Understanding Type II Supernovae: N-Star vs. BH Supernova Explained

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In summary, a Type II supernova occurs when the collapsing neutonium core of a dying large star overshoots its stable neutron degenerate radius, rebounds blasting the leftovers out into space. This occurs due to the instability of the overshot point, which is due to the fusion of silicon to 56Ni and then 56Fe. If the stable density of these nucleons is sufficient to form a black hole, then what prevents them from collapsing all the way down to a black hole at this point? The answer is the acretion of the remaining material, which heats up and gives off tremendous amounts of radiation before falling in.
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turin
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As I understand it, a Type II supernova occurs because the collapsing neutonium core of a dying large star overshoots its stable neutron degenerate radius and therefore rebounds, blasting the leftovers out into space. Is this correct?

How, then, does a dying extremely massive star create a supernova? I did not think that a black hole would (or could) rebound.
 
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  • #2
turin said:
As I understand it, a Type II supernova occurs because the collapsing neutonium core of a dying large star overshoots its stable neutron degenerate radius and therefore rebounds, blasting the leftovers out into space. Is this correct?

How, then, does a dying extremely massive star create a supernova? I did not think that a black hole would (or could) rebound.
The Type II has a "last stage" of silicon fusing to 56NI and then immediately changing to 56Fe before the collapse. The whole link below is pretty good stuff, but see pages 4, 5 and 6 for Type II specifics.

http://users.aber.ac.uk/azb/teaching/ph28010/ph28010-11.pdf [Broken]
 
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  • #3
But after the fusion to iron, then the iron ash heats up to the point that photodesintigration sets in. This takes energy away from the iron ash core which inhibits its ability to support the rest of the star. The disintegrated core therefore collapses as a swarm of nucleons which recedes away from the outer layers of the star, essentially isolating itself for a (very) brief period. These nucleons have a stable density that can be supported by neutron degeneracy pressure. However, they are collapsing so fast that they overshoot this density. Here's where I am having trouble understanding:

If the stable density of these nucleons is sufficient to form a black hole, then what prevents them from forming a black hole when they are at this overshot point in density, which should be more than sufficient for black hole formation? If nothing prevents them from collapsing all the way down to a black hole at this point, then what causes the supernova. It doesn't seem to be the rebound, because there can be no rebound from a black hole state. And the rest of the star material is on its merry way to falling into the black hole, not flying out into space.

Is it the acretion of the remaining material that heats up and gives off tremendous amounts of radiation before falling in?
 
  • #4
turin said:
If the stable density of these nucleons is sufficient to form a black hole, then what prevents them from forming a black hole when they are at this overshot point in density, which should be more than sufficient for black hole formation?
AFAIK, it is NOT sufficient to form a black hole (but I may be mistaken).
 
  • #5
turin said:
But after the fusion to iron, then the iron ash heats up to the point that photodesintigration sets in. This takes energy away from the iron ash core which inhibits its ability to support the rest of the star. The disintegrated core therefore collapses as a swarm of nucleons which recedes away from the outer layers of the star, essentially isolating itself for a (very) brief period. These nucleons have a stable density that can be supported by neutron degeneracy pressure. However, they are collapsing so fast that they overshoot this density. Here's where I am having trouble understanding:

If the stable density of these nucleons is sufficient to form a black hole, then what prevents them from forming a black hole when they are at this overshot point in density, which should be more than sufficient for black hole formation? If nothing prevents them from collapsing all the way down to a black hole at this point, then what causes the supernova. It doesn't seem to be the rebound, because there can be no rebound from a black hole state. And the rest of the star material is on its merry way to falling into the black hole, not flying out into space.

Is it the acretion of the remaining material that heats up and gives off tremendous amounts of radiation before falling in?
I'm typing on an answer to this but have to go out-of town tomorrow morning. The answer is easy enough, but it would take a long post to go through the steps. I may not get it together until I get back in 7-10 days. But, the other guys should have a go at it and maybe it will be resolved by then.
 
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1. What is N-star vs. BH supernova?

N-star vs. BH supernova refers to the different types of supernovae that occur when a star dies. N-star supernovae occur when a star, typically a massive one, runs out of fuel and collapses, causing a massive explosion. BH supernovae occur when a star with a core of more than three solar masses collapses into a black hole, releasing a tremendous amount of energy.

2. How do N-star and BH supernovae differ?

The main difference between N-star and BH supernovae is the initial mass of the star. N-star supernovae occur in stars with a mass of less than three solar masses, while BH supernovae occur in stars with a mass of more than three solar masses. Additionally, the end result of a BH supernova is the formation of a black hole, while N-star supernovae result in the formation of a neutron star.

3. What causes N-star and BH supernovae?

N-star supernovae are caused by the sudden collapse of the star's core, which creates a shockwave that travels through the star's layers, causing it to explode. BH supernovae are caused by the rapid collapse of a massive star's core, which creates a black hole and releases a tremendous amount of energy.

4. Are N-star and BH supernovae dangerous for Earth?

While both N-star and BH supernovae release a huge amount of energy, they are not considered dangerous for Earth unless they occur very close to our planet. The nearest known supernova to Earth was SN 1987A, which was around 168,000 light-years away and did not pose any threat to our planet.

5. Can we observe N-star and BH supernovae from Earth?

Yes, we can observe both N-star and BH supernovae from Earth. N-star supernovae are more common and can often be observed with the naked eye as a bright, new star in the sky. BH supernovae are rarer, but can still be detected through telescopes and other instruments as they release a large amount of radiation and emit high-energy particles.

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