Talk:Neutron star/Archive 3

Archive 1

Archive 2

Archive 3

Neutron Star classification system?

This paper https://arxiv.org/pdf/astro-ph/0204233.pdf talks about a classification system for neutron stars with Roman numerals. Is there really a classification system for neutron stars? 92.185.150.174 (talk) 05:25, 20 November 2019 (UTC)

The classification is introduced in Section 3 of that paper to interpret the model that the authors present. Given that the paper only has 38 citations, I'd say that the classification has not come into widespread use. Best, Wham2001 (talk) 06:47, 20 November 2019 (UTC)

An unknown object with 2.6 solar masses was recently discovered when it was swallowed by a black hole. It may require its own classification. TGCP (talk) 21:37, 24 June 2020 (UTC)

@TGCP: and others - FWIW - more details re the unknown object (new kind of neutron star?) may be found in a newly created article at the following => "GW190814" - iac - Stay Safe and Healthy !! - Drbogdan (talk) 21:45, 24 June 2020 (UTC)

I don’t think so because Neutron Star have their own class in the stellar classification method. Astrophysyst (talk) 01:31, 5 April 2022 (UTC)

Is there an article error in the escape velocity from neutron stars?

The escape velocity from a neutron star is often stated (as in the article) to be one-third to one-half c. If the heaviest, densist neutron star is 2.0 solar masses with a radius of 12-km, this corresponds to a Schwarzschild ratio of 2.0 .... Using the formula for escape velocity it seems the escape velocity is 0.7c Is this correct? 209.150.58.4 (talk)BG — Preceding undated comment added 02:30, 14 May 2022 (UTC)

You seem to be correct. According to the escape velocity is "... over half the speed of light". --Jules (Mrjulesd) 17:30, 16 May 2022 (UTC)

Uncertainties in neutron star properties should be better emphasized (and updated)

Many of the estimates of neutron star properties reported in this article don't effectively represent the uncertainties associated with these quantities and are likely confusing to readers. For example the maximum TOV mass is quite uncertain, and I'm not sure where the 2.1 number quoted comes from, the Chamel paper explicitly gives an upper bound of about 3 solar masses, but both this paper and the Özel paper were published years before the mass measurements of J0740+6620, which gives about a 2.1 solar mass lower bound on the TOV mass. The Rezzolla paper (one of several based on multimessenger data from 170817) also has an associated uncertainty, which places a 90% credible region upper bound closer to 2.3 solar masses, which should be quoted in the article. Neither 2.1 or 2.16 are consistent with the 2.35 +- .17 solar mass number from the intro for PSR J0952–0607 at 90% confidence. In general I think the correct approach here is to quote broad ranges for these values where it is necessary, and report estimates from individual papers clearly with uncertainty. In many places it's impossible to tell if ranges quoted refer to theoretical uncertainties or just natural variation in the population of neutron stars such as: "The neutron star's density varies from... to 6×10¹⁷ or 8×10¹⁷ kg/m³", usually such a statement would explicitly say "a typical 1.4 solar mass neutron star has density such and such". I also have no idea where these numbers come from but they are certainly not from the Lattimer paper, though they may be from Cole Miller's neutron star website which is inexplicably linked to in the reference that's supposed to be Lattimer's intro to neutron stars paper. Even then these numbers don't seem to accurately reflect what the page says, which is that neutron stars will likely have central densities several times nuclear densities (i.e. several times 2.8×10¹⁷ kg/m³) a much larger range than is quoted. INLegred (talk) 07:05, 9 February 2023 (UTC)

"Mass Limit"

It is worth noting that mass limit of a neutron star is dependent on star's mass but also spin and make up. https://adsabs.harvard.edu/full/1975BAAS....7..546B - obese neutron star paper written by Harvard scholar. The Tolman–Oppenheimer–Volkoff limit (or TOV limit) is an upper bound to the mass of cold, non-rotating neutron stars, analogous to the Chandrasekhar limit for white dwarf stars. If the mass of a neutron star reaches the limit it will collapse to a denser form, most likely a black hole. This limit for a while was set at 2.1 solar mass, however this estimate was for non-rotating neutron star. However, fast spinning or rotating neutron stars mass could exceed this limit, for obvious reasons. Anyways, just wanted to ad few pointers here when talking about neutron star mass and that not everything is as clear cut as this wiki article puts it. — Preceding unsigned comment added by 81.78.138.229 (talk) 14:47, 16 February 2023 (UTC)

Move discussion in progress

There is a move discussion in progress on Talk:Neutron Star (short story) which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 11:31, 8 September 2023 (UTC)

Debate on lead artist impression photo featuring bending light

In recent weeks, user Lithopsian has issued a complaint about the appropriateness of this image

as being a good artist's impression of a neutron star. The guideline Wikipedia:Artist's_impressions_of_astronomical_objects describes general criteria for including both government agency produced and third-party made artists' impressions of astronomical objects. According to NASA, a neutron star has enough gravity in such a small space that it bends lights similar to a black hole.https://www.nasa.gov/feature/goddard/2021/nasa-s-nicer-probes-the-squeezability-of-neutron-stars The image is edited by myself from a NASA image of a black hole, but according to the NASA website it's a realistic depiction of a neutron star (with gravitational lensing) from a copyright-free source. In the past (years ago) I've uploaded space engine pictures that were deleted due to Wiki's policy. The image I've generated using editing software is public domain and has been on the Neutron Star article for nearly two years.

Lastly, Wikipedia's ASTROART guidelines are a general template but clearly state not absolute, meaning on a case-by-case basis good faith exceptions are allowed. I believe this case is applicable and request that this image be accepted back into the Neutron Star lead article. Raphael.concorde (talk) 15:34, 13 April 2023 (UTC)

The guideline is there for a reason. It was the result of discussion and essentially consensus. You are certainly free to ignore it, but should at the very least take account of what it says. If you do ignore it and don't present a very good reason why, you should expect some push-back. The guideline is there to prevent artistic impressions that essentially fall foul of Wikipedia's rules on verifiability, that is that are not directly supported by reliable sources (a blatant example would be an exoplanet image showing cloud patterns or colours that are not known to exist). Images from "official" sources are considered automatically to be reliable depictions based on accurate consensus knowledge, although many of them are actually rather "speculative" too. It seems to me that a claim that a neutron star looks a lot like a black hole, and then producing an artistic impression effectively copied from an artistic impression of a black hole fails all sorts of WP:OR and WP:SYNTHESIS tests, exactly the sort of thing the guideline is there to prevent. Lithopsian (talk) 13:17, 14 April 2023 (UTC)

So you're basically saying that my edited photo is "amateur" or "hobbyist" and it's not appropriate to meet the criteria listed in all the guidelines? Also, please explain why the photo was able to be used in the article for nearly two years without a hitch. I know nothing lasts forever but surely yourself or others may have identified its so-called "flaws". Here is another example of a self-made photo of a black hole that was published as original work by a researcher within CERN (the user/uploader worked for the organisation)

, and by coincidence, I had an internship there. Also, other science articles such as this one has used the image I edited.

To conclude, I do acknowledge that this is original work, but if its one that has been reviewed and approved by others on this article for so long (including use by third party science websites) that this constitutes an exception to the rule in Wikipedia:Artist's_impressions_of_astronomical_objects and related. I believe that your argument is simply a personal opinion on how you interpret the guidelines, which are not absolute.Raphael.concorde (talk) 14:39, 14 April 2023 (UTC)

I just noticed this discussion and am trying to understand the situation here. It looks like the original source of this image is a NASA press release with an illustration of an accretion disk and corona around a supermassive black hole in the Seyfert galaxy Markarian 335. From what I can gather, this NASA illustration was taken and modified to change the black hole to make it look white instead of black, along with some other modifications, and then the modified image was given the title "Artist's impression of a neutron star bending light”. Is that correct? If so, this doesn’t seem like something that would satisfy the WP:ASTROART guidelines. Aldebarium (talk) 15:45, 14 April 2023 (UTC)

Yeah thats right, but it was used in the article for nearly two years, giving the impression it would be okay. According to what I've written in the above paragraphs, a neutron star does indeed bend light very similarly just like a black hole. I've added a ref link to supporting NASA article. Raphael.concorde (talk) 16:12, 14 April 2023 (UTC)

Thank you for the reply. I would still prefer to remove the illustration from the WP article, for the reason that taking a reliable source's illustration of an AGN black hole and accretion disk and modifying the illustration doesn't really make it a reliable source illustration of a neutron star. Aldebarium (talk) 18:23, 14 April 2023 (UTC)

Okay man, thanks for your feedback. Lets consider this case closed. Raphael.concorde (talk) 19:47, 14 April 2023 (UTC)

• Endorse removal its an image of a black hole, with a neutron star placed in the centre. This is not a realistic illustration of a neutron star. It fails the first criterion of the guideline, is misleading, and should go. Polyamorph (talk) 18:41, 8 September 2023 (UTC)

References

Inaccurate mass comparison?

With reference to this excerpt:

> Neutron star material is remarkably dense: a normal-sized matchbox containing neutron-star material would have a weight of approximately 3 billion tonnes, the same weight as a 0.5-cubic-kilometer chunk of the Earth (a cube with edges of about 800 meters) from Earth's surface.

Some back of the envelope math makes me think this is wrong. If the cube is 500m to the side, then that's 500x500x500 = 125,000,000 (125 million) cubic meters. 3,000,000,000 / 125,000,000 = 24.

Does a cubic meter of earth's surface weigh 24 tons? That's about 5 wheelbarrows' worth of dirt. Data is being misused here somehow. Aerovistae (talk) 18:42, 18 September 2023 (UTC)

An 800m cube has a volume of 800x800x800 cubic meters: 512 million cubic meters, seems like about 0.5 cubic kilometers. One cubic meter of "average" Earth material weights about five tons, so the matchbox of neutron star doesn't quite get there, but "dirt" from at or near the surface is much less, more like two tons or even less. Everything seems close enough to me. Not sure why you started working with a 500m cube: although "0.5-cubic-kilometer" could be considered ambiguous, it is clarified by the actual 800m size of the cube. Lithopsian (talk) 19:12, 18 September 2023 (UTC)

Am I missing something?

Will someone tell me if this is anything other than intentional disruption? Talk:Fuzzball_(string_theory)#Evidence_of_intent_of_vandalism.

Greg L (talk) 15:54, 3 December 2023 (UTC)

@Greg L: I responded there. Thanks for the heads up. If more of this sort of behavior continues, please let me know here or on my talk page which I will finally set up. MLee1957 (talk) 20:25, 3 December 2023 (UTC)

Lead is too long, too detailed

According to https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Lead_section , 'The lead should stand on its own as a concise overview of the article's topic. ...Apart from basic facts, significant information should not appear in the lead if it is not covered in the remainder of the article. As a general rule of thumb, a lead section should contain no more than four well-composed paragraphs...' Jontel (talk) 10:18, 6 January 2024 (UTC)

Are 'neutron stars are the smallest and densest known class of stellar objects.'?

1. According to https://en.wikipedia.org/wiki/Astronomical_object 'Examples of astronomical objects include planetary systems, star clusters, nebulae, and galaxies, while asteroids, moons, planets, and stars are astronomical bodies.' Should objects be replaced by bodies?

2. Asteroids can be much smaller than neutron stars. Should the reference to smallest be deleted?

Jontel (talk) 10:14, 6 January 2024 (UTC)

Not all 'astronomical bodies' are 'stellar objects', for example, asteroids. I think it's correct to say that neutron stars are the smallest and densest *known* (positively confirmed) class of stellar objects. MathewMunro (talk) 03:51, 7 January 2024 (UTC)

"Energy source" section

This section, mostly by Pmokeefe, is almost entirely wrong. I'm copying it here, because I intend to delete it entirely, it looks unsalvageable (only the first three sentences are free from misleading, outright wrong and/or badly worded statements):

The cooling rate of neutron stars gives direct insight into their internal makeup. A neutron star in the constellation Cassiopeia, was recently observed to decrease in temperature over time, which is unprecedented.[45] For 105 years most of the cooling in a neutron star is controlled by neutrino emission, this has never been observed in young stars.[46] The thermal signature of a neutron star is governed by neutrino luminosity, internal structure, and heat capacity. The internal structure of a neutron star is still unknown, which brings great difficulty in discerning the mechanism of energy generation though theories have been proposed. Though it is unknown what the inner core of a neutron star is composed of, its outer core not far below the surface is known. Here is where electrons, neutrons, and protons of supercharge exist.[47] As the gravitational pressure continues to increase going inward, Neutron degeneracy pressure, a form of degenerate matter, becomes a higher factor which is the force acting against gravitational collapse. Only observation of the global interactions of each part of the star will tell of its energy generation mechanism.

The core consists of neutrons, electrons, and muons, these electrons conduct heat to the star's surface, which is then radiated out by neutrinos.[48] Within the core, protons are converted into neutrons via beta plus or positron decay, and emit copious amounts of neutrinos as byproduct. Positron emission happens within an atoms nucleus when an up-quark changes into a down-quark, releasing a positron and an electron neutrino.

The energy source of neutron stars is most likely rapid beta decay, this process is an aspect of both neutron and neutrino generation within a neutron star.[49] Instead of fusing elements down the periodic table, becoming heavier until Iron becomes its core, a neutron star's radiation must have another source. Since it is driven by the weak force, positron emission would normally have a very low probability of occurrence, but this may be mitigated by the amount of protons in the star.

Let's got through it. "protons of supercharge" is nonsense. "Neutron degeneracy pressure, a form of degenerate matter" is malformed. Pressure is not matter. "Only observation of the global interactions of each part of the star will tell of its energy generation mechanism" - wrong in general and badly worded. "The core consists of neutrons, electrons, and muons, these electrons conduct heat to the star's surface, which is then radiated out by neutrinos" - wrong. Neutrinos are not generated only at the surface, (In fact, they are mostly generated NOT at the surface). "Within the core, protons are converted into neutrons via beta plus or positron decay, and emit copious amounts of neutrinos as byproduct" - generally wrong (this happens only during the formation of the NS, it's not the energy source of an existing NS). "The energy source of neutron stars is most likely rapid beta decay" - wrong. (Linked scientific article discusses behavior of a _disrupted_ NS during merger events). "Instead of fusing elements down the periodic table, becoming heavier until Iron becomes its core, a neutron star's radiation must have another source" - badly worded for encyclopedia. "Since it is driven by the weak force, positron emission would normally have a very low probability of occurrence" - wrong, beta plus decay is not always low probability, probability can be quite high, depending on the nucleus in question. — Preceding unsigned comment added by 213.175.37.10 (talk • contribs)

There's a good and free article on neutron star heat sources here (https://academic.oup.com/mnras/article/442/4/3484/1357581), 'Thermal emission of neutron stars with internal heaters', by A. D. Kaminker, A. A. Kaurov, A. Y. Potekhin and D. G. Yakovlev, Royal Astronomical Society, Volume 442, Issue 4, 21 August 2014, Pages 3484–3494, Published: 02 July 2014. It mentions mergers, binary accretion, and 'viscous friction in the presence of differential rotation', as well as unknown/unspecified sources. MathewMunro (talk) 04:02, 7 January 2024 (UTC)

Inconsistent Mass Limits

I'm not sure whether this is due to more recently discovered neutron stars being listed without the accompanying text being updated but, in the introduction, it is stated that "The most massive neutron star detected so far, PSR J0952–0607, is estimated to be 2.35±0.17 M_☉."

Later, in the Properties section, subsection Mass and Temperature, it is given that "The upper limit of mass for a neutron star is called the Tolman–Oppenheimer–Volkoff limit and is generally held to be around 2.1 M_☉, but a recent estimate puts the upper limit at 2.16 M_☉. The maximum observed mass of neutron stars is about 2.14 M_☉ for PSR J0740+6620 discovered in September, 2019."

Shouldn't it be made clear that the TOV limit applies to static stars, while the limits for rotating neutron stars (hence pulsars) could be 10-20% higher?

Of course, at the two-sigma level, 2.35±0.17 M_☉. does go down as low as 2.01 solar masses so, statistically, there's no contradiction at the 95% confidence level, but I'm not sure your average reader curious about neutron stars is going to realise that. Jim Skea Jimskea (talk) 01:54, 16 February 2024 (UTC)

Weight of neutron star material

The article discusses neutron star density with the weight of a matchbox worth of material but shouldn't that be mass? If using weight should it be clear whether that refers to weight under a neutron star's gravity or under earth's gravity? AlgosLiberDeBauche (talk) 11:34, 20 February 2024 (UTC)

Simplified representation of the formation of neutron stars

This representation is incorrect: the gravity force in the center of a star is zero because for a gravity force in each direction there is an equal gravity force in the opposite direction. The highest gravity is in a sphere somewhere between the surface and center. Zyavrik (talk) 16:28, 5 June 2024 (UTC)