Talk:Neutron star

"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)

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)

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)

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)