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Sol is too small to go SN but if its core instantly vanished would it instantly SN?

  1. Aug 17, 2011 #1
    Would a star that is too small to go supernova (Sol or Alpha Centauri) still go supernova if its core somehow instantly vanished? Wouldn't gravity collapse it and wouldn't that pressure be the same as the pressure that makes larger stars go supernova?
     
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  3. Aug 17, 2011 #2

    Drakkith

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    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    I don't believe so, the new mass of the star would be even less and probably not have enough gravitational attraction to collapse at that kind of speed. Also the star is rotating so the falling matter would spiral in, not simply collapse straight in. In any case a stars core is not going to simply dissappear so the point is pretty much moot.
     
  4. Aug 17, 2011 #3
    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    Thanks! So it would spiral inward but then what? Would it just cool and dissolve?
     
  5. Aug 17, 2011 #4

    Drakkith

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    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    It really just depends on the initial mass of the star and how much is taken away. If the star still has equal mass or greater than Sol currently has, then I think the star will eventually re-ignite and be nearly identical to a normal star of similar mass. But again, this isn't going to happen. Honestly it would be much better to discuss something that can actually occur in nature. Do you know much about supernova's themselves and how they form?
     
  6. Aug 17, 2011 #5
    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    I was curious if a wandering black hole about the size of the core of the sun could sweep through it and void out the core and ignite it into a supernova.
     
  7. Aug 17, 2011 #6

    Drakkith

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    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    Unlikely. The black hole would also disrupt the outer layers of the star as it plows through. Most of the gas would probably end up as matter in its accretion disk.
     
  8. Aug 17, 2011 #7

    Chronos

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    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    Instantly vanishing core? How does that happen? This is a non-starter for me.
     
  9. Aug 17, 2011 #8

    DaveC426913

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    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    Note that

    1] the consumption of the star's core by the BH would not happen instantly; you won't get a hollow sphere of a star.

    2] the mass involved (which is what drives these explosions) would not change. The BH may collapse the star's matter, but the stra's mass mass remains in full effect. And that mass affects the BH in turn.

    3] the star's effect on the BH's trajectory will be significant. It's not like it going to fire in one side and out the other like a bullet.


    BH or no, it's going to happen pretty similar to the way two regular stars would collide.
     
  10. Aug 18, 2011 #9
    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    If you want to detonate the Sun via a collision, then a realistic example would be if a white dwarf collided with it. Being much denser than the Sun, the white dwarf's gravity would cause localized collapse of the Sun and probably push the white dwarf over the Chandrasekhar Limit, causing total disruption of the two in a thermonuclear explosion (a Type Ia Supernova.)
     
  11. Aug 18, 2011 #10

    D H

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    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    You are asking, "What would the laws of physics say would happen if all of the known laws of physics suddenly ceased to exist?" In other words, this is a nonsense question.
     
  12. Aug 18, 2011 #11

    DaveC426913

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    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    I attempted to bring it back to reality by going with the black hole collision scenario he suggested in post #5 (as a thought experiment). The laws of physics aren't violated and nothing happens magically; it's just the collision of two stellar mass objects.
     
  13. Aug 18, 2011 #12

    Ken G

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    Re: Sol is too small to go SN but if its core instantly vanished would it instantly S

    Actually, I think you are being too hard on the question, there is a lot to learn from questions that are not plausible scenarios. Here, we could simply reframe the question, what would happen if you prepared an object that was just like our Sun but with an empty core? That's physically allowable, though impractical of course, but the question is an entry to unearthing some misconceptions about SN that are in evidence in the original question.

    It seems clear to me that Astroboy123 is imagining that a SN occurs due to the gravitational collapse of the envelope down to the core, but that's not really the case-- a SN occurs because of the collapse of the core down to an object about the size of the Earth (if it collapses further into a black hole, it hardly matters). The gravitational energy released by collapsing down to the core is only about the same as the energy that is in the Sun right now, because that's essentially what happened when the Sun formed in fhe first place.

    So what we can learn about a SN from this question is that it requires a runaway effect-- as the core begins to collapse, its gravity increases, so it collapses even more. Eventually the collapse is so total that a huge amount of energy is released, and that's what blasts the envelope into kingdom come. It is a feedback mechanism that does it, not simple gravitational falling of an envelope onto a core, which would be a whimper not a bang.

    (Note also that the envelope falling into the region of the empty core does not produce any more energy, because the gravity is weak in the core if it is empty-- such a fall would just rebuild the core, at similar temperatures to what the Sun is now. Eventually you'd just end up with a lower-mass main sequence star, just like the Sun only a little smaller and cooler. So there's something to be learned about stars here too!)
     
    Last edited: Aug 18, 2011
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