Neutron Stars Partially Dissected

mmol_6453 writes "An article at ScienceDaily details and explains observations that offer the first proof that what we consider neutron stars really are neutron superfluids. The original press release can be found here."

No Lifeguard . . .

[Dausha]

Okay, if it's a superfluid, then is there an adult swim?
Seriously, is ther a star smaller than a quark star but bigger than a black hole? Call me dense, but I've not been more than a casual observer of astronomy.

Repeat?

[Tablespork]

Is this anything other than a summary of this? [slashdot.org]

Re:Repeat?

[trixillion]

no, this isn't a repeat. Why don't you bother reading the articles for a change.

super fluids

[Anonymous Coward]

I would imagine at those super pressures found in a neutron star that our ways of defining states of matter would be of no relative importence. In the soup that is a neutron star, nuclear forces would dissasemble the parts of an atom. Now as we all know, there are 3 states of matter, solid, liquid, and gaseous, but a lot of people don't know about about a forth or even beyond. When one heats up a gas to super temperatures (like that found in a neutron star) the atoms will no longer be bound by their forces within them and neutrons will fly from protons in the nucleus, while the electrons would also start acting strangly. If we up the temp even more, the subatomic particles will start breaking down into their quarks and neutrinos. I am not sure what that state of matter is called, but that can happen in a neutron star. (just for fun, if you keep on heating the quarks and such, you would eventually rip a hole in space/time and I would really recomend leaving the room where you are doing this :)

Now my question is, this slush of various subatomic particles in the star: can you call it liquid? Another question is if you were to disect a neutron star, the subatomic particles would quickly reassemble themselves and you would be left with Hydrogen, wouldn't that leave you with almost no insite to a neutron? I could see how exciting this would be in an attempt to explain the seconds after the big bang, but just to explain superfluids?

bah..

forgot plasma

[wotevah]

As we all know, there are actually four states of matter: solid, liquid, gaseous and plasma.

No, five!

[Black Parrot]

> As we all know, there are actually four states of matter: solid, liquid, gaseous and plasma.

As every Slashdotter knows, there are five states of matter: solid, liquid, gaseous, plasma, and beowulf cluster.

Re:forgot plasma

[nukey56]

As we all know, there are actually four states of matter: solid, liquid, gaseous and plasma.

I believe this was already covered:

but a lot of people don't know about about a forth or even beyond

Come on mods, check your sources!

Re:forgot plasma

[wotevah]

It is generally accepted (read "taught in schools") that there are four states of matter, no ifs and buts. Therefore, the statement "as we all know there are three" is not quite correct.

Re:forgot plasma

[The Red Rooster]

There are actually several more:
solid
liquid
gas
plasma
AND
Bose-Einst ien Condensate
Quark somethingorother
superfluids

BEC's are ultra-cold bodies of matter where all atoms in the conglomerate 'march' to the same drum. In effect, each atom behaves not just exactly the same as all other atoms, but as if the whole she-bang were one single atom.

With the Quarks, inside super-hot, super-dense areas, quarks free themselves, something not normally allowed. The quarks end up shielding themselves from each other so that they cannot recombine quite as easily. IOW, you can actually cool the cloud down just a bit.

Superfluids are states not unlike BEC's wherein all sorts of strange things happen. Helium is the famous example. You can get superfluidic helium to flow uphill in the right conditions.

Re:super fluids

[addaon]

A liquid is a substance which retains its volume, but not its shape. A solid retains both, a gas neither. A neutron star is liquid, as it's volume is stable (due to the balance between gravity and other forces), but any slight deviation from spherical (or non-spherical, if it's spinning... neutronium does weird stuff when it spins, it's not just an ellipsoid) is quickly overwhelmed and pulled flat.

Also, I seem to recall that neutronium is metastable, which would mean that you can at least fiddle it a bit when you dig it out of a star... of course, technical difficulties are another issue entirely.

Re:super fluids

[plluke]

Super hot gasses you refer to are plasma. Actually, that doesn't happen in a neturon star. The gravity is so strong in a neutron star that all you are left with, literally, are neutrons. If I remember correctly, the main force that prevents them squishing in further is the Heisenberg uncertainty principle. In other words, you can pack neutrons on so closely before what you try to achieve goes into the realm of "exact location/position/energy, etc." and we can't ever have that. To go beyond this would require a black hole and nobody knows what goes on in there...

The only subatomic particles that are in neutron stars should be neutrons...nothing else. So making water out of slices of a neutron star is definitely out of the question...

Re:Cool stuff

[Spock the Baptist]

Thought that I'd throw out a few links on the subject of quark stars. Here's a few useful, and informative links:

http://www.aip.org/enews/physnews/2002/split/585 -1 .html
http://itss.raytheon.com/cafe/qadir/q1401.h tml
http://slashdot.org/science/02/04/10/1840222. shtml ?tid=160
http://news.bbc.co.uk/1/hi/sci/tech/1922 574.stm
http://www.fi.uib.no/~nyiri/thesis.html

Re:Cool stuff

[dvd_maximus]

Its core consists mainly of densely-packed neutrons, with a sprinkling of protons and typically 3 times as many electrons as protons

So the core is negatively charged? What part of the neutron star has the balancing positive charge? And more importantly: why?? What keeps the charge separated?

As a neutron star cools and grows ...

I thought neutron stars shrank as they cooled?

Re:Cool stuff

[Iainuki]

Quote from Carroll and Ostlie (a standard undergraduate astrophysics text): "A very general argument involving the general theory of relativity shows that the maximum mass possible for a neutron star cannot exceed about 3 Msun. If a neutron star is to remain dynamically stable and resist collapsing, it must be able to respond to a small disturbance in its structure by rpaidly adjusting its pressure to compensate. However, there is a limit to how quickly such an adjustment can be made becasuet hese changes are conveyed by sound waves that must move more slowly than light. If a neutron star's mass exceeds 3 Msun, it cannot generate pressure quickly enough to avoid collapsing." Neutron stars can't have have masses of 10 suns.

Please back up your assertions!

[Scott Carnahan]

yet within this small region may be over 10 solar masses of material.

Had you read the article, you would have seen that neutron stars are thought to contain the mass of about 1.4 suns. Barring certain speculative theories of exotic matter, no cold (i.e., not undergoing fusion) stellar configuration can have a mass greater than 5 suns. See, for example, Misner, Thorne, Wheeler [amazon.com], page 627.

The result is a gravitational field at the surface of a neutron star about 70 trillion times stronger than that on Earth.

Given that neutron stars have mass about 500,000 times that of the earth, and radius about 1/400 earth radius, one can use the Newtonian inverse-square law approximation to get a factor of about 80 billion, which is considerably less than your figure. Where did you get these numbers?

Its core consists mainly of densely-packed neutrons, with a sprinkling of protons and typically 3 times as many electrons as protons, in a liquid-like state known as neutronisticis.

Do you have a reference for this? Most models of neutron stars treat the core as a degenerate Fermi gas, and as another poster noted, your star seems to have a net negative charge. Where did the protons go? Also, this is the first time I've encountered the word "neutronisticis". A Google search [google.com] turns up nothing but this very post.

As a neutron star cools and grows, strains develop in the crust so that it buckles, causing starquakes equal to 1000 on the richter scale.

Starquakes are thought to be possible, but if our time frame is more than a few seconds after formation, the cause is probably not due to thermal stresses. This is because the thermal contribution to pressure and density is negligible as long as the temperature of a neutron star is below the Fermi energy of matter at nuclear density (about 30MeV, or 3*10^11 K - see MTW page 599, referenced above), and neutrino radiation brings the temperature well below this level very rapidly.

The Richter scale is logarithmic, based at 105 Joules for a degree 0 quake (reference [themeter.net]), and growing by a factor of 1000 for every two degrees. A quake registering 1000 would have to release 1.05*10^1502 Joules, which is much more than the mass-energy contained in the observable universe. Indeed, it is quite impossible for any stellar-scale phenomenon to register more than 40 on the Richter scale, simply because stars don't have enough mass to release that kind of energy.

What is the size boundary for quark stars?

[multiplexo]

My understanding is that when a neutron star becomes too dense it collapses into a black hole. From this it would seem that the size boundaries for quark stars would be very tight, the star would have to be dense enough to liberate the quarks but not so dense as to collapse into a black hole. Or am I on crack here?

Theoretical Physics question

[dukerobinson]

yeah I just had a question for whoever knows the answer. Ok so when a star gets old and dies and whatnot and collapses into a black hole, isn't it true that there is no way for any matter to escape at this point? I thought that this was because the gravity was such that space time curved so sharply that even light would find itself in a perpetual orbit around the black hole if it fell below the event horizon. I always have this picture in my mind of how that might work. ( of course there is no way to visualize it because light couldn't communicate information in a human decypherable way in this state, but you know. ) My thought was that if you could shine a laser at the exact point of the event horizon, the light would instantly loop around and form a perfect eternal circle arount the black hole, If you kept shining the laser for a year, and then were able to look at the event horizon as if it were coming straight on, like watching the sun rise, you would see all of the photons you had propelled into the black hole over that years time all at once, in a perpetual orbit. That is, assuming some space rock or star or something didn't cross their path while plumeting to their doom. Just sick visual imagery, I don't think I am getting my point across. ok But my question was this: If the big bang was an explosion of energy that contained all of the energy ever to exist (and later to cool into matter -- I don't understand that at all, btw) Why was the gravitational pull of all of this shit not enough to curve/rip spacetime into the one big black hole, and creation end there? Also I have heard something to the effect that black holes slowly evaporate by emitting X-rays. If other forms of electromagnetic radiation (light and such) can not escape, then what is special about X-rays? And if black holes do slowly lose mass due to x-ray evaporation, then do they explode all at once when they get back down to a mass that can not sustain such compression, thus weakening gravity, thus exploding bigger, thus weakening gravity some more? Any insight? sorry for my ignorance in physics.