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Thread: Kuiper belt

  1. #1 Kuiper belt 
    Forum Ph.D. Steve Miller's Avatar
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    Hello everyone.

    I recently read about an (actually I believe it's the first one ) exoplanet orbiting an distant star. The star was surrounded by a belt of debris and our sun was surrounded by such a belt of cosmic objects as well. This belt was known to the public as Kuiper belt.

    I'm probably one of the few who not had an immediate notion of the Kuiper belt and of what it was. I'm reading about it at Wikipedia and I'm finished reading the article almost.

    What I think was a little said was, the article does not provide a clue to how this field of debris has accumulated. I mean, I understand it's the actual mass our sun as well as earth and all the planets, the moon and other celestial bodies are conglomerated of, mainly.

    What has not been mentioned in the article was where the Kuiper belt itself came from. This belt was pretty much local and it was the source for our solar system as far as I understand, but where came all the debris from? Do you have a clue to this question?

    Thank you,
    Steve


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  3. #2  
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    As shown in this sequence, a protoplanetary disc is a typical by-product during star formation. Stars are formed from clouds of gas and dust that collapse due to their self-gravity. Even a very small initial spin of one of the embedded cores is increased during the collapse (conservation of angular momentum). Not all material is used - especially in the outer regions of the disc - to form planets. So, the Edgeworth-Kuiper belt is predominantly made of very primordial material left over from the star and planet formation process.


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    Forum Ph.D. Steve Miller's Avatar
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    Hello Dishmaster,

    I thought it's a phenomenon not left over by the formation process of the solar system but that it was there before. Would be interesting. The milky way was another accumulation of several other objects, right. There might be similarities I thought.

    It's logical somehow.

    Doesn't there have to be additional mass for the solar system to structure?

    Steve
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  5. #4  
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    It is a widely accepted hypothesis that this belt is the residual of the formation process of our solar system. The only mass that has existed before the sun and its planets was the dark cloud they were born from. This is happening in different regions of space all the time. How actually such clouds are formed is still unknown and a topic of research. It is clear, however, that much of the ingredients is material of a earlier generation of stars.

    First you have a large cloud of gas (mostly hydrogen, helium and carbon monoxide) and dust (carbon/graphite and silicates=sand). The current standard theory introduces perturbations (possibly galactic density waves) that form random densifications which again can collapse under self gravity, if certain conditions are met. During the collapse, the initial quite cold material (10 - 30 K) heats up to thousands of K until a compact core is formed, the protostar. With the collapse the outer material is flattened to a disc. Eventually, the protostar shrinks even more until the fusion process in its core ignites. At the same time, the viscous disc produces planets, as long as enough material is around.

    The EK belt seems to be a product that is stuck in the planet formation process and formed only relatively small and icy objects, also called proto-comets. The also hypothesised Oort cloud would stem from the early phase, when the proto-solar system was still more a sphere than a disc.

    The formation of galaxies is a different thing.
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  6. #5  
    Forum Ph.D. Steve Miller's Avatar
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    I only was a little curious about how the extra material has become so dense there. The milky way was not the entire galaxy btw. (just to make sure ). I was aiming thereupon since the galaxy was existent in both cases already and surly had a profound effect on the formation of the solar system as well as on the formation of the milky way therefore. If not the galaxy however, then but the black hole the galaxy shapes around spiral like.

    Additionally, the matters were to differ between. Let's say there was a gaseous cloud ones where now our solar system was and an other enrichment of matter known as the milky way. Now as I'm getting there, the gaseous cloud could very well have to be seen in association to the milky way, just like a result of the existens of the accumulation of matter known as the milky way. But, in both cases, it's kind of a same or common pattern, meaning, at some (random ) place some sort of matter gathers for a, like I would say, pretty much still unknown reason at all.

    Steve
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  7. #6  
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    Well, the existence of heavy elements on Earth should tell us that our solar system didn't start as a cloud of hydrogen, but rather as left over components of another, more massive star.

    I don't think there's any iron clad rule that says the components of a star that goes supernova can't stay in clumps as they fly apart. Am I wrong about that? Is there some requirement that the supernova-ing star has to eject its matter in the form of discreet particles, or dust, rather than clumps?



    My take on the Kuiper belt is that, since it sweeps out a larger area than any of the near planets' orbits sweep out, it simply hasn't had time to fully form into planets. It stands to reason that it would take longer if there's more space.
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    Forum Ph.D. Steve Miller's Avatar
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    Hi kojax,

    what about the forming of a black whole in place of where the star once was? Don't had the debris be scattered further than the reach of the Kuiper belt? And why a second star should originate rightly after he first one has gone? The blast had moved all the matter off the position of where the star now was in fact. Does it make sense?

    Steve
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  9. #8  
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    Quote Originally Posted by Steve Miller
    Hi kojax,

    what about the forming of a black whole in place of where the star once was? Don't had the debris be scattered further than the reach of the Kuiper belt?
    It depends upon the size of the Black Hole concerned. If a star goes nova (or supernova), it can do so with a mass only a few times greater than that of our Sun's. The gravitational effects at a distance (Kuiper belt, Oort cloud etc) would not be too hugely different.

    What is special about a Black Hole is not the gigantic mass, rather it's the tiny radius by comparison. As the Swiss collider brouhaha showed, even single protons can become Black Holes, but absolutely nobody need move out of the way to avoid being sucked in.

    In certain circumstances, for instance, even a body with the mass of our Sun could become a Black Hole. If it replaced our Sun (a thought experiment only) we would lose the light and heat we currently gain from it, but gravitationally we would be in exactly the same position.

    Quote Originally Posted by Steve Miller
    And why a second star should originate rightly after he first one has gone?
    Any group of massive objects, whether in the form of a cloud or a star, exerts gravitational force on all its component parts. If a large part of the debris from a nova does not have terminal velocity (at the point of explosion), it will eventually contract back into a ball as it loses momentum and the force of gravity takes over.

    Consider this in the light of Newton's simplification: the centre of gravity of a sphere can be considered the point from which the gravity interacts with other objects. It does not matter whether the sphere is made out of iron-rich minerals, or clouds of space dust.

    Quote Originally Posted by Steve Miller
    The blast had moved all the matter off the position of where the star now was in fact.
    Perhaps the explanation above of contraction due to gravity will help clarify this.

    In addition, consider that any debris 'blown off' by a nova or supernova, has to go somewhere in space, it does not cease to exist. There are, and will probably always be, areas of slightly higher matter concentration in space, and these can attract more floating space dust and get into a feedback cycle as the mass grows and attracts more passing matter etc until there is enough to form a solar system, or even a galaxy. It may not be at the exact location of a former nova (but how would you define that exact place in any case?) but could still be considered a product of it.

    Quote Originally Posted by Steve Miller
    Does it make sense?

    Steve
    I can see where your questions are coming from. Here's hoping you find some of these responses adequate.

    cheer

    shanks
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  10. #9  
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    Quote Originally Posted by kojax
    Well, the existence of heavy elements on Earth should tell us that our solar system didn't start as a cloud of hydrogen, but rather as left over components of another, more massive star.
    Of course, the mixture of the initial material from which stars are formed can change from star to star. I vaguely remember that there were some claims that the sun formed in an area, where the iron rich remnants of a supernova or a planetary nebula was around to form the local cloud from which the sun emerged. So, it is well possible that we witness an enhancement of the iron abundance, but that does not mean that the immediate remnants of a previous supernova or planetary nebula is still around. So, the explanation for the EK belt holds.
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  11. #10  
    Forum Ph.D. Steve Miller's Avatar
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    Hi, sunshinewarrior,

    you somewhat intercepted my conversation with kojax. Did you realize you linked in between us? Just asking. However, In general I don't think a star has such a spectacular dead as a supernova was said to have.

    I think a star will, as an oven does, simply go off at the moment all the material it consists of was burned. And let's think a star needs a galaxy to originate, some accumulation of matter would make perfect sense, however. But, for what reason matter would come together leaves me in the dark, as for now.

    It's all kind of other matter right like the gaseous cloud, or frozen ice and solid matter, but it's kinda grouped. Was the solid matter rocks as well, actually? The Kuiper belt I mean, was it solid matter like rocks. It could be remnants of other events huge celestial bodies or planetary objects have played a roll for.

    I think I read it's not.

    There was a huge amount of time such processes consume easily; and no one asking what it was going to be. Far more than anyone could compare to any other timely distance know from any duration of observable processes on earth.

    Steve
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  12. #11  
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    Quote Originally Posted by Steve Miller
    Hi kojax,

    what about the forming of a black whole in place of where the star once was? Don't had the debris be scattered further than the reach of the Kuiper belt? And why a second star should originate rightly after he first one has gone? The blast had moved all the matter off the position of where the star now was in fact. Does it make sense?

    Steve
    Well, the star that came before would have to be very massive, probably more massive than all the matter in the solar system combined. Probably many times over more massive.

    Its scattered remnants could have formed a lot of solar systems. There's no saying ours happened immediately afterward, either.

    One clue we might have as to how long ago the other star happened (though there may be others) would be the U-235 content of the Uranium found on Earth. We know it steadily decays into U-238, and that it couldn't have started at too high of a U-235 content to begin with or it would have spontaneously reacted.
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  13. #12  
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    Quote Originally Posted by Steve Miller
    In general I don't think a star has such a spectacular dead as a supernova was said to have.

    I think a star will, as an oven does, simply go off at the moment all the material it consists of was burned.
    This is wrong. As star is not a solid body that keeps its shape easily like a billiard ball. A star keeps its spherical shape because of the equilibrium of gravitation that tends to make the star collapse and the radiation pressure from the inside that keeps the star from collapsing. When the fusion stops, the radiation pressure disappears and gravity takes over. The star collapses. The final stage depends on the mass of the star, but you always get a shock wave that tears the star or its shells apart.

    For a less massive star like the sun, only the shells are expelled and the hot core remains. This is called a White Dwarf that slowly cools down. More massive stars produce a stronger shock wave leading to a Supernova of type II. As a result you can have a neutron star (highly compressed matter), nothing (the star totally disintegrates) or a black hole, where the gravity is even stronger than all known sub-atomic forces that could stabilise the stellar remnant.
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  14. #13  
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    : )

    I have just seen it from an other, rather energy dependent, perspective pondering about wherefrom a dying star would take sufficient energy to send out the massive shockwave(s )that it was said to.

    Since, why else should the star die if not therefore it was running out of energy/mass, however.

    : )

    Steve
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  15. #14  
    Administrator KALSTER's Avatar
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    As the H fusion stops, the internal radiation pressure stops and gravity compresses the innards further. This raises the temperature high enough for secondary fusion to occur involving heavier elements. This is where the energy comes from AFAIK.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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  16. #15  
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    So what this tells me, the star, perhaps the already dying star, has to structure some other, separated from each other, spaces, just like an atom to hold several to distinguish pressures.

    Once I saw such a (BBC report I think ) on TV, but couldn't really visualize how it would work in reality. The star would build a crust on top (on its actual outer boundaries ) since there it would be getting colder firstly, the report said.

    This crust then would crumble and crushing inwards and by doing so be causing the enormous shock wave. I'm hoping I recall the program rightly.

    But I never ever think this was true.

    Steve
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  17. #16  
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    So what this tells me, the star, perhaps the already dying star, has to structure some other, separated from each other, spaces, just like an atom to hold several to distinguish pressures.
    I am sorry, I have no idea what you are saying here.

    Stars don't form crusts AFAIK. It is simply as I said; the secondary fusion takes over and provides the suddent energy spike AFAIK, which we have actually witnessed.

    But I never ever think this was true.
    You haven't really explained why you think so.
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    What do you mean by saying,

    Quote Originally Posted by KALSTER
    and gravity compresses the innards further.
    ?

    Was there an inherent suction? Like the 'Newtonian' (the original ) gravity or gravitation was said to effect objects?

    Steve
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    Steve Miller. Stars work by nuclear fusion, making lighter elements into heavier elements with heat and light amongst the byproducts. At some point in a star's life, they build up a crust of heavy elements. This smothers the star and temperature and pressure builds up. At a certain point, they become too much and the star goes nova or if big enough, super-nova, blasting the crust of heavy elements away. The remainder, depending on mass will quickly shrink to a dwarf or neutron star or even a black hole.

    Stars could be said to have "shells" when burning, shells of different temperatures and densities.
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  20. #19  
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    Quote Originally Posted by Cyberia
    Steve Miller. Stars work by nuclear fusion, making lighter elements into heavier elements with heat and light amongst the byproducts. At some point in a star's life, they build up a crust of heavy elements. This smothers the star and temperature and pressure builds up. At a certain point, they become too much and the star goes nova or if big enough, super-nova, blasting the crust of heavy elements away. The remainder, depending on mass will quickly shrink to a dwarf or neutron star or even a black hole.

    Stars could be said to have "shells" when burning, shells of different temperatures and densities.
    Thanks. I would love to wait for what Kalster was about to reply.
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    Quote Originally Posted by Steve Miller
    What do you mean by saying,

    Quote Originally Posted by KALSTER
    and gravity compresses the innards further.
    ?

    Was there an inherent suction? Like the 'Newtonian' (the original ) gravity or gravitation was said to effect objects?

    Steve
    Gravity is a force of attraction between all matter that diminishes by an inverse square relation.

    While the star is burning the radiation and heat expansion pressure acts to expand the star, while the gravity pulling all the matter together acts to, well, pull the matter together. When the H fusion stops the outward pressure decreases and two pressures are no longer in equilibrium. So the star contracts under the effects of gravity. This compression heats up the core some more until it is hot enough for the fusion of heavier elements to occur. When this happens there is a sudden outward pressure that explodes the star, i.e. supernova. This is how I understand it.
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  22. #21  
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    You said 'when the H fusion stops'. This remark to me implies that the star was not one entity. Rather several other regions, which have to be distinguished; since, at the same time the H fusion stops, something else, processes probably which where observable before everywhere are being no longer observable at some of the stars regions.

    That means there are not the same processes going on all over the star. Do you think about a star that way? However, I would think the star was one equal entity, which was same at all of its regions.

    Steve
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  23. #22  
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    Quote Originally Posted by KALSTER
    Quote Originally Posted by Steve Miller
    What do you mean by saying,

    Quote Originally Posted by KALSTER
    and gravity compresses the innards further.
    ?

    Was there an inherent suction? Like the 'Newtonian' (the original ) gravity or gravitation was said to effect objects?

    Steve
    Gravity is a force of attraction between all matter that diminishes by an inverse square relation.

    While the star is burning the radiation and heat expansion pressure acts to expand the star, while the gravity pulling all the matter together acts to, well, pull the matter together. When the H fusion stops the outward pressure decreases and two pressures are no longer in equilibrium. So the star contracts under the effects of gravity. This compression heats up the core some more until it is hot enough for the fusion of heavier elements to occur. When this happens there is a sudden outward pressure that explodes the star, i.e. supernova. This is how I understand it.
    Well, not exactly.

    When H fusion quits at the core, the core contracts and He fusion starts.

    Now you have He fusion at the core, surrounded by a layer of H fusion.

    When He fusion can no longer be maintained at the core, the core contracts and C fusion starts.

    Now you have C fusion surrounded by He fusion, surrounded by H fusion.

    This process continues through Ne, O and Si fusion. Along each step enough energy is produced to prevent collapse of the outer layers of the star.

    Si fusion however produces Fe. Fe doesn't fuse except by a net input of energy. So, a non-fusing iron core begins to form.

    If the star is massive enough, this core will grow to the point that it will not be able to support itself, as even the forces keeping nuclei apart won't be enough. The core quickly collapses, leaving the levels above unsupported. In addition, during the collapse, some higher elements are formed by fusion. Since this takes an input of energy, this takes away from some of the energy produced by the still fusing layers.

    The outer layers then falls in to fill the hollow left by the collapsed core. when it hits the core, it fuses in one single blast with enough energy to not only blow off any remaining outer layers, but also to produce the heavier elements beyond Iron.
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    Uh,

    http://en.wikipedia.org/wiki/Stellar_evolution

    "Maturity

    After millions to billions of years, depending on the initial mass of the star, the continuous fusion of hydrogen into helium will cause a build-up of helium in the core. Larger and hotter stars produce helium more rapidly than cooler and less massive ones.
    The accumulation of helium, which is denser than hydrogen, in the core causes gravitational self-compression and a gradual increase in the rate of fusion. Higher temperatures must be attained to resist this increase in gravitational compression and to maintain a steady state.

    Eventually, the core exhausts its supply of hydrogen, and without the outward pressure generated by the fusion of hydrogen to counteract the force of gravity, it contracts until either electron degeneracy becomes sufficient to oppose gravity, or the core becomes hot enough (around 100 megakelvins) for helium fusion to begin. Which of these happens first depends upon the star's mass."
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  25. #24  
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    Quote Originally Posted by KALSTER
    Did you write the article?
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    Oh, I missed your post Janus. Good thing I've learned to add lots of "as far as I know"'s and "how I understand it"'s all over the place for a situation such as this. :wink:

    Did you write the article?
    I wish!
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  27. #26  
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    Do you think the processes going on all over the star are being similar, at the same time?
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    I must praise Janus' post for its precision. Indeed, dear Steve, a star is a pretty heterogeneous object. At start, the fusion transforming hydrogen into helium only takes place in the core, because only there are the temperatures high enough. The outer layers are a plasma of mostly hydrogen and helium. After a long period, the hydrogen in the core is depleted, the fusion stops and the outer layers compress the stellar core increasing the temperature there. This ignites the helium fusion with hydrogen fusion in a shell around the core. The helium produced by the hydrogen shell burning "rains down" into the core. This period is rather short, because a) helium burning is less efficient than hydrogen burning and b) there is less helium. This continues until iron is formed (high mass stars, see image below). Low-mass stars only make it until carbon. This process is the last that gains energy by fusion. At this point, gravity takes over completely and the star collapses. This produces a strong shock in the core leading to an explosion.
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    Quote Originally Posted by KALSTER
    Oh, I missed your post Janus. Good thing I've learned to add lots of "as far as I know"'s and "how I understand it"'s all over the place for a situation such as this. :wink:

    Did you write the article?
    I wish!
    Quote Originally Posted by Steve Miller
    Do you think the processes going on all over the star are being similar, at the same time?
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  30. #29  
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    As Dishmaster and Janus properly explained, not always.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    The star had to have several structured layer like chambers that also had to be compression resistant, as far as I do understand, which was unlikely the most to me due to the enormous temperature(s ) a star has got.

    I'm was referring to my own previous thoughts. ; ) Or do you think that's not the case, necessarily?

    Steve
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    Quote Originally Posted by Steve Miller
    The star had to have several structured layer like chambers that also had to be compression resistant, as far as I do understand, which was unlikely the most to me due to the enormous temperature(s ) a star has got.
    What do you mean by "compression resistant"? It is as much resistant as the radiation pressure from the inside balances out the gravitational pressure from the outside. The gravitational pressure increases with the depth into the star because of the weight of the layers pushing from above. The radiation pressure is strongest in the core, because the momentum of the photons push on a smaller surface there than at the layers above. So, you get a nice equilibrium in every shell around the core preventing a collapse. But the material is a plasma, i.e. a gas of ions and electrons that is compressible. It is densest in the core leading to the high temperature there. You see, you cannot speak of "compression resistant chambers" like it is made of solid material that cannot be compressed. It is already compressed, but stays in an equilibrium until the situation changes, i.e. the hydrogen in the core is depleted. With the onset of the helium burning, the equilibrium resettles to a new and stable configuration.
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