Short Gamma-ray Bursts Traced to Colliding Stars 135
Astervitude writes "Collisions of the cosmic kind could be the source of one of nature's most lethal explosions. Astronomers have traced the origin of short-duration gamma-ray bursts, or GRBs, to the merger of neutron stars or other dense bodies. Space.com has a report on the scientific detective work that led to the solution of what has been described as a 35-year-old mystery. "Our observations do not prove the coalescence model, but we surely have found a lady with a smoking gun next to a dead body," said Shri Kulkarni, one of over two dozen astronomers who discovered and investigated two short-duration bursts that took place last May and July. Unlike short-duration GRBs, long-duration GRBs are believed to be produced when extremely massive stars collapse and explode as supernovas."
The Science Channel (Score:4, Interesting)
I just think it's weird how some things seem like a trend some times.
The idea of neutron stars colliding is a very old theory but this seems to shed new light on the possibility of it being the main cause.
Re:The Science Channel (Score:2, Interesting)
Correction... (Score:2, Interesting)
Anyway, it is curious that no gamma-ray bursts occured in our galaxy (yet). It is supposed that such an even would generate enough gamma rays to wipe out the ozone layer, and cause life extinction on earth.
Wait... why dinosaurs dissapeared again?
Re:Correction... (Score:2, Funny)
Wait... why dinosaurs dissapeared again?
I thought it was because they took up smoking...
Re:Correction... (Score:1)
> I thought it was because they took up smoking...
No, no! It's because Homer sneezed when his modifed toaster took him back in time, remember?
Re:Correction... (Score:2)
I'm sure that's what you were referring to. Good stuff.
Re:Correction... (Score:1)
And not only that, extinction in mass scale doesn't seem to "sanitize", but "life" seems to find its way out of harsh environment or adapt. Matter of fact, didn't theropod dinosaur survive? After all, what are all these birds doing on earth?
Re:Correction... (Score:2)
No. Many species of dinosaur became extinct of a period, but at a slow rate. The latest evidence is that the final extinction which wiped out the rest was very fast indeed.
And not only that, extinction in mass scale doesn't seem to "sanitize", but "life" seems to find its way out of harsh environment or adapt. Matter of fact, didn't theropod dinosaur survive? After all, wha
Re:Correction... (Score:3, Informative)
They may have, but not pointed in our direction.
It is supposed that such an even would generate enough gamma rays to wipe out the ozone layer, and cause life extinction on earth.
Wiping out the ozone layer would not cause extinction of life, after all, life survived for billions of years without such a layer.
Re:Correction... (Score:2)
If the burst occurs close enough (a few lighyears, maybe even a few tens of lightyears should do), it would essentially sterilize the side of the planet that is facing towards the source of the burst.
Death Stars are for tourists.
Re:Correction... (Score:1)
This gamma ray burst was from within our galaxy !
A GRB of this size within 10 light years would be enough to disrupt (read species die out) on earth.
The nearest worrying sources, magnetars, around 4000-5000 light years away.
Please, please, please, do a little google searching before opening your mouth.
Re:Correction... (Score:2)
You may be confusing this with the recent outburst from (probably) a magnetar on the other side of the galaxy, which is a Soft Gamma Repeater (SGR), a different thing again.
Re: (Score:1)
magnetars (Score:2)
Re:Correction... (Score:2)
TRex to Big mouse thinggy. I am going to eat you.
Mouse: I am getting angrrrrrrryyy. Rarrrr! Mouse Smash!!
THen the mouse beats up the TRex
Re:Correction... (Score:1)
Re:Correction... (Score:2)
Re:Correction... (Score:2)
Where were you last December? The most luminous gamma ray event in the history of measurement occurred based on a gamma ray burst on the other side of our own galaxy. That particular event was cause by starquake and crustal reorganization of a magnetar, a rare type of event expected to explain a small p
Re:Correction... (Score:2)
Gravity Waves (Score:4, Informative)
free music, games, recipes, and more! [earth2willi.com]
Re:Gravity Waves (Score:3, Informative)
We are pretty sure it is a wave because we have seen the effects of gravitational radiation (of waves) in double neutron star orbits. If gravity isn't waves, then general relativity is in trouble, which is unlikely.
Re:Gravity Waves (Score:3, Informative)
The paper itself suggests that observing the waves from such an event would have to wait until the "second generation" LIGOs. I assume by that it means advanced LIGO [caltech.edu], which isn't scheduled to start taking measurements until 2013, so don't hold your breath :-). Even so, LIGO is an amazing project - the sensitivities required are enormous, (to quote the LIGO website: "These changes are minute: just 10-16 centimeters, or one-hundred-millionth the diameter of a hydrogen atom over the 4 kilometer length of the
Re:Gravity Waves (Score:1)
The animation NASA had was cool... (Score:1)
Re:The animation NASA had was cool... (Score:1, Informative)
Get rich quick (Score:3, Funny)
The merger of two dense bodies causes gamma-ray bursts?
Wow! Now I can get rich selling lead underwear the next time there's a Microsoft/AOL merger hoax [re-quest.net]
Science Meets Film Noir (Score:5, Funny)
"Our observations do not prove the coalescence model, but we surely have found a lady with a smoking gun next to a dead body," said Shri Kulkarni
Looks like the Sin City [imdb.com] DVD has been getting a lot of play time down in the lab....
Re:Science Meets Film Noir (Score:1)
you don't say... (Score:1)
Amazing! And here I thought collisions of the microscopic kind caused the most lethal explosions...
A few questions about GRBs (Score:3, Interesting)
What is a typical duration?
How close would you have to be to one to receive a lethal radiation dose?
Re:A few questions about GRBs (Score:2)
b) From less than a second, to a few seconds. VERY brief.
c) A decent magentar flare or decent neutron merger within 10 light years would be enough to disrupt life (read species would die out)
The nearest magnetars are 4000-5000 light years away.
It does beg the question thoughL Which poor people got burned on this burst ?
Re:A few questions about GRBs (Score:3, Insightful)
I dont know if we _EVER_ have observed a GRB in our galaxy, the detected ones are very isotropically distributed over the sky and in the _deep_ background. Most have a z>0.1 and are FAR away.
And the killing ratio for a GRB would be more like 100-250 ly. 10 ly away even a normal supernova would be an extinction event.
Just
Re:A few questions about GRBs (Score:3, Informative)
Re:A few questions about GRBs (Score:2)
Forgive me, but have you been living under a rock the last year? SGR 1806-20 [wikipedia.org] gave rise to a gamma ray burst last December which was the most lumninous event recieved at Earth in the history of gamma ray astronomy, and it was only 50,000 light years away at the other side of our galaxy.
I'll admit, magnetar star quakes aren't as sexy as high end superno
The summary (Score:2, Interesting)
http://www.astro.caltech.edu/~ejb/faq.html [caltech.edu]
especially the portion that said ...."
In practice, over the few seconds that a gamma ray burst occurs, it releases almost the same amount of energy as the entire Universe! "
The article posted on Slashdot is on the short and hard type
Re:The summary (Score:4, Insightful)
Which is, of course, nonsense. It should say 'the same amount of energy as the visible Universe'. Big (very, very big) difference!
A brief history of time (Score:2, Funny)
Then again I could be wrong, a lot of it is over my head.
Re:A brief history of time (Score:2)
It is. Gamma-ray bursts have been observed for a long time: they were first discovered by spysats designed to watch out for nuclear test ban violations. ISTR that it was initially thought that the Soviets were trying to evade the ban by testing in deep space, but it soon became clear that these explosions were from much further afield.
The collision of neutron stars has always bee
But how does this fit... (Score:3, Funny)
So... Colliding stars, eh? (Score:2)
Actually I have a pretty good idea of what's on his site looks like. They'll be somewhere between pages about playing with metallic sodium and his beer recipes.
I don't know about you (Score:1)
Re:article is slightly misleading... (Score:3, Informative)
Re:article is slightly misleading... (Score:1)
It is quite reasonable that stars can colide on their orbits around the galactic core. takes about 200 million years for the solar system to orbit the galactic core. 2 stars could have intersecting orbits and consequen
Re:article is slightly misleading... (Score:5, Informative)
Don't they have to be damn close? (Score:2)
Re:Don't they have to be damn close? (Score:2)
First, they don't go supernova at the same time. One becomes a neutron star, and then the other. When the relationship is asymmetrical, one neutron one star, I think they have more interaction with each other. No shockwave keeping most of their materials apart. Instead material will be spiraling
Re:Don't they have to be damn close? (Score:2)
Re:Don't they have to be damn close? (Score:3, Informative)
No friction! (Score:2)
Not possible! If they are not aimed squarely at each other -- which is damn unlikely -- then they are in a mutual orbit. Could be a closed orbit, circle or ellipse, or it could be an open orbit, e.g. one executes a parabola or hyperbola about the other. But the important point is that every possible orbit is perfectly symmetrical about
Re:article is slightly misleading... (Score:3, Funny)
Dude - never talk about the space in which you would write an explanation. That's like the ultimate jinx. The last time a guy did that, it took the rest of the world 357 years to figure it out.
;)
Re:article is slightly misleading... (Score:2)
Tidal forces.
The tidal forces of the things moving around in orbit sucks energy out of the orbits (specifically, the inertia and friction overcome when the star changes shape is removed from the orbital energy).
Eventually over a long time, objects fall inwards due to this effect. (Earth is doing it too, as the Moon will eventually crash into the Earth... both if nothing else happens first. The energy gets dissapated as he
Re:article is slightly misleading... (Score:2)
2) The moon is moving FURTHER away from Earth, not closer. [cornell.edu]
If I'm not mistaken, tidal forces would INCREASE the distance between two rotating bodies, as the momentum or axis rotation is transfered to orbital momentum. The decay of orbit here happens due
You're right, they're massive enough. (Score:4, Interesting)
Actually, that's an understatement.
According to the wikipedia [wikipedia.org], a neutron star is about 1.5 times massive as the sun... and that would be about 1.5 × 2x10^30 kg = 3x10^30kg, but ONLY 12 miles in diameter. One can just imagine the gravitational force these things have.
I'd appreciate it if someone made calculation: If two neutron stars are say, 10,000 km far from each other, what will be the acceleration? (remember, the greater the mass, the greater the acceleration). And what speed will they have when they collide? Finally, what will be the kinetic force at the time of impact?
Re:You're right, they're massive enough. (Score:2)
Sure, so about 1.5 times the gravitational force of the sun?
Re:You're right, they're massive enough. (Score:2)
Re:You're right, they're massive enough. (Score:1)
Re:You're right, they're massive enough. (Score:1)
Re:You're right, they're massive enough. (Score:2)
The same amount of mass will always produce the same amount of force no matter how compressed. The difference is that you're much closer to the center on the surfa
Re:You're right, they're massive enough. (Score:1)
Diameter of sun is approx 1,400,000 km. So the gravitational field strength at 10,000 km from the centre of the sun will be considerably less than that 10,000 km from the centre of a neutron star. Also it'd be a bit warm - T-shirt and shorts weather, I think.
Re:You're right, they're massive enough. (Score:2)
Don't forget the sunscreen, either. Preferably with a LPF that ends with "e[really large number]"
Re:You're right, they're massive enough. (Score:1)
Re:You're right, they're massive enough. (Score:2)
This theory is utter nonsense. If the gravity was weak, the nucleii would not be bound together!
Proof that this theory is nonsense is that very precise observations of the orbits of binary pulsars have confirmed Einstein's theory of gravity.
Re:You're right, they're massive enough. (Score:4, Informative)
Re:You're right, they're massive enough. (Score:2)
Graviational potential energy between two bodies is -G*(m1m2)/r, so that's 6.673E-11 * (3E30*3E30)/10000km, for just about 6E43 joules, so you're a few orders off. Head-on collision between two bodies of equal mass means each contributes half of that energy,
so each one's contributing 3E43 joules. 3E30kg body would have to be moving at 4472135 m/s to do that. That's 1.49% of c, so it's not strongly relativistic, with a gamma of 1.00011113.
Re:You're right, they're massive enough. (Score:2)
Re:You're right, they're massive enough. F!=a. (Score:1)
Re:You're right, they're massive enough. F!=a. (Score:1)
Force of attraction = G * m_1 * m_2 / r^2
Thus, acceleration of first body = G * m_2 / r^2 which is proportional to the mass of the second body. Similarly the acceleration of the second is proportional to the mass of the first. I think this is what the GP meant - heavier stars, more accn.
Re:They explode, hence blackholes are a impossibil (Score:1)
Unfortunately these ideas are so institutionalized that there won't be much respect paid to challengers.
Re:They explode, hence blackholes are a impossibil (Score:2, Insightful)
people don't believe they exist just because of a GR solution.
they were predicted before GR but believed to be a mathematical trick that would need perfect conditions to form (perfectly symmetrical mass distribution). GR just changed that by removing these conditions (the generation of gravitational waves by mass distributions with a quadrupolar mome
Re:They explode, hence blackholes are a impossibil (Score:2)
Your demands are very high. Providing alernative theories/explainations for observational data most physicists don't know exist is quite out of my reach. (after all physics has gone under the same brutal specialization that other fields have)
By the same token, I could criticize your statements as dubiously adherent to an entrenched model that you probably know far less about than you're letting on.
Re:They explode, hence blackholes are a impossibil (Score:2)
You could, but you'd still be in the uncomfortable position of finding (if you ever bothered to do your own investigation into the matter) that GP's theories fit very well with our current understanding of the universe, and that you don't have a better alternative. It's a "put up or shut up" kind of deal.
Re:They explode, hence blackholes are a impossibil (Score:2)
If you get tired of posting here, I'm sure the ID'ers would welcome your support.
Simple fact is, theories that get entrenched tend to do so for a reason-- they fit the currently available data, and nobody's come up with a better explaination yet. If you don't like the current explaination (presence of ether circa 1901, black holes, evolution, etc),
Re:They explode, hence blackholes are a impossibil (Score:2)
Re:They explode, hence blackholes are a impossibil (Score:2)
Re:They explode, hence blackholes are a impossibil (Score:2)
I might not consider intelligent design in quite the same fashion as many of it's other proponetns, but, if you're willing to accept my stepping out onto the metaphysics branch,
Re:They explode, hence blackholes are a impossibil (Score:2)
Re:They explode, hence blackholes are a impossibil (Score:3, Interesting)
Despite what you may believe, physicists will listen to challenges to almost any theory (and are proven wrong on a regular basis, science advances!). However, if you just sa
Astronomy vs Science (Score:2, Informative)
What this implies is that astrophysics, as practiced, is no more science than, say, sociology. Whenever current astrophysical theories are falsified by observation, a fundame
Re:Astronomy vs Science (Score:3, Insightful)
You have something against sociology? It's a science too. And ALL sciences are practiced by human beings, who need to be convinced by evidence -- as they should.
This, of course, is nonsense. The vast majority of new astrophysical phenomena find explanations within current physics.
Re:Astronomy vs Science (Score:2)
Ha ha. Most sociologists remain Marxists.
All of those observations SUPPORT Big Bang cosmology, rather than contradict it.
Only if you ignore the evidence. Light-element isotope ratios were once trumpeted as supporting the Big Bang. Now that they don't match current models, they aren't discussed at polite conferences. Galactic gravitational lensing puts a strict upper limit on mass, leaving no place to put the dark matter. (Unless... yes! Dar
Re:Astronomy vs Science (Score:1)
Most /. moderators would not recognize mainstream cosmology and astrophysics if it hit them in the face, thus I suspect that systematic discrimination against challenges to it are products of an overactive, paranoid imagination.
From what I have heard talking to several astrophysicists is that they are as uncomfortable with dark energy and inflation as the next guy (dark matter is a little
Re:Astronomy vs Science (Score:2)
The evidence, if you bother to examine it, suggests otherwise. Certainly it's not necessary actually to know anything to moderate down criticism of the referenced articles. The timing suggests that when certain individuals get mod points, they go back and moderate down whatever they have seen recently that t
Re:They explode, hence blackholes are a impossibil (Score:3, Informative)
Re:They explode, hence blackholes are a impossibil (Score:1)
It doens't disappear, it just pushes the universe. ;)
Re:They explode, hence blackholes are a impossibil (Score:1, Informative)
Re:They explode, hence blackholes are a impossibil (Score:2)
Re:They explode, hence blackholes are a impossibil (Score:2)
Furthermore, angular momentum and energy are tw
Re:They explode, hence blackholes are a impossibil (Score:2, Informative)
http://www.wonderquest.com/black-holes-proof.htm [wonderquest.com]
Summarizes very neatly the default hypothesis that they exist
This leaves aside the problem of coming up with a better theory than GR (which has been extensively tested)
After all, the theory of black holes has been contested vigorously from its inception http://en.wikipedia.org/wiki/Chandrasekhar_limi [wikipedia.org]
Re:They explode, hence blackholes are a impossibil (Score:2)
There are alternatives, for example the gravastar:
http://www.absoluteastronomy.com/encyclopedia/g/gr
Such alternatives would yield the same observations.
There are major problems with current black hole theory - for example, the information paradox, and the central singularity. I think it is pretty reasonable to state that current black hole theory is at the very least incomplete, if not
Re:They explode, hence blackholes are a impossibil (Score:1)
Or did you miss the recent discovery that gravity does not exhibit quantum effects? It was actually posted on here a few months ago.
That's not to say we will never have a quantum gravity theory, but simple 'gravitons' seem unlikely. Gravity just does not work like the electronuclear forces.
A lot of people have built a quantum gravity house of cards, but those peopl
Re:They explode, hence blackholes are a impossibil (Score:2)
That is like saying that electrons can't exist because we don't understand what they are! Just because we don't have a theory of quantum gravity does not mean that gravity does not exhibit quantum effects.
Or did you miss the recent discovery that gravity does not exhibit quantum effects? It was actually posted on here a few months ago.
I did. URL?
That's not to say we
Re:They explode, hence blackholes are a impossibil (Score:2)
Sorry for previous comment - I assumed you meant Hawking's recent conjecture that black holes can emit information.
The emission of energy does not help the information problem, as the energy emitted bears no relationship to the material that made up the black hole.
Re:They explode, hence blackholes are a impossibil (Score:2)
No sorry - it definitely bears no relationship at all - it is purely an interaction between the vacuum and the warped space of the event horizon. It is entirely and provably random.
Re:They explode, hence blackholes are a impossibil (Score:5, Informative)
If you'd like to learn more, type "nuclear binding energy" into Google.
Re:They explode, hence blackholes are a impossibil (Score:1, Informative)
Re:They explode, hence blackholes are a impossibil (Score:2)
Re:They explode, hence blackholes are a impossibil (Score:3, Informative)
This is false. Fusion of atoms only releases energy if the atoms are light. Above a certain nuclear size (greater than Iron) fusion takes energy.
Re:They explode, hence blackholes are a impossibil (Score:5, Informative)
That isn't really the primary (theoretical, of course) reason that massive stars "explode" (keep in mind, this is nothing like an explosion as any human understands it). However, the continuing fusion of heavier elements, up to iron, is thought to be the reason for numerous changes a late-lifecycle star experiences.
Once a massive star reaches the point where the majority of exothermic fusionable material consists of silicon, it has very big problem on its "hands." It's got about a day to live. silicon fuses at about 2.7e+9 K (optimimally), so that's one hell of a last day, and an unbelievable amount of iron production (thank the stars for your iron). Now, this entire time the star has been increasingly putting out more and more energy; that energy has tremendous pressure and serves to balance the star's own gravitional force which seeks to collapse it as closely to a point-source as possible (and it is, of course, theorized
At some very critical moment on the last minute of the last hour of that last day, there is no longer enough remaining silicon to keep the reaction going (some of the iron is fusing, but it's endothermic so it's only making the situation worse). Once this magic point is hit, fusion drops off very very rapidly, the remaining lighter-than-iron elements simply won't fuse without enough energy and once its gone
The details that actually occur in those few nanoseconds and microseconds are not completely understood, but it is understood that a great many bizarre interactions take place. The closest anyone can come to understanding this by way of simulation is in a particle accelerator. For one brief moment, this former mega-sized celebrity of a star takes on the apparition of the big bang; unification of forces and other outlandish stylings that no mortal human will ever witness up-close (or would want to if you're half-sane).
So, what really causes supernovae? Gravity winning.
Re:They explode, hence blackholes are a impossibil (Score:2)
I never thought I'd use physics notes for a post on
Re:They explode, hence blackholes are a impossibil (Score:2)
Cheers!