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Chandra Sees Black Hole Rip Star Apart
beeplet writes "Nasa just sent out this press release titled about an exciting Chandra observation. It states: "Thanks to two orbiting X-ray observatories, astronomers have the first strong evidence of a supermassive black hole ripping apart a star and consuming a portion of it.
The event, captured by NASA's Chandra and ESA's XMM-Newton X-ray Observatories, had long been predicted by theory, but never confirmed."
There is more information on the Chandra home page, including the x-ray and optical observations that were involved in the discovery." Note that the star-ripping pictured on the front page is labeled an illustration, rather than an recorded image.
The site is becoming a little slow already, so here is a text-only version. The http://chandra.harvard.edu site seems to be slashdoted already.
Here's an interesting site (google cache) about black holes. I'm not sure how long it would take, but to an outside observer, it would seem like forever, relatively speaking. :)
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The phenomenon is termed "large-amplitude X-ray variability." It appears that they've finally advanced their models and observation techniques to the point where they are willing to state publicly that this is indeed caused by a black hole. But it's been suspected for years and years.
The X-rays are not emitted from the center. They are emitted from outside the event horizon by hot gas (millions of degrees) orbiting at huge velocities. Centrifugal force spins the gas out into an "accretion disk" and superheats it as it slowly spirals into the black hole.
We don't have to be outside the solar system to see gravitational waves, but even LIGO wouldn't be sensitive enough to see gravitational radiation from something like this. At best, LIGO might be able to see a neuton star spiralling into a super-massive black hole, because it would be able to fall further in before being torn apart by tidal forces.
The gravitational patterns around a black hole are like that of a star until you get very close to it. Just imagine what would happen if a star passed within the planetary space of the Sun. All the planetary orbits would be perturbed. Earth would probably freeze or burn.
If by some astronomical chance the Earth collided with this black hole the planet would be torn apart first by the differential effect of gravity from the black hole. As an object gets closer to a massive gravity sink it orbits more and more quickly, so the close part of the Earth would be torn from the far part. This process would continue until nothing but gas and sand was left.
Then this material would rub against itself while orbiting the black hole at high speed, giving off all kinds of EM energy. Eventually the orbits of this debris would decay and would slip inside the event horizon. The contents of that sphere cannot be explained by physics.
So to answer your question, I think what would probably happen is that first most people would die of starvation as all plants die from the extreme heat/cold. Then most of the remaining survivors would die of asphyxiation as the atmosphere gets ripped off the planet. Then if anyone was left they would be ripped into a fog of dead cells.
But the bright side is we would probably have plenty of time since we would almost certainly detect a black hole years before it contacted our system. We would see the perturbations caused by its gravity, and black holes cause all kinds of interesting EM radiation when they get close to matter.
I know, I know, this is slashdot, and people can't really be bothered to read the articles... but when someone actually links to something, I expect *them* to have read their own article!
:)
"this too should form black holes. These will be about a million times smaller than the nucleus of an atom and will survive for barely an instant.
The physicist Stephen Hawking predicted in the 1970s that black holes would evaporate by radiating away their energy. For astrophysical black holes this is a very slow process, but extremely small black holes should last about as long as a snowflake in hell."
You can stop building that black hole shelter now
People, please get that streight: In empirical science (that's pretty much any science besides math and philosophy), *nothing* can be proven. You can observe *evidence*, and can *disprove* a theory by providing contradicting evidence. But one can not prove a theory, by definition. You can show it's consitent with other theories. But you can't prove it has anything to do with *reality* (whatever that is). Teach your selfs some basic epistomology/phenomenology.
Ok. Now to black holes: IANAPhysicist, but as far as i know even though black holes can not be observed *directly* you can very well observe their effects like gravitational distortion, the radiation emitted by matter being sucked in, and according to S. Hawkings also a type a quantum radiation which causes black holes to evaporate over time (i'm not claimin i understood that).
As to the question of wether black holes are real? -- WE JUST DON'T KNOW. But i like the idea...;)
end of rant.
I have discovered a truly remarkable sig which this 120 chars is too small to contain.
There are a number of experiments that show that an object exists at a particular location with an enormous mass and an incredibly small radius. No other object than a black hole fits the data, so we take this indirect evidence as proof of the existence of black holes. From my point of view, the best evidence is the orbit of stars around the black hole at the center of the Milky Way. Check out a movie here.
http://apnews.myway.com/article/20040218/D80PREA80 .html
includes "illustration"
i thought black holes were not proven to exist, or am i living in the past?
It depends on what one means by "exist," I suppose.
The phenomenological data supports the existence of black holes, very clearly and without controversy. But what "exists" within the event horizon (the radius at which the gravitational force equals the speed of light) of the object we call a black hole is unobservable, and cannot be described by standard models.
Consider that the time dilation at the event horizon is "infinite" according to relativity, thus an infalling particle would require infinite time to cross this boundary. On the other hand, the lifespan of the "black hole" is, according to Hawking, finite. Thus, the event horizon would evaporate before the particle crossed it.
Alternately, the particle might "quantum jump" across the event horizon, this was suggested to me by Dr. Michael Shara at the Space Telescope Science Institute (Johns Hopkins) about 15 years ago. If he's right, black holes may indeed exist.
Or, the particle might be negated by a Hawking anti-particle before it crosses the event horizon.
Finally, the particle might only cross the event horizon when it evaporates, which is to say, if and when the black hole becomes a white hole.
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All the sites seem to be slow, and the Chandra site seems to be down, so I have put up some mirrors.
Chandra article mirror here.
NASA article mirror here.
Picture of rxj1242 is here.
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Incorrect, Einstein's theory has allows for "gravity waves," i.e. you can find a periodic propagating solution for the stress-energy tensor that "looks" like a wave traveling through, or in this case, by, distorting space-time.
Similar to classical E+M, which allows E+M waves, GR doesn't state that these are propagators of the force just solutions that exist.
Hope this clarifies.
I'm talking primarily about the resolution (Chandra resolution is 0.5 arcseconds, ROSAT resolution like 50 arcseconds). XMM also has a huge improvement in collecting area which may be something like 100 times better sensitivity, at least for harder energies, but I'd have to look up the numbers for a quantitative comparison. I think it's fair to say in general that the new X-ray telescopes are a couple of orders of magnitude "better" (in terms of resolution and sensitivity) than the previous generation of X-ray telescopes like ROSAT. Not to denigrate ROSAT, which was great for its time and produced wonderful science.
Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)
That's pretty much what's happening, except (for the picky bastards out there):
Even as you read this, your pants are strangling your loins! Aaa!
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Those screaming about her left boob, which was the one left covered, were not social conservatives, but rather the strip club crowd.
There really isn't much to fear from getting sucked into an artificial black holes, from being turned into strange matter, or from other proposed Armageddon scenarios. This is explained in this article from Popular Science and this paper on speculative Disaster Scenarios at another particle collider. Basically, there is a large probability that - if these objects are really dangerous - then they would have been already been produced by natural particle collisions in outer space near enough to destroy the earth. Since we exist, these objects can't really be dangerous!
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dear golly. there is NO CHANCE of the black holes being produced being a danger to anything for a number of reasons.
1. many more, much much larger (but still very small) black holes are constantly being created in our atmosphere by cosmic rays. these have not swallowed the earth. the energy of the collisions we can create is still insignifigant compared to what occurs naturally.
2. black holes do not attract matter because they are black holes. they attract due to gravity, just like planets, stars and all other matter. we are creating black holes the size of subatomic particles. A black hole the size of a proton has exactly the same gravitational pull as a proton. A protons gravitational pull is not going to cause any effect on anything. remember gravity is the weakest force that exists. by a whole lot. gravity is not amplified because it is eminating from a singularity rather than a particle.
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you are simply wrong.
1. "our" understanding is that any massive particle travelling at less than the speed of light (in a vacuum) cannot be accelerated up to the speed of light. [it is possible (but AFAIK all attempts to detect have given a null result) that faster-than-light particles (tachyons) exist, but they would be created with speeds > light in the first place.]
2. in certain x-ray experiments you can have x-rays for which both the phase and group speeds are greater than the speed of light. however, they are highly dispersive and so cannot be used for communications. hence the more accurate version of your statement is "information cannot travel faster than the speed of light".
3. in the quantum-mechanical view, light travels from A to B with all speeds and along all paths, however the different paths interfere destructively such that the most probable path by far is in a straight line at speed c. the effect of these different paths is seen in interference experiments, most famously Young's double-slit experiment.
no I didn't see that particular story, I guess I was too busy actually *doing* physics.
dark matter isn't actually the basis of many theories (or at least not any good ones), it itself is a theory to account for observations.
Yes, you're right in general but the problem is that X-rays tend to go through things like mirrors if you build a conventional mirror. To focus them you need to use glancing angles and this means that you need to build enormous and super accurate mirrors to get the equivalent of any substantial diameter. The Chandra mirrors are probably the finest optics ever produced and consist of nested, gold-coated paraboloids (I think) that cost some $200 million just on their own.
Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)
Centrifugal force spins the gas out into an "accretion disk" and superheats it as it slowly spirals into the black hole.
Well, technically there's no such thing as centrifugal force, it's just an expression of angular momentum.
Yes, it's a nitpick.
m-
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because they are predicted by general relativity, so if they don't exist there must be something very wrong with general relativity.
also, many explanations of observations rely on them, such as active galactic nuclei (AGN). these are very bright galaxies, emitting ridiculous amounts of energy. black holes explain them perfectly, so if we don't have black holes we have a very big problem of what's causing all this radiation.
black holes are actually the most efficient "engines" known, far more efficient that nuclear fusion that powers the Sun and maybe one day our power stations.
Actually you're definition of a blackhole is a bit off.
Every object has a point at which gravity is so intense that light cannot escape it. This is called the schwarzschild radius. However, black holes are unique in that their radius lies OUTSIDE the object, whereas every non-black hole object's radius lies INSIDE the object.
The earth, even you or I have this radius too. For the earth however it is underground; were you to attempt to approach it (by digging down for instance) gravitational force would decrease as you decsended. As this force decreases the schwarzschild radius would decrease as a result. Thus you would never be able to reach the schwarzschild radius of the earth because it would always be receeding from you the closer you approached it.
Two black holes that come too close together will simply merge, becoming a single black hole with the combined mass (or nearly, as some will escape in the form of gravitational radiation during the merger). Such mergers (between stellar-mass black hole binaries, for example) are one of the things LIGO should be able to see in the near future...
One theory of supermassive black holes at the centre of galaxies is that they formed by successive mergers of smaller black holes as smaller galaxies collided to form larger ones. There have been observations of binary black holes in some galaxies, and these will eventually merge... It won't look like anything spectacular to the naked eye, though, since the only energy being released is in the form of gravitational waves.
The merger won't be that simple, the black holes will most likely end up orbiting each other, and emitting very powerful gravitational waves in the process. The waves will leech orbital energy from the system, causing them to fall closer and closer together, increasing the wave frequency as they go until a final massive gravitational wave burst as one reaches the other's event horizon and it merges into a new rapidly rotating black hole. It should be a very easily recognizable signature from ligo, assuming ligo works as planned.