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Looking Down the Barrel of A Gamma Ray Burst

3 Mar , 2008 by

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.

11 image stack.  Image Credit:  University of Sydney
“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


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Mike
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Mike
March 3, 2008 9:09 PM

So how do we know this one didn’t go supernova 7999 years ago? Is there anyway to tell?

Entropy4121
Member
March 3, 2008 10:16 PM

Uh oh.

Spencer
Guest
Spencer
March 3, 2008 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.

Jason Kurant
Member
Jason Kurant
March 4, 2008 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.

Patrick Carrasco
Guest
Patrick Carrasco
March 4, 2008 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!

Myyrdn
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Myyrdn
March 4, 2008 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

Irwin Weisberg
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Irwin Weisberg
March 4, 2008 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?

alastair
Guest
March 4, 2008 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/

john
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john
March 4, 2008 5:13 AM

curious, interesting to see the further analysis

Rick Eyerdam
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Rick Eyerdam
March 4, 2008 7:16 AM

Blasted by a ray gun 8000 light years away, What a way to go!!

W. Scott
Guest
W. Scott
March 4, 2008 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… Read more »
Peter
Member
Peter
March 4, 2008 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… Read more »
geokstr
Member
geokstr
March 4, 2008 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.

John Mendenhall
Member
John Mendenhall
March 4, 2008 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.

BrianT
Member
March 4, 2008 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

Skip
Guest
Skip
March 4, 2008 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.

AHJ
Guest
AHJ
March 4, 2008 1:47 PM

Damn. There go the primaries!!!

Excalibur
Member
Excalibur
March 4, 2008 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… Read more »
hd
Guest
hd
March 4, 2008 9:42 PM

Hi Brian,

do you have an estimate how bright that explosion would be.

Will it turn night into day?

Stanley Allan
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Stanley Allan
March 5, 2008 5:37 AM

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