Slashdot Mirror
Scientists Spot Rare 'In Between' Black Hole
An anonymous reader writes "Scientists have found a doomed star orbiting what appears to be a medium-sized black hole. This black hole appears to be a theorized 'in-between' category of black hole that has eluded confirmation and frustrated scientists for more than a decade."
...gray hole?
Authority questions you. Return the favor.
It's a trap!
[Fuck Beta]
o0t!
saved for posterity before it gets slashdotted
Dying Star Reveals More Evidence for New Kind of Black Hole
Submitted by BJS on Sun, 2006-01-08 11:58.
Posted in space | login or register to post comments | printer friendly page
Scientists using NASA's Rossi X-ray Timing Explorer have found a doomed star orbiting what appears to be a medium-sized black hole - a theorized "in-between" category of black hole that has eluded confirmation and frustrated scientists for more than a decade.
With the discovery of the star and its orbital period, scientists are now one step away from measuring the mass of such a black hole, a step which would help verify its existence. The star's period and location already fit into the main theory of how these black holes could form.
A team led by Prof. Philip Kaaret of the University of Iowa, Iowa City, announced these results today in Science Express. The results will also appear in the Jan. 27 issue of Science.
"We caught this otherwise ordinary star in a unique stage in its evolution, toward the end of its life when it has bloated into a red giant phase," said Kaaret. "As a result, gas from the star is spilling into the black hole, causing the whole region to light up. This is a well-studied region of the sky, and we spotted the star with a little luck and a lot of perseverance."
A black hole is an object so dense and with a gravitational force so intense that nothing, not even light, can escape its pull once within its boundary. A black hole region becomes visible when matter falls toward it and heats to high temperatures. This light is emitted before the matter crosses the border, called the event horizon.
Our galaxy is filled with millions of stellar-mass black holes, each with the mass of a few suns. These form from the collapse of very massive stars. Most galaxies possess at their core a supermassive black hole, containing the mass of millions to billions of suns confined to a region no larger than our solar system. Scientists do not know how these form, but it likely entails the collapse of enormous quantities of primordial gas.
"In the past decade, several satellites have found evidence of a new class of black holes, which could be between 100 and 10,000 solar masses," said Dr. Jean Swank, Rossi Explorer project scientist at NASA's Goddard Space Flight Center, Greenbelt, Md. "There has been debate about the masses and how these black holes would form. Rossi has provided major new insight."
These suspected mid-mass black holes are called ultra-luminous X-ray objects because they are bright sources of X-rays. In fact, most of these black hole mass estimates have been based solely on a calculation of how strong a gravitational pull is needed to produce light of a given intensity.
Kaaret's group at the University of Iowa, which includes Prof. Cornelia Lang and Melanie Simet, an undergraduate, made a measurement that can be used in the equation to directly calculate mass. Using straightforward Newtonian physics, scientists can calculate an object's mass once they know an orbital period and velocity of smaller objects rotating around it.
"We found a rise and fall in X-ray light every 62 days, likely caused by the orbit of the companion star around the black hole," said Simet. "The velocity will be hard to determine, however, because the star is located in such a dust-obscured area. This makes it hard for optical and infrared telescopes to observe the star and make velocity calculations. Yet for now, knowing just the orbital period is very revealing."
The suspected mid-mass black hole, known as M82 X-1, is a well-studied ultra-luminous X-ray object in a nearby star cluster containing about a million stars packed into a region only about 100 light years across. A leading theory proposes that a multitude of star collisions over a short period in a crowded region will create a short-lived gigantic star that collapses into a 1,000-solar-mass black hole. The cluster near M82 X-1 has a high-enough density to f
If stars had been given categories like 'Doomed', i think i'd have paid more attention in my astronomy course. What Would Chandrasekar Do?
-AlexC
anyways, someone care to explain this for me?
Yes- The gas circling the black hole, outside the event horizon, heats up due to friction. It gets hot enough to emit light along with UV, xrays, and often gamma rays. This gas isn't inside the black hole, so light can still get out. Once it falls into the black hole, no more light comes from it, but before then, there is usually a lot of light.
Once light crosses the event horizon, it cannot escape. As matter approaches the event horizon and accelerates, it becomes excited and emits energy in the EM spectrum. The faster it goes, the higher the frequency (from IR to visible to X-ray). A large black hole would be able to attract large amounts of matter, and that matter would accelerate very quickly, and thus would shine (in the X-Ray range) very brightly.
In fact, you said it perfectly yourself without realizing it. Light is escapeing from the vicinity of the black hole, not the black hole itself.
my pet machine
I think elements heavier than iron (the heaviest element that can be produced by fusion while making energy, rather than using it) are formed *during* the supernova, which only lasts a few seconds (or maybe hours/days - ask an expert - it doesn't matter though) and don't have time to fall to the centre because they're already exploding outwards - it's the explosion itself that produces them (pressure wave causes high density, causes fusion).
The key to creating heavy elements is a large neutron flux from the supernova. Nuclei pick up lots of neutrons quickly during a time span of a few seconds (shorter than the free neutron half life of 13 minutes) and then undergo a quick succession of beta decays followed by a longer beta decay series over millions of years to form stuff like gold and uranium.
A thought just occured to me. They say nothing can escape from a black hole due to it's huge gravity. Not even light. We know photons are the carriers of the electromagnetic force, one of the 4 fundamental forces in nature. I believe we have identified the carriers of the nuclear strong force and the nuclear weak force as well. But the suposed graviton has remained elusive and unidentified. By their very nature, though, shouldn't we be able to conclude that in order for black holes to generate such intense gravitational fields, they must allow their own gravitons to interact with nearby objects? In other words, the carriers for the force of gravity must be allowed to escape the black hole in order to exert that very force. Wait a minute....I can't be saying that right. Let's try again, suppose communication through an event horizon is possible - with gravity waves.
?????
Profit?
Stay sentient. Don't drink bad milk.
What scientists spotted it? What scientists were frustrated? I'm really tired of stories sourced to 'scientists' and 'officials'. I'm sure that TFA has some of the material that I want, but that's not the point. On a by-the-word basis, the internet is, for all intents and purposes, free. Putting 5-7 words of additional information in the story wouldn't break the bank and it would really make this thing feel less lazy.
One way to think about how black holes work is to think of a general potential energy well. Once the black hole gets to a certain mass, there will be a region in which the energy of a photon is less than that to escape the gravitational potential energy well (i.e. the photon is now in a bound system). There are many bound systems that occur in nature (our solar system, electrons around an atom, nucleons in the nucleus, etc.), but they are bound by only one force. Unless a graviton can exert a force on another graviton (which of course assumes that a graviton exists), there is no reason to believe that a graviton will be gravitationally bound in a black hole. As far as general relativistic issues, a graviton will have the same significance as a photon, in theory. It will travel at the speed of light relative to any particle. It is important to remember, that you can use the geometric considerations of general relativity (which doesn't define a graviton), or the views of geometrodynamics (quantum theory of gravity where gravitons are the force carriers), but not both at the same time. You can say gravity curves space, but you can't say the gravity curves 'gravity' (or affects gravitons).
In fusion, most things up to Iron can be produced.
Um. No. A fusion reaction can create any substance up to uranium and beyond. In fact, humans are continually creating substances beyond uranium (plutonium being one) through fusion reactions. It's just that fusion reactions to produce elements heavier than iron require energy, rather than giving off energy.
In the early stages of a star's life, it's fusing hydrogen atoms to produce helium. This is the most energetic fusion reaction, and is the only fusion reaction we're likely to be able to sustainably exploit to our own ends through artificial means. As the star grows older, and has less hydrogen, it will increasingly generate its energy through other fusion reactions, producing elements up to iron. (These reactions will occur throughout the star's life; it's just that they will become proportionally more important as the star ages.)
Eventually, the energy produced through these fusions will die off, and the star will undergo gravitational collapse. During this phase, the energy consuming fusion reactions will occur, generating the heavier-than-iron elements. This phase only occurs in massive supernova; it won't happen in our sun -- it's not big enough.
I have had a martini made with Old Raj so bare with me and my grammer, please. A black hole is an object whose mass vs radius is smaller than the shwartz (somehting or another) radius, meaning that a black hole need not be made of a lot of material. You could theoretically make a black hole with only a few atoms, provided their shwartz(and some stuff) raduis was suffiecently small. The shwartz* radius is related to the inverse square law of gravity. In otherwords blackholes need not be menacing and made of a lot of matter. One of the accelerators someplace was making very small blackholes to study them. Their gravity wasn't particularly scary, they just had a radius small enough that light could not escape the miniscule gravitational feild. This concludes your episode of poor spelling and grammar, thanks for reading.
I am a physicist. Two points: Information cannot come out of a black hole. This is why hawking radiation is high entropy. Information is lost. A chair falls in. Hawking radiation comes out, much higher entropy which is a loss of information. Nothing can pass outwards through the event horizon. Well, nothing with positive mass, positive energy, velocities less than or equal to the speed of light, essentially, nothing that is currently recognized as real. Pink unicorns...maybe... Hawking radiation does not pass outwards through the event horizon. It is a quantum mechanical process that occurs outside the event horizon, and involves anti-particles falling into the blackhole. Gravity does not have a well understood mechanism. My field is stellar astrophysics, not string theory or fundamental physics, so i don't know the current cutting edge in those fields well. However, in practice, we understand very closely how gravity acts on objects, we can very precisely predict its effects. We don't really know much about the mechanism. There's a lot of theorizing in some circles, but with no experimental data to verify any of it, its not really meaningful.
There are three ways in which elements heavier than iron are produced. In two (s and r process), the basic process is to add neutrons one at a time to a nucleus. In the p process, protons are added one at a time.
What you describe is the r (rapid) process. A very high neutron flux adds neutrons very quickly. Once the neutron pulse has passed, the highly-neutron-rich nuclei beta-decay (neturon turns to proton) multiple times until a stable element is reached.
The s (slow) process has a low neutron flux, so that there is sufficient time after each neutron is absorbed for beta decay to occur. The neutrons come from a comparatively neutron-rich nucleus left over from the CNO cycle for burning hydrogen (N15?) At sufficient temperature/pressure, it starts to lose its excess neutron. The new heavy nuclei can then convect to the surface of the star and escape in the stellar wind. The detection of technetium (which has no stable isotope) in the spectra of these stars is the smoking gun proving this scenario.
I don't know much about the p process.
The r and p processes occur in supernovae. The s process occurs in red giant stars (strictly, asymptotic giant branch stars.) In terms of importance in creating heavy elements on the earth, s process is most important, followed by r process and then p process. From memory, it is something like 90% s proccess, 9% r process, 1% p process, but that is *very* rough.
Now we need a q process, so we can p, q, r and s processes. (Or S, P, Q, R if you're a Romanophile.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.