of the star containing only the inert heavy element remnants of past nuclear activity – the star dies in a huge explosion – a supernova - the central remnants crushed by increasing gravitational force to a single point of infinite gravity and infinite mass forming a singularity (a black hole). Matter and gas blown outwards wend their way across space, seeding the formation of new stars and planets. It’s how we came to exist – all matter in the universe came from such destruction – it’s the only place the heavy elements are made. We are all made of start stuff. These things are pretty tame – you’d have to be within, say, 20 light years of a regular supernova to suffer any adverse effects from it.
But, just occasionally, instead of this more typical supernova, something else can occur: sometimes, when a star is massive enough, as well as the outburst of material and the crushing of the inner core the explosion can unleash a torrent of gamma radiation – a gamma-ray burst.
Since their existence was first observed and origins suggested, astronomers, cosmologists and astrophysicists have studied gamma-ray bursts. They are incredible things: they last anywhere from seconds to a few minutes, and the energy unleashed by the star in such an event can be far greater than our Sun will put out in its entire lifetime. The energy is released in two pencil-thin streams, one from each of the stars’ poles – and they utterly destroy anything that lies in their path.
Well, yeah. But what are the odds that we would even be in the path of such a burst?
Well, as it turns out, the odds ore actually pretty good. See, the image above shows the gases around the stars in a familiar pinwheel shape. The gas and material ejected by the star moves outwards, and as the stars spin around their axis, the material is pushed out into a flat plane about the equatorial area – like the old ice-skater’s arms analogy. So, what does the image tell us? It tells us that if we see the star as a pinwheel, then we can only be facing one place - one of the poles. We are lined up with the axis, more or less. The pole. We could be staring right down the barrel of a loaded gun.
So, let’s assume for a minute that Earth is lined up exactly, and that a gamma-ray burst occurs. What would happen? Well, it is suggested that at the very least, the gamma radiation would destroy ozone in our atmosphere and create a smog of nitrogen dioxide. Not so bad then.
Not quite. It is thought that it could burn off up to 50% of the Earth’s ozone by ripping apart the ozone molecules in the atmosphere. When you think that the issues we are having now with regards to global warming are caused by a mere 5% depletion of the ozone layer, 50% sounds like a bad thing. And the nitrogen oxide could be a thick blanket that would not only block out the sun – putting a supervolcano’s feeble efforts to shame – but would also be water soluble, precipitating out as acid rain. And this is the best-case scenario. Add to that the theory – still hotly debated at this stage – that the incredible numbers of cosmic rays beating down could lead to mass extinctions (this is radiation – there is a reason the Apollo missions were scheduled during periods when it was assumed solar activity was at a minimum) and it begins to seem that this may not be a good thing at all, and there would be no way to “escape” the effect.
Now, it is not known for sure that the second star will emit such a burst. Heck, astronomers cannot even really agree on how far the binary system really is from Earth. Maybe 5000 light years, maybe 8000 (any astronomer will tell you that distance is one of the hardest things you can try to measure). And there is also some evidence that perhaps we are not quite so perfectly lined up with the poles – the burst could, as physicist Michio Kaku puts is, “graze the earth“. And, it has to be said, we have no way to know if this will happen tomorrow, next week, or in a milllion years. But it certainly gets you thinking.
And the best bit? the burst would travel at the speed of light, The same speed as the light from the explosion. So that would, basically give us no warning at all. We would only know it happened, when it happened. For all we know, it happned many years ago.
Maybe even 8000 years ago.