Looking Down the Barrel of A Gamma Ray Burst
Written by Nancy Atkinson
A team of astronomers from the University of Sydney in Australia have been keeping an eye on a binary star system called Wolf-Rayet 104, located in the constellation Sagittarius. Wolf-Rayet stars are hot, gargantuan, older stars that are losing their masses, and astronomers consider these stars as ticking bombs: they could go supernova at any time within the next few hundred thousand years. That’s a relatively short fuse for astronomers. Images of this system from the Keck Telescope show an almost perfect spiral nebula formed by the two stars orbiting each other as they each blow off streams of gas. The way this system is spinning caught the eyes of these astronomers, who say Earth could be in the line of fire when the system blows.
Usually, a supernova explosion would be harmless at interstellar distances like the 8000 lightyears that this system lays from Earth, and it would just provide an impressive show for stargazers. But astronomers say the only way WR 104 could appear as an almost perfect spiral is if those of us on Earth were looking down the spin-axis of the system. Astronomer Peter Tuthill says that sometimes, supernovae focus their energy into a narrow beam of very destructive gamma-ray radiation along the axis of the system. A gamma-ray burst is a super-duper supernova that sometimes happens to massive stars, like the ones in WR 104.
As of now, no one can say for sure when the system will go supernova, or how massive and powerful the explosion might be. But the way these two stars are spinning about each other has astronomers thinking this system won’t provide just a run-of-the-mill explosion.
And an intensive gamma-ray burst at that distance could possibly be harmful to life on Earth.
But right now, this is all speculation, and more study on this system is needed before anyone needs to get worried. And this is all definitely very fascinating.
"I used to appreciate this spiral just for its beautiful form, but now I can't help a twinge of feeling that it is uncannily like looking down a rifle barrel," says Dr. Peter Tuthill.
With a sequence of 11 different images, the astronomers were able to portray how the spiral nebula of this system is rotating in a circle every 8 months.
Original News Source: University of Sydney Press Release
Filed under: Gamma Ray Bursts
March 3rd, 2008 at 9:09 pm
So how do we know this one didn't go supernova 7999 years ago? Is there anyway to tell?
March 3rd, 2008 at 10:16 pm
Uh oh.
March 3rd, 2008 at 10:53 pm
We wouldn't know if they have collided until the light reached us. I imagine this system will be closely monitored and in time we will be able to determine their orbital decay and possible jet collimation and propagation details.
March 4th, 2008 at 12:13 am
Oh, man! This is truly scary, indeed! I mean gamma ray bursts are some of the most — if not the most — powerful explosions in the universe today. I'm sure this very large star would easily outshine the rest of the 200 billion or so stars in the Milky Way. And having that jet pointed at the Earth from only 8000 light years away is truly perilous.
March 4th, 2008 at 12:20 am
Is it possible that with forces such as gravitational lensing, dark energy, dark matter, (etc.?), our perspective is distorted and we're actually not looking down the barrel? And then of course a layman such as myself would think that the different levels of energy (what we see now, versus what we see when she actually blows) would also be affected differently by dark energy et al… So, perhaps looking down the barrel at this distance doesn't necessarily mean the gamma burst will hit us?
Help!
March 4th, 2008 at 2:30 am
I like the conjecture of 7999 years ago,if it is/was the case. You watch all local UFO activity should diminish very soon. But watch out for outer system activity hehehehe
Myyrdn
March 4th, 2008 at 4:47 am
Both systems are moving, relative to each other. How long would it take before we are safely off axis to the blast, and how diffused would it be at 8000 light years?
March 4th, 2008 at 5:05 am
@Patrick:
It wouldn't matter if our perspective is distorted by gravity, since the gamma rays would be distorted in a similar manner. If we can see it and it looks like it's aimed at us, then it is.
But at a distance of 8,000 light years, it would have to be almost totally spot on to hit such a tiny target as the Earth; if it is even 1° out, then at a distance of 8,000 light years that would mean that a GRB would miss us by 8000 x tan 1° = 139.6 light years.
Further, before worrying too much, you should read these:
http://www.badastronomy.com/bablog/2008/03/03/wr-104-a-nearby-gamma-ray-burst/
http://isiria.wordpress.com/2008/03/04/wolf-rayet-104-is-it-a-death-star/
March 4th, 2008 at 5:13 am
curious, interesting to see the further analysis
March 4th, 2008 at 7:16 am
Blasted by a ray gun 8000 light years away, What a way to go!!
March 4th, 2008 at 8:02 am
Patrick Carrasco wrote "Is it possible that with forces such as gravitational lensing, dark energy, dark matter, (etc.?), our perspective is distorted and we're actually not looking down the barrel?"
Unfortunately, any lensing would apply to the gamma ray burst as well. If the axis appears to be pointed at us when the system goes supernova, a cone of super-intense gamma rays will be ejected in our direction, following the same gravitational contours as the light we've been viewing.
As for "how do we know that it didn't go supernova 7999 years ago…" well, that's a fair question. We don't–because it takes 8000 years for that light to reach Earth.
Thing is, this is just one case that is easy to see, and obviously dicey. For all we know, something much closer could have gone bang about six thousand years ago, before the Chinese were keeping dutiful astronomical records, and we could even now be facing a shower of deadly gamma rays speeding towards us. There is no way to tell until they get here, and by then, it's too late.
But the odds are much higher that most life on Earth will be wiped out by a collision with a high-speed Near Earth Object long before then. So don't lose any sleep over the gamma rays. Earth has many other dangers to face from space… provided we manage to avoid killing ourselves even faster with pollution and overpopulation, which is by no means certain.
The Universe tends to be an "all bets are off" kind of place, and because it's so scary, and because our technology is woefully insufficient to protects us from most of the dangers out there, it's just easier to say "well, if it happens, it happens… so what's for lunch?"
March 4th, 2008 at 8:11 am
Patrick, you might as well ask how this might be affected by the plot of All my Children. Dark Matter and Energy were not confirmed (as much as they are) til lately on account of them having no discernible effect in these matters. Dark Energy works at enormous distances and is a slow, consistent effect. Dark matter would have no effect as ordinary matter and radiation do not interact with it. Gravitational lensing is interesting but has simply nothing to do with this issue. Try for a basic understanding of these phenomena before tossing around their names. 8000 light years is pretty close as cosmic distances go, and gamma bursts are nearly instantaneous. If we did get early warning of this one, it would be a first. Volcanologists have been trying to give fair warning of eruptions for years and they still get killed with surprised looks on their faces.
March 4th, 2008 at 8:22 am
Gravitational lensing is a transitory phenomena, caused by the random but perfect alignment of two distant bodies. If we are seeing this via lensing based on light that left 8,000 years ago, odds are extremely high that those two objects will not be in alignment very long, as they continue their own separate orbital paths. It would seem we would have more to worry about from lensing effects if any, that we will never see coming until they get here.
March 4th, 2008 at 10:19 am
"Mike Says:
March 3rd, 2008 at 9:09 pm
So how do we know this one didn't go supernova 7999 years ago? Is there anyway to tell?"
No. Whatever has happened to this star in the 8000 years since the light we see left it, is in our future, and cannot be observed until then. Look up 'light cones' in the Wiki articles on relativity.
March 4th, 2008 at 11:17 am
8000 light years is probably too far away to have a catastrophic impact on the Earth. My colleagues and I have studied GRB effects on the Earth and determined that a distance of 6500 ly would be serious.
At 8000 ly there would definitely be a measurable effect and maybe some impact on the biosphere, but probably not at mass extinction levels. Still, wear your sunscreen!!
You can read the details of our work at the sites below and others. There was also an episode about GRBs on the program "Mega Disasters" which aired on the History Channel.
http://www.nasa.gov/vision/universe/starsgalaxies/gammaray_extinction.html
http://arxiv.org/abs/astro-ph/0505472
March 4th, 2008 at 12:05 pm
Not much sense in worrying about such an event. Probably by the time we detected such a jet, it would be too late.
Blazars also put out jets at almost relativistic speeds (within a small percentage of the speed of light).
If such a jet from a blazar were to be heading our way, we wouldn't know about it until very very shortly before it struck our solar system.
March 4th, 2008 at 1:47 pm
Damn. There go the primaries!!!
March 4th, 2008 at 7:32 pm
To Spencer:
The two stars are not actually going to collide. Instead it is the implication of this face-on orbiting system that is the potential threat. The colliding winds from the two stars create 'focused streams of gas that move outwards, and as the system rotates it looks like a spiral.
1. The lack of 'tilt' in the spiral indicates the orbits are face-on here.
2. A face-on orbiting system likely means their poles point approximately straight towards us Likely, but not necessary.
3 Gammaray bursts are suspected to come from some types of supernova, being shot out from the magnetic poles - magnetic poles often align somewhat with the rotational poles - thotugh some stars seem to have really large magnetic tilts.
4. Both stars are WR.stars, expected to go supernova - one after the other. And WR-stars dont have long before they end their life, they are expected to go boom quite soon (in astronomical timings)
So this is a possible threat, but there are still alot of uncertainties in this scenario.
March 4th, 2008 at 9:42 pm
Hi Brian,
do you have an estimate how bright that explosion would be.
Will it turn night into day?
March 5th, 2008 at 5:37 am
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March 5th, 2008 at 6:06 am
Does anyone have an approximate attenuation rate for narrowly focused gamma rays from a GRB?
March 5th, 2008 at 6:27 am
The fact that we can detect GRBs prove that they are not as collinear as laser beams. The ejected material should be deflecting and dispersing a lot of power.
In the 4.5 Billion lifetime we must have been down such barrel several times.
Could Tunguska be such an incident?
March 5th, 2008 at 1:16 pm
Thanx to all of you who helped me understand this. And I apologize to Peter K. who was offended that I asked for enlightenment!
March 5th, 2008 at 4:09 pm
hd - Well, if you took all the power of the GRB, say 10^44 Watts and converted that into visible light, at a distance of 8000 ly it would be as bright as daylight.
But! The GRB itself is a blast of gamma rays, not visible light. However, the gamma rays would interact with the atmosphere to down-scatter and probably produce some visible light, kind of like how sunlight scatters and makes the sky blue. There is an "afterglow" that includes optical light, but it's much less powerful that the gamma part.
So, it would be much dimmer than daylight, but still could be pretty bright, especially compared to other night-time objects.
March 5th, 2008 at 4:13 pm
Mike Birman - shouldn't be much attenuation, unless there is significant dust along the line of sight.
Essel - the current consensus is that the opening angle of the beam is a few degrees. So, not an extremely tight beam, but still pretty small. So the ones we see we are really looking down the barrel, but they are so bright that most of the ones we see are hundreds of millions to billions of light years away.
The Earth may get blasted once every billion years or so.
The Tunguska event was definitely an asteroid, I don't think there's any disagreement about that. A GRB would certainly not flatten a forest - mostly it ionizes the atmosphere, destroying ozone and leading to really bad sunburns!
March 5th, 2008 at 5:31 pm
Sweet!!! I see it as a Perfect End.
March 10th, 2008 at 9:02 am
What I notice is how similar it looks to the Hunab Ku ancient
symbol. Can this all be part of the "cosmic clock"?
March 11th, 2008 at 4:55 am
"In the 4.5 Billion lifetime we must have been down such barrel several times" ….
Possible … but then how do we know that on every such incident life was not wiped off (partially or completely)
March 24th, 2008 at 2:05 pm
Sub: search from Heart of Universe
Supernova -Phenomena is the Heart. How does this balance in a Three-Tier Universe mode.
A top tier Drives , Mid Tier Balances and observational plane is the Lower Tier..
There appears to be a lot of mix-up in interpretation Observational data
Cosmology Vedas- provide the Knowledge route and a Magnetic Pole forms an essential link
Vidyardhi Nanduri
March 26th, 2008 at 1:28 am
Patrick…
Pay little attention to the Peter K's and ilk. None of us mere mortals were fortunate to have emerged from the womb in possession of near divine knowledge of the cosmos such as the obviously self-satisfied Mr K. How marvelous it must be to not contend with an inquisitive mind, having all such wisdom pre-installed.
But, I'd wager that you're lot cooler to hang around with.
Keep asking - and just overlook such smug vanity.