Is a neutron star really made of neutrons?

[Neil Russell]

In 1932 Chadwick proved the existence of the neutron.
In 1934 Baade and Zwicky proposed that a super nova could form a neutron star.
In 1965 Hewish and Okoye discovered the Crab Nebula neutron star.

When Baade and Zwicky theorised the neutron star they were unaware of black holes or that supernova by nucleosynthesis formed the elements above iron. We can assume that they were believing they had discovered the densest form of matter in existence?

1/ Where are the heavier elements? Nucleosynthesis would lead us to believe that the star left after a supernova would be rich in heavy elements.

2/ Spectrometry tells us that a neutron star has an at6mosphere of carbon. How can anelement, carbon exist on the surface of a neutron star without being broken down into more neutrons?

3/ The neutron star has a very strong magnetic field. By definition how can a neutral star consisting of just one component, neutrons form a magnetic field. We are told that electrons are the bearers of the magnetic moment, but there are none in the neutron star.

So if it is not a neutron star, but rather a plasma of heavy elements, then no problem forming a magnetic field and no problem holding an atmosphere of caqrbon.

We are left to explain what appears to be their incredible spin rate. Maybye what we are seeing is not spin, but rather flicker. We know the earths magnetic poles reverse from time to time ( a very long time). Therefore it could be possible that our star can reverse its magnetic field in the order of fractions of a second.

[Fortis]

3/ The neutron star has a very strong magnetic field. By definition how can a neutral star consisting of just one component, neutrons form a magnetic field. We are told that electrons are the bearers of the magnetic moment, but there are none in the neutron star.

Just a quick answer to number 3 (but I'm sure that others will chip in.)

Were you aware that the neutron possessed a magnetic moment?

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

[Strange]

1/ Where are the heavier elements? Nucleosynthesis would lead us to believe that the star left after a supernova would be rich in heavy elements.

Some are blown away in the supernova explosion, the rest would have been squished into neutrons.


2/ Spectrometry tells us that a neutron star has an at6mosphere of carbon. How can anelement, carbon exist on the surface of a neutron star without being broken down into more neutrons?

Same way the Earth can have an atmosphere. Gravity falls off as distance squared. At some point it is weak enough to allow elements to exist without being squished into neutrons.


3/ The neutron star has a very strong magnetic field. By definition how can a neutral star consisting of just one component, neutrons form a magnetic field. We are told that electrons are the bearers of the magnetic moment, but there are none in the neutron star.

What Fortis said.

[tusenfem]

Also, the term "neutron star" is rather misleading, as not all matter is actually turned into neutrons. The outer layers of a neutron star is actually white dwarf material. Just to go with an "oldie but goodie" Black holes, white dwarfs and neutron stars by Shapiro and Teukolsky, there is a the following build-up of a 1.4 solar mass neutron star:


Surface: (density > 106 g/cc) a region in which the temperatures and magnetic fields expected from most neutron start can significantly affect the equations of state
Outer crust: (density 106 - 4.3 1011 g/cc) a solid region in which a Coulomb lattice of heavy nuclei coexists in β-equilibrium with a relativistic degenerate electron gas (cf. white dwarf equations of state)
Inner crust: (density 4.3 1011 - (2-2.4) 1014 g/cc) which consists of a lattice of neutron-rich nuclei together with a superfluid neutron gas and an electron gas
Neutron liquid: (density (2-2.4) 1014 g/cc - core density) which contains chiefly superfluid neutrons with a smaller concentration of superfluid protons and normal electrons
Core region: (density > core density) which may or may not exist in some stars and depends on whether or not pion condensation occurs ...


Now, the magnetic field of a neutron star is maintained by e.g. the superfluids protons and is generally created by the collapse of the progenitor star while conserving its magnetic flux.

At the same time the spin rate of the neutron stars is high because of the initial spin of the progenitor star, and keeping angular momentum (except for the stuff that gets thrown off, naturally).

Thus the shrinking of the core of the star has two effects, it increases both the magnetic field strength and the rotation rate.

The "flicker" we are seeing from neutron stars, or better Pulsars, cannot be created by "flipping of the magnetic field" because that would be totally inconsistent with the profiles of the emissions. These clearly show that the emission is coming from a "funnel" at the magnetic pole, which sweeps over our viewing direction

The magnetic field of our Sun does change polarity, but not as fast as you would like, only every 11 years.

[forrest noble]

Neil Russel,


So if it is not a neutron star, but rather a plasma of heavy elements, then no problem forming a magnetic field and no problem holding an atmosphere of carbon.

Of course all know it's still theory but there are a number of reasons to suspect/ theorize that at least the core of such stars are made up of neutrons, theorized to be a type of thick plasma state.

Maybe the most important reason is gravitational influence per volume, the perceived density. Like a stellar black hole, some of those that are being observed are believed to have a strong gravitational field based upon observed influences, more so than is thought possible based upon stellar plasma of heavy elements alone. If stellar plasma were forced together it would seemingly join as neutrons in the stellar core. Many such stars spin very rapidly and some radiate as pulsars. Such a spin rate would not accordingly be possible with normal stellar plasma. Like normal stars they are known to have atmospheres. Such a spin rate and having an atmosphere can produce a strong magnetic field. There are other theoretical possibilities but the neutron star idea/ theory is widely accepted theory.

There are still questions. Where is fusion taking place and why doesn't that disturb a neutron core. Could there be another type material at the core such as black hole type material or a quark type plasma of some kind? These are a few other ideas that I've heard of.

[tusenfem]

Like normal stars they are known to have atmospheres. Such a spin rate and having an atmosphere can produce a strong magnetic field. There are other theoretical possibilities but the neutron star idea/ theory is widely accepted theory.


HUH??? An atmosphere does not create a magnetic field. This is completely ATM



There are still questions. Where is fusion taking place and why doesn't that disturb a neutron core. Could there be another type material at the core such as black hole type material or a quark type plasma of some kind? These are a few other ideas that I've heard of.

What fusion? There is no fusion in a neutron star, but for the occasional flash after accreted matter has reached the fusion limit.

As to the core, as I quoted for Shapiro and Teukolsky, the equation of state is not known there, it could well be a quark plasma or something. I doubt greatly that there would be a black hole in the core though, for obvious reasons.

[Neil Russell]

Thank you Fortis, my reading hast me down, I read that the magnetic moment was held by electrons and muons, no mention of neutrons?
Strange I read that the most common element in the Crab cloud was Neon and a few others, no mention of other heavier elements. We know for a fact the carbon atmosphere exists, I am surprised that it could rest on a bed of neutrons. My objection is that what is happening is theories being built on top of each other to explain more theories. What if Baade was wrong? Thank you Tusenfem for the ifo, again I would say we have no idea of the interior of these stars and what we are dealing with are theories trying to explain what might be?

[Strange]

Strange I read that the most common element in the Crab cloud was Neon and a few others, no mention of other heavier elements.

I imagine the most common elements would be helium and hydrogen. Others up to neon (oxygen, carbon, etc) will also be common. Someone more familiar with nucleosynthesis and/or the Crab Nebula can probably provide more detail. I don't think the original star was large enough to produce very heavy elements (but I could be wrong)..


We know for a fact the carbon atmosphere exists, I am surprised that it could rest on a bed of neutrons.

I don't imagine that there is an abrupt transition from neutrons to a carbon atmosphere. There is almost certainly a layer with more loosely bound neutrons - presumably in some sort of dynamic equilibrium with H and He and perhaps other elements. There must be some very interesting stuff going on there. Above that a layer of carbon (which I gather is likely to be only inches thick)


My objection is that what is happening is theories being built on top of each other to explain more theories.

That is what science does. Luckily theories are pretty rock solid foundations for building on. Or are you confused by the common usage of the word which doesn't really differentiate it from speculation?


What if Baade was wrong?

Do you have any reason to think they might be wrong?


what we are dealing with are theories trying to explain what might be?

That is pretty much all science ever does.

[tusenfem]

Strange I read that the most common element in the Crab cloud was Neon and a few others, no mention of other heavier elements.


The heavier an element, the less it will be produced inside a star and during the supernova explosion. You might want to read up on nucleosynthesis (http://en.wikipedia.org/wiki/Supernova_nucleosynthesis) and how things work with the r and s process, and read up on the species that are readily available in the progenitor star that goes SN. A good place therefore would be the Astrophysics I & II books by Bowers & Deeming.



We know for a fact the carbon atmosphere exists, I am surprised that it could rest on a bed of neutrons.


Yeah there is a carbon atmosphere, and there is no problem (see my post above about the build-up of a neutron star), because the outer layer is "white dwarf" material and it is usual for white dwarfs to have carbon. And it is NOT resting on "a bed of neutrons." The outer layers of a neutron star are neutron rich but absolutely not pure neutron, you really need to get away from that idea.



My objection is that what is happening is theories being built on top of each other to explain more theories. What if Baade was wrong? Thank you Tusenfem for the ifo, again I would say we have no idea of the interior of these stars and what we are dealing with are theories trying to explain what might be?

Our theoretical models about how matter behaves are pretty good, the pressure that matter is put under in a neutron star is easily calculated (unless you want to reject also basic physics). It is very much doubtful that Baade was wrong about the idea of a neutron star, as all we know now and have discovered since then pretty much confirms what one would expect at a neutron star. Yes, he may have been wrong giving it the name "neutron star" as that star is not 100% neutrons.

Indeed, we have no direct information what happens inside a neutron star, but we also actually have no direct information about what is happening inside our sun, does that mean that our model of the sun is wrong? Should we reject fusion in the sun, because we cannot observe e.g. the CNO cycle under a microscope? And theories building on top of each other is always the case, for everything, so the you might as well reject all of physics. In the realm of neutron stars there is just gravity (to get the collapsing force), thermodynamics (to calculate the gas pressure against gravity), quantum mechanics (when the matter gets compressed and you need. e.g. Pauli's exclusion principle) and particle physics (to calculate the melting together of electrons and protons to neutrons), all of those are extremely well known.

And then again, in astrophysics theories are always about "what might be," as basically everything is out of our reach.

[AndreasJ]

Yes, he may have been wrong giving it the name "neutron star" as that star is not 100% neutrons.

If a tangent be excused, it's strange to me how people get hung up on some names. No-one (AFAIK) ever thinks that a carbon star needs to be all carbon, and seemingly none of the people who object to "dwarf planets" not being planets have the same objection to "minor planets".

[Ilya]

We know for a fact the carbon atmosphere exists, I am surprised that it could rest on a bed of neutrons.
It does not. What you do not seem to realize is that it is not gravity per se which squeezes matter into neutronium (or into dwarf-star matter) - it is pressure. Think of a hydrogen atom on the surface of a neutron star, and I mean truly on the surface - vacuum on one side. There is a tremendous force pulling both the proton and the electron to the other (non-vacuum) side, but no particular force to push them toward each other. Barring very high temperature, that atom will remain as is.

Yet the next atom down does have considerable force applied to its electron shell(s) - the weight of the topmost atom, i.e. pressure! The next one suffers twice that, etc. It adds up to every neutron star having an "atmosphere" of gaseous carbon several centimeters thick. At the bottom of this atmosphere the pressure is great enough to crush electron shells and to form dwarf-star matter. Then there are several tens of meters of dwarf-star matter until pressure becomes high enough to force electrons into protons and to form neutronium.

Even that does not begin abruptly, but there is a gradual change from dwarf-star matter to neutronium. At a density around 4x10^11 g/cm^3, you reach the "neutron drip" layer. At this layer, it becomes energetically favorable for neutrons to float out of the nuclei and move freely around, so the neutrons "drip" out. Even further down, you mainly have free neutrons, with a 5%-10% sprinkling of protons and electrons. As the density increases, you find what has been dubbed the "pasta-antipasta" sequence. At relatively low (about 10^12 g/cm^3) densities, the nucleons are spread out like meatballs that are relatively far from each other. At higher densities, the nucleons merge to form spaghetti-like strands, and at even higher densities the nucleons look like sheets (such as lasagna). Increasing the density further brings a reversal of the above sequence, where you mainly have nucleons but the holes form (in order of increasing density) anti-lasagna, anti-spaghetti, and anti-meatballs (also called Swiss cheese).

When the density exceeds the nuclear density 2.8x10^14 g/cm^3 by a factor of 2 or 3, really exotic stuff might be able to form, like pion condensates, lambda hyperons, delta isobars, and quark-gluon plasmas.

Here are a couple PDF's which go over it in detail:

http://www.jinaweb.org/docs/nstar.pdf
http://www.int.washington.edu/PROGRAMS/Page_etal_Proposal-2007-2.pdf

And yes, all of it is entirely "mainstream" - but for some reason tends not to make its way into popular literature, which proliferates the fallacies like "gravity squeezes matter into neutrons". The only non-technical work which describes all of this in detail is "Dragon's Egg" SF story by late Robert Forward.

[baric]

This conversation is fascinating. Unfortunately, I am unable to contribute to it beyond thanking everyone else for their detail explanations of the current mainstream views on the internal structures of neutron stars.

[forrest noble]

This is a link concerning stellar magnetic field theory: (which seemingly could also apply to neutron stars if valid)


……Thus the equator of the star can rotate at a different angular velocity than the higher latitudes. These differences in the rate of rotation within a star may have a significant role in the generation of a stellar magnetic field.

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

The potential of Neutron Stars' Crust and Fusion Reactions

…..the possibility that
fusion reactions of neutron-rich nuclei in the Crust are an important source of heat.

Or maybe just accreting neutron stars.

http://www.physics.wustl.edu/events/2010/05/event-124

[tusenfem]

This is a link concerning stellar magnetic field theory: (which seemingly could also apply to neutron stars if valid)


Differential rotation in stars is one of the players in the game of the α-ω-dynamo.
I do not think it is expected that differential rotation occurs in a neutron star as the matter is too compact to allow for differential rotation.



The potential of Neutron Stars' Crust and Fusion Reactions


I guess I already addressed that, an accreting neutron star will reach the fusion point and then flash, it's what we call a Nova.

[Neil Russell]

Lots of lovely information, thank you people. I still believe that something is not quite right about the carbon atmosphere. We have on one hand neutrons compressed in the order of one billion tons per teaspoon full with an atmosphere of carbon above? We are told that the neutron star becomes denser, more homongeous the deeper we go. Surely with that pressure/gravity there would not be intermediate stages but rather it should be an all or nothing collapse of the atoms.
Yes I am saying Baade could have got it wrong, in light of later discoveries. If he did then theories based on the existence of neutron stars as fact could be in error.

[Strange]

Lots of lovely information, thank you people. I still believe that something is not quite right about the carbon atmosphere. We have on one hand neutrons compressed in the order of one billion tons per teaspoon full with an atmosphere of carbon above?

Are you being misled by the word "atmosphere"? It is not a thin gas like the atmosphere of the earth.


We are told that the neutron star becomes denser, more homongeous the deeper we go. Surely with that pressure/gravity there would not be intermediate stages but rather it should be an all or nothing collapse of the atoms.

How is an abrupt change in density from neutrons to hard vacuum more plausible than a gradual change with descreasing gravity/pressure? If you don't think there should be changes in density, then why should there be an "edge" to the neutron star at all? Shouldn't the whole universe be a giant neutron star?


Yes I am saying Baade could have got it wrong, in light of later discoveries. If he did then theories based on the existence of neutron stars as fact could be in error.

Can you point out specifically where his errors are? Or is this all just an argument from personal incredulity?

[tusenfem]

Indeed, it is well known that in a gravitating body, the pressure slowly increases towards the centre, going in deeper you feel the weight of the mass that is above you pressing onto you. The pressure gradient (for classical bodies easily calculated, do it on a rainy day) will have to make that on the surface of the body the pressure is equal to what is outside the body. If it would be smaller, it would be compressed more, if it would be greater, the body would expand.

In the case of a non-classical model the "problem" is that some of the pressures (namely the degeneracy pressures, be it electrons or ions) are indeed constant over the whole volume where that pressure is dominant. That in and of itself does not mean that there are abrupt jumps in the pressure near the boundaries. There will, most definitely, be a small conversion layer between the two regions in which different degeneracy dominate.

The atmosphere is a strongly compressed gas of material that is e.g. accreting to the neutron star. First of all let me make it clear, which you do not seem to have understood until now A NEUTRON STAR DOES NOT EXIST EXCLUSIVELY OF NEUTRONS, so you don't have "neutrons compressed in the order of billion tons per teaspoon" you have highly compressed, neutron rich matter which is compressed. Go back to my post #4 or ilya's post #11 and read those again and get a grip on what a neutron star is made of. And no, it would not collapse. Once there is a pressure, be it thermal pressure of a gas or degeneracy pressure of gas, which is "equal to the weight" of the mass in the layers above it, there will be no more collapse and the situation is stable. If such things would not happen, then you would fall through every floor you'd walk on.

To come back to the atmosphere, look at Venus which has a very very dense atmosphere, unlike the Earth. In the same way there can be an even denser atmosphere on a neutron star, indeed it HAS to be dense, otherwise we would not have Novae, where suddenly all matter in the accreted atmosphere starts fusion and lights up the neutron star like a Christmas tree.

[Strange]

BTW I don't believe all neutron stars have a carbon atmosphere. I assume H/He is more common or possibly Fe?

The density of the carbon atmosphere on Cassiopeia A is apparently about the same as diamond. So not what you would normally think of as "atmosphere"!

And another good summary here: http://en.wikipedia.org/wiki/Neutron_star#Structure (even though tusenfem's and Ilya's posts were both excellent).

[Sir Knots A Lot]

The density of the carbon atmosphere on Cassiopeia A is apparently about the same as diamond. So not what you would normally think of as "atmosphere"!


Magnetars are primarily characterized by their extremely powerful magnetic field, which can often reach the order of ten gigateslas. These magnetic fields are hundreds of thousands of times stronger than any man-made magnet, and quadrillions of times more powerful than the field surrounding Earth. As of 2010, they are the most magnetic objects ever detected in the universe.

A magnetic field of 10 gigateslas is enormous relative to magnetic fields typically encountered on Earth. Earth has a geomagnetic field of 30–60 microteslas, and a neodymium based rare earth magnet has a field of about 1 tesla, with a magnetic energy density of 4.0×105 J/m3. A 10 gigatesla field, by contrast, has an energy density of 4.0×1025 J/m3, with an E/c2 mass density >104 times that of lead. The magnetic field of a magnetar would be lethal even at a distance of 1000 km, tearing tissues due to the diamagnetism of water. At a distance halfway to the moon, a magnetar could strip information from all credit cards on Earth.

What would the 'atmosphere' of a magnetar be if the magnetic field is already 104 times denser than lead?

[Ilya]

We have on one hand neutrons compressed in the order of one billion tons per teaspoon full with an atmosphere of carbon above? We are told that the neutron star becomes denser, more homongeous the deeper we go. Surely with that pressure/gravity there would not be intermediate stages but rather it should be an all or nothing collapse of the atoms

Please re-read my previous post, carefully. Gravity DOES NOT suddenly turn normal matter into neutronium. As I said, with nothing on top of it a hydrogen (or a carbon) atom remains a hydrogen atom, no matter what the gravity field is. It takes weight of something above to first crush atoms into dwarf-star matter, then to more neutron-rich matter, then to neutronium, then to quark matter. Note that there is very little difference in gravity between surface of a neutron star and 1 km down. But there is huge difference in pressure.

And yes, your complains do sound like arguments from incredulity.

[Ilya]

What would the 'atmosphere' of a magnetar be if the magnetic field is already 104 times denser than lead?
Rows of atoms lined up along magnetic lines and not moving. Basically, a forest of solid needles. And since these needles are embedded in something 104 times denser than they are, no more important than veins in a slab of marble.

[tusenfem]

What would the 'atmosphere' of a magnetar be if the magnetic field is already 104 times denser than lead?

That is not a real density, that is only the energy of the magnetic field converted into a mass density using eisemseeskwared. It is a fun calculation, but for the rest it is rather useless.

The "atmosphere" would actually be highly magnetized and as it can be expected to be hot, it could be "vibrating" at the cyclotron frequency of the ions. However, based on the enormous strength of the field I think that very quickly the particles would drop down to be motionless on the magnetic field (sort of like an electron going to a lower shell)

[Neil Russell]

Yes I still believe Baade could have got it wrong, when he did his calculations he was not aware of black holes nor of element formation by super novas.
Ilya and Strange we are at odds still, we know the super nova compressed (pressure) the star, forming neutrons? If that was all, it would have released the pressure afterward and expanded out again into normal matter. That this did not happen is due to gravity! We are told that the escape velocity is about a third of the speed of light, some serious gravity there. Again I say that with the density and the gravity acting on carbon, whether it be diamond or super hot liquid it should not be able to exist there. To suggest that there is some kind of mix in the upper levels of the star is not taking into acount the truly huge differences between the elements of such a mixture and they should not be able to exist side by side.

[Strange]

Yes I still believe Baade could have got it wrong, when he did his calculations he was not aware of black holes nor of element formation by super novas.

Perhaps you could go through the math and show us where it is wrong?


We are told that the escape velocity is about a third of the speed of light, some serious gravity there.

And that (1/3 c) is exactly why black holes are irrelevant.


Again I say that with the density and the gravity acting on carbon, whether it be diamond or super hot liquid it should not be able to exist there.

Perhaps you could do the math to demonstrate that to us?


To suggest that there is some kind of mix in the upper levels of the star is not taking into acount the truly huge differences between the elements of such a mixture and they should not be able to exist side by side.

Can you show the math to prove that?

[Fortis]

Yes I still believe Baade could have got it wrong, when he did his calculations he was not aware of black holes nor of element formation by super novas.
Ilya and Strange we are at odds still, we know the super nova compressed (pressure) the star, forming neutrons? If that was all, it would have released the pressure afterward and expanded out again into normal matter. That this did not happen is due to gravity! We are told that the escape velocity is about a third of the speed of light, some serious gravity there. Again I say that with the density and the gravity acting on carbon, whether it be diamond or super hot liquid it should not be able to exist there. To suggest that there is some kind of mix in the upper levels of the star is not taking into acount the truly huge differences between the elements of such a mixture and they should not be able to exist side by side.
You seem to be very convinced about this. Presumably this is because you know what the pressure at the sruface of the star is, and the pressure range within which carbon can exist. Please can you tell us what the relevant pressures are, along with either a derivation or a reference?

[tusenfem]

Yes I still believe Baade could have got it wrong, when he did his calculations he was not aware of black holes nor of element formation by super novas.



(sorry to be moderating now in a thread I am involved in, but I think it is warrented)
Neil Russell it is time you start to give some evidence for your claims, how the knowledge of "black holes" (which accidentally predates Baade) or the element formation would lead to another conclusion.




Ilya and Strange we are at odds still, we know the super nova compressed (pressure) the star, forming neutrons?


A supernova is an explosion.
The fusion in the layers of the progenitor star stops because of lack of fuel, and then the the star starts to shrink as the plasma pressure can no longer withstand the gravitational inward force.
Then at one point it comes to an explosive fusion that blows off the outer layers of the star and leaves the core, which, without an energy source starts to collapse further under its own gravity and then the various regions (as shown above by me and Ilya) are created and no the whole neutron star does NOT exist of only neutrons.



If that was all, it would have released the pressure afterward and expanded out again into normal matter. That this did not happen is due to gravity! We are told that the escape velocity is about a third of the speed of light, some serious gravity there.


And ... that has been said the whole time. Whatever the escape velocity is is irrelevant, where are you going with this?



Again I say that with the density and the gravity acting on carbon, whether it be diamond or super hot liquid it should not be able to exist there.


I have to say this: THIS IS UTTER NONSENSE!!!!! Apparently you have your own conceptions how stars work. Yes there is strong gravity, so what? Why do you think that there would no carbon layer possible there. What exactly would be the reason for that? Explain us to the fullest, please.



To suggest that there is some kind of mix in the upper levels of the star is not taking into acount the truly huge differences between the elements of such a mixture and they should not be able to exist side by side.

And this word salad can only be categorized as, once more, nonsense.

[Sir Knots A Lot]

Just to throw in my 2 cents for Neil...

The transition from neutron degenerate matter to a 'carbon atmosphere' in the core would have a shell of proton-electron degenerate matter between them.

It's not like it goes directly from a neutron core to a diamond outer shell.

[Neil Russell]

Tusenfem my reading is that BH was first used in 1967 and that subsequently to that date BH were proved to exist. In 1934 Baade wo0uld not know of the BH concept, as I said he was probably theorising what he believed was the densest state of matter that existed. I am saying he could have been wrong and that neutrons may not be an intermediate stage between "normal" matter and the total collapse that is a BH. Again the formation of the heavy elements, surely would occur at the core of the super nova due to the pressure/implosion of the nova. That being so the core should hold the heavy elements, not neutrons!, so where are the heavy elements?
Sorry Strange, I dont do maths!! We seem to be at cross purposes with our pressure and gravity discussions..Yes pressure is zero at the surface of a star and increases with depth, my view is that it is now gravity that keeps the neutrons compressed this works from the surface down and I repeat how can a carbon molecule exist on the surface of a neutron when the density difference is in the billions the gravity difference should collapse the carbon molecule down to its component neutrons. The difference is so great I see no room for intermediate states.The theory says the atom is compressed, billions of times? forcing the electron to join with the proton forming a second neutron, where is the intermediate, it either collapses completely or it will bounce back to the atom stage.

[Strange]

Tusenfem my reading is that BH was first used in 1967 and that subsequently to that date BH were proved to exist.

1780-something, I think you will find


In 1934 Baade wo0uld not know of the BH concept, as I said he was probably theorising what he believed was the densest state of matter that existed. I am saying he could have been wrong and that neutrons may not be an intermediate stage between "normal" matter and the total collapse that is a BH.

As has been repeatedly pointed out, it ain't just neutrons. (did you look at the documents linked by Ilya?) Also, there is insufficient mass/gravity to form a black hole so their existence or otherwise is irrelevant.


Sorry Strange, I dont do maths!!

And there's the problem. You find the idea intuitively unacceptable. But so what. The universe doesn't have to satisfy your intuitions.


my view is that it is now gravity that keeps the neutrons compressed this works from the surface down and I repeat how can a carbon molecule exist on the surface of a neutron when the density difference is in the billions the gravity difference should collapse the carbon molecule down to its component neutrons.

How do you know what it "should" do if you "don't do maths" ?


The difference is so great I see no room for intermediate states.

How can you see that if you "don't do maths" ?


The theory says the atom is compressed, billions of times? forcing the electron to join with the proton forming a second neutron, where is the intermediate, it either collapses completely or it will bounce back to the atom stage.

Look at the descriptions linked by Ilya. It is almost nothing but intermediate states.

[Ilya]

Yes pressure is zero at the surface of a star and increases with depth, my view is that it is now gravity that keeps the neutrons compressed this works from the surface down
Well, your view is just plain wrong.

[whimsyfree]

In the world of real physics there is a good deal of modelling going on of the structure of neutron stars that suggests that strange particles called hyperons are a substantial part pf their composition. arXiv neutron star hyperon.

[Geo Kaplan]

Sorry Strange, I dont do maths!! We seem to be at cross purposes with our pressure and gravity discussions.

"Cross purposes?" Do you not understand that the ATM forum's fundamental structure is adversarial? You make an assertion, and the rest of us see if it holds water.

In this particular case, you have made a number of statements based entirely on your feelings about how nature should work. But by your own admission, you "don't do maths." You seem not to understand that this lack prevents you from developing the intuition necessary to be correct.

Do you have any calculations at all to support your assertions? If the answer is no, then perhaps you ought to hit the books first ("get thee to a library").

[VanderL]

The "flicker" we are seeing from neutron stars, or better Pulsars, cannot be created by "flipping of the magnetic field" because that would be totally inconsistent with the profiles of the emissions. These clearly show that the emission is coming from a "funnel" at the magnetic pole, which sweeps over our viewing direction

The magnetic field of our Sun does change polarity, but not as fast as you would like, only every 11 years.

Tusenfem, I would like to point out that while we do not know the origin of our Sun's reversals appr. every 11 years (it is not very constant), why can't a pulsar be described as a "fast oscillator".

Apparently not every scientist is convinced that field polarity reversals are inconsistent with pulsar observations. See This recent paper (http://arxiv.org/abs/0709.4315) with a follow-up paper (http://arxiv4.library.cornell.edu/abs/1008.3764) that shows inconsistencies in the original pulsar model paper (Pulsar Electrodynamics by Goldreich & Julian in 1969).


We constructed the magnetic field oscillation model (hereafter the MO model) by analogizing the periodically reversing phenomenon of the solar magnetic field to pulsars. Almost all kinds of pulsar radiation phenomena are best explained using the MO model, especially polarization characteristics, glitch, generation rate, the geodetic precession of pulsars and the configuration of pulsar-wind nebula of the Crab. The MO model also provides a satisfactory explanation of other characteristics of pulsars, e.g., interpulse, spin-down, pulse nulling, beat and pulse drift, the loss rate of the rotating energy, and the accuracy of frequency. We present six verification methods for the MO model. In addition, we predict that the pulsar PSR B1913+16 will not disappear from our line of sight after the year 2025, which is antithetical to the prediction made by some astronomers.

Cheers.

[tusenfem]

Unfortunately, neither paper of Liang's papers have been published in peer reviewed journals, only arxiv "publications" and one presentation at COSPAR 2006.

In the first paper, I notice assumed pole reversal periods without any reference for (cool) white dwarfs, and they put in pulsars, which is actually what they want to find.
Then they talk about "reversal of rotation"? I do hope they mean reversal of polarization here, but hey, how would I know? Apparently, they are working here with Faraday rotation, but it would be nice if they would actually give a model of the pulsar magnetosphere and show how this rotation works out.
Then they make the mistake that they identify any wind that may come off a pulsar would be the same as the cone of electromagnetic (radio) emissions from the magnetic poles of the neutron star. They talk about faculae and annular structures that are supposet (not) to be seen in Fig. 3, without even a caption for the figure what exactly is shown.

Up to now, basically anything we are given is words, at the bottom of page 8 they write:



Our proposal is that the factors that control reversals of the stellar magnetic field are the stellar components, geometric dimension, rotating frequency, temperature, and charge radiant rate, rather than the very random behavior of eddies. Because these factors have very high long-term stability, the reversal
frequency of the stellar magnetic field must have a very high long-term stability.


Well, as the magnetic field in the sun is generated by eddies and dynamo action, this is a pretty controversial statement. Maybe they should give us some evidence? Well, no they don't they give us some rather weird explanation why the Earth's frequency is so bad (because of "environmental effects") and for the sun it is also not so good because:



It is important to ask why the accuracy of the solar magnetic field period is lower than that of pulsars. One of the reasons is that there are just 11 periods
(22 half- periods) in which to record oscillations in the solar magnetic field. If only 11 signal periods of a pulsar are considered, the resulting period accuracy
is also very low, probably approximately the same as that of the solar period. This indicates that there is no clear difference between the short-term stability
of the sun and that of pulsars. There is presently no way of knowing the longterm stability of the sun.


Say what now?
Then lots of blahblah, no real model is ever presented and so we find on page 13:



According to the MO model, the factor that controls particle acceleration is the rate of change of the magnetic flux, rather than the strength of magnetic
induction. When the magnetic field density changes through the zero point, the majority of the magnetic energy changes into electric field energy to accelerate
the particles; the rate of energy utilization is much greater than that described in the lighthouse model.


Ehhhhh, let's see, induction is the generation of an electric field through a time varying magnetic field. This part just drips induction, however, they say that it is not, is there something I am missing here?

Then they just blatantly lie on page 14



It is difficult to explain the fine structure of a pulse with reference to the lighthouse model. Assuming that the fine structure of each pulse corresponds
to the fine structure of the radiation region, our calculations show that even if completely coherent radiation is generated in all of the fine regions, just
as would occur if the array was composed of many lasers, it is impossible to generate such a fine micro-pulse.


What calculations? There has not been an equation up to this point, let alone that they actually calculated something. Well they try to use laser theory to explain that the emission region cannot be as small as it must be because the micropulse it too narrow. However, I am not sure if their equation (1) is applicable. Not that their MO model brings a solution, because they claim that the pulses are like lightning:



According to the MO model, the signal of pulsars is a real time-domain signal, as with lightning radiation on earth. The characteristic of this kind of signal
is that the greater the propagation distance, the weaker the signal, but the fine structure of a pulse is retained in its entirety.


Yeah, but that would not explain the actual observations we have from pulsars, now does it? Then every neutron star would be a pulsar that we can observe flash, which we know is not true.

I will just stop there, because, after 17 pages, they come to Verification method : har har har har ROTFLOL, excuse me, but what is there to verify? This "paper" is written in the style of an ATM thread here on BAUT, just complain about mainstream, do not present a REAL alternative model but just give keywords, don't calculate anything at all, and then come to the conclusion that (after never ever clearly and quantitatively going through the MO model):



Compared to the lighthouse model, the MO model is better able to explain all kinds of radiation characteristics of pulsars, especially the characteristics of
pulse polarization, the microstructure of profile, the glitch, the configuration of PWN. Although the reason why the oscillation of the magnetic field of pulsars
remains unknown, its observation characteristics lead us to believe that the magnetic field oscillation should be the source of pulsar radiation.


Hah! That I not laugh, as the Austrians would say (literally translated, that looks nicer).

I am not surprised that this "paper" has not been published (nor any others of Zhu-Xing Liang), nothing more than arxiv.

Then one comment on the second linked "paper"

Already in the beginning of the "follow up paper" they make a wrong interpretation of the E + v x B = 0 equation, through their first interpretation that this is the Lorenz force, which although related, it is not. Therefore, they don't understand why Goldreich & Juilan repace v with Omega x r as the velocity. Equation 1 can be used to calculate the fields for a stationary observer watching a spinning magnetized neutron star and has nothing to do with the possibilites of particles moving perpendicularly to the magnetic field. So I guess if they make a mistake in the first subsection, I don't need to read on.

[tusenfem]

Tusenfem, I would like to point out that while we do not know the origin of our Sun's reversals appr. every 11 years (it is not very constant), why can't a pulsar be described as a "fast oscillator".


We know that because from our models the quantum behaviour of the particles inside the neutron star binds the magnetic fields into "current tubes" and these are not moveable anymore. In the case of a neutron star the magnetic field is more like a permanent magnet or better even a superconducting magnet than like a dynamo generated magnetic field like in the Earth or in the Sun. These are not prone to field reversals, which is inherently a dynamic (chaotic??) process.

Here is a list of papers (http://esoads.eso.org/cgi-bin/nph-abs_connect?db_key=AST&db_key=PRE&qform=AST&arxiv_sel=astro-ph&arxiv_sel=cond-mat&arxiv_sel=cs&arxiv_sel=gr-qc&arxiv_sel=hep-ex&arxiv_sel=hep-lat&arxiv_sel=hep-ph&arxiv_sel=hep-th&arxiv_sel=math&arxiv_sel=math-ph&arxiv_sel=nlin&arxiv_sel=nucl-ex&arxiv_sel=nucl-th&arxiv_sel=physics&arxiv_sel=quant-ph&arxiv_sel=q-bio&sim_query=YES&ned_query=YES&adsobj_query=YES&aut_logic=OR&obj_logic=OR&author=&object=&start_mon=&start_year=&end_mon=&end_year=&ttl_logic=OR&title=&txt_logic=AND&text=pulsar+magnetic+field+current+vortices+&nr_to_return=200&start_nr=1&jou_pick=NO&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&obj_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1) on ADS where I searched on the abstract words: pulsar magnetic field current vortices .

[HenrikOlsen]

...Yes pressure is zero at the surface of a star and increases with depth, my view is that it is now gravity that keeps the neutrons compressed this works from the surface down and I repeat how can a carbon molecule exist on the surface of a neutron when the density difference is in the billions the gravity difference should collapse the carbon molecule down to its component neutrons.
Let's try to work with this for a little while.
Pressure at a specific depth is basically the weight of all the material in a column straight above you, e.g. the pressure at the surface of the earth is the weight of the column of air above you.
A neutron star doesn't go straight from hard vacuum to a surface of neutrons, but rather goes from the hard vacuum far out, though wisps of nothing, through gas, carbon condensate, diamond-like sorta-solid and so on, down to the neutronium inner part, likely with other layers in-between that I missed.
At each boundary there's dynamic mixing and a gradual change in composition and pressure so the sharp boundaries your intuition complains about don't actually exist. The problem isn't that you intuition is wrong about what would be needed to make those sharp boundaries, it is that you're wrong about those sharp boundaries existing at all.

[Neil Russell]

I find it enlightening that we are in debate over the surface composition, the pressure v gravity question. I read a report of a discovery of a new neutron star where the discoverer ( he must have maths!!) described a layer?"atmosphere" carbon 10 inches thick over a solid surface. Ilya is understandably upset with me given the current models he quotes, but the reality is there are many models out there and no one can say for sure that their model is the correct one! Remember I am arguing that it is not a "neutron" but a star composed of heavy elements giving it a much higher density than compared to our sun for example. Given that a carbon shell is quite possible.

GeoKaplan, so without maths I cannot "develop the intution necessary" what to solve problems? to visulise? come on sir that is a bit uncalled for. Surely first comes the idea, the vision then comes the math, if you have it!! and as I am sugesting here the maths does not always make it right.

[publiusr]

So lets say a cosmic string were to tear off the upper layers of a neutron star, what would be left at the core?

[Geo Kaplan]

GeoKaplan, so without maths I cannot "develop the intution necessary" what to solve problems? to visulise? come on sir that is a bit uncalled for. Surely first comes the idea, the vision then comes the math, if you have it!! and as I am sugesting here the maths does not always make it right.

If this forum were for the collaborative development of new ideas, you'd have a legitimate gripe. However, the ATM forum is governed by a well-defined set of rules that specifically preclude that collaboration. The mods recently posted a much-clarified, succinct summary of these rules. Perhaps you'd be less aggrieved if you actually were to take a look at that summary.

And to answer your question, without the maths, you cannot develop the intuition necessary. Sorry you believe otherwise, but science is hard. Lots of notions that seem reasonable (e.g., "heavy objects fall faster -- duh!") turn out to be totally wrong. Without math, you can't work out what actually is reasonable, and thus you are unable to develop important insights. You've already demonstrated the truth of my statement by making numerous assertions that are flat-out wrong. I must assume that they seemed reasonable to you when you made them. Do you understand what all that implies?

[tusenfem]

I find it enlightening that we are in debate over the surface composition, the pressure v gravity question. I read a report of a discovery of a new neutron star where the discoverer ( he must have maths!!) described a layer?"atmosphere" carbon 10 inches thick over a solid surface. Ilya is understandably upset with me given the current models he quotes, but the reality is there are many models out there and no one can say for sure that their model is the correct one! Remember I am arguing that it is not a "neutron" but a star composed of heavy elements giving it a much higher density than compared to our sun for example. Given that a carbon shell is quite possible.

GeoKaplan, so without maths I cannot "develop the intution necessary" what to solve problems? to visulise? come on sir that is a bit uncalled for. Surely first comes the idea, the vision then comes the math, if you have it!! and as I am sugesting here the maths does not always make it right.


Neil Russel, you have been requested in post #26 that you have to present your ATM, this is not a discussion corner. You seem to have a gripe with the accepted mainstream ideas about the build up of neutron stars. Nobody will deny that, e.g. a carbon layer can happen in some neutronstars, but you may want to link to the information that you have obtained.

Now, please come up with something significant about your ATM, and not "I feel that it is wrong" or "I don't believe it can be that way". Your idea is that a neutron star can be actually a heavy element star. Now start explaining how it works, how it comes to an equilibrium that it does not collapse, is there still fusion inside or not etc. etc. etc. (and yah, that includes "the math").

You will present this in your next message, otherwise you this thread will be closed and you will get an infraction. Up to now only other members of BAUT have done real work in this thread.

[Neil Russell]

Tusefem, it is pointless for me to continue this, as without maths I would seem to be at a serious disadvantage v the others whom expect maths based answers! So thank you all for your interest. The field of neutron stars is truly interesting and challenging, thank you. (yes I must read the rules again)

[Jim]

Based on Neil Russell's latest post, this thread is closed.