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Thread: the core of a supernova, hypernova

  1. #1 the core of a supernova, hypernova 
    ray
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    when a hypernova/ supernova explodes leaving a black hole, is it possible to calculate ( roughly) its mass?.
    Is it more than, say, 20% of the original mass of the star? how long does explosion lasts? can it last for years?
    thanks


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    Quote Originally Posted by ray View Post
    when a hypernova/ supernova explodes leaving a black hole, is it possible to calculate ( roughly) its mass?.
    Is it more than, say, 20% of the original mass of the star? how long does explosion lasts? can it last for years?
    thanks

    Wonderful question.

    SNe 1a are such "hypernovae". They last a few days or a week, at most. They are so well characterized, both observationally and theoretically, that their production of a Supermassive Black Hole in one step is predictable along with the SBH mass, total entropy, spin and hyperbolic gravitational field profile. SNe 1a are useful as "standard candles" at the far edge of our ability to detect in the visible spectrum. Two groups studied very distant SNe 1a, but their data had to be reconciled. This process of reconciliation alone produced the hypothesis of accelerating rate of expansion (the Hubble Constant is supposed to be not constant, but increasing). Dark Energy was invented to explain the taste of this fudge. Dark Matter was invented as a condiment - frosting on the fudge.

    God, this makes me thirsty for a cuppa. Folger's this time.


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    Quote Originally Posted by Gary Anthony Kent View Post
    Quote Originally Posted by ray View Post
    when a hypernova/ supernova explodes leaving a black hole, is it possible to calculate ( roughly) its mass?.
    Is it more than, say, 20% of the original mass of the star? how long does explosion lasts? can it last for years?
    thanks

    Wonderful question.

    SNe 1a are such "hypernovae".
    No. Hypernovae are something different. SNe of Type Ia are, well, supernovae.

    Quote Originally Posted by Gary Anthony Kent View Post
    They last a few days or a week, at most. They are so well characterized, both observationally and theoretically, that their production of a Supermassive Black Hole in one step is predictable along with the SBH mass, total entropy, spin and hyperbolic gravitational field profile.
    Stellar BHs or not supermassive BHs. The latter are only found in the centre of galaxies.

    Quote Originally Posted by Gary Anthony Kent View Post
    SNe 1a are useful as "standard candles" at the far edge of our ability to detect in the visible spectrum. Two groups studied very distant SNe 1a, but their data had to be reconciled. This process of reconciliation alone produced the hypothesis of accelerating rate of expansion (the Hubble Constant is supposed to be not constant, but increasing). Dark Energy was invented to explain the taste of this fudge. Dark Matter was invented as a condiment - frosting on the fudge.
    No, Dark Matter was postulated to account for the flat galactic rotation curves. The cosmological Dark Matter was postulated to allow the potential wells to form early enough so that galaxies can be formed quickly after the universe became transparent.
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    Quote Originally Posted by ray View Post
    when a hypernova/ supernova explodes leaving a black hole, is it possible to calculate ( roughly) its mass?.
    Well the Iron component of the core will begin to collapse when its mass exceeds 1.4 solar masses. (See Chandrasekhar limit) However the core is made up of more than just iron, it also contains silicon, oxygen, carbon etc. As far as i'm aware the mass of these components would depend on the mass of the whole star and maybe how long it's been burning.
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    Quote Originally Posted by ray View Post
    , is it possible to calculate ( roughly) its mass?.
    can it last for years?
    [QUOTE=Gary Anthony Kent;283463]
    Quote Originally Posted by ray View Post
    . They last a few days or a week, at most. .
    so, explosion lasts for a week, could you now answer the main question? let's reverse the question:

    1) the (black hole) BH in our backyard Sgr A* has an estimated mass of 4M solar masses, can you figure out (roughly) the mass of the original star ?

    2) is it possible in principle that no mass, no BH remains after an explosion?

    probably I should make a new thread for this (probably-not-wonderful) question, but can you tell me if in principle is it possible to make a BH explode? if it not possible in real world
    3) can you calculate what energy is required to make Sgr A* explode?
    Last edited by ray; September 15th, 2011 at 01:08 AM.
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    Quote Originally Posted by ray View Post
    Quote Originally Posted by ray View Post
    , is it possible to calculate ( roughly) its mass?.can it last for years?
    Quote Originally Posted by Gary Anthony Kent View Post
    They last a few days or a week, at most. .
    so, explosion lasts for a week,
    It depends on how you see it. The implosion of the stellar core happens very quickly. But the detectable increase in brightness can last several days. Please, note that this brightness increase is caused by the decay of radioactive Nickel. The expansion of the released shell lasts for thousands of years. The gas remains very hot during the entire duration. The result is supernova remnants like the Crab nebula (M1).
    Quote Originally Posted by ray View Post
    could you now answer the main question? let's reverse the question:

    1) the (black hole) BH in our backyard Sgr A* has an estimated mass of 4M solar masses, can you figure out (roughly) the mass of the original star ?

    This supermassive BH has no stellar progenitor. You have to distinguish between stellar and galactic BHs. The BH in the centre of the Milky Way was formed by the conglomeration of stars and gas.
    Quote Originally Posted by ray View Post
    2) is it possible in principle that no mass, no BH remains after an explosion?

    Theoretically, yes. The alternative is a stellar BH. The typical remainder of a SN is a neutron star that is often detected as a pulsar.
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    Quote Originally Posted by Dishmaster View Post
    1)This supermassive BH has no stellar progenitor.
    Thanks, Dishmaster for your reply, My example was not appropriate, I apologize!
    1) could you give me an example of stellar BH with its estimated mass and then answer the question if we can figure out the mass of the original star?
    2)if I got it right an exploding star can expel all its mass and leave no core. I asked this because I thoght that the pressure generated by explosion MUST compress something anyway, isn't it so?
    3) they say a BH is a singularity, space is infinitely small, density infinitely great, radiation energy is destroyed when it trespasses event horizon, right?, so, how can energy get to the core of the BH and make it explode?, I am referring to BBtheory
    thank you
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    Quote Originally Posted by Dishmaster View Post
    Quote Originally Posted by Gary Anthony Kent View Post
    Quote Originally Posted by ray View Post
    when a hypernova/ supernova explodes leaving a black hole, is it possible to calculate ( roughly) its mass?.
    Is it more than, say, 20% of the original mass of the star? how long does explosion lasts? can it last for years?
    thanks

    Wonderful question.

    SNe 1a are such "hypernovae".
    No. Hypernovae are something different. SNe of Type Ia are, well, supernovae.


    Hypernova (pl. hypernovae) refers to an exceptionally large star that collapses at the end of its lifespan.
    i.e. a SN 1a

    G.A.K.


    Quote Originally Posted by Gary Anthony Kent View Post
    They last a few days or a week, at most. They are so well characterized, both observationally and theoretically, that their production of a Supermassive Black Hole in one step is predictable along with the SBH mass, total entropy, spin and hyperbolic gravitational field profile.
    Stellar BHs or not supermassive BHs. The latter are only found in the centre of galaxies.

    Quote Originally Posted by Gary Anthony Kent View Post
    SNe 1a are useful as "standard candles" at the far edge of our ability to detect in the visible spectrum. Two groups studied very distant SNe 1a, but their data had to be reconciled. This process of reconciliation alone produced the hypothesis of accelerating rate of expansion (the Hubble Constant is supposed to be not constant, but increasing). Dark Energy was invented to explain the taste of this fudge. Dark Matter was invented as a condiment - frosting on the fudge.
    No, Dark Matter was postulated to account for the flat galactic rotation curves. The cosmological Dark Matter was postulated to allow the potential wells to form early enough so that galaxies can be formed quickly after the universe became transparent.
    There is a distinction between "Dark Matter" and "cosmological Dark Matter"? Come on. The quantum variation or ripple effect is enough to quiclkly form galaxies. But it is hard for many to accept because it would mean that the universe is still, even now, under the macroscopic influence of quantum law. This opens a whole new can of worms. Lke John Wheeler's or Hugh Everett's.

    What is "supermassive"? Some stellar BHs are born this way, as are SNe 1a. It's what makes them unusual, besides their incredible brightness.
    Last edited by Gary Anthony Kent; September 15th, 2011 at 07:58 AM.
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    Quote Originally Posted by Dishmaster View Post
    You have to distinguish between stellar and galactic BHs. .
    How do you tell a stellar from a galactic BH. Have they different characteristics?
    Can a conglomeration of stars produce a BH without an explosion?
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    Quote Originally Posted by ray View Post
    Quote Originally Posted by Dishmaster View Post
    You have to distinguish between stellar and galactic BHs. .
    How do you tell a stellar from a galactic BH. Have they different characteristics?
    Can a conglomeration of stars produce a BH without an explosion?
    An "explosion" is not necessarily connected to the formation of BH. A BH is just a dense configuration of mass so that it is smaller than its Schwarzschild radius. One progenitor might be a SN explosion. Here, the core of the massive star collapses, because the nuclear fusion is stopped or at least reduced so that self gravity takes over. This collapse is what forms the dense object, e.g. a BH. The shockwave that is produced during this collapse leads to the explosion of the star.

    So, yes, a BH can form without explosions. There are stars and gas transported to the centre of the galaxy, where they might gather and form a very dense object. Try to calculate the Schwarzschild radius of a 4 million solar mass BH (the one that is in the centre of the Milky way) and try to derive how much space (volume) there is for a single star (mean stellar mass = 1 solar mass).
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    Quote Originally Posted by Gary Anthony Kent View Post
    There is a distinction between "Dark Matter" and "cosmological Dark Matter"? Come on. The quantum variation or ripple effect is enough to quiclkly form galaxies. But it is hard for many to accept because it would mean that the universe is still, even now, under the macroscopic influence of quantum law. This opens a whole new can of worms. Lke John Wheeler's or Hugh Everett's.

    What is "supermassive"? Some stellar BHs are born this way, as are SNe 1a. It's what makes them unusual, besides their incredible brightness.
    Ever heard of hot and cold DM? Youshould read up the current theory. Cold DM is needed in the standard model to allow for the early growth of gravitational potentials before the expansion flattened out the gravitational potential wells coming from the baryonic DM.

    So, what is a supermassive BH? Stellar progenitors of stellar BHs have not more than around 100 solar masses, and they are very rare. How much mass would a stellar BH have after the SN/Hypernova? Certainly not millions of solar masses like we find them in galaxies like the Milky Way. SN Ia are NOT supermassive BHs. Their progenitors are either two merging White Dwarfs or a White Dwarf that accretes matter from his companion star until the Chandrasekhar limit is reached.
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    Quote Originally Posted by ray View Post
    when a hypernova/ supernova explodes leaving a black hole, is it possible to calculate ( roughly) its mass?.
    Is it more than, say, 20% of the original mass of the star?thanks
    could someone answer the main question of OP?
    1) is there a (even rough, rule-of-thumb ) method to calculate what will mass in BH be, if a H/S-nova explodes (and viceversa)?
    2) is it possible in reality that no trace whatsoever be left of the original star?
    (3) how did they get to the conclusion that Sgr A* is not stellar, only because of its size?
    Last edited by ray; September 17th, 2011 at 07:23 AM.
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    The theories of BH formation are well developed by now and I am not an expert. Dishmaster points out some things that I did not know, for instance. But, this discussion surely was useful to you, though we did not answer your main question (above).

    Yes, there are methods, based on supercomputer models, that you may rely upon like the models of global weather patterns or the ones your local weatherman invokes when he/she predicts a 10 day forecast. Details like the exact stellar mass, its rotation speed, its composition, especially at the core (which we could only guess), the close proximity of other stars, and so on would all go into the model. I think rules of thumb are not going to be found unless they may be next to useless.

    As I recall, the putative object in Sgr A is OUR galactic supermassive BH, is it not? So, its very position in space gives it away. Red-shifts tell velocities of the orbiting stars that may not be obscured by dust. Dust itself could be a target of observation. The mathematical laws of gravity and Kepler's corollaries help us compute the orbits based on our knowledge of distances and speed. Some of the stars may be moving so fast that their motion is directly observable.

    Those gases and dust may result from old novae but surely also come from the tenuous far reaches of the galaxy after thousands of years of migration inward from the "hinterland". They get concentrated nearer the center by gravity while the SBH sucks them up like a vacuum cleaner. It is too bad we may never see a SBH in action. But, I'll bet astrophysicists are working right now on ways to record images of activity in the various radio bands, infrared and near infrared. If we sent a probe straight "up" (galaxywise), in several score years, we might get a different enough perspective so that we could actually see something happening, like a large star crashing down toward the event horizon. I know - not likely. But, simulations might tell us more about what we really could achieve.

    I am a chemist interested in stellar and BB nucleosynthesis so the composition of these dust clouds is of interest in their own right to me. I am fascinated by the processes whereby elements and even isotopes get segregated and concentrated. We are about 2/3 of the way out from the core. So, we are at a minimum of very many hundreds of light years distant from the center of our galaxy. Still, it may be worth it to send a probe directly toward the center (yeah, I know, it's not that simple). After a few decades of travel at top speed, it could start sending back useful data. With careful navigation, we could avoid most hazards until its robotic sense would take over and it would be on its own. We could have a semimillenium anniversary party of its launch come 2511. It would take at least ten years to prepare for a launch. Make it 2521.
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    Quote Originally Posted by Gary Anthony Kent View Post
    Those gases and dust may result from old novae but surely also come from the tenuous far reaches of the galaxy after thousands of years of migration inward from the "hinterland". They get concentrated nearer the center by gravity while the SBH sucks them up like a vacuum cleaner. .
    thanks, Gary
    So, we have a SBH as a core of a GBH, because concentration of gases by itself can never produce the necessary pressure.
    Do you say SgrA* is a galactic BH just because it is supermassive?
    Dishmaster said that in principle you can make a BH explode, is it possible in reality? how do you get to the core of the BH?
    Last edited by ray; September 17th, 2011 at 07:25 AM.
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    Quote Originally Posted by ray View Post
    Dishmaster said that in principle you can make a BH explode, ...
    No, I didn't. I said that one progenitor of a stellar BH might be a SN explosion.
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    [QUOTE=Dishmaster;283678]
    Quote Originally Posted by ray View Post
    So, yes, a BH can form without explosions.).
    Quote Originally Posted by Gary Anthony Kent View Post
    . (gases) .. get concentrated nearer the center by gravity while the SBH sucks them up like a vacuum cleaner..
    Sorry, Dishmaster, I referred to wrong question.

    1) You say a BH (do you refer to SgrA ?) can be formed by concentration of gases, 2) Gary says that gases are concentrated by a pre-existing SBH. (If I got it right), (also wiki says a supermassive BH is formed through accretion)
    now if 1 is true, where do you get the huge necessary pressure from?

    the other question was unanswered: "isn't it impossible to make a (Schwartzchild) BH explode, since necessary energy cannot come neither from inside nor outside"?
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    Quote Originally Posted by ray View Post
    1) You say a BH (do you refer to SgrA ?) can be formed by concentration of gases, 2) Gary says that gases are concentrated by a pre-existing SBH. (If I got it right), (also wiki says a supermassive BH is formed through accretion)
    now if 1 is true, where do you get the huge necessary pressure from?
    The idea of a pre-existing SHB is a bit awkward, because it needs a formation process of such a BH. To me it seems, he has got it all backwards. The neccessary "pressure" is the gravity of the matter that is located in the centre of a galaxy, probably a primordial configuration of the galaxy formation. So, first you a concentration of matter that exerts a gravitational force which then pulls at the matter that is funneled into the centre. One possible engine for such a matter movement are the bars that are present in nearly all spiral galaxies. It s known that stars and gas are channeled through this bar. The more mass is conentrated, the more this confguration is shifted towards a BH. It may also be possible that the BH already was formed along with the galaxy altogether.
    Quote Originally Posted by ray View Post
    the other question was unanswered: "isn't it impossible to make a (Schwartzchild) BH explode, since necessary energy cannot come neither from inside nor outside"?
    Nobody knows. Everything is speculation. There is the idea of an evaprotating BH which could happen in an accelerated manner, finally leading to an explosion. But this has never been confirmed by observation.
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    I researched a bit on the properties and nature of hypernovae. Apparently, they are more violent versions of supernovae. The favoured model is that the core of a very massive star (e.g. Wolf Rayet star) collapses near the end of the lifetime of the parent star - just like the Type II SNe. But here, if the core is more massive than a certain threshold (3 solar masses seems to be the canonical value) there is nothing we know of that could prevent a gravitational collapse into a Black Hole. This happens so quickly that the nuclear fusion in the shells of the parent star continues. The newly formed Black Hole starts to accrete the surrounding stellar material which leads to the formation of a bipolar jet that disprupts the star. The ejection is very fast and highly relativistic. The ejecta become very hot and synchrotron radiation is emitted which can - under certain circumstances - be detected as a gamma ray burst. The remaining object is a BH of few solar masses.
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