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Author Topic: What are neutron stars?  (Read 5800 times)

Offline Karen W.

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What are neutron stars?
« on: 24/04/2015 10:55:46 »
Hey guys...This is actually a question from my youngest son Nathan... The below quote..I took from his facebook page...In as much as he knows he would still like to know what the neutron stars are made up of to make them so dense?  Maybe you guys can give him the answers he never recieved?


"Nathan Warvi asks,"

["So whats with neutron stars? This article I was reading said that " Neutron stars are typically small, with diameters of about 12 miles (19 kilometers) or so, but they are so dense that a neutron star's mass may be about the same as that of the sun. A chunk of a neutron star the size of a sugar cube can weigh as much as 100 million tons, making neutron stars the densest objects in the universe besides black holes."]


« Last Edit: 24/04/2015 23:04:29 by chris »


 

Online Colin2B

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Re: So whats with neutron stars?
« Reply #1 on: 24/04/2015 12:44:25 »
Hey guys...This is actually a question from my youngest son Nathan... The below quote..I took from his facebook page...In as much as he knows he would still like to know what the neutron stars are made up of to make them so dense?  Maybe you guys can give him the answers he never recieved?
How old is your son, might help the experts in this area to pitch the reply at the right level.

My top level understanding is that they are made of the same material as ordinary stars, but they have collapsed under gravitational pressure so that the nuclei of the atoms are pushed so close together that they are touching. The protons and electrons are also pushed together to form neutrons, so all the atoms are composed of only neutrons, hence they are called neutron stars.
In a normal star (if there is such a thing!) there is a lot of space between the nuclei of the atoms, so the mass occupies a larger volume (hence less dense) than the compressed neutron star.

Hopefully others will be able to give more detail, or explanation.
 

Offline chiralSPO

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Re: So whats with neutron stars?
« Reply #2 on: 24/04/2015 14:00:10 »
To give an idea of the scale:

Protons and neutrons are about the same size. If a proton were the size of a tennis ball, a hydrogen atom (one electron and one proton) would be about the size of a football stadium. This incredible size disparity holds for all atoms under normal conditions, but in the case of neutron stars, the gravity is so strong that the electrons get crushed inward to the point that they are touching (or combined with) the protons in the nucleus.

If you had somehow managed to get a sugar lump chunk of a neutron star, as soon as the star's gravity was no longer keeping the matter so compressed, it would spontaneously explode into 100 million tons of normal matter--probably in the form of heavy atoms like iridium and uranium, and several radioactive elements that would just fall apart. Actually, you could think of the chunk (or the whole star) as a single atom without being too far off from reality. It would be an extremely neutron-rich atom, and therefore be unstable (radioactive) so it would undergo fission and beta decay to produce other more stable atoms.
 

Offline PmbPhy

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Re: So whats with neutron stars?
« Reply #3 on: 24/04/2015 15:54:34 »
I can't add very much to what the others have already posted but I do have one comment. The reason it's called a neutron star is as they've said above, i.e. a when a star which has a large enough mass burns too much of its fuel then the force which was holding the star from collapsing can no longer support the weight of the stellar material to keep it from collapsing thus starts to collapse. The atoms of which the star is composed then come in contact with each other and then no longer can stop the repulsive forces due to the electric charges keeping them separated. The electrons are then absorbed by the protons and become neutrons. The laws of quantum mechanics prevent them from collapsing any further so in the end you end up with material consisting of only neutrons which are in contact with each other. Thus the star is essentially a enormous neutral nucleus consisting of only neutrons. Further collapse is halted due to a quantum mechanical force called quantum degeneracy pressure. See http://en.wikipedia.org/wiki/Degenerate_matter  Since protons and neutrons have almost the same mass the resultant star has approximately the same density as the nucleus of an atom, which is extremely dense.
« Last Edit: 26/04/2015 02:46:06 by PmbPhy »
 

Online Colin2B

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Re: What are neutron stars?
« Reply #4 on: 24/04/2015 23:55:17 »
Karen
Hope these replies help.
I assume your son knows what proton, neutron, electrons are. If not he could post a question here, I'm sure jccc would be delighted to enphoton him!  :)

 

Offline alancalverd

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Re: What are neutron stars?
« Reply #5 on: 25/04/2015 01:03:11 »
This is an oversimplification but it's a start to understanding.

Ordinary atoms contain charged particles, and also have mass. Things with mass are attracted to one another by gravity, but like charges repel, so there's a limit to the density of ordinary materials - the charged particles can't get very close to each other.

Neutrons on the other hand have mass but no charge, so they can stick very close to each other by gravity alone.

Try unpopping some popcorn! You (or at least a small boy) can probably stand on a box of popcorn without crushing it, but if you squish it really hard, but by bit, you can crush it down to a very dense material - corn! - and it won't spring back into popcorn.   

Incidentally you can demonstrate the repulsive force of charge by making a popcorn electroscope.
 

Offline jccc

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Re: What are neutron stars?
« Reply #6 on: 25/04/2015 15:46:05 »
at 20's, best time for learning/creating everything. look einstein.

he should wiki googled, invite him to this thread.

i suggest him to challenge all doubts in science.



« Last Edit: 28/04/2015 23:25:09 by jccc »
 

Online Colin2B

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Re: What are neutron stars?
« Reply #7 on: 25/04/2015 23:58:57 »
. Thus the star is essentially a enormous atom consisting of only neutrons. Further collapse is halted due to a quantum mechanical force called quantum degeneracy pressure. See http://en.wikipedia.org/wiki/Degenerate_matter 


On the way to being an enormous atom, it might work it's way through a periodic table of elements far heavier than anything we have on earth. Is there any evidence of this in spectrum lines during the collapse?

 

Offline PmbPhy

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Re: What are neutron stars?
« Reply #8 on: 26/04/2015 02:48:07 »
. Thus the star is essentially a enormous atom consisting of only neutrons. Further collapse is halted due to a quantum mechanical force called quantum degeneracy pressure. See http://en.wikipedia.org/wiki/Degenerate_matter 


On the way to being an enormous atom, it might work it's way through a periodic table of elements far heavier than anything we have on earth. Is there any evidence of this in spectrum lines during the collapse?
I made an error when I wrote that part about being an enormous atom. I should have said that it's an enormous neutral nucleus consisting of only neutrons. I went back and changed my post to reflect this. Thanks for pointing this out to me in a round about way.
 

Online Colin2B

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Re: What are neutron stars?
« Reply #9 on: 26/04/2015 09:58:56 »
... Thanks for pointing this out to me in a round about way.
Entirely born of ignorance, my simplistic view would assume that an atom definition might cover one consisting of all neutrons, but thinking about it, it wouldn't behave as the smallest part of a chemical element which I assume is the definition of an atom.
I'll stop rambling and go look up some definition.
Thanks
 

Offline evan_au

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Re: What are neutron stars?
« Reply #10 on: 26/04/2015 12:03:37 »
Neutron stars are the "ashes" of a star which has reached the end of its life; it is like a fire which has burnt all its fuel, and it starts to cool down.
There is no more heat in its center to hold the star against its own enormous gravity, so the center is crushed, and it collapses into a neutron star.
In the process of combining protons and electrons into neutrons, a blast of ghostly neutrino particles is emitted, which rips away the outer layers of the star in a supernova explosion, which, for a short period, can outshine an entire galaxy with billions of stars.

Neutron stars can spin very quickly, and emit radio signals. When the first neutron star was discovered, for a while they thought the regular "blip" might be a message from an alien civilization. These types of neutron stars are now called "pulsars".

Only stars of a certain size become neutrons stars; if they are too small, the center of stars remain as a plasma - like a very hot gas.
If the star is too large, it does not stop as a neutron star, but continues to collapse into a black hole.
 

Offline Karen W.

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Re: What are neutron stars?
« Reply #11 on: 08/05/2015 14:40:26 »
Thank you fellows..my son Nathan is 27 years old...I will point him to these answers after he gets home Sunday  from his inlaws..his wife lost her father this week..Thank you for all the wonderful answers! He will be delighted!
 

Offline Karen W.

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Re: What are neutron stars?
« Reply #12 on: 25/05/2015 06:23:51 »
I just sent Nathan the link to this thread. I thank all of you Guys, and I appreciate you all!
« Last Edit: 25/05/2015 06:41:00 by Karen W. »
 

Offline David Cooper

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Re: What are neutron stars?
« Reply #13 on: 25/05/2015 17:21:40 »
There may be another category of object with a density between neutron stars and black holes. http://en.wikipedia.org/wiki/Quark_star
 

Offline ScientificSorcerer

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Re: What are neutron stars?
« Reply #14 on: 26/05/2015 14:59:17 »
like the others have said, the neutron star is ALMOST as dense as you can get. The only thing more dense is a black hole. How you get something like a black hole is a bit of a mystery.

People tend to think of protons neutrons and electrons as orbs (particles) as if they were tiny tennis balls but they are far from it.  particles are not like tiny balls, they are more like "fields" a bit like magnetic a "field" (which 2 out of 3 particles have) they are these bundles of fields of probability, they are very ghostly believe it or not.  It may be possible for particles to occupy the same space if they are forced to with enough energy.

I believe that particle's fields overlap inside black hole and all the countless particles are in the same spot in space and that's why black holes are so incredibly dense.

It's a rather abstract concept that goes deep into quantum physics.  But if you are familiar with the particle cloud idea then you might understand what I mean by "ghost particle" and why these particles would be capable of overlapping in space.

Just because something has mass does not mean it is a solid thing, that's a huge miss conception that makes people tend to think of such a theory as impossible but you decide for yourself what you believe.
« Last Edit: 26/05/2015 15:18:52 by ScientificSorcerer »
 

Offline PmbPhy

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Re: What are neutron stars?
« Reply #15 on: 26/05/2015 16:31:52 »
Quote from: ScientificSorcerer
How you get something like a black hole is a bit of a mystery.
There's no mystery about that. They can be formed several ways such as stellar black holes form which are formed when the center of a very massive star collapses in upon itself.

Quote from: ScientificSorcerer
People tend to think of protons neutrons and electrons as orbs (particles) as if they were tiny tennis balls ...
Who are these people that you're talking about. They're certainly not trained physicists or chemists.

Quote from: ScientificSorcerer
particles are not like tiny balls, they are more like "fields" a bit like magnetic a "field" (which 2 out of 3 particles have) they are these bundles of fields of probability, they are very ghostly believe it or not.
Not at all. A particle, by definition, is something that is localized in space. In fact the term particle is defined as a small localized object.

Quote from: ScientificSorcerer
   It may be possible for particles to occupy the same space if they are forced to with enough energy.
That's not true. Two fermions, one of which has no charge, can occupy the same space at the same time with no energy requirements to be concerned with.

Quote from: ScientificSorcerer
I believe that particle's fields overlap inside black hole and all the countless particles are in the same spot in space and that's why black holes are so incredibly dense.
The density of black holes was demonstrated using classical mechanics, not quantum mechanics. The density is so large because the gravitational field runs away with itself making the star so dense that it goes to infinity, i.e. beyond which we have the knowledge to describe it. It has nothing to do with overlapping fields.

Quote from: ScientificSorcerer
It's a rather abstract concept that goes deep into quantum physics.  But if you are familiar with the particle cloud idea then you might understand what I mean by "ghost particle" and why these particles would be capable of overlapping in space.
The term "cloud" is only used to refer to electron clouds. It's a term used in analogy with atmospheric clouds to give the impression that there is no definite place that a particle is found but that the probability density is finite and continuous like a cloud. The notion of a "ghost particle" is meaningless.

Quote from: ScientificSorcerer
Just because something has mass does not mean it is a solid thing, that's a huge miss conception that makes people tend to think of such a theory as impossible but you decide for yourself what you believe.
Why bring it up. Nobody mentioned it!
 

Offline evan_au

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Re: What are neutron stars?
« Reply #16 on: 26/05/2015 21:02:25 »
Quote from: ScientificSorcerer
countless particles are in the same spot in space
This is the meaning of a "singularity" - something which is infinite (at least in theory). In this case, it is the density which approaches infinity.

To date, there is no unified theory of gravity and quantum theory which has been proven to work near the event horizon of a black hole, let alone inside it! But "countless particles in the same spot in space" is a reasonable first approximation.
« Last Edit: 26/05/2015 21:08:37 by evan_au »
 

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Re: What are neutron stars?
« Reply #16 on: 26/05/2015 21:02:25 »

 

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