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I think the introduction has too much unnecessary jargon in it. I think it should be simplified and made more clear.17:25, 26 October 2008 (UTC) —Preceding unsigned comment added by 75.150.72.237 ( talk)
The information on gravity and escape velocity don't belong in this section and since it is already included in the properties section it is also redundant. It should be deleted from this section
Furthermore, I think there should be, if possible, more detail put into the formation.
Alexa7890 (
talk)
19:00, 26 October 2008 (UTC)
This section is really short. Perhaps it would be a good idea to include the end of a neutron star and change it from just a "formation" section to a "formation and end" section. Alexa7890 ( talk) 07:04, 27 October 2008 (UTC)
Is the information on the Equation of State correct? The citation that is given (#3) goes to the German page on neutron stars. I have come across articles that discuss the EoS for Neutron Stars which would imply that an EoS is known. Alexa7890 ( talk) 13:16, 27 October 2008 (UTC)
No, the EOS is not known with ANY certainty. There are infact many competing modals. You should be cautious with neutron stars - they tend to publish "facts" about them decades before an issue is settled, or even properly explored. —Preceding unsigned comment added by 75.153.125.20 ( talk) 01:42, 13 December 2008 (UTC)
The escape velocity is listed as 30% of speed of light and as 50% the speed of light, if it does vary that much it needs to be mentioned, as it is now it conflicts with the previous paragraph —Preceding unsigned comment added by Edman007 ( talk • contribs) 16:59, 17 November 2008 (UTC)
The information of the density seems to belong in the properties section. The second paragraph needs to be considerably cleaned up. The "proceeding deeper" vocabulary isn't something that would be in an encyclopedia and the information should be made more clear. —Preceding unsigned comment added by Alexa7890 ( talk • contribs) 23:14, 22 October 2008 (UTC)
The crust is 1 meter or 1 mile thick? (section on structure). The text and the figure are contradicting themselves. 201.80.110.49 ( talk) 05:31, 30 November 2007 (UTC)
The thing that is being referred to as 1 meter thick is the atmosphere, however from what I know this is incorrect. According to The Internet Encyclopedia of Science what can be called an atmosphere is maybe only a few micrometers thick. The figure is correct according to Universe Today and Space.com Alexa7890 ( talk) 15:13, 22 October 2008 (UTC)
All the calculations regarding the volume and density of a neutron star that I have seen assume that the space inside a neutron star is flat. However, inside an object as massive as a neutron star, doesn't the curvature of space become significant? Wouldn't that mean that the internal volume is larger than the standard formula for a Euclidean sphere would suggest? I hope someone more familiar with General Relativity can answer these questions. Clement Cherlin 01:16, 16 November 2007 (UTC)
Isn't a magnetar's power source it's magnetic field energy?
See http://solomon.as.utexas.edu/~duncan/magnetar.html#New_Kind_Of_Star
there is alot of argument over this. It seems like it is it's magnetic field - but the origin of the field itself is open to discussion. It's like saying your TV is electric powered - ignoreing the coal plant on the other end. Also, most neutron stars are rotation powered - the high field stars seem to be an exception, but we really don't know with any certainty. —Preceding unsigned comment added by 75.153.125.20 ( talk) 01:44, 13 December 2008 (UTC)
89.48.108.46 ( talk) 16:22, 11 December 2007 (UTC)
SOME ISSUES HERE WITH THE SOLAR MASS OF THE NEUTRON STAR AND THE SUN. IF IT IS 1.35 SOLAR MASSES, THEN IT WOULD NOT BE SMALLER THAN THE SUN —Preceding unsigned comment added by 155.214.128.4 ( talk) 15:38, 26 February 2008 (UTC)
The value of 2×1012 g is far too high. If approximated by Newton's Law of gravity a 2 solar mass neutron star with 10 km radius would have about 2.7×1012 m/s² = 2.7×1011 g. A 3 solar mass black hole would have about 5×1011 g (at the Schwarzschild radius of 9 km}}. Although one would have to use the relativistic equations for a correct result the Newtonion equation should at least give the correct order of magnitude. I have therefore corrected the value in the properties section; the range of 2×1011 to 2×1012 g given a few lines above remains as a matter of further check (with relativistic formulae, if possible).-- SiriusB ( talk) 15:02, 26 December 2008 (UTC)
How does a neutron star end it's life, what happens to it? And how? It doesn't have fuel like a regular star, and it's gravity holds it together, how long can they stay that way? The snare ( talk) 05:51, 19 August 2008 (UTC)
Jakezing, I asked my astronomy professor about this and she said that a neutron star will remain mostly static, although they will cool down a bit Alexa7890 ( talk) 02:26, 28 October 2008 (UTC)
A neutron star will end it's life quietly - the professor is correct. At least for most stars. And yes, that doesn't make him necessarily correct, but noone is ever necessarily correct. Vacuous statement. —Preceding unsigned comment added by 75.153.125.20 ( talk) 01:45, 13 December 2008 (UTC)
I'm still a little confused, so it will cool down, but then what? Break apart and dissipate somehow? And how will it do that? The snare ( talk) 03:20, 24 January 2009 (UTC)
So, you're saying neutron stars are eternal as far as we know? When there is nothing but photons left in the universe, there will also be neutron stars literally forever? Also, don't neutrons become protons, at least when they are alone and not in a nucleus? The snare ( talk) 02:22, 2 February 2009 (UTC)
Don't atoms (normal ones, so a deuterium atom in this example- just so we have one neutron) eventually break down and dissipate? They don't last forever, so I've been told, they aren't perpetual motion machines, don't know about neutron stars though. The snare ( talk) 03:14, 16 April 2009 (UTC)
Don't forget about the gravity of the thing. It's really strong and makes it hard for matter to escape, so the example with deuterium doesn't really apply here. And yes, neutron star isn't a perpetual motion machine, it emits a lot of energy during it's lifetime - that's why it cools down. Regarding the topic, it's really hard to say how does the star end it's life because we can't see the really old ones - they're too cool and therefore emit too little energy to be observed. In theory they can live forever or collapse into a black hole as said by Potekhin or maybe they change into a basket full of oranges ;), we will probably never be sure of that. -- Siberie ( talk) 04:55, 24 May 2009 (UTC)
How is it possible for a neutron star to be very hot. Atoms and molecules are to be in motion for the flow of charge of heat while there is no charge on neutron star. Myktk ( talk) 15:36, 21 October 2008 (UTC) Khattak
The above poster claiming that charge and heat are different is correct. But to answer your question more fully - Temperature is related to the ratio of a change in entropy to a change in energy. A very small change in entropy here requires a massive change in energy, because the star has such high density. The result is that the temperature is very high. To the poster who claimed that neutron stars are like black holes - thats really not a fair comparison. Black holes violate in principle every law of physics. People like Hawking, Wheeler, and Unruh have spent their lives figureing out how our laws of thermodynamics can exist next to black holes - forget working INSIDE them! —Preceding unsigned comment added by 75.153.125.20 ( talk) 01:49, 13 December 2008 (UTC)
It's not clear to me what the original poster meant with that question. He mentions the fact that neutrons are not charged particles but does not explain why he thinks that the presence of charged particles should be required in order for something to be very hot. He might want to better explain his position. He seems to believe that only charged particles can have a temperature. That's simply not true. Dauto ( talk) 05:21, 29 January 2009 (UTC)
I've wondered this too. Heat is determined by how fast the electrons are moving, but since a neutron star is all neutrons and no electrons, how can it have heat? The snare ( talk) 03:10, 16 April 2009 (UTC)
the core is reached, by definition the point where they disappear altogether." (a quote from current article) I wonder about the accuracy or at least the clarity. The sentence seems to be saying that a "neutron star" must "by definition" have at least some location where matter exists only as neutrons(and thus must at least have it in the core), but I doubt astronomers think that way. Astronomers probably identified some objects that they suspected had that property, and called them neutron stars, but they're not defined by that, but probably by observational characteristics, whether or not astronomers now know if some or all neutron stars have matter of this form.Astronomers don't define their universe, they (try to) describe it.--Richard Peterson 75.45.97.146 ( talk) 18:10, 7 May 2009 (UTC) Rich ( talk) 21:12, 7 May 2009 (UTC)
"Outside the nucleus, free neutrons are unstable and have a mean lifetime of 885.7±0.8 s (about 15 minutes), decaying by emission of a negative electron and antineutrino to become a proton:[6]" Source: http://en.wikipedia.org/wiki/Neutron So its life time should not be more than 15 second.
Also, if surface gravity of neutron star increases 7x10^14 every meter in one second then is this figure higher than speed of light? 96.52.178.55 ( talk) 17:00, 31 May 2009 (UTC)Khattak
Yes, I meant 15 minutes. Thanks. 96.52.178.55 ( talk) 04:29, 3 June 2009 (UTC) khattak
Neutron stars are very hot and are supported against further collapse because of the Pauli exclusion principle. - This statement is not entirely correct. Of course the exclusion principle is important here, but it's too weak to support the star. The major contribution to force that counters gravity are repulsive nuclear forces which come into the game because of huge density. I think it should be corrected. Any comments? Siberie ( talk) 14:57, 25 May 2009 (UTC)
This subject is not even discussed and needs to be a prominent part of the article. Magnetic fields of 10×108 Tesla are common or 100 million times greater than a rare earth magnet This is one of the MAIN properties of a neutron star. Magnetic poles are usually not aligned with the axis of rotation which gives a pulsar. Trojancowboy ( talk) 03:02, 28 May 2009 (UTC)
Actually it is mentioned 8 times. But I too think it deserves a section to itself. I'll get out my college textbook and look it up. Marx01 Tell me about it 00:20, 28 September 2009 (UTC)
I found some lists of known neutron star on Gooogle but some without distances. I'm wondering how far away the closest is. —Preceding unsigned comment added by 71.186.61.183 ( talk) 13:10, 14 July 2009 (UTC)
I came to this article looking to find out how a conventional star made up of atoms (protons/neutrons/electrons) ends up with the protons and electrons gone and the neutrons remaining. Any chance there's a guru out there that can explain it? After all, that's sort of the whole neutron star formation thing. Grumpyoldgeek ( talk) 21:00, 11 June 2009 (UTC)
The concept of the atom can be boiled down to it's being an almost in contact accumulation of deuteron pairs plus extra neutrons and surrounded by a cloud of electrons. And a Neutron star concept further whittles the size down such that the space for the cloud of electrons is eliminated. And the presumption of neutral atomic charge pretty much assumes that each electron must return to it's associated proton. So everything is neutral. And the concept of the continued existence of individual nucleons requires a packing system similar to what exists in the nucleus of the normal atom, which is pretty closely packed. But it's hard on the accumulated repulsive force theory and might require some rethinking about that. And it makes you wonder about the quark electrostatic charge existence and change mechanism logic, but we wouldn't want to do that. WFPM ( talk) 19:07, 4 May 2010 (UTC)
How does this article relate to the Schwarzschild radius? http://en.wikipedia.org/wiki/Schwarzschild_radius Should there be a connection of ideas between these two ideas?
Reddwarf2956 ( talk) 19:40, 31 August 2009 (UTC)
How close (what range of distance) to a neutron star does pair production happen? It is know that near heavy dense atoms in which a two times electron rest mass energy gamma ray comes close pair production happens. How much mass is gained/loss by this production?
Reddwarf2956 ( talk) 19:52, 31 August 2009 (UTC)
The sixth source in this article is said to be the germans wikipedia. i dont think that is right. could someone mark that as unverified and get someone to get a verifiable source for that information [1] 66.90.164.132 ( talk) 18:55, 5 November 2009 (UTC)HTU-Student
At the end of the second paragraph, the article states, "This density is approximately equivalent to the mass of the entire human population compressed to the size of a sugar cube."
With over 7 million humans currently inhabiting the Earth, within the parameters of errors, deaths, and unrecorded populations (tribes disconnected from the outside world), this is not a valid argument. Likewise, without a statistical date, one could describe the density of a neutron star as being similar to that of the human population of the plague-ridden medieval age. For something so immensely dense as a neutron star, it likely doesn't matter much the mass of humans it would take to approximate the density of a neutron star. It's a simple fact that the original statement is too vague to be a valid statement.
Christopher, Salem, OR (
talk)
12:53, 18 May 2010 (UTC)
Since my last posting on the discussion of this article, I have taken note of the addition of the reference as I requested. Though I am unfamiliar with Ankit Srivastava page (
http://www.ankitsrivastava.net/2010/06/neutron-stars-sugar-cubes-and-squeezed-humans/), I feel that this reference goes above and beyond at clarifying the statement, "This density is approximately equivalent to the mass of the entire human population compressed to the size of a sugar cube."
Well done. Now there's some numbers to wrap 'round our brains.
Christopher, Salem, OR (
talk)
10:51, 18 June 2010 (UTC)
This is my first time on a talk page, so please forgive and correct me if I do anything wrong.
There is a small fact in the top paragraph stating that neutrons have roughly the same mass as protons. Would it be acceptable for me to change that to "a slightly larger mass than protons"?
I decided to go with the "be bold" principle. And for anyone who is worried, I will watch my spelling in actual article edits.
KKPie ( talk) 15:36, 18 June 2010 (UTC)
Could the article mention that the core degeneracy pressure at collapse approaches the maximum possible theoretical pressure of P = pc2 , where p is the density? 172.129.30.241 ( talk) 01:19, 18 August 2010 (UTC) BG
1. Can the article give an approximate range for estimated core pressures in a neutron star? For starters wouldn’t the non-relativistic core pressure of a neutron star be given approximately by P(c) = KGM2/(πR4), where K is a constant dependant on the density profile, but nominally equal to 1. For 1.35 to 2.1 solar mass stars, this would give estimated pressures of about 1 X 1034 to 2 X 1034 kg/m2. The magnitude of this approximate pressure is mind boggling. It would be equivalent to about the entire weight of the sun pressing down on 1 cm2 at the earth’s surface. This is a sloppy calculation and maybe others could improve it. It would be nice if someone could give a better equation for core pressure or at least the results. Does someone have Tolman–Oppenheimer–Volkoff equation solutions for a neutron star? I don't accept the TOV equation but many others do.
2. To diverge, why should collapse of this type structure lead to a point singularity? If during collapse the mass not blown away is large enough to form a black hole, shouldn’t the resulting high temperature essentially convert all this mass into contained radiation? The basic pressure formula for this intense radiation would likely be P = pc2 (where p is the equivalent mass density of the energy). This should prevent collapse to a singularity since this pressure has no limit and increases as 1/R3, faster than the increase of gravitational force. 172.162.242.8 ( talk) 19:59, 23 September 2010 (UTC)BG
Good idea. Your comments are welcome at http://www.physicsforums.com/showthread.php?p=2905538#post2905538 ````BG —Preceding unsigned comment added by 172.129.106.208 ( talk) 00:29, 29 September 2010 (UTC)
Maybe you directed me to the forums as punishment. Perhaps some there believe a BH is made of chocolate pudding. Now I long for the days when conversations were dominated by singularity advocates. 172.163.115.55 ( talk) 18:37, 29 September 2010 (UTC)BG
Yes. Radiation pressure of pc^2 or (pc^2)/3 shows why collapse should not occur in the core of a black hole. But it does not explain why collapse should not occur at the black hole surface. But based on E = mc^2, the absolute maximum pressure P that matter should be able to support is P = pc^2, where p is the density of the matter. Its interesting that neutron star cores at collapse approach this pressure. 172.162.222.11 ( talk) 13:18, 5 October 2010 (UTC)BG
It would be interesting to know if neutron star core collapse occurs at a pressure of (pc2)/3, at pc2, or somewhere in between. Does anybody have this information or an estimate? Possibly it could be added to the article. 172.130.75.73 ( talk) 19:42, 17 October 2010 (UTC)BG
I was bold and removed the Disrupted Recycled Pulsar section as it was copyrighted. The origin of this section was from this link http://www.scientificcomputing.com/news-DS-Einstein-at-Home-Citizen-Scientists-Discover-New-Pulsar-081210.aspx
Notice at the bottom of the article "Science Express, August 12, 2010". This section was added on August 31, 2010 as shown in this link: http://en.wikipedia.org/?title=Neutron_star&oldid=382083718
Obviously a copyright violation. Good information if worded differently but until that is done, we can't have it on Wikipedia. —Preceding unsigned comment added by 97.112.196.161 ( talk) 00:01, 1 September 2010 (UTC)
How come the slow down rate/ rotation occur after a century or million years when we all know that free neutrons undergo beta decay with a half-life of about 10 minutes and are not readily found in nature, except in cosmic rays. 68.147.41.231 ( talk) 04:55, 7 November 2010 (UTC)khattak#1
The first paragraph has the following: "Neutron stars are very hot and are supported against further collapse because of the Pauli exclusion principle." The principle describes the force, it is not the force itself. Can this be rephrased so that it doesn't sound as if our theories cause the phenomena? —Preceding unsigned comment added by 24.22.166.163 ( talk) 00:16, 10 December 2010 (UTC)
Neutron Star
The statement that "Neutron stars ... are supported against further collapse because of the Pauli exclusion principle." is incorrect. Pauli's exclusion principle is a very important physics principle, but in itself it does not generate the force that prevents a neutron star from further collapsing. There is a confusion here of a "principle" with a "force". — Preceding unsigned comment added by Macedonio5 ( talk • contribs) 22:00, 4 February 2011 (UTC)
You're mistaken. The article is correct. Dauto ( talk) 03:00, 5 February 2011 (UTC)
Formation
I wish this section could be considerably improved. It doesn't really contain any information on how a neutron star is formed.
— Preceding unsigned comment added by Macedonio5 ( talk • contribs) 22:00, 4 February 2011 (UTC)
The Properties section seems to have some discussion in it (e.g. the third paragraph calls the previous paragraph invalid.) RJFJR ( talk) 18:03, 16 February 2011 (UTC)
"The neutron star's density varies from below 1×109 kg/m3 in the crust,"
There is a crust? Or just a surface? — Preceding unsigned comment added by Darsie42 ( talk • contribs) 18:57, 6 January 2013 (UTC)
The side illustration in Properties has the following "In natural units, the mass of the depicted star is 1". This does not state the units of mass. John W. Nicholson ( talk) 16:42, 7 January 2013 (UTC)
Thanks -- John W. Nicholson ( talk) 02:10, 12 January 2013 (UTC)
With the idea of high mass and this statement "Even at 1 million kelvin, most of the light generated by a neutron star is in X-rays." I could not help but think of Gravitational red shift. How strong is it? Are x-rays shifted into visible light? John W. Nicholson ( talk) 02:15, 12 January 2013 (UTC)
Is correct? Currently, it is stated as . — Preceding unsigned comment added by Reddwarf2956 ( talk • contribs) 10:43, 12 January 2013 (UTC)
"Neutron stars, sugar cubes, and squeezed humans By Ankit | June 3, 2010 The wikipedia article on Neutron star says the following,
'The density of a neutron star is approximately equivalent to the mass of the entire human population compressed to the size of a sugar cube.'
I hope we can all agree that whoever came up with the idea of measuring the density of stars in the units of compressed human beings was a great visionary. Too bad for him, then, that wikipedia shackles his imagination by demanding facts. In this case, the above statement is followed by a superscript saying 'citation needed.' When someone has come up with such a great idea, I thought it's my moral duty to carry on his legacy and provide some concreteness to his ideas by doing some small calculations.
The problem we want to solve is to calculate approximately how many human beings need to be compressed to the size of a sugar cube in order to have the same density as that of a neutron star. A neutron star has a density 3 E^17 kg/m^3. One sugar cube, according to Yahoo answers, is half an inch (1.27 cm) long per side. Which makes the volume of the sugar cube to be 2.05 E^-6 m^3. If the sugar cube has the density of a neutron star, the total mass it should contain is 615 billion kg. Taking the average weight of a human to be about 80 kg, about 7.7 billion people are needed to be squeezed together in order to attain the astronomical densities we are talking about - which is not too different from the current population of the world.
If we are only talking about order of magnitude approximations, the wikipedia comment is acceptable. But we can go further. The current population of the world is about 6.8 billion and growing at about 1.1% which means that the magic figure of 7.7 billion will be reached sometime near 2021. At around that time, with the assumption of an average weight of 80 kg, the wikipedia statement would be truer than it is today. But then the assumption of 80 kg is obviously on shaky grounds. With so many kids who invariably fail at tipping the weighing machine beyond the 30 kg mark, our noble aim is but a mirage. For all these underweight human beings, it is upon McDonalds and Burger King to maintain the required balance. If it was not for these noble institutions, humanity would still be decades away from the day when sugar cubes, neutron stars and squeezed humans could be spoken of in one single sentence.
Anyway, I hope this little calculation added to our understanding of neutron stars. I think the citation that the wikipedia article required has finally been found" 76.218.104.120 ( talk) 04:54, 6 February 2013 (UTC)
I simply wish to know the source of the magnetic field, what mechanism creates it? Misibacsi ( talk) 08:53, 10 February 2013 (UTC)
An earlier version of this article claimed that electrons and protons makes up a substantial fraction of a neutron star. The introduction here claims the star is "almost entirely" neutrons. A citation is needed. Can someone clean this terrible article up? There are random fragments of sentences and poorly structured paragraphs all over! I owuld do it myself if I felt I was competent to do so. 173.189.75.106 ( talk) 10:27, 25 March 2013 (UTC)
The article includes this: " In visible light, neutron stars probably radiate approximately the same energy in all parts of visible spectrum, and therefore appear white.". If it is approximately a black body, that is incorrect, the colour would be pale blue as shown below, just slightly more blue than Sirius (apologies for the large size, I can't see how to specify something smaller):
George Dishman (
talk)
11:22, 8 June 2013 (UTC)
It has been suggested in June 9th 2013 of the journal Nature Physics that there is evidence to suggest that matter in the core of a neutron star exists as a type of " Nuclear pasta", perhaps the article should be edited to include these findings? Sonicology ( talk) 19:03, 1 August 2013 (UTC)
This section states the nucleus is hold together by the strong force. I'm sure it's hold together by the weak force (or at least, as I've often read, "nuclear decay is mediated by the weak force"). Does someone know better (can they explain it)
Never mind. "Residual strong force" does not mean "not particularly significant force".
— Preceding
unsigned comment added by
68.7.59.69 (
talk)
20:54, 28 December 2013 (UTC)
Does anyone know how to find this graph to be added to the page or should the note be removed?
A neutron star's density increases as its mass increases, and its radius decreases non-linearly. (NASA mass radius graph)
http://ixo.gsfc.nasa.gov/old_conx_pages/images/science/neutron_stars/ns_mass_radius.gif
Jgoemat ( talk) 21:23, 5 December 2013 (UTC)
George Dishman ( talk) 13:00, 4 February 2014 (UTC)
"having only the diameter of a city" - city is a loose term which can be a specific incorporated area, a community or even consolidated into something larger such as a prefecture. Therefore you can't describe something as being "the diameter of a city", as it could mean three miles or twenty miles. In fact, why not just put miles in the lead. Rcsprinter (chatter) @ 19:21, 14 January 2014 (UTC)
Will a Neutron star ever "run out" of temperature? The article just makes comments to the temperature at the beginning of the life span of a Neutron star and that it cools in its first year, but not what happens afterwards. How long will it last until the temperature of a Neutron star reaches approximately 0 K?-- 31.17.153.69 ( talk) 07:20, 25 March 2014 (UTC)
From the article:
> Larger nuclei, particularly rich in neutrons, are formed, and materials that on Earth would be radioactive are stable in this environment, such as nickel-62.
Nickel-62 is stable on Earth, so I've removed the reference to it.
2601:0:AF00:226:A288:B4FF:FEC0:218C ( talk) 14:23, 2 April 2014 (UTC)
I almost just removed the figures quoted because 1) they just seemed so implausible and 2) they were unsourced, but I figured it would be best to bring the issue up here. Maybe there is some factor at play that I just don't understand.
The entry reads "The neutron star's density also gives it very high surface gravity, up to 7×10^12 m/s^2". It also goes on to say "One measure of such immense gravity is the fact that neutron stars have an escape velocity of around 100,000 km/s". That doesn't make any sense to me. How can the surface gravity be 70 million times greater than the escape velocity? To add to that, if something were to be accelerated at 7×10^12 m/s for one second, wouldn't it be going 23349.5 times faster than the speed of light? I understand that if something were accelerated like that it wouldn't exceed the speed of light, but just add an insane amount of relativistic mass, but with those numbers wouldn't we be dealing with a super-supermassive black hole or something?
Apologies if this is just me not understanding physics and astronomy, but these numbers just don't make any sense to me. 50.174.135.49 ( talk) 01:39, 27 June 2014 (UTC)
It looks like the maximum size of neutron stars is about 2 solar masses. Measured radius is about 10 – 15 km? A 2 SM neutron star has a Schwarzchild radius of 6 km which should contain light up to 12 – 18 km, so wouldn’t a 10-km neutron star have some light containment? There should be formulas for the effectiveness of light containment of a neutron star or black hole based on internal star radius. A hypothetical compact star or internal black hole star of 3GM/(c^^2) radius should contain light, but not as effectively as a Schwarzchild radius star or point singularity. When matter falls into a black hole, wouldn’t infalling matter eject more radiation (jets?) if the black hole contained a finite sized star instead of a point singularity? 72.69.11.171 ( talk) 16:56, 26 July 2014 (UTC)BG
wwwwwwwwwwwwwwwwwwwwwwwww Bold text — Preceding unsigned comment added by TheBluePotato646 ( talk • contribs) 16:26, 6 December 2014 (UTC)
NS mass is limited by some process, and measured data indicates this is about 2 solar masses. (My vote is this is because above 2 SM neutrons in the core collapse into mostly radiation and some quark matter .... the radiation would exit the star and the quark matter would quickly recombine to neutrons.) Apparently the radius of a neutron star does not increase much with mass, so IF a stable neutron star 3 SM or greater existed it would partially contain light and we could call it a black hole. 72.69.11.171 ( talk) 23:41, 31 July 2014 (UTC)BG
From my reading the current thinking is that collapsed stars with a mass over about 2 MSun are not composed of neutrons but either have quark matter cores or are entirely quark matter. That makes the designation "neutron star" inappropriate. http://arxiv.org/find/astro-ph/1/ti:+AND+quark+star/0/1/0/2012,2013,2014/0/1?per_page=100 Is this too new for inclusion? Qemist ( talk) 03:08, 25 April 2014 (UTC)
Recent observations indicate neutron stars over about 2 SM do not exist. See recent edits and comments below. Apparently there are no compact stars between about 2 - 5 SM. The smallest observed black holes are 5 SM and they could be quark matter and radiation. There might be a simple explanation why there are no black holes smaller than 5 SM: A collapsing 4 SM neutron core is about equal to its Schwarzchild radius (12 km) and about 5 SM total is contained. A hypothetical about 3 SM neutron star isn't strong enough to contain its contents Schwarzchild style but collapses and ejects radiation as it pops down to below 2 SM where it is stable. 72.69.11.171 ( talk) 14:26, 7 August 2014 (UTC)BG
Links on what specifically? Maximum observed mass of neutron stars? Minimum observed mass of black holes? — Preceding unsigned comment added by 72.69.11.171 ( talk) 06:54, 10 August 2014 (UTC)
The article makes several references to acceleration, escape velocity and speed of light using km/s. The speed of light is just under 300,000,000 m/s. It looks like some of the units are incorrectly marked km/s. From the text: ..."and would do so at around 2000 kilometers per second." Sherumgroup ( talk) 16:42, 20 August 2014 (UTC)
The range of masses in the lede is confusing and probably wrong. It states compact stars of less than 1.44 solar masses are white dwarfs, yet there are neutron stars in the literature with well constrained masses less than that, e.g. the companion to PSR J1756-2251 (1.230+/-0.007 MS), PSR J0737−3039 B (1.25 MS), and PSR J1906+0746 (also 1.25 MS). Then it states that compact stars between this limit and 3 MS "should" be neutron stars, but later that the maximum mass of a neutron star is about 2 MS. That is contradictory as to the state of objects with masses between 2 MS and 3 MS. Qemist ( talk) 02:14, 10 August 2014 (UTC)
The figure of 2.4 SM is incorrect. Do you have a source for this other than the Black Widow Pulsar Wiki article? From this source the lower mass limit for this neutron star is about 1.6 SM: http://arxiv.org/abs/1009.5427 See the Wiki articles on PSR_J1614-2230 AND PSR J0348+0432. 72.69.11.171 ( talk) 22:28, 13 August 2014 (UTC)
Lets consider for now 2 is the max for a neutron star and 5 the min for a black hole. A 5 22.5-km radius ultra-relativistic star has about the same gravitational acceleration and core pressure of a 2 13-km neutron star, yet a 5 22.5-km ultra-relativistic star theoretically contains light and a 2 13-km neutron star does not. (Note 25-km is 1.5 times the Schwarzchild radius) For an ultra-relativistic star gravitational acceleration and core pressure decrease as size increases. It does not collapse. 72.69.11.171 ( talk) 14:32, 14 August 2014 (UTC)
BTW, there is an interesting formula about the radius and radiated energy from infalling matter into a neutron or compact star: Accretion energy conversion efficiency = (Schwarzchild radius)/(2R) ..... where R is the radius of the star. (see: http://www3.mpifr-bonn.mpg.de/staff/mmassi/lezione2WEdd.pdf ) If a black hole is a point singularity its image should be different than that of a neutron star. 72.69.11.171 ( talk) 19:07, 1 October 2014 (UTC)BG
This article is suffering from a rather serious case of ledeclutter, at five paragraphs with comparisons to the sun, Manhattan, atomic nuclei, a 747, sand, a matchbook, and rock, as well as a lot of specific information (Neutron stars have overall densities of 3.7×1017 to 5.9×1017 kg/m3 (2.6×1014 to 4.1×1014 times the density of the Sun) etc. I propose consolidating the important information into a nice three or four paragraph summary and moving details to the body. Comments? A( Ch) 08:48, 13 January 2015 (UTC)
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I have removed a large section of text from the "Properties" section that appears to be a copyright violation, directly lifted from the Philip's Astronomy Encyclopedia (2002), pg 281-282.
What is the nearest neutron star? In the see also section it says PSR J0108-1431 (424 ly), but in the body RX J1856.5-3754 (400 ly) is mentioned alongside it. -- JorisvS ( talk) 09:00, 1 February 2015 (UTC)
The approximate mass of a matchbox of neutron star material is blatantly incorrect as the quoted density of a neutron star is 3.7*10^14 tons/m^3, which would make a soda can (355ml) weigh 3.7*10^14*355/10^6 or 131 gigatons, yet the lede claims 5000 gigatons for a matchbox. That's a big matchbox! The average density of rock is ~ 2.7 tons/m^3, or 2.7*10^9 tons/km^3 or 2.7 gigatons, yet the lede claims 1 km^3 of rock weighs 5000 gigatons! A soda can of neutron star material would weigh close to 3.7^10^14*355/10^6/2.7/10^9 = 48.6 km^3 of rock. David.Anderson.unique ( talk) 13:49, 5 July 2015 (UTC)
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To avoid anymore vandalism if not any. — 73.47.37.131 ( talk) 21:27, 31 July 2015 (UTC)
Please add temperatures that normal people can understand. Example: What does a surface temperature around "~6×105 K" mean? Can we have plain numbers please. Not everyone knows that K means Kelvin, and even less people are able to figure out the value of "105". Urbanus Secundus ( talk) 20:59, 13 June 2015 (UTC)
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I'm concerned about these 2 sentences at the beginning of the article: "A neutron star has a mass of at least 1.1 and perhaps up to 3 solar masses (M☉),[1][2] though the highest observed mass is 2.01 M☉. Neutron stars typically have a surface temperature around 6×105 K."
Maybe it should say "A neutron star has a theoretical mass of 1.1 - 3 solar masses". Also giving one specific temperature value is misleading. 173.56.18.42 ( talk) 14:54, 8 February 2016 (UTC)BG
It is stated on the Wikipedia page for gold that it is most likely made by colliding neutron stars. I came to this page to find out what other elements in the periodic table might be made by these events. This section needs to be created
Amphibio ( talk) 17:07, 24 February 2016 (UTC)
"There are thought to be around 100 million neutron stars in the Milky Way, a figure obtained by estimating the number of stars that have gone supernova." How many stars in the Milky Way total? Percent of whole might give me some insight about how rare this is Cegandodge ( talk) 19:31, 18 March 2016 (UTC)
A logical explanation for neutron star mass being limited to about 2.01 M☉ is the collapse of core nuclei. Note that at about 2 M☉ and 12-km radius the relativistic gravitational core pressure is about equal to (rho)(c^2)/3. A logical equation for nuclei disintegration is: proton → positron + 938MeV. This reaction should either heat the star or result in a 450MeV maximum electrically neutral positron-electron jet. 108.30.181.243 ( talk) 12:09, 11 June 2016 (UTC)BG
The equation
appears to have mixed dimensions in the denominator.
R has a dimension of length
is dimensionless
— Preceding
unsigned comment added by
50.45.15.139 (
talk •
contribs)
The article's editors continually write that neutron degeneracy pressure supports the neutron star against collapse. This is mostly untrue and should not be the sole reason given here. The editors are generally working from the false analogy that if a white dwarf is supported by electron degeneracy pressure, the neutron star must be supported by neutron degeneracy pressure. Note that none of their sources actually state that neutron degeneracy pressure supports the star - it's just "assumed."
Real neutron stars are supported against collapse mostly due to the strong nucleon-nucleon force. (No, the strong force does not act only in attraction - see /info/en/?search=Nuclear_force.) At the short nucleon-nucleon distances within the core of a neutron star, the strong force will act to repel nucleons (here, mostly neutrons) from one another. This repulsion - unrelated to degeneracy pressure - is stronger than degeneracy pressure within neutron stars. It supports the neutron star against collapse.
Sources: http://www.astro.princeton.edu/~burrows/classes/403/neutron.stars.pdf (page 3) "...using the relativistically correct equation of hydrostatic equilibrium (eq. (5)), and assuming a non-interacting degenerate gas of neutrons, Oppenheimer & Volkov (1939) derived a maximum neutron star mass of 0.7 M⊙, ∼eight times smaller. Observed neutron-star masses are clearly larger than this. The reason is that the strong repulsive nuclear force trumps neutron degeneracy pressure by a wide margin, resulting in less compact and more rigid structures supported by a stiffer EOS."
https://www.astro.umd.edu/~jph/A320_White_Dwarfs.pdf (page 10) "At densities of ρ ∼ 10^15 g cm−3, neutrons are not an ideal gas. These are the densities we find within an atomic nucleus, and the neutrons interact with one another via the strong force. Thus we see that to model neutron stars we need the TOV equation and an equation of state that includes not only degeneracy but the nuclear forces between the neutrons."
http://www.aanda.org/articles/aa/full/2001/46/aa1755/aa1755.right.html "The EOS is predominantly determined by the nuclear (strong) interaction between elementary constituents of dense matter."
http://www.rpi.edu/dept/phys/Courses/Astronomy/NeutStarsAJP.pdf Demonstrates that the strong force must be considered. The overall picture is not simple and not totally understood, as our knowledge of nucleon-nucleon interactions is incomplete.
I look forward to seeing discussion of the strong force's role permanently and prominently displayed in this article.
60.45.238.24 ( talk) 15:28, 4 October 2016 (UTC)
The terms AP4, MS2, and "(for EOS FPS, UU, APR or L respectively)" are used with no definitions nor links to anything which might explain them. It makes those passages less than helpful.
P.S. to the authors: Thanks for an otherwise nice article. — Preceding unsigned comment added by Oldmeat ( talk • contribs) 01:36, 1 March 2017 (UTC)
As we all know, with regular stars, nuclear fusion takes place place in their cores, and this nuclear fusion is what produces the energy emitted thereby.
Neutron stars also produce protons, but I wouldn't guess that nuclear fusion is taking place in their cores. Would I be wrong to assume it's not? And, assuming I am correct to guess that there is no nuclear fusion taking place therein, the question then remains: what produces the energy emitted by neutron stars?
If you know the answer to these questions, please help improve this article by adding details about neutron stars' source of energy.
allixpeeke ( talk) 15:39, 27 June 2017 (UTC); augmented 12:08, 30 June 2017 (UTC)
A short section explaining what the long-term evolution of neutron stars is expected to be would be nice. Can a neutron star cool down to near zero absolute and remain stable against gravitational collapse? Ho wmuch time would the cooling take? (I'd expect this to be orders of magnitude more than the current age of the Universe) Urhixidur ( talk) 17:00, 29 September 2017 (UTC)
Really, this is accepted quality for wikipedia? I expected better 188.175.76.2 ( talk) 07:24, 16 December 2017 (UTC)
Transient condensates are core properties ranging from Axion matter to various Parton matter to Quark matter to Neutron matter. This Condensate matter makes up over 95% of all matter in the infinite universe. The core does not undergo fusion. It keeps on attracting matter into it. In the case of our Sun its core will photo-disintergrate atoms such as Fe(and all other) to neutrons and protons(change to Neutron) that would become part of the core. The gauge field on the lattice is the resultant property forming a dipolar electromagnetic effect producing vortices, that expel neutrons into the solar envelope that change to protons that than take part in fusion reactions H+H= Helium etc forming all the elements. The Sun's energy is produced by the core 65%, Fusion reactions within the solar envelope 35% and about 5% fission. It all about the core and its properties. Images created by condensates as in the Kilonova hour glass and the release of condensate droplets that produce giant bubbles. — Preceding unsigned comment added by Harry Costas ( talk • contribs) 00:20, 2 January 2018 (UTC)
A neutron star is so dense that one teaspoon (5 milliliters) of its material would have a mass over 5.5×1012 kg (that is 1100 tonnes per 1 nanolitre), about 900 times the mass of the Great Pyramid of Giza. In the enormous gravitational field of a neutron star, its weight would be 1.1×1025 N, which is about 15 times the weight of the Moon.[c]
The article states, "At present, there are about 2,000 known neutron stars in the Milky Way..." I was going to contribute an estimated percentage of neutron stars, as compared to the total estimated number of all stars, in our galaxy, but the range from NASA to Swinburne sources were a billion down to 100,000. NASA's figure is from 2007 and Swinburne's much more recent, but perhaps another editor can figure out the most credible current estimate. This is relevant not only for curiosity sake but especially now that the supernova origin of heavy elements theory is disfavored for a neutron star/black hole collision hypothesis. Bob Enyart, Denver KGOV radio host ( talk) 21:42, 27 June 2019 (UTC)
In response to an old request, I have begun to find information regarding the energy production of neutron stars. I agree this is an improvement to the article itself as this important subject seems non-existent referencing this type of star. It can also help make sense of the star's internal structure, why it is so could be extrapolated further. This will not be a heavy edit since there is not much discussion in the literature about how neutron stars produce their energy, and it is the first time this topic has been attributed to properties of a neutron star in this article to allow further iteration and collaboration.
Neutron stars lose heat energy by emitting neutrinos and electron conduction within. Over time this is radiated away from the star in the form of neutrinos and X-rays. Most emissions are not thermal, at around one million Kelvin it has most radiation being high energy x rays or UV rays. Neutron stars are not black bodies, so it does not emit very much thermal energy which has caused speculation as to how they produce such high energy.
ChromeDragon ( talk) 23:23, 15 September 2019 (UTC)
I removed a "Citation needed" tag from the first intro paragraph. There is a reference at the end of the next sentence. Wikipedia Style asks that editors place as few copies of a single reference as possible, and in particular if two, or several, contiguous sentences, each with a distinct fact, are all supported by the same reference, then Wikipedia asks that that reference be placed once at the end of the contiguous sentences. Unless the editor who inserted the "Citation needed" tag has actual knowledge that the reference at the end of the next sentence does not support the fact they tagged, they should not tag it. Nick Beeson ( talk) 15:31, 17 September 2019 (UTC)
I have moved this statement here pending a reference - it was tagged 13 months ago: " It is statistically probable based on known populations that there is at least one neutron star within 10 parsecs of the Sun, significantly closer than the current nearest known neutron star. citation needed " — Preceding unsigned comment added by HammerFilmFan ( talk • contribs) 18:50, 17 May 2020 (UTC)
"... the same weight as a 0.5 cubic kilometre chunk of the Earth (a cube with edges of about 800 metres)"
A 0.5 cubic km would have edges of exactly 500 metres... Just saying. 2403:6200:8856:563C:D011:4BA2:409E:1E ( talk) 04:53, 16 November 2020 (UTC)
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I think the introduction has too much unnecessary jargon in it. I think it should be simplified and made more clear.17:25, 26 October 2008 (UTC) —Preceding unsigned comment added by 75.150.72.237 ( talk)
The information on gravity and escape velocity don't belong in this section and since it is already included in the properties section it is also redundant. It should be deleted from this section
Furthermore, I think there should be, if possible, more detail put into the formation.
Alexa7890 (
talk)
19:00, 26 October 2008 (UTC)
This section is really short. Perhaps it would be a good idea to include the end of a neutron star and change it from just a "formation" section to a "formation and end" section. Alexa7890 ( talk) 07:04, 27 October 2008 (UTC)
Is the information on the Equation of State correct? The citation that is given (#3) goes to the German page on neutron stars. I have come across articles that discuss the EoS for Neutron Stars which would imply that an EoS is known. Alexa7890 ( talk) 13:16, 27 October 2008 (UTC)
No, the EOS is not known with ANY certainty. There are infact many competing modals. You should be cautious with neutron stars - they tend to publish "facts" about them decades before an issue is settled, or even properly explored. —Preceding unsigned comment added by 75.153.125.20 ( talk) 01:42, 13 December 2008 (UTC)
The escape velocity is listed as 30% of speed of light and as 50% the speed of light, if it does vary that much it needs to be mentioned, as it is now it conflicts with the previous paragraph —Preceding unsigned comment added by Edman007 ( talk • contribs) 16:59, 17 November 2008 (UTC)
The information of the density seems to belong in the properties section. The second paragraph needs to be considerably cleaned up. The "proceeding deeper" vocabulary isn't something that would be in an encyclopedia and the information should be made more clear. —Preceding unsigned comment added by Alexa7890 ( talk • contribs) 23:14, 22 October 2008 (UTC)
The crust is 1 meter or 1 mile thick? (section on structure). The text and the figure are contradicting themselves. 201.80.110.49 ( talk) 05:31, 30 November 2007 (UTC)
The thing that is being referred to as 1 meter thick is the atmosphere, however from what I know this is incorrect. According to The Internet Encyclopedia of Science what can be called an atmosphere is maybe only a few micrometers thick. The figure is correct according to Universe Today and Space.com Alexa7890 ( talk) 15:13, 22 October 2008 (UTC)
All the calculations regarding the volume and density of a neutron star that I have seen assume that the space inside a neutron star is flat. However, inside an object as massive as a neutron star, doesn't the curvature of space become significant? Wouldn't that mean that the internal volume is larger than the standard formula for a Euclidean sphere would suggest? I hope someone more familiar with General Relativity can answer these questions. Clement Cherlin 01:16, 16 November 2007 (UTC)
Isn't a magnetar's power source it's magnetic field energy?
See http://solomon.as.utexas.edu/~duncan/magnetar.html#New_Kind_Of_Star
there is alot of argument over this. It seems like it is it's magnetic field - but the origin of the field itself is open to discussion. It's like saying your TV is electric powered - ignoreing the coal plant on the other end. Also, most neutron stars are rotation powered - the high field stars seem to be an exception, but we really don't know with any certainty. —Preceding unsigned comment added by 75.153.125.20 ( talk) 01:44, 13 December 2008 (UTC)
89.48.108.46 ( talk) 16:22, 11 December 2007 (UTC)
SOME ISSUES HERE WITH THE SOLAR MASS OF THE NEUTRON STAR AND THE SUN. IF IT IS 1.35 SOLAR MASSES, THEN IT WOULD NOT BE SMALLER THAN THE SUN —Preceding unsigned comment added by 155.214.128.4 ( talk) 15:38, 26 February 2008 (UTC)
The value of 2×1012 g is far too high. If approximated by Newton's Law of gravity a 2 solar mass neutron star with 10 km radius would have about 2.7×1012 m/s² = 2.7×1011 g. A 3 solar mass black hole would have about 5×1011 g (at the Schwarzschild radius of 9 km}}. Although one would have to use the relativistic equations for a correct result the Newtonion equation should at least give the correct order of magnitude. I have therefore corrected the value in the properties section; the range of 2×1011 to 2×1012 g given a few lines above remains as a matter of further check (with relativistic formulae, if possible).-- SiriusB ( talk) 15:02, 26 December 2008 (UTC)
How does a neutron star end it's life, what happens to it? And how? It doesn't have fuel like a regular star, and it's gravity holds it together, how long can they stay that way? The snare ( talk) 05:51, 19 August 2008 (UTC)
Jakezing, I asked my astronomy professor about this and she said that a neutron star will remain mostly static, although they will cool down a bit Alexa7890 ( talk) 02:26, 28 October 2008 (UTC)
A neutron star will end it's life quietly - the professor is correct. At least for most stars. And yes, that doesn't make him necessarily correct, but noone is ever necessarily correct. Vacuous statement. —Preceding unsigned comment added by 75.153.125.20 ( talk) 01:45, 13 December 2008 (UTC)
I'm still a little confused, so it will cool down, but then what? Break apart and dissipate somehow? And how will it do that? The snare ( talk) 03:20, 24 January 2009 (UTC)
So, you're saying neutron stars are eternal as far as we know? When there is nothing but photons left in the universe, there will also be neutron stars literally forever? Also, don't neutrons become protons, at least when they are alone and not in a nucleus? The snare ( talk) 02:22, 2 February 2009 (UTC)
Don't atoms (normal ones, so a deuterium atom in this example- just so we have one neutron) eventually break down and dissipate? They don't last forever, so I've been told, they aren't perpetual motion machines, don't know about neutron stars though. The snare ( talk) 03:14, 16 April 2009 (UTC)
Don't forget about the gravity of the thing. It's really strong and makes it hard for matter to escape, so the example with deuterium doesn't really apply here. And yes, neutron star isn't a perpetual motion machine, it emits a lot of energy during it's lifetime - that's why it cools down. Regarding the topic, it's really hard to say how does the star end it's life because we can't see the really old ones - they're too cool and therefore emit too little energy to be observed. In theory they can live forever or collapse into a black hole as said by Potekhin or maybe they change into a basket full of oranges ;), we will probably never be sure of that. -- Siberie ( talk) 04:55, 24 May 2009 (UTC)
How is it possible for a neutron star to be very hot. Atoms and molecules are to be in motion for the flow of charge of heat while there is no charge on neutron star. Myktk ( talk) 15:36, 21 October 2008 (UTC) Khattak
The above poster claiming that charge and heat are different is correct. But to answer your question more fully - Temperature is related to the ratio of a change in entropy to a change in energy. A very small change in entropy here requires a massive change in energy, because the star has such high density. The result is that the temperature is very high. To the poster who claimed that neutron stars are like black holes - thats really not a fair comparison. Black holes violate in principle every law of physics. People like Hawking, Wheeler, and Unruh have spent their lives figureing out how our laws of thermodynamics can exist next to black holes - forget working INSIDE them! —Preceding unsigned comment added by 75.153.125.20 ( talk) 01:49, 13 December 2008 (UTC)
It's not clear to me what the original poster meant with that question. He mentions the fact that neutrons are not charged particles but does not explain why he thinks that the presence of charged particles should be required in order for something to be very hot. He might want to better explain his position. He seems to believe that only charged particles can have a temperature. That's simply not true. Dauto ( talk) 05:21, 29 January 2009 (UTC)
I've wondered this too. Heat is determined by how fast the electrons are moving, but since a neutron star is all neutrons and no electrons, how can it have heat? The snare ( talk) 03:10, 16 April 2009 (UTC)
the core is reached, by definition the point where they disappear altogether." (a quote from current article) I wonder about the accuracy or at least the clarity. The sentence seems to be saying that a "neutron star" must "by definition" have at least some location where matter exists only as neutrons(and thus must at least have it in the core), but I doubt astronomers think that way. Astronomers probably identified some objects that they suspected had that property, and called them neutron stars, but they're not defined by that, but probably by observational characteristics, whether or not astronomers now know if some or all neutron stars have matter of this form.Astronomers don't define their universe, they (try to) describe it.--Richard Peterson 75.45.97.146 ( talk) 18:10, 7 May 2009 (UTC) Rich ( talk) 21:12, 7 May 2009 (UTC)
"Outside the nucleus, free neutrons are unstable and have a mean lifetime of 885.7±0.8 s (about 15 minutes), decaying by emission of a negative electron and antineutrino to become a proton:[6]" Source: http://en.wikipedia.org/wiki/Neutron So its life time should not be more than 15 second.
Also, if surface gravity of neutron star increases 7x10^14 every meter in one second then is this figure higher than speed of light? 96.52.178.55 ( talk) 17:00, 31 May 2009 (UTC)Khattak
Yes, I meant 15 minutes. Thanks. 96.52.178.55 ( talk) 04:29, 3 June 2009 (UTC) khattak
Neutron stars are very hot and are supported against further collapse because of the Pauli exclusion principle. - This statement is not entirely correct. Of course the exclusion principle is important here, but it's too weak to support the star. The major contribution to force that counters gravity are repulsive nuclear forces which come into the game because of huge density. I think it should be corrected. Any comments? Siberie ( talk) 14:57, 25 May 2009 (UTC)
This subject is not even discussed and needs to be a prominent part of the article. Magnetic fields of 10×108 Tesla are common or 100 million times greater than a rare earth magnet This is one of the MAIN properties of a neutron star. Magnetic poles are usually not aligned with the axis of rotation which gives a pulsar. Trojancowboy ( talk) 03:02, 28 May 2009 (UTC)
Actually it is mentioned 8 times. But I too think it deserves a section to itself. I'll get out my college textbook and look it up. Marx01 Tell me about it 00:20, 28 September 2009 (UTC)
I found some lists of known neutron star on Gooogle but some without distances. I'm wondering how far away the closest is. —Preceding unsigned comment added by 71.186.61.183 ( talk) 13:10, 14 July 2009 (UTC)
I came to this article looking to find out how a conventional star made up of atoms (protons/neutrons/electrons) ends up with the protons and electrons gone and the neutrons remaining. Any chance there's a guru out there that can explain it? After all, that's sort of the whole neutron star formation thing. Grumpyoldgeek ( talk) 21:00, 11 June 2009 (UTC)
The concept of the atom can be boiled down to it's being an almost in contact accumulation of deuteron pairs plus extra neutrons and surrounded by a cloud of electrons. And a Neutron star concept further whittles the size down such that the space for the cloud of electrons is eliminated. And the presumption of neutral atomic charge pretty much assumes that each electron must return to it's associated proton. So everything is neutral. And the concept of the continued existence of individual nucleons requires a packing system similar to what exists in the nucleus of the normal atom, which is pretty closely packed. But it's hard on the accumulated repulsive force theory and might require some rethinking about that. And it makes you wonder about the quark electrostatic charge existence and change mechanism logic, but we wouldn't want to do that. WFPM ( talk) 19:07, 4 May 2010 (UTC)
How does this article relate to the Schwarzschild radius? http://en.wikipedia.org/wiki/Schwarzschild_radius Should there be a connection of ideas between these two ideas?
Reddwarf2956 ( talk) 19:40, 31 August 2009 (UTC)
How close (what range of distance) to a neutron star does pair production happen? It is know that near heavy dense atoms in which a two times electron rest mass energy gamma ray comes close pair production happens. How much mass is gained/loss by this production?
Reddwarf2956 ( talk) 19:52, 31 August 2009 (UTC)
The sixth source in this article is said to be the germans wikipedia. i dont think that is right. could someone mark that as unverified and get someone to get a verifiable source for that information [1] 66.90.164.132 ( talk) 18:55, 5 November 2009 (UTC)HTU-Student
At the end of the second paragraph, the article states, "This density is approximately equivalent to the mass of the entire human population compressed to the size of a sugar cube."
With over 7 million humans currently inhabiting the Earth, within the parameters of errors, deaths, and unrecorded populations (tribes disconnected from the outside world), this is not a valid argument. Likewise, without a statistical date, one could describe the density of a neutron star as being similar to that of the human population of the plague-ridden medieval age. For something so immensely dense as a neutron star, it likely doesn't matter much the mass of humans it would take to approximate the density of a neutron star. It's a simple fact that the original statement is too vague to be a valid statement.
Christopher, Salem, OR (
talk)
12:53, 18 May 2010 (UTC)
Since my last posting on the discussion of this article, I have taken note of the addition of the reference as I requested. Though I am unfamiliar with Ankit Srivastava page (
http://www.ankitsrivastava.net/2010/06/neutron-stars-sugar-cubes-and-squeezed-humans/), I feel that this reference goes above and beyond at clarifying the statement, "This density is approximately equivalent to the mass of the entire human population compressed to the size of a sugar cube."
Well done. Now there's some numbers to wrap 'round our brains.
Christopher, Salem, OR (
talk)
10:51, 18 June 2010 (UTC)
This is my first time on a talk page, so please forgive and correct me if I do anything wrong.
There is a small fact in the top paragraph stating that neutrons have roughly the same mass as protons. Would it be acceptable for me to change that to "a slightly larger mass than protons"?
I decided to go with the "be bold" principle. And for anyone who is worried, I will watch my spelling in actual article edits.
KKPie ( talk) 15:36, 18 June 2010 (UTC)
Could the article mention that the core degeneracy pressure at collapse approaches the maximum possible theoretical pressure of P = pc2 , where p is the density? 172.129.30.241 ( talk) 01:19, 18 August 2010 (UTC) BG
1. Can the article give an approximate range for estimated core pressures in a neutron star? For starters wouldn’t the non-relativistic core pressure of a neutron star be given approximately by P(c) = KGM2/(πR4), where K is a constant dependant on the density profile, but nominally equal to 1. For 1.35 to 2.1 solar mass stars, this would give estimated pressures of about 1 X 1034 to 2 X 1034 kg/m2. The magnitude of this approximate pressure is mind boggling. It would be equivalent to about the entire weight of the sun pressing down on 1 cm2 at the earth’s surface. This is a sloppy calculation and maybe others could improve it. It would be nice if someone could give a better equation for core pressure or at least the results. Does someone have Tolman–Oppenheimer–Volkoff equation solutions for a neutron star? I don't accept the TOV equation but many others do.
2. To diverge, why should collapse of this type structure lead to a point singularity? If during collapse the mass not blown away is large enough to form a black hole, shouldn’t the resulting high temperature essentially convert all this mass into contained radiation? The basic pressure formula for this intense radiation would likely be P = pc2 (where p is the equivalent mass density of the energy). This should prevent collapse to a singularity since this pressure has no limit and increases as 1/R3, faster than the increase of gravitational force. 172.162.242.8 ( talk) 19:59, 23 September 2010 (UTC)BG
Good idea. Your comments are welcome at http://www.physicsforums.com/showthread.php?p=2905538#post2905538 ````BG —Preceding unsigned comment added by 172.129.106.208 ( talk) 00:29, 29 September 2010 (UTC)
Maybe you directed me to the forums as punishment. Perhaps some there believe a BH is made of chocolate pudding. Now I long for the days when conversations were dominated by singularity advocates. 172.163.115.55 ( talk) 18:37, 29 September 2010 (UTC)BG
Yes. Radiation pressure of pc^2 or (pc^2)/3 shows why collapse should not occur in the core of a black hole. But it does not explain why collapse should not occur at the black hole surface. But based on E = mc^2, the absolute maximum pressure P that matter should be able to support is P = pc^2, where p is the density of the matter. Its interesting that neutron star cores at collapse approach this pressure. 172.162.222.11 ( talk) 13:18, 5 October 2010 (UTC)BG
It would be interesting to know if neutron star core collapse occurs at a pressure of (pc2)/3, at pc2, or somewhere in between. Does anybody have this information or an estimate? Possibly it could be added to the article. 172.130.75.73 ( talk) 19:42, 17 October 2010 (UTC)BG
I was bold and removed the Disrupted Recycled Pulsar section as it was copyrighted. The origin of this section was from this link http://www.scientificcomputing.com/news-DS-Einstein-at-Home-Citizen-Scientists-Discover-New-Pulsar-081210.aspx
Notice at the bottom of the article "Science Express, August 12, 2010". This section was added on August 31, 2010 as shown in this link: http://en.wikipedia.org/?title=Neutron_star&oldid=382083718
Obviously a copyright violation. Good information if worded differently but until that is done, we can't have it on Wikipedia. —Preceding unsigned comment added by 97.112.196.161 ( talk) 00:01, 1 September 2010 (UTC)
How come the slow down rate/ rotation occur after a century or million years when we all know that free neutrons undergo beta decay with a half-life of about 10 minutes and are not readily found in nature, except in cosmic rays. 68.147.41.231 ( talk) 04:55, 7 November 2010 (UTC)khattak#1
The first paragraph has the following: "Neutron stars are very hot and are supported against further collapse because of the Pauli exclusion principle." The principle describes the force, it is not the force itself. Can this be rephrased so that it doesn't sound as if our theories cause the phenomena? —Preceding unsigned comment added by 24.22.166.163 ( talk) 00:16, 10 December 2010 (UTC)
Neutron Star
The statement that "Neutron stars ... are supported against further collapse because of the Pauli exclusion principle." is incorrect. Pauli's exclusion principle is a very important physics principle, but in itself it does not generate the force that prevents a neutron star from further collapsing. There is a confusion here of a "principle" with a "force". — Preceding unsigned comment added by Macedonio5 ( talk • contribs) 22:00, 4 February 2011 (UTC)
You're mistaken. The article is correct. Dauto ( talk) 03:00, 5 February 2011 (UTC)
Formation
I wish this section could be considerably improved. It doesn't really contain any information on how a neutron star is formed.
— Preceding unsigned comment added by Macedonio5 ( talk • contribs) 22:00, 4 February 2011 (UTC)
The Properties section seems to have some discussion in it (e.g. the third paragraph calls the previous paragraph invalid.) RJFJR ( talk) 18:03, 16 February 2011 (UTC)
"The neutron star's density varies from below 1×109 kg/m3 in the crust,"
There is a crust? Or just a surface? — Preceding unsigned comment added by Darsie42 ( talk • contribs) 18:57, 6 January 2013 (UTC)
The side illustration in Properties has the following "In natural units, the mass of the depicted star is 1". This does not state the units of mass. John W. Nicholson ( talk) 16:42, 7 January 2013 (UTC)
Thanks -- John W. Nicholson ( talk) 02:10, 12 January 2013 (UTC)
With the idea of high mass and this statement "Even at 1 million kelvin, most of the light generated by a neutron star is in X-rays." I could not help but think of Gravitational red shift. How strong is it? Are x-rays shifted into visible light? John W. Nicholson ( talk) 02:15, 12 January 2013 (UTC)
Is correct? Currently, it is stated as . — Preceding unsigned comment added by Reddwarf2956 ( talk • contribs) 10:43, 12 January 2013 (UTC)
"Neutron stars, sugar cubes, and squeezed humans By Ankit | June 3, 2010 The wikipedia article on Neutron star says the following,
'The density of a neutron star is approximately equivalent to the mass of the entire human population compressed to the size of a sugar cube.'
I hope we can all agree that whoever came up with the idea of measuring the density of stars in the units of compressed human beings was a great visionary. Too bad for him, then, that wikipedia shackles his imagination by demanding facts. In this case, the above statement is followed by a superscript saying 'citation needed.' When someone has come up with such a great idea, I thought it's my moral duty to carry on his legacy and provide some concreteness to his ideas by doing some small calculations.
The problem we want to solve is to calculate approximately how many human beings need to be compressed to the size of a sugar cube in order to have the same density as that of a neutron star. A neutron star has a density 3 E^17 kg/m^3. One sugar cube, according to Yahoo answers, is half an inch (1.27 cm) long per side. Which makes the volume of the sugar cube to be 2.05 E^-6 m^3. If the sugar cube has the density of a neutron star, the total mass it should contain is 615 billion kg. Taking the average weight of a human to be about 80 kg, about 7.7 billion people are needed to be squeezed together in order to attain the astronomical densities we are talking about - which is not too different from the current population of the world.
If we are only talking about order of magnitude approximations, the wikipedia comment is acceptable. But we can go further. The current population of the world is about 6.8 billion and growing at about 1.1% which means that the magic figure of 7.7 billion will be reached sometime near 2021. At around that time, with the assumption of an average weight of 80 kg, the wikipedia statement would be truer than it is today. But then the assumption of 80 kg is obviously on shaky grounds. With so many kids who invariably fail at tipping the weighing machine beyond the 30 kg mark, our noble aim is but a mirage. For all these underweight human beings, it is upon McDonalds and Burger King to maintain the required balance. If it was not for these noble institutions, humanity would still be decades away from the day when sugar cubes, neutron stars and squeezed humans could be spoken of in one single sentence.
Anyway, I hope this little calculation added to our understanding of neutron stars. I think the citation that the wikipedia article required has finally been found" 76.218.104.120 ( talk) 04:54, 6 February 2013 (UTC)
I simply wish to know the source of the magnetic field, what mechanism creates it? Misibacsi ( talk) 08:53, 10 February 2013 (UTC)
An earlier version of this article claimed that electrons and protons makes up a substantial fraction of a neutron star. The introduction here claims the star is "almost entirely" neutrons. A citation is needed. Can someone clean this terrible article up? There are random fragments of sentences and poorly structured paragraphs all over! I owuld do it myself if I felt I was competent to do so. 173.189.75.106 ( talk) 10:27, 25 March 2013 (UTC)
The article includes this: " In visible light, neutron stars probably radiate approximately the same energy in all parts of visible spectrum, and therefore appear white.". If it is approximately a black body, that is incorrect, the colour would be pale blue as shown below, just slightly more blue than Sirius (apologies for the large size, I can't see how to specify something smaller):
George Dishman (
talk)
11:22, 8 June 2013 (UTC)
It has been suggested in June 9th 2013 of the journal Nature Physics that there is evidence to suggest that matter in the core of a neutron star exists as a type of " Nuclear pasta", perhaps the article should be edited to include these findings? Sonicology ( talk) 19:03, 1 August 2013 (UTC)
This section states the nucleus is hold together by the strong force. I'm sure it's hold together by the weak force (or at least, as I've often read, "nuclear decay is mediated by the weak force"). Does someone know better (can they explain it)
Never mind. "Residual strong force" does not mean "not particularly significant force".
— Preceding
unsigned comment added by
68.7.59.69 (
talk)
20:54, 28 December 2013 (UTC)
Does anyone know how to find this graph to be added to the page or should the note be removed?
A neutron star's density increases as its mass increases, and its radius decreases non-linearly. (NASA mass radius graph)
http://ixo.gsfc.nasa.gov/old_conx_pages/images/science/neutron_stars/ns_mass_radius.gif
Jgoemat ( talk) 21:23, 5 December 2013 (UTC)
George Dishman ( talk) 13:00, 4 February 2014 (UTC)
"having only the diameter of a city" - city is a loose term which can be a specific incorporated area, a community or even consolidated into something larger such as a prefecture. Therefore you can't describe something as being "the diameter of a city", as it could mean three miles or twenty miles. In fact, why not just put miles in the lead. Rcsprinter (chatter) @ 19:21, 14 January 2014 (UTC)
Will a Neutron star ever "run out" of temperature? The article just makes comments to the temperature at the beginning of the life span of a Neutron star and that it cools in its first year, but not what happens afterwards. How long will it last until the temperature of a Neutron star reaches approximately 0 K?-- 31.17.153.69 ( talk) 07:20, 25 March 2014 (UTC)
From the article:
> Larger nuclei, particularly rich in neutrons, are formed, and materials that on Earth would be radioactive are stable in this environment, such as nickel-62.
Nickel-62 is stable on Earth, so I've removed the reference to it.
2601:0:AF00:226:A288:B4FF:FEC0:218C ( talk) 14:23, 2 April 2014 (UTC)
I almost just removed the figures quoted because 1) they just seemed so implausible and 2) they were unsourced, but I figured it would be best to bring the issue up here. Maybe there is some factor at play that I just don't understand.
The entry reads "The neutron star's density also gives it very high surface gravity, up to 7×10^12 m/s^2". It also goes on to say "One measure of such immense gravity is the fact that neutron stars have an escape velocity of around 100,000 km/s". That doesn't make any sense to me. How can the surface gravity be 70 million times greater than the escape velocity? To add to that, if something were to be accelerated at 7×10^12 m/s for one second, wouldn't it be going 23349.5 times faster than the speed of light? I understand that if something were accelerated like that it wouldn't exceed the speed of light, but just add an insane amount of relativistic mass, but with those numbers wouldn't we be dealing with a super-supermassive black hole or something?
Apologies if this is just me not understanding physics and astronomy, but these numbers just don't make any sense to me. 50.174.135.49 ( talk) 01:39, 27 June 2014 (UTC)
It looks like the maximum size of neutron stars is about 2 solar masses. Measured radius is about 10 – 15 km? A 2 SM neutron star has a Schwarzchild radius of 6 km which should contain light up to 12 – 18 km, so wouldn’t a 10-km neutron star have some light containment? There should be formulas for the effectiveness of light containment of a neutron star or black hole based on internal star radius. A hypothetical compact star or internal black hole star of 3GM/(c^^2) radius should contain light, but not as effectively as a Schwarzchild radius star or point singularity. When matter falls into a black hole, wouldn’t infalling matter eject more radiation (jets?) if the black hole contained a finite sized star instead of a point singularity? 72.69.11.171 ( talk) 16:56, 26 July 2014 (UTC)BG
wwwwwwwwwwwwwwwwwwwwwwwww Bold text — Preceding unsigned comment added by TheBluePotato646 ( talk • contribs) 16:26, 6 December 2014 (UTC)
NS mass is limited by some process, and measured data indicates this is about 2 solar masses. (My vote is this is because above 2 SM neutrons in the core collapse into mostly radiation and some quark matter .... the radiation would exit the star and the quark matter would quickly recombine to neutrons.) Apparently the radius of a neutron star does not increase much with mass, so IF a stable neutron star 3 SM or greater existed it would partially contain light and we could call it a black hole. 72.69.11.171 ( talk) 23:41, 31 July 2014 (UTC)BG
From my reading the current thinking is that collapsed stars with a mass over about 2 MSun are not composed of neutrons but either have quark matter cores or are entirely quark matter. That makes the designation "neutron star" inappropriate. http://arxiv.org/find/astro-ph/1/ti:+AND+quark+star/0/1/0/2012,2013,2014/0/1?per_page=100 Is this too new for inclusion? Qemist ( talk) 03:08, 25 April 2014 (UTC)
Recent observations indicate neutron stars over about 2 SM do not exist. See recent edits and comments below. Apparently there are no compact stars between about 2 - 5 SM. The smallest observed black holes are 5 SM and they could be quark matter and radiation. There might be a simple explanation why there are no black holes smaller than 5 SM: A collapsing 4 SM neutron core is about equal to its Schwarzchild radius (12 km) and about 5 SM total is contained. A hypothetical about 3 SM neutron star isn't strong enough to contain its contents Schwarzchild style but collapses and ejects radiation as it pops down to below 2 SM where it is stable. 72.69.11.171 ( talk) 14:26, 7 August 2014 (UTC)BG
Links on what specifically? Maximum observed mass of neutron stars? Minimum observed mass of black holes? — Preceding unsigned comment added by 72.69.11.171 ( talk) 06:54, 10 August 2014 (UTC)
The article makes several references to acceleration, escape velocity and speed of light using km/s. The speed of light is just under 300,000,000 m/s. It looks like some of the units are incorrectly marked km/s. From the text: ..."and would do so at around 2000 kilometers per second." Sherumgroup ( talk) 16:42, 20 August 2014 (UTC)
The range of masses in the lede is confusing and probably wrong. It states compact stars of less than 1.44 solar masses are white dwarfs, yet there are neutron stars in the literature with well constrained masses less than that, e.g. the companion to PSR J1756-2251 (1.230+/-0.007 MS), PSR J0737−3039 B (1.25 MS), and PSR J1906+0746 (also 1.25 MS). Then it states that compact stars between this limit and 3 MS "should" be neutron stars, but later that the maximum mass of a neutron star is about 2 MS. That is contradictory as to the state of objects with masses between 2 MS and 3 MS. Qemist ( talk) 02:14, 10 August 2014 (UTC)
The figure of 2.4 SM is incorrect. Do you have a source for this other than the Black Widow Pulsar Wiki article? From this source the lower mass limit for this neutron star is about 1.6 SM: http://arxiv.org/abs/1009.5427 See the Wiki articles on PSR_J1614-2230 AND PSR J0348+0432. 72.69.11.171 ( talk) 22:28, 13 August 2014 (UTC)
Lets consider for now 2 is the max for a neutron star and 5 the min for a black hole. A 5 22.5-km radius ultra-relativistic star has about the same gravitational acceleration and core pressure of a 2 13-km neutron star, yet a 5 22.5-km ultra-relativistic star theoretically contains light and a 2 13-km neutron star does not. (Note 25-km is 1.5 times the Schwarzchild radius) For an ultra-relativistic star gravitational acceleration and core pressure decrease as size increases. It does not collapse. 72.69.11.171 ( talk) 14:32, 14 August 2014 (UTC)
BTW, there is an interesting formula about the radius and radiated energy from infalling matter into a neutron or compact star: Accretion energy conversion efficiency = (Schwarzchild radius)/(2R) ..... where R is the radius of the star. (see: http://www3.mpifr-bonn.mpg.de/staff/mmassi/lezione2WEdd.pdf ) If a black hole is a point singularity its image should be different than that of a neutron star. 72.69.11.171 ( talk) 19:07, 1 October 2014 (UTC)BG
This article is suffering from a rather serious case of ledeclutter, at five paragraphs with comparisons to the sun, Manhattan, atomic nuclei, a 747, sand, a matchbook, and rock, as well as a lot of specific information (Neutron stars have overall densities of 3.7×1017 to 5.9×1017 kg/m3 (2.6×1014 to 4.1×1014 times the density of the Sun) etc. I propose consolidating the important information into a nice three or four paragraph summary and moving details to the body. Comments? A( Ch) 08:48, 13 January 2015 (UTC)
Prior content in this article duplicated one or more previously published sources. Copied or closely paraphrased material has been rewritten or removed and must not be restored, unless it is duly released under a compatible license. (For more information, please see "using copyrighted works from others" if you are not the copyright holder of this material, or "donating copyrighted materials" if you are.) For legal reasons, we cannot accept copyrighted text or images borrowed from other web sites or published material; such additions will be deleted. Contributors may use copyrighted publications as a source of information, and according to fair use may copy sentences and phrases, provided they are included in quotation marks and referenced properly. The material may also be rewritten, but only if it does not infringe on the copyright of the original or plagiarize from that source. Therefore such paraphrased portions must provide their source. Please see our guideline on non-free text for how to properly implement limited quotations of copyrighted text. Wikipedia takes copyright violations very seriously, and persistent violators will be blocked from editing. While we appreciate contributions, we must require all contributors to understand and comply with these policies. Thank you. Znbn ( talk) 22:39, 19 January 2015 (UTC)
I have removed a large section of text from the "Properties" section that appears to be a copyright violation, directly lifted from the Philip's Astronomy Encyclopedia (2002), pg 281-282.
What is the nearest neutron star? In the see also section it says PSR J0108-1431 (424 ly), but in the body RX J1856.5-3754 (400 ly) is mentioned alongside it. -- JorisvS ( talk) 09:00, 1 February 2015 (UTC)
The approximate mass of a matchbox of neutron star material is blatantly incorrect as the quoted density of a neutron star is 3.7*10^14 tons/m^3, which would make a soda can (355ml) weigh 3.7*10^14*355/10^6 or 131 gigatons, yet the lede claims 5000 gigatons for a matchbox. That's a big matchbox! The average density of rock is ~ 2.7 tons/m^3, or 2.7*10^9 tons/km^3 or 2.7 gigatons, yet the lede claims 1 km^3 of rock weighs 5000 gigatons! A soda can of neutron star material would weigh close to 3.7^10^14*355/10^6/2.7/10^9 = 48.6 km^3 of rock. David.Anderson.unique ( talk) 13:49, 5 July 2015 (UTC)
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To avoid anymore vandalism if not any. — 73.47.37.131 ( talk) 21:27, 31 July 2015 (UTC)
Please add temperatures that normal people can understand. Example: What does a surface temperature around "~6×105 K" mean? Can we have plain numbers please. Not everyone knows that K means Kelvin, and even less people are able to figure out the value of "105". Urbanus Secundus ( talk) 20:59, 13 June 2015 (UTC)
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I'm concerned about these 2 sentences at the beginning of the article: "A neutron star has a mass of at least 1.1 and perhaps up to 3 solar masses (M☉),[1][2] though the highest observed mass is 2.01 M☉. Neutron stars typically have a surface temperature around 6×105 K."
Maybe it should say "A neutron star has a theoretical mass of 1.1 - 3 solar masses". Also giving one specific temperature value is misleading. 173.56.18.42 ( talk) 14:54, 8 February 2016 (UTC)BG
It is stated on the Wikipedia page for gold that it is most likely made by colliding neutron stars. I came to this page to find out what other elements in the periodic table might be made by these events. This section needs to be created
Amphibio ( talk) 17:07, 24 February 2016 (UTC)
"There are thought to be around 100 million neutron stars in the Milky Way, a figure obtained by estimating the number of stars that have gone supernova." How many stars in the Milky Way total? Percent of whole might give me some insight about how rare this is Cegandodge ( talk) 19:31, 18 March 2016 (UTC)
A logical explanation for neutron star mass being limited to about 2.01 M☉ is the collapse of core nuclei. Note that at about 2 M☉ and 12-km radius the relativistic gravitational core pressure is about equal to (rho)(c^2)/3. A logical equation for nuclei disintegration is: proton → positron + 938MeV. This reaction should either heat the star or result in a 450MeV maximum electrically neutral positron-electron jet. 108.30.181.243 ( talk) 12:09, 11 June 2016 (UTC)BG
The equation
appears to have mixed dimensions in the denominator.
R has a dimension of length
is dimensionless
— Preceding
unsigned comment added by
50.45.15.139 (
talk •
contribs)
The article's editors continually write that neutron degeneracy pressure supports the neutron star against collapse. This is mostly untrue and should not be the sole reason given here. The editors are generally working from the false analogy that if a white dwarf is supported by electron degeneracy pressure, the neutron star must be supported by neutron degeneracy pressure. Note that none of their sources actually state that neutron degeneracy pressure supports the star - it's just "assumed."
Real neutron stars are supported against collapse mostly due to the strong nucleon-nucleon force. (No, the strong force does not act only in attraction - see /info/en/?search=Nuclear_force.) At the short nucleon-nucleon distances within the core of a neutron star, the strong force will act to repel nucleons (here, mostly neutrons) from one another. This repulsion - unrelated to degeneracy pressure - is stronger than degeneracy pressure within neutron stars. It supports the neutron star against collapse.
Sources: http://www.astro.princeton.edu/~burrows/classes/403/neutron.stars.pdf (page 3) "...using the relativistically correct equation of hydrostatic equilibrium (eq. (5)), and assuming a non-interacting degenerate gas of neutrons, Oppenheimer & Volkov (1939) derived a maximum neutron star mass of 0.7 M⊙, ∼eight times smaller. Observed neutron-star masses are clearly larger than this. The reason is that the strong repulsive nuclear force trumps neutron degeneracy pressure by a wide margin, resulting in less compact and more rigid structures supported by a stiffer EOS."
https://www.astro.umd.edu/~jph/A320_White_Dwarfs.pdf (page 10) "At densities of ρ ∼ 10^15 g cm−3, neutrons are not an ideal gas. These are the densities we find within an atomic nucleus, and the neutrons interact with one another via the strong force. Thus we see that to model neutron stars we need the TOV equation and an equation of state that includes not only degeneracy but the nuclear forces between the neutrons."
http://www.aanda.org/articles/aa/full/2001/46/aa1755/aa1755.right.html "The EOS is predominantly determined by the nuclear (strong) interaction between elementary constituents of dense matter."
http://www.rpi.edu/dept/phys/Courses/Astronomy/NeutStarsAJP.pdf Demonstrates that the strong force must be considered. The overall picture is not simple and not totally understood, as our knowledge of nucleon-nucleon interactions is incomplete.
I look forward to seeing discussion of the strong force's role permanently and prominently displayed in this article.
60.45.238.24 ( talk) 15:28, 4 October 2016 (UTC)
The terms AP4, MS2, and "(for EOS FPS, UU, APR or L respectively)" are used with no definitions nor links to anything which might explain them. It makes those passages less than helpful.
P.S. to the authors: Thanks for an otherwise nice article. — Preceding unsigned comment added by Oldmeat ( talk • contribs) 01:36, 1 March 2017 (UTC)
As we all know, with regular stars, nuclear fusion takes place place in their cores, and this nuclear fusion is what produces the energy emitted thereby.
Neutron stars also produce protons, but I wouldn't guess that nuclear fusion is taking place in their cores. Would I be wrong to assume it's not? And, assuming I am correct to guess that there is no nuclear fusion taking place therein, the question then remains: what produces the energy emitted by neutron stars?
If you know the answer to these questions, please help improve this article by adding details about neutron stars' source of energy.
allixpeeke ( talk) 15:39, 27 June 2017 (UTC); augmented 12:08, 30 June 2017 (UTC)
A short section explaining what the long-term evolution of neutron stars is expected to be would be nice. Can a neutron star cool down to near zero absolute and remain stable against gravitational collapse? Ho wmuch time would the cooling take? (I'd expect this to be orders of magnitude more than the current age of the Universe) Urhixidur ( talk) 17:00, 29 September 2017 (UTC)
Really, this is accepted quality for wikipedia? I expected better 188.175.76.2 ( talk) 07:24, 16 December 2017 (UTC)
Transient condensates are core properties ranging from Axion matter to various Parton matter to Quark matter to Neutron matter. This Condensate matter makes up over 95% of all matter in the infinite universe. The core does not undergo fusion. It keeps on attracting matter into it. In the case of our Sun its core will photo-disintergrate atoms such as Fe(and all other) to neutrons and protons(change to Neutron) that would become part of the core. The gauge field on the lattice is the resultant property forming a dipolar electromagnetic effect producing vortices, that expel neutrons into the solar envelope that change to protons that than take part in fusion reactions H+H= Helium etc forming all the elements. The Sun's energy is produced by the core 65%, Fusion reactions within the solar envelope 35% and about 5% fission. It all about the core and its properties. Images created by condensates as in the Kilonova hour glass and the release of condensate droplets that produce giant bubbles. — Preceding unsigned comment added by Harry Costas ( talk • contribs) 00:20, 2 January 2018 (UTC)
A neutron star is so dense that one teaspoon (5 milliliters) of its material would have a mass over 5.5×1012 kg (that is 1100 tonnes per 1 nanolitre), about 900 times the mass of the Great Pyramid of Giza. In the enormous gravitational field of a neutron star, its weight would be 1.1×1025 N, which is about 15 times the weight of the Moon.[c]
The article states, "At present, there are about 2,000 known neutron stars in the Milky Way..." I was going to contribute an estimated percentage of neutron stars, as compared to the total estimated number of all stars, in our galaxy, but the range from NASA to Swinburne sources were a billion down to 100,000. NASA's figure is from 2007 and Swinburne's much more recent, but perhaps another editor can figure out the most credible current estimate. This is relevant not only for curiosity sake but especially now that the supernova origin of heavy elements theory is disfavored for a neutron star/black hole collision hypothesis. Bob Enyart, Denver KGOV radio host ( talk) 21:42, 27 June 2019 (UTC)
In response to an old request, I have begun to find information regarding the energy production of neutron stars. I agree this is an improvement to the article itself as this important subject seems non-existent referencing this type of star. It can also help make sense of the star's internal structure, why it is so could be extrapolated further. This will not be a heavy edit since there is not much discussion in the literature about how neutron stars produce their energy, and it is the first time this topic has been attributed to properties of a neutron star in this article to allow further iteration and collaboration.
Neutron stars lose heat energy by emitting neutrinos and electron conduction within. Over time this is radiated away from the star in the form of neutrinos and X-rays. Most emissions are not thermal, at around one million Kelvin it has most radiation being high energy x rays or UV rays. Neutron stars are not black bodies, so it does not emit very much thermal energy which has caused speculation as to how they produce such high energy.
ChromeDragon ( talk) 23:23, 15 September 2019 (UTC)
I removed a "Citation needed" tag from the first intro paragraph. There is a reference at the end of the next sentence. Wikipedia Style asks that editors place as few copies of a single reference as possible, and in particular if two, or several, contiguous sentences, each with a distinct fact, are all supported by the same reference, then Wikipedia asks that that reference be placed once at the end of the contiguous sentences. Unless the editor who inserted the "Citation needed" tag has actual knowledge that the reference at the end of the next sentence does not support the fact they tagged, they should not tag it. Nick Beeson ( talk) 15:31, 17 September 2019 (UTC)
I have moved this statement here pending a reference - it was tagged 13 months ago: " It is statistically probable based on known populations that there is at least one neutron star within 10 parsecs of the Sun, significantly closer than the current nearest known neutron star. citation needed " — Preceding unsigned comment added by HammerFilmFan ( talk • contribs) 18:50, 17 May 2020 (UTC)
"... the same weight as a 0.5 cubic kilometre chunk of the Earth (a cube with edges of about 800 metres)"
A 0.5 cubic km would have edges of exactly 500 metres... Just saying. 2403:6200:8856:563C:D011:4BA2:409E:1E ( talk) 04:53, 16 November 2020 (UTC)
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