![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 |
Do black holes exits at the center of neutron stars? Read something to that affect on a cosmology blog. Don't know if it's true or not though.
For the escape velocity of the neutron star, I wonder, was that found by using the traditional newtonian physics equation for gravitational potential energy, converting it into kinetic energy and finding the escape velocity? [ sqrt((2GM)/r) ] However, as it says, 150,000 km/s is half the speed of light, wouldn't you have to use general relativity to figure it out instead? Mercury has a much lower speed, yet even its orbit has certain relativistic effects. Are there any math geniuses that can confirm or refute the escape velocity of 150,000 km/s? It isn't important but it's sort of interesting to think about and I'd like to know. —The preceding unsigned comment was added by 72.59.2.127 ( talk • contribs) .
Question: what is the internal structure of a neutron star like? Where are the boundaries between neutronium, degenerate and normal matter located? What percentage of the stars mass or volume are each? What is degenerate matter? What do the boundaries between the layers look like? What is there shape? (I suppose some of these questions may not have answers yet...) -- SJK
Whoever deleted the term 'neutronium' from the main page -- if you are saying not to use that term, note we already have a page neutronium. Secondly, I find your new version hard to follow -- whats an 'iron layer'? Finally, but 'quark matter' you mean what? -- SJK
Sorry, it was made in a haste. Iron layer is a thin crust of metalic iron, by quark matter i mean a soup where not even individual neutrons exist, but a mixture of quarks of different kinds. "strange" matter is matter partially composed by "strange" quarks. What i tried to emphasize is that there was a comtinuum of compositions inside a neutron star, and that telling "a crust of degenerate matter and and interior of neutronium" was an oversimplification that also hided the fact that there is no aggreement respect to what's in the core. AN
From the article:
I don't think that pulsars were ever seriously thought to be evidence of extraterrestrial intelligence, at least not by the researchers who were actually investigating them. The first pulsar discovered was dubbed "BEM-1" (Bug-Eyed Monster 1) as a joke by its discoverers, if I recall correctly. But since this is all from memory, anyone have any references handy? Bryan Derksen
As a non-physicist, how does this sentence:
relate to black holes? Thanks, [[User:Meelar| Meelar (talk)]] 19:04, Sep 10, 2004 (UTC)
I'm not well read in astrophysics, but mass and [density] are two separate things. Compare traffic in New York to traffic in California. New York has tons of traffic jams and everyone is stuck together. California might have more cars overall, but they're more spread out for the main part. The same is true for black holes and neutron stars, black holes have more mass, but neutron stars are more closely packed. Presuming the statement above is correct. If anyone more knowledgable can confirm this that would be good.
I believe you are correct in your distinctions between mass and density, however I think a black hole is still infinitly dense, even if you determine it's size by it's Schwartzchild radius. Rmrfstar 00:38, 5 Apr 2005 (UTC)
The real problem, though, with black holes, is that we have never seen a black hole; no one has, because it is impossible to observe one, and we can only see their effects. So, in a sense, black holes are not "known", per se, while neutron stars can be and have been observed directly, even if what we know is, in fact, based on mostly mathematical models. —The preceding unsigned comment was added by 67.160.131.117 ( talk • contribs) on 08:04, 2 March 2006.
Indeed, one must define "observe" carefully when speaking of physics. Very little in physics is directly observable by the human eye, but much is quite certain nonetheless. Most of steller physics is known through taking spectra of stars for example - we don't "see" what stars are made of, but the science tells us clearly by examing absoption/emission lines of stars and comparing to the quantum nature of various elements, also deduced through mathematics and observations of careful experimentation.
First off, density ~ Mass/Radius^3. The above discussion is confusing the physics: Stars begin their life as "fluffy" balls of gas, slowly reacting to create slightly heavier elements than the Hydrogen and Helium they begin with. This process of nuclear fusion keeps powering the star over its Main Sequence, or primary lifespan. Depending on the star's mass, it will have a proportional amount of energy during the inevitable and eventual collapse, once nuclear fusion runs out. This occurs once the mass avaliable is insufficient to continue to raise the temperature enough to promote more fusion, or if the fusion process has gone all the way to Iron - the most bound of all atomic nuclei. There can be no fusion after reaching Iron, so the pressure keeping the star from collapsing under gravity disappears, and the star collapses. When it collapses the density increases dramatically. Due to Heisenburg's Uncertainty Principle, electrons and neutrons can only be "pushed together" so much. If the density reaches a critical point, electron degeneracy pressure maintains the stars integrity, and the star becomes a white dwarf. It the white dwarf has more than 1.4 solar masses (whether at time of initial collapse or from accretion), it was collapse because the gravitational force will overcome the electron degeneracy. At this point, neutron degeneracy can take over and support the star, creating a neutron star. If the neutron star accretes mass somehow, it would collapse eventually into a blackhole. —This unsigned comment was added by 70.25.24.27 ( talk • contribs) on 05:04, 23 March 2006.
The article specifies slow down rates that appear far, far too small (10-12 and 10-19 second for each century), in fact too small to logically produce the older slower-rotating stars within the universe's current age the article also mentions. Googling around, I see zebu.uoregon.edu has "about 10-15 seconds per rotation", so I suspect "per century" should be changed to "per rotation", and this would change the next sentence as follows, for a star initially rotating at 1 second: In other words, a neutron star now rotating in 1 second will rotate in 1.000003 seconds after a century, or 1.03 seconds after 1 million years. Does this look sensible? - Wikibob | Talk 22:49, 2005 Apr 19 (UTC)
The Neutron star article states:
"Another class of neutron star, known as the magnetar, exists. These have a magnetic field of above 10 gigateslas, strong enough to wipe a credit card from the distance of the Sun and strong enough to be fatal from the distance of the Moon. By comparison, Earth's natural magnetic field is 50 microteslas, and on Earth a fatal magnetic field is only a theoretical possibility; some of the strongest fields generated are actually used in medical imaging. A small neodymium based rare earth magnet has a field of about a tesla, and most media used for data storage can be erased with milliteslas."
The Magnetar article states:
"A magnetic field above 10 gigateslas is strong enough to wipe a credit card from half the distance of the Moon from the Earth1. A small neodymium based rare earth magnet has a field of about a tesla, Earth has a geomagnetic field of 30-60 microteslas, and most media used for data storage can be erased with a millitesla field.
The magnetic field of a magnetar would be lethal at a distance of up to 1000 km, by warping the atoms in living flesh2."
The two don't agree too well, though they are clearly derived from similar source material. Maybe someone who knows which version is correct can fix the incorrect one? Thanks!-- Ailicec 01:18, 7 Jun 2005 (UTC)
"The matter at the surface of a neutron star is composed of ordinary nuclei as well as ionized electrons." Surely the person writing this meant "ionized atoms" eg ions?
Early in the article: "Neutron stars have a mass of the same order as the mass of the Sun. Their size (radius) is of order 10 km, about 70,000 times smaller than the Sun." Later in the redundant 5th paragraph: "Neutron stars are typically about 20 km in diameter, have greater than 1.4 times the mass of our Sun"
This site: 1 says it's 10km
But this one: 2 says it must be at least 18km
Merick June 29, 2005 15:52 (UTC)
In 1933 Walter Baade and Fritz Zwicky (Phys. Rev. 45 "Supernovae and Cosmic rays") proposed the existence of the neutron star, only a year after Chadwick's discovery of the neutron. In seeking an explanation for the origin of a supernova, they proposed that the neutron star is formed in a supernova.
Should this reference be
'Remarks on Super-Novae and Cosmic Rays'
W. Baade and F. Zwicky
Phys. Rev. 46, 76-77 (1934)
The paper was in Phys.Rev. in 1934, but the discovery was still in 1933.
Keep up the good work!!!
-- JDC
Is it known why some neutron stars are pulsars and some aren't? Or are they all, and it just isn't observable?
Response:
If I may, there are several models of static neutron stars (non rotating) which are still used to date to model parameters, which would not be considered 'pulsars', since any received beam of radio waves wouldn't 'pulse'. I suppose the question is - will a neutron star emit the radio waves if it isn't rotating?
One of the main advantages of pulsars is that they can be detected via these pulses. Neutron stars are otherwise very small, very dark, and extremely hard to find.
-- JDC
Concerning Fxer's new introduction, I'm ambivilant about keeping it. The new intro is less of a definition and is slower to give a clear idea of what a neutron star is and its importance (first theororized astromical object). For instance, that new sentence of the "weight" of a spoonful of a neutron star: Is that the kind of statistic we want in the intro paragraph? Also there is now presented irrelevant information on black holes and white dwarfs, which should be mentioned later... On a more positive note, the newer introduction correctly names Neutron stars as types of degenerate stars. Any other thoughts? -- Rmrfstar 00:17, 21 July 2005 (UTC)
Part of the current intro is confusing to the lay reader (namely, me):
A typical neutron star has a mass between 1.35 to about 2.1 solar masses, with a corresponding radius between 20 and 10 km (they shrink as their mass increases) — 30,000 to 70,000 times smaller than the Sun. Thus, neutron stars have densities of 8×1013 to 2×1015 g/ cm³, about the density of an atomic nucleus. [1] Compact stars of less than 1.44 solar masses, the Chandrasekhar limit, are white dwarfs; above three to five solar masses (the Tolman-Oppenheimer-Volkoff limit), gravitational collapse occurs, inevitably producing a black hole.
Now, I'm hardly an astrophysicist, but I'm having trouble understanding exactly how the Chandrasekhar Limit applies to neutron stars specifically. It doesn't make sense that a neutron star with a mass below the limit would utlimately collapse into a white dwarf. How exactly does the Limit apply - can someone clarify? UndercoverParrothead 22:48, 14 October 2006 (UTC)
Would anyone object to the radius of a neutron star being pushed down to 10km? This is the research I am doing at the moment, and literature / my results point to 10km. Cheers.
-- JDC
To the person/people who continually and intentionally add errors to WikiPedia pages. Please stop. There is an entire encyclopedia out there for you to destroy. Please go to uncyclopedia or kamelopedia if you are going to ruin pages. These are here for genuine interest.
-- JDC
Will some knowledgeable person please either add some references establishing the "atmosphere/crust" structural version of a neutron star, or else rewrite it to remove that wording? I'm no astrophysicist, but as a physics grad student and a follower of such things as much as I have been able in the scientific and popular literature, I have never heard of such a thing. Not saying it's false, just that we ought to have some sort of documentation.
-- JDC 00:32, 4 October 2005 (UTC)
The edit involving the 'fudge factor' is fine by me. The only observational parameters we have (to a decent degree) are mass limits. We construct models to one day test via experiments.
-- JDC 23:52, 4 October 2005 (UTC)
Can someone please tell me how neutron stars get their huge magnetic flux. I don't see how something made up of mostly neutrons can have a magnetic flux so large with an area of so small. Where exactly does the magnetic flux come from? I can't seem to find any articles or publications on this matter.
New Scientist and Physics Web report the discovery of a neutron star that rotates 716 times per second. (newscientist.com 12 january 2006)
The current "one revolution can take anything from thirty seconds to one six-hundredth of a second" could be updated to reflect this (seven-hundreth of a second) —The preceding unsigned comment was added by 212.123.21.4 ( talk • contribs) on 19:34, 6 February 2006.
New stars found called Rotating Radio Transients, or RRATs http://news.yahoo.com/s/space/20060215/sc_space/astronomersdiscoverpeekaboostars Can someone create a new article? —The preceding unsigned comment was added by 66.25.142.153 ( talk • contribs) .
I have edited the section that says the Tsar bomb was 100 MT. The bomb (in the form tested) was only 50MT. There was a plan to make a 100MT 'dirty bomb' but this was never tested - nor created I think.
I think we could take this into consideration: http://www.space.com/scienceastronomy/060501_mm_starquake.html It's probably nothing significant, but I just wanted everyone to know. —The preceding unsigned comment was added by Uni4dfx ( talk • contribs) on 12:00, 1 May 2006.
"Due to its small size and high density, a neutron star possesses a very high rotation speed..." Isn't the high rotational speed due to conservation of angular momentum in conjunction with the drastically reduced radius of the star? Clarityfiend 08:39, 9 June 2006 (UTC)
The credit card analogy in the magnetars section is unclear. Does it mean 'wipe' as in demagnetise? Or is 'wipe' a typo for 'swipe', as in it could read the CC info from that distance?-- Anchoress 01:10, 24 June 2006 (UTC)
To the sentence about what it would be like to fall on a neutron star:
I had added the comment: and probably not survive.
This contribution of mine to Wikipedia lasted only about 15 minutes; it was reverted by Bryan Derksen, saying:
This seems to imply that there is no place for humor on WP, no matter how obvious it might be (my comment certainly could not be taken for serious and mislead someone - let alone lead to serious consequences, like someone really going off to jump on a neutron star, more on that below). Surely someone is going to point to some Be dead serious with a straight face official guideline about that that I overlooked.
However, just for revenge, I want to say that Bryan's own comment is itself misleading; indeed, it is false:
It might be objected that if it is indeed impossible for a human to fall on a neutron star, then any sentence starting by "if an average human were to encounter a neutron star" is true. All implications are true from a false premise. But then it would be just as true to say the impact would produce the energy of a 1000 gigaton bomb, or that of lighting a match. That in turn would mean that the whole sentence is irrelevant, devoid of content. That cannot be the case, see the Everything on Wikipedia is 100% reliable relevant and perfect guideline. So this objection is dismissed.
Now, can I put my comment back?
David Olivier 13:11, 25 June 2006 (UTC)
I'd like to get rid of this metaphorical and visual reference of a human striking at 100megatons a neutron star, i mean if its mathematically and theoretically correct, in terms of the velocity, and energy, then one would require workings to show such an impossible situations, in the future of our race, as a moral relativist, this part should be deleted or expanded!!! The Idiot 14:21, 26 July 2006 (UTC)
I also think that the analogy is tortured and confusing. More than anything I think it's not a "real world" example of what would happen if a human struck a neutron star and it's misleading to suggest that this is what would happen. No, this is just what you get when you plug some uncommonly big numbers into a basic physics formula, and then divide by the yield of a big nuclear bomb. It doesn't help anybody understand what's really going on -- if anything it confuses the issue by suggesting that a human body could get close to a neutron star and that we could measure the effect of the impact. Accordingly, I am removing it. Eliot 20:13, 24 October 2006 (UTC)
There's now been 3 instances of vandalism by 172.142.102.49. This is the only page he's editing, but he keeps editing the pulsars section to refer to penises. Took me a second to work it out. Lawful Hippo 04:55, 27 November 2006 (UTC)
The article says the following: "they shrink as their mass increases". How can their mass increase ? Perhaps the articles means "density". There is no hint in the article as to why the mass would increase.
I was wondering if this page is going to list the type of neutron stars.
Thanks, CarpD 14/1/06
"The fact that stellar and biological evolution are so slow in our matter universe does not mean that no faster universe is possible. Even today, some people suggest that in the super-fast reactions in the quark soup of neutron stars, living structures with the complexity of civilisations might arise and pass in what to us would be the blink of an eye."
—Jon Richfield from Sumerset West, South Africa writing a response to a question sent to the Last Word column of the New Scientist, published in Does Anything East Wasps: And 101 Other Quetsions (2005)
I thought this was very interesting. Does anyone know what Jon is talking about? —The preceding
unsigned comment was added by
124.62.212.69 (
talk)
11:54, 17 February 2007 (UTC).
I saw a news article today on BBC about an irregular neutron star they had discovered named Calvera. I think information about it should be added to the article. Trees r cool 21:59, 20 August 2007 (UTC)
Hey, I'm the student who co-authored the study about Calvera. In the interest of not risking NPOV violations, I'll leave it to someone else to modify the article if they see fit, but thanks for noticing our work. ;-) Magnetar 02:11, 21 August 2007 (UTC)Magnetar
Can anyone comment on the validity of the trivia section? I myself don't know enough about neutron stars to know one way or another. Thanks. soldierx40k 00:33, 3 September 2007 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 |
Do black holes exits at the center of neutron stars? Read something to that affect on a cosmology blog. Don't know if it's true or not though.
For the escape velocity of the neutron star, I wonder, was that found by using the traditional newtonian physics equation for gravitational potential energy, converting it into kinetic energy and finding the escape velocity? [ sqrt((2GM)/r) ] However, as it says, 150,000 km/s is half the speed of light, wouldn't you have to use general relativity to figure it out instead? Mercury has a much lower speed, yet even its orbit has certain relativistic effects. Are there any math geniuses that can confirm or refute the escape velocity of 150,000 km/s? It isn't important but it's sort of interesting to think about and I'd like to know. —The preceding unsigned comment was added by 72.59.2.127 ( talk • contribs) .
Question: what is the internal structure of a neutron star like? Where are the boundaries between neutronium, degenerate and normal matter located? What percentage of the stars mass or volume are each? What is degenerate matter? What do the boundaries between the layers look like? What is there shape? (I suppose some of these questions may not have answers yet...) -- SJK
Whoever deleted the term 'neutronium' from the main page -- if you are saying not to use that term, note we already have a page neutronium. Secondly, I find your new version hard to follow -- whats an 'iron layer'? Finally, but 'quark matter' you mean what? -- SJK
Sorry, it was made in a haste. Iron layer is a thin crust of metalic iron, by quark matter i mean a soup where not even individual neutrons exist, but a mixture of quarks of different kinds. "strange" matter is matter partially composed by "strange" quarks. What i tried to emphasize is that there was a comtinuum of compositions inside a neutron star, and that telling "a crust of degenerate matter and and interior of neutronium" was an oversimplification that also hided the fact that there is no aggreement respect to what's in the core. AN
From the article:
I don't think that pulsars were ever seriously thought to be evidence of extraterrestrial intelligence, at least not by the researchers who were actually investigating them. The first pulsar discovered was dubbed "BEM-1" (Bug-Eyed Monster 1) as a joke by its discoverers, if I recall correctly. But since this is all from memory, anyone have any references handy? Bryan Derksen
As a non-physicist, how does this sentence:
relate to black holes? Thanks, [[User:Meelar| Meelar (talk)]] 19:04, Sep 10, 2004 (UTC)
I'm not well read in astrophysics, but mass and [density] are two separate things. Compare traffic in New York to traffic in California. New York has tons of traffic jams and everyone is stuck together. California might have more cars overall, but they're more spread out for the main part. The same is true for black holes and neutron stars, black holes have more mass, but neutron stars are more closely packed. Presuming the statement above is correct. If anyone more knowledgable can confirm this that would be good.
I believe you are correct in your distinctions between mass and density, however I think a black hole is still infinitly dense, even if you determine it's size by it's Schwartzchild radius. Rmrfstar 00:38, 5 Apr 2005 (UTC)
The real problem, though, with black holes, is that we have never seen a black hole; no one has, because it is impossible to observe one, and we can only see their effects. So, in a sense, black holes are not "known", per se, while neutron stars can be and have been observed directly, even if what we know is, in fact, based on mostly mathematical models. —The preceding unsigned comment was added by 67.160.131.117 ( talk • contribs) on 08:04, 2 March 2006.
Indeed, one must define "observe" carefully when speaking of physics. Very little in physics is directly observable by the human eye, but much is quite certain nonetheless. Most of steller physics is known through taking spectra of stars for example - we don't "see" what stars are made of, but the science tells us clearly by examing absoption/emission lines of stars and comparing to the quantum nature of various elements, also deduced through mathematics and observations of careful experimentation.
First off, density ~ Mass/Radius^3. The above discussion is confusing the physics: Stars begin their life as "fluffy" balls of gas, slowly reacting to create slightly heavier elements than the Hydrogen and Helium they begin with. This process of nuclear fusion keeps powering the star over its Main Sequence, or primary lifespan. Depending on the star's mass, it will have a proportional amount of energy during the inevitable and eventual collapse, once nuclear fusion runs out. This occurs once the mass avaliable is insufficient to continue to raise the temperature enough to promote more fusion, or if the fusion process has gone all the way to Iron - the most bound of all atomic nuclei. There can be no fusion after reaching Iron, so the pressure keeping the star from collapsing under gravity disappears, and the star collapses. When it collapses the density increases dramatically. Due to Heisenburg's Uncertainty Principle, electrons and neutrons can only be "pushed together" so much. If the density reaches a critical point, electron degeneracy pressure maintains the stars integrity, and the star becomes a white dwarf. It the white dwarf has more than 1.4 solar masses (whether at time of initial collapse or from accretion), it was collapse because the gravitational force will overcome the electron degeneracy. At this point, neutron degeneracy can take over and support the star, creating a neutron star. If the neutron star accretes mass somehow, it would collapse eventually into a blackhole. —This unsigned comment was added by 70.25.24.27 ( talk • contribs) on 05:04, 23 March 2006.
The article specifies slow down rates that appear far, far too small (10-12 and 10-19 second for each century), in fact too small to logically produce the older slower-rotating stars within the universe's current age the article also mentions. Googling around, I see zebu.uoregon.edu has "about 10-15 seconds per rotation", so I suspect "per century" should be changed to "per rotation", and this would change the next sentence as follows, for a star initially rotating at 1 second: In other words, a neutron star now rotating in 1 second will rotate in 1.000003 seconds after a century, or 1.03 seconds after 1 million years. Does this look sensible? - Wikibob | Talk 22:49, 2005 Apr 19 (UTC)
The Neutron star article states:
"Another class of neutron star, known as the magnetar, exists. These have a magnetic field of above 10 gigateslas, strong enough to wipe a credit card from the distance of the Sun and strong enough to be fatal from the distance of the Moon. By comparison, Earth's natural magnetic field is 50 microteslas, and on Earth a fatal magnetic field is only a theoretical possibility; some of the strongest fields generated are actually used in medical imaging. A small neodymium based rare earth magnet has a field of about a tesla, and most media used for data storage can be erased with milliteslas."
The Magnetar article states:
"A magnetic field above 10 gigateslas is strong enough to wipe a credit card from half the distance of the Moon from the Earth1. A small neodymium based rare earth magnet has a field of about a tesla, Earth has a geomagnetic field of 30-60 microteslas, and most media used for data storage can be erased with a millitesla field.
The magnetic field of a magnetar would be lethal at a distance of up to 1000 km, by warping the atoms in living flesh2."
The two don't agree too well, though they are clearly derived from similar source material. Maybe someone who knows which version is correct can fix the incorrect one? Thanks!-- Ailicec 01:18, 7 Jun 2005 (UTC)
"The matter at the surface of a neutron star is composed of ordinary nuclei as well as ionized electrons." Surely the person writing this meant "ionized atoms" eg ions?
Early in the article: "Neutron stars have a mass of the same order as the mass of the Sun. Their size (radius) is of order 10 km, about 70,000 times smaller than the Sun." Later in the redundant 5th paragraph: "Neutron stars are typically about 20 km in diameter, have greater than 1.4 times the mass of our Sun"
This site: 1 says it's 10km
But this one: 2 says it must be at least 18km
Merick June 29, 2005 15:52 (UTC)
In 1933 Walter Baade and Fritz Zwicky (Phys. Rev. 45 "Supernovae and Cosmic rays") proposed the existence of the neutron star, only a year after Chadwick's discovery of the neutron. In seeking an explanation for the origin of a supernova, they proposed that the neutron star is formed in a supernova.
Should this reference be
'Remarks on Super-Novae and Cosmic Rays'
W. Baade and F. Zwicky
Phys. Rev. 46, 76-77 (1934)
The paper was in Phys.Rev. in 1934, but the discovery was still in 1933.
Keep up the good work!!!
-- JDC
Is it known why some neutron stars are pulsars and some aren't? Or are they all, and it just isn't observable?
Response:
If I may, there are several models of static neutron stars (non rotating) which are still used to date to model parameters, which would not be considered 'pulsars', since any received beam of radio waves wouldn't 'pulse'. I suppose the question is - will a neutron star emit the radio waves if it isn't rotating?
One of the main advantages of pulsars is that they can be detected via these pulses. Neutron stars are otherwise very small, very dark, and extremely hard to find.
-- JDC
Concerning Fxer's new introduction, I'm ambivilant about keeping it. The new intro is less of a definition and is slower to give a clear idea of what a neutron star is and its importance (first theororized astromical object). For instance, that new sentence of the "weight" of a spoonful of a neutron star: Is that the kind of statistic we want in the intro paragraph? Also there is now presented irrelevant information on black holes and white dwarfs, which should be mentioned later... On a more positive note, the newer introduction correctly names Neutron stars as types of degenerate stars. Any other thoughts? -- Rmrfstar 00:17, 21 July 2005 (UTC)
Part of the current intro is confusing to the lay reader (namely, me):
A typical neutron star has a mass between 1.35 to about 2.1 solar masses, with a corresponding radius between 20 and 10 km (they shrink as their mass increases) — 30,000 to 70,000 times smaller than the Sun. Thus, neutron stars have densities of 8×1013 to 2×1015 g/ cm³, about the density of an atomic nucleus. [1] Compact stars of less than 1.44 solar masses, the Chandrasekhar limit, are white dwarfs; above three to five solar masses (the Tolman-Oppenheimer-Volkoff limit), gravitational collapse occurs, inevitably producing a black hole.
Now, I'm hardly an astrophysicist, but I'm having trouble understanding exactly how the Chandrasekhar Limit applies to neutron stars specifically. It doesn't make sense that a neutron star with a mass below the limit would utlimately collapse into a white dwarf. How exactly does the Limit apply - can someone clarify? UndercoverParrothead 22:48, 14 October 2006 (UTC)
Would anyone object to the radius of a neutron star being pushed down to 10km? This is the research I am doing at the moment, and literature / my results point to 10km. Cheers.
-- JDC
To the person/people who continually and intentionally add errors to WikiPedia pages. Please stop. There is an entire encyclopedia out there for you to destroy. Please go to uncyclopedia or kamelopedia if you are going to ruin pages. These are here for genuine interest.
-- JDC
Will some knowledgeable person please either add some references establishing the "atmosphere/crust" structural version of a neutron star, or else rewrite it to remove that wording? I'm no astrophysicist, but as a physics grad student and a follower of such things as much as I have been able in the scientific and popular literature, I have never heard of such a thing. Not saying it's false, just that we ought to have some sort of documentation.
-- JDC 00:32, 4 October 2005 (UTC)
The edit involving the 'fudge factor' is fine by me. The only observational parameters we have (to a decent degree) are mass limits. We construct models to one day test via experiments.
-- JDC 23:52, 4 October 2005 (UTC)
Can someone please tell me how neutron stars get their huge magnetic flux. I don't see how something made up of mostly neutrons can have a magnetic flux so large with an area of so small. Where exactly does the magnetic flux come from? I can't seem to find any articles or publications on this matter.
New Scientist and Physics Web report the discovery of a neutron star that rotates 716 times per second. (newscientist.com 12 january 2006)
The current "one revolution can take anything from thirty seconds to one six-hundredth of a second" could be updated to reflect this (seven-hundreth of a second) —The preceding unsigned comment was added by 212.123.21.4 ( talk • contribs) on 19:34, 6 February 2006.
New stars found called Rotating Radio Transients, or RRATs http://news.yahoo.com/s/space/20060215/sc_space/astronomersdiscoverpeekaboostars Can someone create a new article? —The preceding unsigned comment was added by 66.25.142.153 ( talk • contribs) .
I have edited the section that says the Tsar bomb was 100 MT. The bomb (in the form tested) was only 50MT. There was a plan to make a 100MT 'dirty bomb' but this was never tested - nor created I think.
I think we could take this into consideration: http://www.space.com/scienceastronomy/060501_mm_starquake.html It's probably nothing significant, but I just wanted everyone to know. —The preceding unsigned comment was added by Uni4dfx ( talk • contribs) on 12:00, 1 May 2006.
"Due to its small size and high density, a neutron star possesses a very high rotation speed..." Isn't the high rotational speed due to conservation of angular momentum in conjunction with the drastically reduced radius of the star? Clarityfiend 08:39, 9 June 2006 (UTC)
The credit card analogy in the magnetars section is unclear. Does it mean 'wipe' as in demagnetise? Or is 'wipe' a typo for 'swipe', as in it could read the CC info from that distance?-- Anchoress 01:10, 24 June 2006 (UTC)
To the sentence about what it would be like to fall on a neutron star:
I had added the comment: and probably not survive.
This contribution of mine to Wikipedia lasted only about 15 minutes; it was reverted by Bryan Derksen, saying:
This seems to imply that there is no place for humor on WP, no matter how obvious it might be (my comment certainly could not be taken for serious and mislead someone - let alone lead to serious consequences, like someone really going off to jump on a neutron star, more on that below). Surely someone is going to point to some Be dead serious with a straight face official guideline about that that I overlooked.
However, just for revenge, I want to say that Bryan's own comment is itself misleading; indeed, it is false:
It might be objected that if it is indeed impossible for a human to fall on a neutron star, then any sentence starting by "if an average human were to encounter a neutron star" is true. All implications are true from a false premise. But then it would be just as true to say the impact would produce the energy of a 1000 gigaton bomb, or that of lighting a match. That in turn would mean that the whole sentence is irrelevant, devoid of content. That cannot be the case, see the Everything on Wikipedia is 100% reliable relevant and perfect guideline. So this objection is dismissed.
Now, can I put my comment back?
David Olivier 13:11, 25 June 2006 (UTC)
I'd like to get rid of this metaphorical and visual reference of a human striking at 100megatons a neutron star, i mean if its mathematically and theoretically correct, in terms of the velocity, and energy, then one would require workings to show such an impossible situations, in the future of our race, as a moral relativist, this part should be deleted or expanded!!! The Idiot 14:21, 26 July 2006 (UTC)
I also think that the analogy is tortured and confusing. More than anything I think it's not a "real world" example of what would happen if a human struck a neutron star and it's misleading to suggest that this is what would happen. No, this is just what you get when you plug some uncommonly big numbers into a basic physics formula, and then divide by the yield of a big nuclear bomb. It doesn't help anybody understand what's really going on -- if anything it confuses the issue by suggesting that a human body could get close to a neutron star and that we could measure the effect of the impact. Accordingly, I am removing it. Eliot 20:13, 24 October 2006 (UTC)
There's now been 3 instances of vandalism by 172.142.102.49. This is the only page he's editing, but he keeps editing the pulsars section to refer to penises. Took me a second to work it out. Lawful Hippo 04:55, 27 November 2006 (UTC)
The article says the following: "they shrink as their mass increases". How can their mass increase ? Perhaps the articles means "density". There is no hint in the article as to why the mass would increase.
I was wondering if this page is going to list the type of neutron stars.
Thanks, CarpD 14/1/06
"The fact that stellar and biological evolution are so slow in our matter universe does not mean that no faster universe is possible. Even today, some people suggest that in the super-fast reactions in the quark soup of neutron stars, living structures with the complexity of civilisations might arise and pass in what to us would be the blink of an eye."
—Jon Richfield from Sumerset West, South Africa writing a response to a question sent to the Last Word column of the New Scientist, published in Does Anything East Wasps: And 101 Other Quetsions (2005)
I thought this was very interesting. Does anyone know what Jon is talking about? —The preceding
unsigned comment was added by
124.62.212.69 (
talk)
11:54, 17 February 2007 (UTC).
I saw a news article today on BBC about an irregular neutron star they had discovered named Calvera. I think information about it should be added to the article. Trees r cool 21:59, 20 August 2007 (UTC)
Hey, I'm the student who co-authored the study about Calvera. In the interest of not risking NPOV violations, I'll leave it to someone else to modify the article if they see fit, but thanks for noticing our work. ;-) Magnetar 02:11, 21 August 2007 (UTC)Magnetar
Can anyone comment on the validity of the trivia section? I myself don't know enough about neutron stars to know one way or another. Thanks. soldierx40k 00:33, 3 September 2007 (UTC)