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Astronomy:Neutron star
Short description: Collapsed core of a massive star
Simulated view of a Neutron star with accretion disk. The disk appears distorted near the star due to extreme gravitational lensing
Radiation from the rapidly spinning pulsar PSR B1509-58 makes nearby gas emit X-rays (gold) and illuminates the rest of the nebula, here seen in infrared (blue and red).
A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich.[1] Except for black holes, and some hypothetical objects (e.g. white holes, quark stars, and strange stars), neutron stars are the smallest and densest currently known class of stellar objects.[2] Neutron stars have a radius on the order of 10 kilometres (6.2 mi) and a mass of about 1.4 solar masses.[3] They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei.
Once formed, they no longer actively generate heat, and cool over time; however, they may still evolve further through collision or accretion. Most of the basic models for these objects imply that neutron stars are composed almost entirely of neutrons (subatomic particles with no net electrical charge and with slightly larger mass than protons); the electrons and protons present in normal matter combine to produce neutrons at the conditions in a neutron star. Neutron stars are partially supported against further collapse by neutron degeneracy pressure, a phenomenon described by the Pauli exclusion principle, just as white dwarfs are supported against collapse by electron degeneracy pressure. However, neutron degeneracy pressure is not by itself sufficient to hold up an object beyond 0.7M☉[4][5] and repulsive nuclear forces play a larger role in supporting more massive neutron stars.[6][7] If the remnant star has a mass exceeding the Tolman–Oppenheimer–Volkoff limit of around 2 solar masses, the combination of degeneracy pressure and nuclear forces is insufficient to support the neutron star and it continues collapsing to form a black hole. The most massive neutron star detected so far, PSR J0740+6620, is estimated to be 2.14 solar masses.
Neutron stars that can be observed are very hot and typically have a surface temperature of around 600000 K.[8][9][10][11][lower-alpha 1] They are so dense that 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 kilometre chunk of the Earth (a cube with edges of about 800 metres) from Earth's surface.[12][13] Their magnetic fields are between 108 and 1015 (100 million to 1 quadrillion) times stronger than Earth's magnetic field. The gravitational field at the neutron star's surface is about 2×1011 (200 billion) times that of Earth's gravitational field.
As the star's core collapses, its rotation rate increases as a result of conservation of angular momentum, and newly formed neutron stars hence rotate at up to several hundred times per second. Some neutron stars emit beams of electromagnetic radiation that make them detectable as pulsars. Indeed, the discovery of pulsars by Jocelyn Bell Burnell and Antony Hewish in 1967 was the first observational suggestion that neutron stars exist. The radiation from pulsars is thought to be primarily emitted from regions near their magnetic poles. If the magnetic poles do not coincide with the rotational axis of the neutron star, the emission beam will sweep the sky, and when seen from a distance, if the observer is somewhere in the path of the beam, it will appear as pulses of radiation coming from a fixed point in space (the so-called "lighthouse effect"). The fastest-spinning neutron star known is PSR J1748-2446ad, rotating at a rate of 716 times a second[14][15] or 43,000 revolutions per minute, giving a linear speed at the surface on the order of 0.24 c (i.e., nearly a quarter the speed of light).
There are thought to be around one billion neutron stars in the Milky Way,[16] and at a minimum several hundred million, a figure obtained by estimating the number of stars that have undergone supernova explosions.[17] However, most are old and cold and radiate very little; most neutron stars that have been detected occur only in certain situations in which they do radiate, such as if they are a pulsar or part of a binary system. Slow-rotating and non-accreting neutron stars are almost undetectable; however, since the Hubble Space Telescope detection of RX J185635−3754 in the 1990s, a few nearby neutron stars that appear to emit only thermal radiation have been detected. Soft gamma repeaters are conjectured to be a type of neutron star with very strong magnetic fields, known as magnetars, or alternatively, neutron stars with fossil disks around them.[18]
Neutron stars in binary systems can undergo accretion which typically makes the system bright in X-rays while the material falling onto the neutron star can form hotspots that rotate in and out of view in identified X-ray pulsar systems. Additionally, such accretion can "recycle" old pulsars and potentially cause them to gain mass and spin-up to very fast rotation rates, forming the so-called millisecond pulsars. These binary systems will continue to evolve, and eventually the companions can become compact objects such as white dwarfs or neutron stars themselves, though other possibilities include a complete destruction of the companion through ablation or merger. The merger of binary neutron stars may be the source of short-duration gamma-ray bursts and are likely strong sources of gravitational waves. In 2017, a direct detection (GW170817) of the gravitational waves from such an event was observed,[19] and gravitational waves have also been indirectly observed in a system where two neutron stars orbit each other.
1 Formation
2.1 Mass and temperature
2.2 Density and pressure
2.3 Magnetic field
2.4 Gravity and equation of state
4.1 Pulsars
4.2 Non-pulsating neutron stars
4.3 Spectra
5 Rotation
5.1 Spin down
5.2 Spin up
5.3 Glitches and starquakes
5.4 "Anti-glitches"
6 Population and distances
7 Binary neutron star systems
7.1 X-ray binaries
7.2 Neutron star binary mergers and nucleosynthesis
8 Subtypes table
9 Examples of neutron stars
10.1 Video – animation
13.1 Sources
Simplified representation of the formation of neutron stars.
Any main-sequence star with an initial mass of above 8 times the mass of the sun (8 M☉) has the potential to produce a neutron star. As the star evolves away from the main sequence, subsequent nuclear burning produces an iron-rich core. When all nuclear fuel in the core has been exhausted, the core must be supported by degeneracy pressure alone. Further deposits of mass from shell burning cause the core to exceed the Chandrasekhar limit. Electron-degeneracy pressure is overcome and the core collapses further, sending temperatures soaring to over 5×109 K. At these temperatures, photodisintegration (the breaking up of iron nuclei into alpha particles by high-energy gamma rays) occurs. As the temperature climbs even higher, electrons and protons combine to form neutrons via electron capture, releasing a flood of neutrinos. When densities reach nuclear density of 4×1017 kg/m3, a combination of strong force repulsion and neutron degeneracy pressure halts the contraction.[20] The infalling outer envelope of the star is halted and flung outwards by a flux of neutrinos produced in the creation of the neutrons, becoming a supernova. The remnant left is a neutron star. If the remnant has a mass greater than about 3 M☉, it collapses further to become a black hole.[21]
As the core of a massive star is compressed during a Type II supernova or a Type Ib or Type Ic supernova, and collapses into a neutron star, it retains most of its angular momentum. But, because it has only a tiny fraction of its parent's radius (and therefore its moment of inertia is sharply reduced), a neutron star is formed with very high rotation speed, and then over a very long period it slows. Neutron stars are known that have rotation periods from about 1.4 ms to 30 s. The neutron star's density also gives it very high surface gravity, with typical values ranging from 1012 to 1013 m/s2 (more than 1011 times that of Earth).[11] One measure of such immense gravity is the fact that neutron stars have an escape velocity ranging from 100,000 km/s to 150,000 km/s, that is, from a third to half the speed of light. The neutron star's gravity accelerates infalling matter to tremendous speed. The force of its impact would likely destroy the object's component atoms, rendering all the matter identical, in most respects, to the rest of the neutron star.
Mass and temperature
A neutron star has a mass of at least 1.1 solar masses (M☉). 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☉,[22][23] but a recent estimate puts the upper limit at 2.16 M☉.[24] The maximum observed mass of neutron stars is about 2.14 M☉ for PSR J0740+6620 discovered in September, 2019.[25] Compact stars below the Chandrasekhar limit of 1.39 M☉ are generally white dwarfs whereas compact stars with a mass between 1.4 M☉ and 2.16 M☉ are expected to be neutron stars, but there is an interval of a few tenths of a solar mass where the masses of low-mass neutron stars and high-mass white dwarfs can overlap. It is thought that beyond 2.16 M☉ the stellar remnant will overcome the strong force repulsion and neutron degeneracy pressure so that gravitational collapse will occur to produce a black hole, but the smallest observed mass of a stellar black hole is about 5 M☉.[lower-alpha 2] Between 2.16 M☉ and 5 M☉, hypothetical intermediate-mass stars such as quark stars and electroweak stars have been proposed, but none have been shown to exist.[lower-alpha 2]
The temperature inside a newly formed neutron star is from around 1011 to 1012 kelvins.[27] However, the huge number of neutrinos it emits carry away so much energy that the temperature of an isolated neutron star falls within a few years to around 106 kelvins.[27] At this lower temperature, most of the light generated by a neutron star is in X-rays.
Some researchers have proposed a neutron star classification system using Roman numerals (not to be confused with the Yerkes luminosity classes for non-degenerate stars) to sort neutron stars by their mass and cooling rates: type I for neutron stars with low mass and cooling rates, type II for neutron stars with higher mass and cooling rates, and a proposed type III for neutron stars with even higher mass, approaching 2 M☉, and with higher cooling rates and possibly candidates for exotic stars.[28]
Density and pressure
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),[lower-alpha 3] which is comparable to the approximate density of an atomic nucleus of 3×1017 kg/m3.[29] The neutron star's density varies from about 1×109 kg/m3 in the crust—increasing with depth—to about 6×1017 or 8×1017 kg/m3 (denser than an atomic nucleus) deeper inside.[27] A neutron star is so dense that one teaspoon (5 milliliters) of its material would have a mass over 5.5×1012 kg, about 900 times the mass of the Great Pyramid of Giza. In the enormous gravitational field of a neutron star, that teaspoon of material would weigh 1.1×1025 N, which is 15 times what the Moon would weigh if it were placed on the surface of the Earth.[lower-alpha 4] The entire mass of the Earth at neutron star density would fit into a sphere of 305 m in diameter (the size of the Arecibo Telescope). The pressure increases from 3.2×1031 to 1.6×1034 Pa from the inner crust to the center.[30]
The equation of state of matter at such high densities is not precisely known because of the theoretical difficulties associated with extrapolating the likely behavior of quantum chromodynamics, superconductivity, and superfluidity of matter in such states. The problem is exacerbated by the empirical difficulties of observing the characteristics of any object that is hundreds of parsecs away, or farther.
A neutron star has some of the properties of an atomic nucleus, including density (within an order of magnitude) and being composed of nucleons. In popular scientific writing, neutron stars are therefore sometimes described as "giant nuclei". However, in other respects, neutron stars and atomic nuclei are quite different. A nucleus is held together by the strong interaction, whereas a neutron star is held together by gravity. The density of a nucleus is uniform, while neutron stars are predicted to consist of multiple layers with varying compositions and densities.
The magnetic field strength on the surface of neutron stars ranges from c. 104 to 1011 tesla.[31] These are orders of magnitude higher than in any other object: For comparison, a continuous 16 T field has been achieved in the laboratory and is sufficient to levitate a living frog due to diamagnetic levitation. Variations in magnetic field strengths are most likely the main factor that allows different types of neutron stars to be distinguished by their spectra, and explains the periodicity of pulsars.[31]
The neutron stars known as magnetars have the strongest magnetic fields, in the range of 108 to 1011 tesla,[32] and have become the widely accepted hypothesis for neutron star types soft gamma repeaters (SGRs)[33] and anomalous X-ray pulsars (AXPs).[34] The magnetic energy density of a 108 T field is extreme, greatly exceeding the mass-energy density of ordinary matter.[lower-alpha 5] Fields of this strength are able to polarize the vacuum to the point that the vacuum becomes birefringent. Photons can merge or split in two, and virtual particle-antiparticle pairs are produced. The field changes electron energy levels and atoms are forced into thin cylinders. Unlike in an ordinary pulsar, magnetar spin-down can be directly powered by its magnetic field, and the magnetic field is strong enough to stress the crust to the point of fracture. Fractures of the crust cause starquakes, observed as extremely luminous millisecond hard gamma ray bursts. The fireball is trapped by the magnetic field, and comes in and out of view when the star rotates, which is observed as a periodic soft gamma repeater (SGR) emission with a period of 5–8 seconds and which lasts for a few minutes.[36]
The origins of the strong magnetic field are as yet unclear.[31] One hypothesis is that of "flux freezing", or conservation of the original magnetic flux during the formation of the neutron star.[31] If an object has a certain magnetic flux over its surface area, and that area shrinks to a smaller area, but the magnetic flux is conserved, then the magnetic field would correspondingly increase. Likewise, a collapsing star begins with a much larger surface area than the resulting neutron star, and conservation of magnetic flux would result in a far stronger magnetic field. However, this simple explanation does not fully explain magnetic field strengths of neutron stars.[31]
Gravity and equation of state
Gravitational light deflection at a neutron star. Due to relativistic light deflection over half the surface is visible (each grid patch represents 30 by 30 degrees).[37] In natural units, this star's mass is 1 and its radius is 4, or twice its Schwarzschild radius.[37]
The gravitational field at a neutron star's surface is about 2×1011 times stronger than on Earth, at around 2.0×1012 m/s2.[38] Such a strong gravitational field acts as a gravitational lens and bends the radiation emitted by the neutron star such that parts of the normally invisible rear surface become visible.[37] If the radius of the neutron star is 3GM/c2 or less, then the photons may be trapped in an orbit, thus making the whole surface of that neutron star visible from a single vantage point, along with destabilizing photon orbits at or below the 1 radius distance of the star.
A fraction of the mass of a star that collapses to form a neutron star is released in the supernova explosion from which it forms (from the law of mass–energy equivalence, E = mc2). The energy comes from the gravitational binding energy of a neutron star.
Hence, the gravitational force of a typical neutron star is huge. If an object were to fall from a height of one meter on a neutron star 12 kilometers in radius, it would reach the ground at around 1400 kilometers per second.[39] However, even before impact, the tidal force would cause spaghettification, breaking any sort of an ordinary object into a stream of material.
Because of the enormous gravity, time dilation between a neutron star and Earth is significant. For example, eight years could pass on the surface of a neutron star, yet ten years would have passed on Earth, not including the time-dilation effect of the star's very rapid rotation.[40]
Neutron star relativistic equations of state describe the relation of radius vs. mass for various models.[41] The most likely radii for a given neutron star mass are bracketed by models AP4 (smallest radius) and MS2 (largest radius). BE is the ratio of gravitational binding energy mass equivalent to the observed neutron star gravitational mass of "M" kilograms with radius "R" meters,[42]
[math]\displaystyle{ BE = \frac{0.60\,\beta}{1 - \frac{\beta}{2}} }[/math] [math]\displaystyle{ \beta \ = G\,M/R\,{c}^{2} }[/math]
Given current values
[math]\displaystyle{ G = 6.67408\times10^{-11}\, \text{m}^3\text{kg}^{-1}\text{s}^{-2} }[/math][43]
[math]\displaystyle{ c = 2.99792458 \times10^{8}\, \text{m}/\text{s} }[/math][43]
[math]\displaystyle{ M_\odot = 1.98855\times10^{30}\, \text{kg} }[/math]
and star masses "M" commonly reported as multiples of one solar mass,
[math]\displaystyle{ M_x = \frac{M}{M_\odot} }[/math]
then the relativistic fractional binding energy of a neutron star is
[math]\displaystyle{ BE = \frac{886.0 \,M_x}{R_{\left[\text{in meters}\right]} - 738.3\,M_x} }[/math]
A 2 M☉ neutron star would not be more compact than 10,970 meters radius (AP4 model). Its mass fraction gravitational binding energy would then be 0.187, −18.7% (exothermic). This is not near 0.6/2 = 0.3, −30%.
The equation of state for a neutron star is not yet known. It is assumed that it differs significantly from that of a white dwarf, whose equation of state is that of a degenerate gas that can be described in close agreement with special relativity. However, with a neutron star the increased effects of general relativity can no longer be ignored. Several equations of state have been proposed (FPS, UU, APR, L, SLy, and others) and current research is still attempting to constrain the theories to make predictions of neutron star matter.[11][44] This means that the relation between density and mass is not fully known, and this causes uncertainties in radius estimates. For example, a 1.5 M☉ neutron star could have a radius of 10.7, 11.1, 12.1 or 15.1 kilometers (for EOS FPS, UU, APR or L respectively).[44]
Cross-section of neutron star. Densities are in terms of ρ0 the saturation nuclear matter density, where nucleons begin to touch.
Current understanding of the structure of neutron stars is defined by existing mathematical models, but it might be possible to infer some details through studies of neutron-star oscillations. Asteroseismology, a study applied to ordinary stars, can reveal the inner structure of neutron stars by analyzing observed spectra of stellar oscillations.[11]
Current models indicate that matter at the surface of a neutron star is composed of ordinary atomic nuclei crushed into a solid lattice with a sea of electrons flowing through the gaps between them. It is possible that the nuclei at the surface are iron, due to iron's high binding energy per nucleon.[45] It is also possible that heavy elements, such as iron, simply sink beneath the surface, leaving only light nuclei like helium and hydrogen.[45] If the surface temperature exceeds 106 kelvins (as in the case of a young pulsar), the surface should be fluid instead of the solid phase that might exist in cooler neutron stars (temperature <106 kelvins).[45]
The "atmosphere" of a neutron star is hypothesized to be at most several micrometres thick, and its dynamics are fully controlled by the neutron star's magnetic field. Below the atmosphere one encounters a solid "crust". This crust is extremely hard and very smooth (with maximum surface irregularities on the order of millimetres or less), due to the extreme gravitational field.[46][47]
Proceeding inward, one encounters nuclei with ever-increasing numbers of neutrons; such nuclei would decay quickly on Earth, but are kept stable by tremendous pressures. As this process continues at increasing depths, the neutron drip becomes overwhelming, and the concentration of free neutrons increases rapidly. In that region, there are nuclei, free electrons, and free neutrons. The nuclei become increasingly small (gravity and pressure overwhelming the strong force) until the core is reached, by definition the point where mostly neutrons exist. The expected hierarchy of phases of nuclear matter in the inner crust has been characterized as "nuclear pasta", with fewer voids and larger structures towards higher pressures.[48] The composition of the superdense matter in the core remains uncertain. One model describes the core as superfluid neutron-degenerate matter (mostly neutrons, with some protons and electrons). More exotic forms of matter are possible, including degenerate strange matter (containing strange quarks in addition to up and down quarks), matter containing high-energy pions and kaons in addition to neutrons,[11] or ultra-dense quark-degenerate matter.
Computer renders of a neutron star with accretion disk, with magnetic field lines projected, showing bursts of powerful X-rays and Radio Waves. The simulations are taken from 2017 data from NASA's NuSTAR and Swift, and ESA's XMM-Newto observatories
File:Pulsar anim.ogv
Main page: Astronomy:Pulsar
Neutron stars are detected from their electromagnetic radiation. Neutron stars are usually observed to pulse radio waves and other electromagnetic radiation, and neutron stars observed with pulses are called pulsars.
Pulsars' radiation is thought to be caused by particle acceleration near their magnetic poles, which need not be aligned with the rotational axis of the neutron star. It is thought that a large electrostatic field builds up near the magnetic poles, leading to electron emission.[49] These electrons are magnetically accelerated along the field lines, leading to curvature radiation, with the radiation being strongly polarized towards the plane of curvature.[49] In addition, high energy photons can interact with lower energy photons and the magnetic field for electron−positron pair production, which through electron–positron annihilation leads to further high energy photons.[49]
The radiation emanating from the magnetic poles of neutron stars can be described as magnetospheric radiation, in reference to the magnetosphere of the neutron star.[50] It is not to be confused with magnetic dipole radiation, which is emitted because the magnetic axis is not aligned with the rotational axis, with a radiation frequency the same as the neutron star's rotational frequency.[49]
If the axis of rotation of the neutron star is different to the magnetic axis, external viewers will only see these beams of radiation whenever the magnetic axis point towards them during the neutron star rotation. Therefore, periodic pulses are observed, at the same rate as the rotation of the neutron star.
Non-pulsating neutron stars
In addition to pulsars, non-pulsating neutron stars have also been identified, although they may have minor periodic variation in luminosity.[51][52] This seems to be a characteristic of the X-ray sources known as Central Compact Objects in Supernova remnants (CCOs in SNRs), which are thought to be young, radio-quiet isolated neutron stars.[51]
In addition to radio emissions, neutron stars have also been identified in other parts of the electromagnetic spectrum. This includes visible light, near infrared, ultraviolet, X-rays, and gamma rays.[50] Pulsars observed in X-rays are known as X-ray pulsars if accretion-powered, while those identified in visible light are known as optical pulsars. The majority of neutron stars detected, including those identified in optical, X-ray, and gamma rays, also emit radio waves;[53] the Crab Pulsar produces electromagnetic emissions across the spectrum.[53] However, there exist neutron stars called radio-quiet neutron stars, with no radio emissions detected.[54]
Neutron stars rotate extremely rapidly after their formation due to the conservation of angular momentum; in analogy to spinning ice skaters pulling in their arms, the slow rotation of the original star's core speeds up as it shrinks. A newborn neutron star can rotate many times a second.
Spin down
P–P-dot diagram for known rotation-powered pulsars (red), anomalous X-ray pulsars (green), high-energy emission pulsars (blue) and binary pulsars (pink)
Over time, neutron stars slow, as their rotating magnetic fields in effect radiate energy associated with the rotation; older neutron stars may take several seconds for each revolution. This is called spin down. The rate at which a neutron star slows its rotation is usually constant and very small.
The periodic time (P) is the rotational period, the time for one rotation of a neutron star. The spin-down rate, the rate of slowing of rotation, is then given the symbol [math]\displaystyle{ \dot{P} }[/math] (P-dot), the derivative of P with respect to time. It is defined as periodic time increase per unit time; it is a dimensionless quantity, but can be given the units of s⋅s−1 (seconds per second).[49]
The spin-down rate (P-dot) of neutron stars usually falls within the range of 10−22 to 10−9 s⋅s−1, with the shorter period (or faster rotating) observable neutron stars usually having smaller P-dot. As a neutron star ages, its rotation slows (as P increases); eventually, the rate of rotation will become too slow to power the radio-emission mechanism, and the neutron star can no longer be detected.[49]
P and P-dot allow minimum magnetic fields of neutron stars to be estimated.[49] P and P-dot can be also used to calculate the characteristic age of a pulsar, but gives an estimate which is somewhat larger than the true age when it is applied to young pulsars.[49]
P and P-dot can also be combined with neutron star's moment of inertia to estimate a quantity called spin-down luminosity, which is given the symbol [math]\displaystyle{ \dot{E} }[/math] (E-dot). It is not the measured luminosity, but rather the calculated loss rate of rotational energy that would manifest itself as radiation. For neutron stars where the spin-down luminosity is comparable to the actual luminosity, the neutron stars are said to be "rotation powered".[49][50] The observed luminosity of the Crab Pulsar is comparable to the spin-down luminosity, supporting the model that rotational kinetic energy powers the radiation from it.[49] With neutron stars such as magnetars, where the actual luminosity exceeds the spin-down luminosity by about a factor of one hundred, it is assumed that the luminosity is powered by magnetic dissipation, rather than being rotation powered.[55]
P and P-dot can also be plotted for neutron stars to create a P–P-dot diagram. It encodes a tremendous amount of information about the pulsar population and its properties, and has been likened to the Hertzsprung–Russell diagram in its importance for neutron stars.[49]
Spin up
Neutron star rotational speeds can increase, a process known as spin up. Sometimes neutron stars absorb orbiting matter from companion stars, increasing the rotation rate and reshaping the neutron star into an oblate spheroid. This causes an increase in the rate of rotation of the neutron star of over a hundred times per second in the case of millisecond pulsars.
The most rapidly rotating neutron star currently known, PSR J1748-2446ad, rotates at 716 revolutions per second.[56] A 2007 paper reported the detection of an X-ray burst oscillation, which provides an indirect measure of spin, of 1122 Hz from the neutron star XTE J1739-285,[57] suggesting 1122 rotations a second. However, at present, this signal has only been seen once, and should be regarded as tentative until confirmed in another burst from that star.
Glitches and starquakes
NASA artist's conception of a "starquake", or "stellar quake".
Sometimes a neutron star will undergo a glitch, a sudden small increase of its rotational speed or spin up. Glitches are thought to be the effect of a starquake—as the rotation of the neutron star slows, its shape becomes more spherical. Due to the stiffness of the "neutron" crust, this happens as discrete events when the crust ruptures, creating a starquake similar to earthquakes. After the starquake, the star will have a smaller equatorial radius, and because angular momentum is conserved, its rotational speed has increased.
Starquakes occurring in magnetars, with a resulting glitch, is the leading hypothesis for the gamma-ray sources known as soft gamma repeaters.[58]
Recent work, however, suggests that a starquake would not release sufficient energy for a neutron star glitch; it has been suggested that glitches may instead be caused by transitions of vortices in the theoretical superfluid core of the neutron star from one metastable energy state to a lower one, thereby releasing energy that appears as an increase in the rotation rate.[59]
"Anti-glitches"
An "anti-glitch", a sudden small decrease in rotational speed, or spin down, of a neutron star has also been reported.[60] It occurred in the magnetar 1E 2259+586, that in one case produced an X-ray luminosity increase of a factor of 20, and a significant spin-down rate change. Current neutron star models do not predict this behavior. If the cause was internal, it suggests differential rotation of solid outer crust and the superfluid component of the magnetar's inner structure.[60]
Population and distances
Central neutron star at the heart of the Crab Nebula.[61]
At present, there are about 2,000 known neutron stars in the Milky Way and the Magellanic Clouds, the majority of which have been detected as radio pulsars. Neutron stars are mostly concentrated along the disk of the Milky Way, although the spread perpendicular to the disk is large because the supernova explosion process can impart high translational speeds (400 km/s) to the newly formed neutron star.
Some of the closest known neutron stars are RX J1856.5−3754, which is about 400 light-years from Earth, and PSR J0108−1431 about 424 light years.[62] RX J1856.5-3754 is a member of a close group of neutron stars called The Magnificent Seven. Another nearby neutron star that was detected transiting the backdrop of the constellation Ursa Minor has been nicknamed Calvera by its Canadian and American discoverers, after the villain in the 1960 film The Magnificent Seven. This rapidly moving object was discovered using the ROSAT/Bright Source Catalog.
Neutron stars are only detectable with modern technology during the earliest stages of their lives (almost always less than 1 million years) and are vastly outnumbered by older neutron stars that would only be detectable through their blackbody radiation and gravitational effects on other stars.
Binary neutron star systems
Circinus X-1: X-ray light rings from a binary neutron star (24 June 2015; Chandra X-ray Observatory)
About 5% of all known neutron stars are members of a binary system. The formation and evolution of binary neutron stars can be a complex process.[63] Neutron stars have been observed in binaries with ordinary main-sequence stars, red giants, white dwarfs, or other neutron stars. According to modern theories of binary evolution, it is expected that neutron stars also exist in binary systems with black hole companions. The merger of binaries containing two neutron stars, or a neutron star and a black hole, has been observed through the emission of gravitational waves.[64][65]
X-ray binaries
Main page: Astronomy:X-ray binary
Binary systems containing neutron stars often emit X-rays, which are emitted by hot gas as it falls towards the surface of the neutron star. The source of the gas is the companion star, the outer layers of which can be stripped off by the gravitational force of the neutron star if the two stars are sufficiently close. As the neutron star accretes this gas, its mass can increase; if enough mass is accreted, the neutron star may collapse into a black hole.[66]
Neutron star binary mergers and nucleosynthesis
Main page: Astronomy:Stellar collision
The distance between two neutron stars in a close binary system is observed to shrink as gravitational waves are emitted.[67] Ultimately, the neutron stars will come into contact and coalesce. The coalescence of binary neutron stars is one of the leading models for the origin of short gamma-ray bursts. Strong evidence for this model came from the observation of a kilonova associated with the short-duration gamma-ray burst GRB 130603B,[68] and finally confirmed by detection of gravitational wave GW170817 and short GRB 170817A by LIGO, Virgo, and 70 observatories covering the electromagnetic spectrum observing the event.[69][70][71][72] The light emitted in the kilonova is believed to come from the radioactive decay of material ejected in the merger of the two neutron stars. This material may be responsible for the production of many of the chemical elements beyond iron,Cite error: Closing </ref> missing for <ref> tag[lower-alpha 6] less than two years after the discovery of the neutron by James Chadwick.[75] In seeking an explanation for the origin of a supernova, they tentatively proposed that in supernova explosions ordinary stars are turned into stars that consist of extremely closely packed neutrons that they called neutron stars. Baade and Zwicky correctly proposed at that time that the release of the gravitational binding energy of the neutron stars powers the supernova: "In the supernova process, mass in bulk is annihilated". Neutron stars were thought to be too faint to be detectable and little work was done on them until November 1967, when Franco Pacini pointed out that if the neutron stars were spinning and had large magnetic fields, then electromagnetic waves would be emitted. Unbeknown to him, radio astronomer Antony Hewish and his research assistant Jocelyn Bell at Cambridge were shortly to detect radio pulses from stars that are now believed to be highly magnetized, rapidly spinning neutron stars, known as pulsars.
In 1965, Antony Hewish and Samuel Okoye discovered "an unusual source of high radio brightness temperature in the Crab Nebula".[76] This source turned out to be the Crab Pulsar that resulted from the great supernova of 1054.
In 1967, Iosif Shklovsky examined the X-ray and optical observations of Scorpius X-1 and correctly concluded that the radiation comes from a neutron star at the stage of accretion.[77]
In 1967, Jocelyn Bell Burnell and Antony Hewish discovered regular radio pulses from PSR B1919+21. This pulsar was later interpreted as an isolated, rotating neutron star. The energy source of the pulsar is the rotational energy of the neutron star. The majority of known neutron stars (about 2000, as of 2010) have been discovered as pulsars, emitting regular radio pulses.
In 1968, Richard V. E. Lovelace and collaborators discovered period [math]\displaystyle{ P\!\approx 33 }[/math] ms of the Crab pulsar using Arecibo Observatory.[78][79] After this discovery, scientists concluded that pulsars were rotating neutron stars.[80] Before that, many scientists believed that pulsars were pulsating white dwarfs.
In 1971, Riccardo Giacconi, Herbert Gursky, Ed Kellogg, R. Levinson, E. Schreier, and H. Tananbaum discovered 4.8 second pulsations in an X-ray source in the constellation Centaurus, Cen X-3.[81] They interpreted this as resulting from a rotating hot neutron star. The energy source is gravitational and results from a rain of gas falling onto the surface of the neutron star from a companion star or the interstellar medium.
In 1974, Antony Hewish was awarded the Nobel Prize in Physics "for his decisive role in the discovery of pulsars" without Jocelyn Bell who shared in the discovery.[82]
In 1974, Joseph Taylor and Russell Hulse discovered the first binary pulsar, PSR B1913+16, which consists of two neutron stars (one seen as a pulsar) orbiting around their center of mass. Albert Einstein's general theory of relativity predicts that massive objects in short binary orbits should emit gravitational waves, and thus that their orbit should decay with time. This was indeed observed, precisely as general relativity predicts, and in 1993, Taylor and Hulse were awarded the Nobel Prize in Physics for this discovery.[83]
In 1982, Don Backer and colleagues discovered the first millisecond pulsar, PSR B1937+21.[84] This object spins 642 times per second, a value that placed fundamental constraints on the mass and radius of neutron stars. Many millisecond pulsars were later discovered, but PSR B1937+21 remained the fastest-spinning known pulsar for 24 years, until PSR J1748-2446ad (which spins more than 700 times a second) was discovered.
In 2003, Marta Burgay and colleagues discovered the first double neutron star system where both components are detectable as pulsars, PSR J0737−3039.[85] The discovery of this system allows a total of 5 different tests of general relativity, some of these with unprecedented precision.
In 2010, Paul Demorest and colleagues measured the mass of the millisecond pulsar PSR J1614−2230 to be 1.97±0.04 M☉, using Shapiro delay.[86] This was substantially higher than any previously measured neutron star mass (1.67 M☉, see PSR J1903+0327), and places strong constraints on the interior composition of neutron stars.
In 2013, John Antoniadis and colleagues measured the mass of PSR J0348+0432 to be 2.01±0.04 M☉, using white dwarf spectroscopy.[87] This confirmed the existence of such massive stars using a different method. Furthermore, this allowed, for the first time, a test of general relativity using such a massive neutron star.
In August 2017, LIGO and Virgo made first detection of gravitational waves produced by colliding neutron stars.[88]
In October 2018, astronomers reported that GRB 150101B, a gamma-ray burst event detected in 2015, may be directly related to the historic GW170817 and associated with the merger of two neutron stars. The similarities between the two events, in terms of gamma ray, optical and x-ray emissions, as well as to the nature of the associated host galaxies, are "striking", suggesting the two separate events may both be the result of the merger of neutron stars, and both may be a kilonova, which may be more common in the universe than previously understood, according to the researchers.[89][90][91][92]
In July 2019, astronomers reported that a new method to determine the Hubble constant, and resolve the discrepancy of earlier methods, has been proposed based on the mergers of pairs of neutron stars, following the detection of the neutron star merger of GW170817.[93][94] Their measurement of the Hubble constant is 70.3+5.3
−5.0 (km/s)/Mpc.[95]
A 2020 study by University of Southampton PhD student Fabian Gittins suggested that surface irregularities ("mountains") may only be fractions of a millimeter tall (about 0.000003% of the neutron star's diameter), hundreds of times smaller than previously predicted, a result bearing implications for the non-detection of gravitational waves from spinning neutron stars.[47][96][97]
Subtypes table
Different Types of Neutron Stars (24 June 2020)
Neutron star
Isolated neutron star (INS):[50][51][98][99] not in a binary system.
Rotation-powered pulsar (RPP or "radio pulsar"):[51] neutron stars that emit directed pulses of radiation towards us at regular intervals (due to their strong magnetic fields).
Rotating radio transient (RRATs):[51] are thought to be pulsars which emit more sporadically and/or with higher pulse-to-pulse variability than the bulk of the known pulsars.
Magnetar: a neutron star with an extremely strong magnetic field (1000 times more than a regular neutron star), and long rotation periods (5 to 12 seconds).
Soft gamma repeater (SGR).[50]
Anomalous X-ray pulsar (AXP).[50]
Radio-quiet neutron stars.
X-ray dim isolated neutron stars.[51]
Central compact objects in supernova remnants (CCOs in SNRs): young, radio-quiet non-pulsating X-ray sources, thought to be Isolated Neutron Stars surrounded by supernova remnants.[51]
X-ray pulsars or "accretion-powered pulsars": a class of X-ray binaries.
Low-mass X-ray binary pulsars: a class of low-mass X-ray binaries (LMXB), a pulsar with a main sequence star, white dwarf or red giant.
Millisecond pulsar (MSP) ("recycled pulsar").
"Spider Pulsar", a pulsar where their companion is a semi-degenerate star.[100]
"Black Widow" pulsar, a pulsar that falls under the "Spider Pulsar" if the companion has extremely low mass (less than 0.1 solar masses).
"Redback" pulsar, are if the companion is more massive.
Sub-millisecond pulsar.[101]
X-ray burster: a neutron star with a low mass binary companion from which matter is accreted resulting in irregular bursts of energy from the surface of the neutron star.
Intermediate-mass X-ray binary pulsars: a class of intermediate-mass X-ray binaries (IMXB), a pulsar with an intermediate mass star.
High-mass X-ray binary pulsars: a class of high-mass X-ray binaries (HMXB), a pulsar with a massive star.
Binary pulsars: a pulsar with a binary companion, often a white dwarf or neutron star.
X-ray tertiary (theorized).[102]
Theorized compact stars with similar properties.
Protoneutron star (PNS), theorized.[103]
Exotic star
Thorne–Żytkow object: currently a hypothetical merger of a neutron star into a red giant star.
Quark star: currently a hypothetical type of neutron star composed of quark matter, or strange matter. As of 2018, there are three candidates.
Electroweak star: currently a hypothetical type of extremely heavy neutron star, in which the quarks are converted to leptons through the electroweak force, but the gravitational collapse of the neutron star is prevented by radiation pressure. As of 2018, there is no evidence for their existence.
Preon star: currently a hypothetical type of neutron star composed of preon matter. As of 2018, there is no evidence for the existence of preons.
Examples of neutron stars
Artist's impression of disc around a neutron star RX J0806.4-4123.[104]
Black Widow Pulsar – a millisecond pulsar that is very massive.
LGM-1 (now known as PSR B1919+21) – the first recognized radio-pulsar. It's discovered by Jocelyn Bell Burnell in 1967.
PSR B1257+12 – the first neutron star discovered with planets (a millisecond pulsar).
PSR B1509−58 – source of the "Hand of God" photo shot by the Chandra X-ray Observatory.
PSR J0108−1431 – closest neutron star.
The Magnificent Seven, a group of nearby, X-ray dim isolated neutron stars.
PSR J0348+0432 – the most massive neutron star with a well-constrained mass, 2.01 ± 0.04 M☉.
RX J0806.4-4123 – neutron star source of infrared radiation.[105]
SWIFT J1756.9-2508 – a millisecond pulsar with a stellar-type companion with planetary range mass (below brown dwarf).
Swift J1818.0-1607 - youngest known magnetar
Neutron stars containing 500,000 Earth-masses in 25 km (16 mi) diameter sphere
Neutron stars colliding
Neutron star collision
Dragon's Egg
Neutron star merger
Neutronium
Preon-degenerate matter
Rotating radio transient
Little green men
IRAS 00500+6713 (in 10,000 y)
↑ A neutron star's density increases as its mass increases, and its radius decreases non-linearly. (archived image: NASA mass radius graph) A newer page is here: "RXTE Discovers Kilohertz Quasiperiodic Oscillations". NASA. https://heasarc.gsfc.nasa.gov/docs/xte/Greatest_Hits/khz.qpo.html. (specifically the image [1])
↑ 2.0 2.1 A 10 M☉ star will collapse into a black hole.[26]
↑ 3.7×1017 kg/m3 derives from mass 2.68×1030 kg / volume of star of radius 12 km; 5.9×1017 kg/m3 derives from mass 4.2×1030 kg per volume of star radius 11.9 km
↑ The average density of material in a neutron star of radius 10 km is 1.1×1012 kg/cm3. Therefore, 5 ml of such material is 5.5×1012 kg, or 5 500 000 000 metric tons. This is about 15 times the total mass of the human world population. Alternatively, 5 ml from a neutron star of radius 20 km radius (average density 8.35×1010 kg/cm3) has a mass of about 400 million metric tons, or about the mass of all humans. The gravitational field is ca. 2×1011g or ca. 2×1012 N/kg. Moon weight is calculated at 1g.
↑ Magnetic energy density for a field B is U = μ0 B2⁄2 .[35] Substituting B = 108 T , get U = 4×1021 J/m3 . Dividing by c2 one obtains the equivalent mass density of 44500 kg/m3, which exceeds the standard temperature and pressure density of all known materials. Compare with 22590 kg/m3 for osmium, the densest stable element.
↑ Even before the discovery of neutron, in 1931, neutron stars were anticipated by Lev Landau, who wrote about stars where "atomic nuclei come in close contact, forming one gigantic nucleus".[73] However, the widespread opinion that Landau predicted neutron stars proves to be wrong.[74]
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↑ ``Crab nebula pulsar NP 0532 1969, J. M. Comella, H. D. Craft, R. V. E. Lovelace, J. M. Sutton, G. L. Tyler Nature 221 (5179), 453-454
↑ ``Digital Search Methods for Pulsars 1969, R. V. E. Lovelace, J. M. Sutton, E. E. Salpeter Nature 222 (5190), 231-233
↑ ``On the discovery of the period of the Crab Nebula pulsar R. V. E. Lovelace and G. L. Tyler 2012, The Observatory, 132, 186.
↑ Ghosh, Pranab (2007). Rotation and Accretion Powered Pulsars (illustrated ed.). World Scientific. p. 8. ISBN 978-981-02-4744-7. https://books.google.com/books?id=fmtqDQAAQBAJ&pg=PA8.
↑ Lang, Kenneth (2007). A Companion to Astronomy and Astrophysics: Chronology and Glossary with Data Tables (illustrated ed.). Springer Science & Business Media. p. 82. ISBN 978-0-387-33367-0. https://books.google.com/books?id=aUjkKuaVIloC&pg=PA82.
↑ Haensel, Paweł; Potekhin, Alexander Y.; Yakovlev, Dmitry G. (2007). Neutron Stars 1: Equation of State and Structure (illustrated ed.). Springer Science & Business Media. p. 474. ISBN 978-0-387-47301-7. https://books.google.com/books?id=fgj_TZ06niYC&pg=PA474.
↑ Graham-Smith, Francis (2006). Pulsar Astronomy (illustrated ed.). Cambridge University Press. p. 11. ISBN 978-0-521-83954-9. https://books.google.com/books?id=AK9N3zxL4ToC&pg=PA11.
↑ Ghosh, Pranab (2007). Rotation and Accretion Powered Pulsars (illustrated ed.). World Scientific. p. 281. ISBN 978-981-02-4744-7. https://books.google.com/books?id=fmtqDQAAQBAJ&pg=PA281.
↑ Demorest, Paul B.; Pennucci, T.; Ransom, S. M.; Roberts, M. S.; Hessels, J. W. (2010). "A two-solar-mass neutron star measured using Shapiro delay". Nature 467 (7319): 1081–1083. doi:10.1038/nature09466. PMID 20981094. Bibcode: 2010Natur.467.1081D.
↑ Antoniadis, John (2012). "A Massive Pulsar in a Compact Relativistic Binary". Science 340 (6131): 1233232. doi:10.1126/science.1233232. PMID 23620056. Bibcode: 2013Sci...340..448A.
↑ Burtnyk, Kimberly M. (16 October 2017). "LIGO Detection of Colliding Neutron Stars Spawns Global Effort to Study the Rare Event". https://www.ligo.caltech.edu/news/ligo20171016.
↑ University of Maryland (16 October 2018). "All in the family: Kin of gravitational wave source discovered - New observations suggest that kilonovae -- immense cosmic explosions that produce silver, gold and platinum--may be more common than thought". EurekAlert!. https://www.eurekalert.org/pub_releases/2018-10/uom-ait101518.php.
↑ Troja, E. (16 October 2018). "A luminous blue kilonova and an off-axis jet from a compact binary merger at z = 0.1341". Nature Communications 9 (4089 (2018)): 4089. doi:10.1038/s41467-018-06558-7. PMID 30327476. Bibcode: 2018NatCo...9.4089T.
↑ Mohon, Lee (16 October 2018). "GRB 150101B: A Distant Cousin to GW170817". NASA. https://www.nasa.gov/mission_pages/chandra/images/grb-150101b-a-distant-cousin-to-gw170817.html.
↑ Wall, Mike (17 October 2018). "Powerful Cosmic Flash Is Likely Another Neutron-Star Merger". Space.com. https://www.space.com/42158-another-neutron-star-crash-detected.html.
↑ National Radio Astronomy Observatory (8 July 2019). "New method may resolve difficulty in measuring universe's expansion - Neutron star mergers can provide new 'cosmic ruler'". EurekAlert!. https://www.eurekalert.org/pub_releases/2019-07/nrao-nmm070819.php.
↑ Finley, Dave (8 July 2019). "New Method May Resolve Difficulty in Measuring Universe's Expansion". National Radio Astronomy Observatory. https://public.nrao.edu/news/new-method-measuring-universe-expansion/.
↑ Hotokezaka, K. (8 July 2019). "A Hubble constant measurement from superluminal motion of the jet in GW170817". Nature Astronomy 3 (10): 940–944. doi:10.1038/s41550-019-0820-1. Bibcode: 2019NatAs...3..940H.
↑ Plait, Phil (23 July 2021). "The tallest mountain on a neutron star may be a fraction of a millimeter tall". Syfy. https://www.syfy.com/syfywire/tallest-mountain-neutron-star-fraction-millimeter-tall. Retrieved 25 July 2021.
↑ Gittins, Fabian; Andersson, Nils (2021). "Modelling neutron star mountains in relativity". Monthly Notices of the Royal Astronomical Society (stab2048). doi:10.1093/mnras/stab2048.
↑ Mereghetti, Sandro (April 2010). "X-ray emission from isolated neutron stars". High-Energy Emission from Pulsars and their Systems. Astrophysics and Space Science Proceedings. 21. pp. 345–363. doi:10.1007/978-3-642-17251-9_29. ISBN 978-3-642-17250-2. Bibcode: 2011ASSP...21..345M.
↑ Pavlov, George; Zavlin, Slava; Sanwal, Divas; Kargaltsev, Oleg; Romani, Roger. "Thermal Radiation from Isolated Neutron Stars". SLAC National Accelerator Laboratory. http://www.slac.stanford.edu/econf/C041213/presents/0041_TLK.PDF.
↑ E. Parent, et al.; Eight Millisecond Pulsars Discovered in the Arecibo PALFA Survey
↑ Nakamura, T. (1989). "Binary Sub-Millisecond Pulsar and Rotating Core Collapse Model for SN1987A". Progress of Theoretical Physics 81 (5): 1006–1020. doi:10.1143/PTP.81.1006. Bibcode: 1989PThPh..81.1006N.
↑ Rosanne Di Stefano; The Dynamical Roche Lobe in Hierarchical Triples
↑ Thompson, Todd A.; Neutrino-Driven Protoneutron Star Winds
↑ "Artist's impression of disc around a neutron star". https://www.spacetelescope.org/images/opo1843a/.
↑ "HubbleSite: News - Hubble Uncovers Never Before Seen Features Around a Neutron Star". https://hubblesite.org/contents/news-releases/2018/news-2018-43.html.
"The following points are made by R.N. Manchester (Science 2004 304:542)". 2004. http://scienceweek.com/2004/sb040806-1.htm.
Glendenning, Norman K.; Kippenhahn, R.; Appenzeller, I.; Borner, G.; Harwit, M. (2000). Compact Stars (2nd ed.).
Kaaret, P.; Prieskorn, Z.; in 't Zand, J.J.M.; Brandt, S.; Lund, N.; Mereghetti, S. et al. (2006). "Evidence for 1122 Hz X-ray burst oscillations from the neutron-star X-ray transient XTE J1739-285". The Astrophysical Journal 657 (2): L97. doi:10.1086/513270. Bibcode: 2007ApJ...657L..97K.
Introduction to neutron stars
Hessels, Jason W. T; Ransom, Scott M; Stairs, Ingrid H; Freire, Paulo C. C; Kaspi, Victoria M; Camilo, Fernando (2003). "Neutron Stars for Undergraduates". American Journal of Physics 72 (2004): 892–905. doi:10.1119/1.1703544. Bibcode: 2004AmJPh..72..892S.
Silbar, Richard R; Reddy, Sanjay (2005). "Erratum: "Neutron stars for undergraduates" [Am. J. Phys. 72 (7), 892–905 (2004)]". American Journal of Physics 73 (3): 286. doi:10.1119/1.1852544. Bibcode: 2005AmJPh..73..286S.
NASA on pulsars
"NASA Sees Hidden Structure Of Neutron Star In Starquake". SpaceDaily.com. April 26, 2006
"Mysterious X-ray sources may be lone neutron stars" David Shiga. New Scientist. 23 June 2006
"Massive neutron star rules out exotic matter". New Scientist. According to a new analysis, exotic states of matter such as free quarks or BECs do not arise inside neutron stars.
"Neutron star clocked at mind-boggling velocity". New Scientist. A neutron star has been clocked traveling at more than 1500 kilometers per second.
Radio-quiet
Single pulsars
Soft gamma repeater
Anomalous X-ray
Binary pulsars
X-ray pulsar
X-ray binary
X-ray burster
Millisecond
Be/X-ray
Spin-up
Blitzar
Fast radio burst
Bondi accretion
Chandrasekhar limit
Gamma-ray burst
Neutron-star oscillation
Pulsar kick
Quasi-periodic oscillation
Relativistic
Rp-process
Starquake
Timing noise
Tolman–Oppenheimer–Volkoff limit
Urca process
Gamma-ray burst progenitors
Astroseismology
Compact star
Quark star
Supernova remnant
Kilonova
Quark-nova
Stellar black hole
Radio star
Pulsar planet
Pulsar wind nebula
Thorne–Żytkow object
LGM-1
Centaurus X-3
Timeline of white dwarfs, neutron stars, and supernovae
Rossi X-ray Timing Explorer
Fermi Gamma-ray Space Telescope
Compton Gamma Ray Observatory
Chandra X-ray Observatory
X-ray pulsar-based navigation
Tempo software program
Astropulse
PG 1159 star
Stellar evolution
Hertzsprung–Russell diagram
Mira variable
Black dwarf
Type Ia supernova
Extreme helium star
Subdwarf B star
Helium planet
In binary
Dwarf nova
Symbiotic nova
Cataclysmic variable star
AM CVn star
Intermediate polar
Super soft X-ray source
Binary pulsar
Helium flash
Carbon detonation
Pulsating
Electron-degenerate matter
Quasi-periodic oscillations
Planetary nebula
RAMBOs
White dwarf luminosity function
Schwarzschild
Kugelblitz
Planck particle
Extremal
Microquasar
Intermediate-mass
Supermassive
Active galactic nucleus
Gravitational collapse
Binary black hole
Gravitational singularity
Ring singularity
Photon sphere
Innermost stable circular orbit
Ergosphere
Penrose process
Blandford–Znajek process
Accretion disk
Hawking radiation
Gravitational lens
M–sigma relation
Immirzi parameter
Schwarzschild radius
Spaghettification
Black hole complementarity
Information paradox
Cosmic censorship
ER=EPR
Final parsec problem
Firewall (physics)
Holographic principle
No-hair theorem
Schwarzschild (Derivation)
Reissner–Nordström
Kerr–Newman
Nonsingular black hole models
Dark-energy star
Gravastar
Magnetospheric eternally collapsing object
Planck star
Q star
Fuzzball
Analogs
Optical black hole
Sonic black hole
Most massive
Microquasars
Black Hole Initiative
Black hole starship
Preon star
Gravity well
Hypercompact stellar system
Membrane paradigm
Quasi-star
Timeline of black hole physics
White hole
Stellar core collapse
Metallicity
Stellar physics
Stellar plasma
Supergiant
Stellar processes
Surface fusion
Nucleosynthesis
R-process
Supernova nucleosynthesis
Accretion (Bondi accretion)
Electron capture
Carbon detonation / deflagration
Orbital decay
Supernovae
Type Ia
Type Ib and Ic
Pair instability
Compact and exotic objects
Electroweak star
Observational timeline
Particles, forces, and interactions
Elementary particles
Fundamental interactions
Strong interaction
Weak interaction
Pair production
Inverse beta decay (electron capture)
Degeneracy pressure
Electron degeneracy pressure
Pauli exclusion principle
Quantum hydrodynamics
Quantum chromodynamics (QCD)
Lattice QCD
Color confinement
Deconfinement
Degenerate matter
Neutron matter
QCD matter
Quark matter
Quark–gluon plasma
Preon matter
Nuclear astrophysics
Physics of shock waves
Accretion
Molecular cloud
Bok globule
Young stellar object
Protostar
Pre-main-sequence
Herbig Ae/Be
T Tauri
FU Orionis
Herbig–Haro object
Hayashi track
Henyey track
Main sequence
Red-giant branch
Horizontal branch
Red clump
Asymptotic giant branch
Protoplanetary nebula
Dredge-up
Instability strip
Luminous blue variable
Blue straggler
Stellar population
Superluminous supernova / Hypernova
Brown dwarf
Subdwarf
Subgiant
Bright giant
Hypergiant
Chemically peculiar
Ap/Bp
HgMn
Helium-weak
Extreme helium
Lambda Boötis
B[e]
Burster
Blue dwarf
Boson
Electroweak
Dark-energy
Deuterium burning
Lithium burning
Proton–proton chain
CNO cycle
Triple-alpha process
Alpha process
Carbon burning
Neon burning
Oxygen burning
Silicon burning
S-process
Symbiotic
Luminous red nova
Microturbulence
Radiation zone
Starspot
Chromosphere
Stellar wind
Bipolar outflow
Asteroseismology
Helioseismology
Eddington luminosity
Kelvin–Helmholtz mechanism
Effective temperature
Absolute magnitude
Photometric system
Color–color diagram
Star systems
Common envelope
Eclipsing
Globular
Planetary system
Earth-centric
Pole star
Circumpolar
Apparent
Radial velocity
Proper motion
Photometric-standard
Highest temperature
Largest volume
Smallest volume
Most luminous
Nearest bright
With exoplanets
Brown dwarfs
Milky Way novae
Planetary nebulae
Timeline of stellar astronomy
Substellar object
Sub-brown dwarf
Tidal disruption event
'Category:Stars · '
Type II (IIP, IIL, IIn, and IIb)
Superluminous
Pair-instability
Physics of
Calcium-rich
Near-Earth
Phillips relationship
P-process
Neutrinos
pulsational pair-instability
Progenitors
Wolf–Rayet star
Zombie star
Local Bubble
Superbubble
Orion–Eridanus
History of supernova observation
Massive stars
Most distant
In fiction
Barnard's Loop
Crab Nebula
iPTF14hls
Tycho's
Kepler's
SN 1987A
SN 185
SN 1006
SN 2003fg
Remnant G1.9+0.3
SN 2007bi
SN 2011fe
SN 2014J
SN Refsdal
Vela Remnant
ASAS-SN
Calán/Tololo Survey
High-Z Supernova Search Team
Katzman Automatic Imaging Telescope
Monte Agliale Supernovae and Asteroid Survey
Nearby Supernova Factory
Sloan Supernova Survey
Supernova/Acceleration Probe
Supernova Cosmology Project
SuperNova Early Warning System
Supernova Legacy Survey
Texas Supernova Search
Book:Supernovae
Category:Supernovae
Commons:Supernovae
Original source: https://en.wikipedia.org/wiki/ Neutron star. Read more
Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:Neutron_star&oldid=2412016"
Star types
Exotic matter
Compact stars
Portal templates with all redlinked portals
Portal-inline template with redlinked portals


text:
La massothérapie englobe un ensemble de techniques de massage des tissus mous qui, malgré leurs différences de philosophie et de manipulations, partagent un certain nombre de principes et de méthodes qui ont pour objectif de favoriser la détente (musculaire et nerveuse), la circulation sanguine et lymphatique, l'assimilation et la digestion des aliments, le fonctionnement des organes vitaux et l'éveil à une conscience psychocorporelle.

Réglementation au Québec
Au Québec, l'autorégulation par les associations professionnelles est en vigueur. La plus ancienne d'entre elles, la Fédération québécoise des massothérapeutes (FQM) est la seule à effectuer des démarches en faveur de la création d'un ordre professionnel afin d'encadrer la pratique de la massothérapie. C'est un acteur pionnier dans la reconnaissance de la profession au Québec. Elle a ainsi réussi à obtenir l'appui du Collège des médecins en faveur de l'encadrement de la massothérapie en 2014. L'Association professionnelle des massothérapeutes spécialisés du Québec (AQTN) regroupe en 2016 plus de  ce qui en fait une des plus grandes associations au Québec.

Notes et références

Voir aussi

Articles connexes
 Parafangothérapie

Liens externes

Médecine non conventionnelle
Massage

redpajama_set_name: RedPajamaWikipedia


Database audit and protection (DAP) tools provide comprehensive security for relational database management systems (RDBMSs). DAP tools have their roots in the basic monitoring capabilities of database activity monitoring (DAM) tools. In response to expanded client requirements, vendors have added additional capabilities, such as data discovery and classification, threat and vulnerability management, application-level analysis, intrusion prevention and activity blocking, and identity and access management analysis.


These help topics document the Blackboard Collaborate Launcher available in versions 4.4 and later of the Blackboard Collaborate Building Block.
The Blackboard Collaborate Launcher is a utility for Windows and Mac that provides a convenient and reliable way for you to launch your Blackboard Collaborate web conferencing sessions and recordings. When you select Join Room on the Room Details page or a recording link in the Recordings table, Blackboard Collaborate checks to see if you have the launcher installed. If you don't, Blackboard Collaborate prompts you to download it.
When the launcher is installed, selecting a session or recording link triggers the download of a .collab file. The launcher uses this file to launch Blackboard Collaborate using Java. Because the launcher includes the required Java, you don't need to install and maintain the system version of Java.


I know i've been so absent on the blog, so much has been happening in the past 6 months (when doesn't it..!).
I have a LOT of blogging to catch up on, and a LOT of stories to tell!
They're all gonna be coming in stream across the next few weeks so… be prepared for lots of photos!
I'm gonna get my Christmas post out of the way first. Cos it was almost 2 months ago. How time flies when you're having fun.
So at this point of time, my decision is still on pink.
Now it's just deciding WHAT shade of pink it would be.
My kitchen! I really should do a single blogpost bout my new place but urm when i'm done with blogging about my trips la yeah.
Some Japanese homeware i got across two trips to Tokyo.
Baby came over for date night and we put up the Christmas tree together! I ended up throwing pom poms and sparkle all over it. And ultimately cursed myself when i had to tidy it up before Chinese New Year.
Left: With Jason & Emily at their wedding. I've known Jason since we were kids.
Right: The fairy-themed Christmas deco at BSC which got me silently screaming to myself when i saw it.
With Jon and Kishan. Jon used to sit in front of me in Form 3, and i used to copy his math homework, which he would copy from the head prefect sitting next to him. Haha.
Unfortunately i lamely forgot to take pix of the food before the rest slayed them in seconds.
Secret Santa time! We've been doing it annually for awhile now.
We killed all the food Jun made and picked the bones clean.
I started using Bespoke during Christmas to run my errands for me like pick up the pots and trays of food from Jun's kitchen to send to mine.
You can read more about what Bespoke is on this article i found online.
On another night I had the Lovelies over for our Christmas potluck of sorts.
Jun, again, sent over mains of roasted chicken + vegetables, salad, and brioche he made. Dhanya made a chia mango dessert, Steph brought mozzarella and prosciutto, Aps brought salad(?). Sorry this is why i should have blogged earlier, i forget!
We took a slow tour of my new place, and they each got into the shower. I was so tempted to turn it on when Cammy and i were in there fully-clothed but… i was closer to the shower. Then we all got into my tent together just to see if we could!
Not the most flattering shot of me but anyway.
Went to have lunch with Lisa before she moved to Australia with the kids. We went to Ju Ne at Publika.
On a Friday night i was working from home, Shannon was downstairs and came up for a beer while i attempted to do household chores like measure the balcony to estimate the cost of astroturf. He couldn't tahan watching me, took the measuring tape from me and said, "Joyce. THIS is how you use a measuring tape," before helping me measure it instead. Guys can be useful at times.
A Sunday afternoon i refused to do work and had the cutest nap corner in front of me.
Christmas dinner with my Boracray girls at Ben's in Publika. It was our second attempt at an Xmas meet up. Lexie brought Christmas crackers and half of us (not difficult to do the math here…) forgot the Christmas presents.
Drinks with Rajan and Rahul after that at El Cuarto.
Lunch with Louis at A' Perfetto. They serve a reasonable Japanese-Italian menu and I love sneaking there for salads.
Ok fine i had the beef + fish roe + egg rice too.
Dinner at Caroline's one weekend night.
Get together at Rahul's one night, Atif is one of my favourite huggers in town!
I happened to be the only girl there… i'm one of the boys?
Dhanya and Deepak had Jun & i over for some leftover traditional Indian dishes from their mum's birthday celebration. It was YUMMEH.
Went for Mya's 100-day old birthday party one weekend.
In prep for Christmas day itself, i tried Wine Talk for the first time. It's an online store for red/white wine, spirits and champagne, which is GREAT so i don't have to lug bottles home myself. I told the resident sommelier my preference – medium to full-bodied reds, dry whites, favour Shiraz and Malbecs – and they sent over a selection based on a set budget.
Valid till 31st December 2016, and you get free delivery too as RM120 is minimum spend for that.
Christmas Day at #CasaFairy! The pink flowers are from Mummy!
I woke up at 7am to dry the turkey and start cooking, while Jun went off to his own kitchen to prep the other dishes.
I roasted turkey and two legs of lamb, while Jun made all the gravies and sides (tempeh + brussel sprouts, pumpkin mash, mushroom salad). I must say the meal wouldn't have been as glorious without them!
Chocs on right from Kim & Keith!
My usual thing is to have family over for lunch first, then friends after.
This is such a stupid picture but i've decided i'll just leave it up.
I think the party ended at 2am… i was knackered by then cos i'd been up for 18 hours (and drinking for 12… or more). I don't think i even have pictures with everyone who came!
Aftermath for recycling the next day.
After the cleaner was gone, we just sank into our hangovers (well, i did), nibbled on Christmas leftovers Jun threw together and opened presents.
One of my presents was a set of crystal whiskey glasses! They're so pretty in my home!
Post-Christmas salad dinner at Mattrena's.
And THAT. Was my Christmas in a speedy nutshell.


text:
Q: How to lower wattage of circuit I want to power a computer fan from a 12v motorcycle battery.
Disregarding the motorcycle battery being 12.6 volts (not charging), lets say that it's a regulated constant voltage source of 12 volts.
The fan needs to be 12v driven where 0.58 Amps will be drawn.
It is a very old fan, and I can't find a datasheet. But it is exactly this one:
https://www.ebay.com/c/1472102822
Ohms law says that a 24 ohm resistor is good for 0.5 Amps or current. However, Ohms law also says that the power being drawn will be 6 Watts. Most resistors do not have this high of a power rating.
How do I power my computer fan the right way without getting a high wattage? I am not looking forward to using bulky, high wattage resistors.

A: You have linked to an eBay ad instead of a datasheet. The fan has four wires so it probably has a PWM speed control input on it and electronics to efficiently control the speed  without the high heat loss of a resistor.
Internally the fan is not a simple brushed motor but is a miniature brushless DC motor with a chip generating a three-phase supply to the coils. You will find plenty of reading material on the web explaining their operation.
"No datasheet? No sale!"

A: The fan you show is a 4-wire PC case fan. Very common, nothing special. Being 4-wire, it includes the ability to do PWM control. If you feed it a PWM signal the power will be reduced in proportion to the duty cycle.
Here's a link to how to make a PWM control using the venerable 555 IC: https://www.electronics-tutorials.ws/blog/pulse-width-modulation.html
Another option is to use a 12V to 5V DC-DC step-down, and use a 5V fan instead. These tend run at lower current than 12V ones. This is a bit like your series resistor idea, but without the losses.

A: I just realised that ohm's law doesn't apply to a fan since the fan isn't a resistor. The fan takes what it needs in power. When I connect the fan to the 12V battery (which I just tested), the fans spins and draws the amount of current it needs.
If I want to turn the fan on or off using a microcontroller, I just need to switch the voltage supply to the fan. Nothing else, nothing more.
I hope I help someone else who stumbled upon this "problem"
Thanks commenters for your help!

redpajama_set_name: RedPajamaStackExchange


text:
#region License
//
// Copyright (c) 2018, Fluent Migrator Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;
using System.Data;
using FluentMigrator.Runner.Generators.SqlServer;
using NUnit.Framework;
using Shouldly;

namespace FluentMigrator.Tests.Unit.Generators.SqlServer2000
{
    [TestFixture]
    [Category("SqlServer2000")]
    [Category("Generator")]
    [Category("TypeMap")]
    public abstract class SqlServer2000TypeMapTests
    {
        private SqlServer2000TypeMap TypeMap { get; set; }

        [SetUp]
        public void Setup()
        {
            TypeMap = new SqlServer2000TypeMap();
        }

        [TestFixture]
        public class AnsistringTests : SqlServer2000TypeMapTests
        {
            [Test]
            public void ItMapsAnsistringByDefaultToVarchar255()
            {
                var template = TypeMap.GetTypeMap(DbType.AnsiString, size: null, precision: null);

                template.ShouldBe("VARCHAR(255)");
            }

            [Test]
            [TestCase(1)]
            [TestCase(4000)]
            [TestCase(8000)]
            public void ItMapsAnsistringWithSizeToVarcharOfSize(int size)
            {
                var template = TypeMap.GetTypeMap(DbType.AnsiString, size, precision: null);

                template.ShouldBe($"VARCHAR({size})");
            }

            [Test]
            [TestCase(8001)]
            [TestCase(2147483647)]
            public void ItMapsAnsistringWithSizeAbove8000ToText(int size)
            {
                var template = TypeMap.GetTypeMap(DbType.AnsiString, size, precision: null);

                template.ShouldBe("TEXT");
            }
        }

        [TestFixture]
        public class AnsistringFixedLengthTests : SqlServer2000TypeMapTests
        {
            [Test]
            public void ItMapsAnsistringFixedLengthByDefaultToChar255()
            {
                var template = TypeMap.GetTypeMap(DbType.AnsiStringFixedLength, size: null, precision: null);

                template.ShouldBe("CHAR(255)");
            }

            [Test]
            [TestCase(1)]
            [TestCase(4000)]
            [TestCase(8000)]
            public void ItMapsAnsistringFixedLengthWithSizeToCharOfSize(int size)
            {
                var template = TypeMap.GetTypeMap(DbType.AnsiStringFixedLength, size, precision: null);

                template.ShouldBe($"CHAR({size})");
            }

            [Test]
            public void ItThrowsIfAnsistringFixedLengthHasSizeAbove8000()
            {
                Should.Throw<NotSupportedException>(
                    () => TypeMap.GetTypeMap(DbType.AnsiStringFixedLength, 8001, precision: null));
            }
        }

        [TestFixture]
        public class StringTests : SqlServer2000TypeMapTests
        {
            [Test]
            public void ItMapsStringByDefaultToNvarchar255()
            {
                var template = TypeMap.GetTypeMap(DbType.String, size: null, precision: null);

                template.ShouldBe("NVARCHAR(255)");
            }

            [Test]
            [TestCase(1)]
            [TestCase(4000)]
            public void ItMapsStringWithSizeToNvarcharOfSize(int size)
            {
                var template = TypeMap.GetTypeMap(DbType.String, size, precision: null);

                template.ShouldBe($"NVARCHAR({size})");
            }

            [Test]
            [TestCase(4001)]
            [TestCase(1073741823)]
            public void ItMapsStringWithSizeAbove4000ToNtext(int size)
            {
                var template = TypeMap.GetTypeMap(DbType.String, size, precision: null);

                template.ShouldBe("NTEXT");
            }

            [Test]
            public void ItMapsStringWithSizeAbove1073741823ToNtextToAllowIntMaxvalueConvention()
            {
                var template = TypeMap.GetTypeMap(DbType.String, int.MaxValue, precision: null);

                template.ShouldBe("NTEXT");
            }
        }

        [TestFixture]
        public class StringFixedLengthTests : SqlServer2000TypeMapTests
        {
            [Test]
            public void ItMapsStringFixedLengthByDefaultToNchar255()
            {
                var template = TypeMap.GetTypeMap(DbType.StringFixedLength, size: null, precision: null);

                template.ShouldBe("NCHAR(255)");
            }

            [Test]
            [TestCase(1)]
            [TestCase(4000)]
            public void ItMapsStringFixedLengthWithSizeToNcharOfSize(int size)
            {
                var template = TypeMap.GetTypeMap(DbType.StringFixedLength, size, precision: null);

                template.ShouldBe($"NCHAR({size})");
            }

            [Test]
            public void ItThrowsIfStringFixedLengthHasSizeAbove4000()
            {
                Should.Throw<NotSupportedException>(
                    () => TypeMap.GetTypeMap(DbType.StringFixedLength, 4001, precision: null));
            }
        }

        [TestFixture]
        public class BinaryTests : SqlServer2000TypeMapTests
        {
            [Test]
            public void ItMapsBinaryByDefaultToVarbinary8000()
            {
                var template = TypeMap.GetTypeMap(DbType.Binary, size: null, precision: null);

                template.ShouldBe("VARBINARY(8000)");
            }

            [Test]
            [TestCase(1)]
            [TestCase(4000)]
            [TestCase(8000)]
            public void ItMapsBinaryWithSizeToVarbinaryOfSize(int size)
            {
                var template = TypeMap.GetTypeMap(DbType.Binary, size, precision: null);

                template.ShouldBe($"VARBINARY({size})");
            }

            [Test]
            [TestCase(8001)]
            [TestCase(int.MaxValue)]
            public void ItMapsBinaryWithSizeAbove8000ToImage(int size)
            {
                var template = TypeMap.GetTypeMap(DbType.Binary, size, precision: null);

                template.ShouldBe("IMAGE");
            }
        }

        [TestFixture]
        public class NumericTests : SqlServer2000TypeMapTests
        {
            [Test]
            public void ItMapsBooleanToBit()
            {
                var template = TypeMap.GetTypeMap(DbType.Boolean, size: null, precision: null);

                template.ShouldBe("BIT");
            }

            [Test]
            public void ItMapsByteToTinyint()
            {
                var template = TypeMap.GetTypeMap(DbType.Byte, size: null, precision: null);

                template.ShouldBe("TINYINT");
            }

            [Test]
            public void ItMapsInt16ToSmallint()
            {
                var template = TypeMap.GetTypeMap(DbType.Int16, size: null, precision: null);

                template.ShouldBe("SMALLINT");
            }

            [Test]
            public void ItMapsInt32ToInt()
            {
                var template = TypeMap.GetTypeMap(DbType.Int32, size: null, precision: null);

                template.ShouldBe("INT");
            }

            [Test]
            public void ItMapsInt64ToBigint()
            {
                var template = TypeMap.GetTypeMap(DbType.Int64, size: null, precision: null);

                template.ShouldBe("BIGINT");
            }

            [Test]
            public void ItMapsSingleToReal()
            {
                var template = TypeMap.GetTypeMap(DbType.Single, size: null, precision: null);

                template.ShouldBe("REAL");
            }

            [Test]
            public void ItMapsDoubleToDoublePrecision()
            {
                var template = TypeMap.GetTypeMap(DbType.Double, size: null, precision: null);

                template.ShouldBe("DOUBLE PRECISION");
            }

            [Test]
            public void ItMapsCurrencyToMoney()
            {
                var template = TypeMap.GetTypeMap(DbType.Currency, size: null, precision: null);

                template.ShouldBe("MONEY");
            }

            [Test]
            public void ItMapsDecimalByDefaultToDecimal195()
            {
                var template = TypeMap.GetTypeMap(DbType.Decimal, size: null, precision: null);

                template.ShouldBe("DECIMAL(19,5)");
            }

            [Test]
            [TestCase(1)]
            [TestCase(20)]
            [TestCase(38)]
            public void ItMapsDecimalWithPrecisionToDecimal(int precision)
            {
                var template = TypeMap.GetTypeMap(DbType.Decimal, (int?)precision, 1);

                template.ShouldBe($"DECIMAL({precision},1)");
            }

            [Test]
            public void ItThrowsIfDecimalPrecisionIsAbove38()
            {
                Should.Throw<NotSupportedException>(
                    () => TypeMap.GetTypeMap(DbType.Decimal, 39, precision: null));
            }
        }

        [TestFixture]
        public class GuidTests : SqlServer2000TypeMapTests
        {
            [Test]
            public void ItMapsGUIDToUniqueidentifier()
            {
                var template = TypeMap.GetTypeMap(DbType.Guid, size: null, precision: null);

                template.ShouldBe("UNIQUEIDENTIFIER");
            }
        }

        [TestFixture]
        public class DateTimeTests : SqlServer2000TypeMapTests
        {
            [Test]
            public void ItMapsTimeToDatetime()
            {
                var template = TypeMap.GetTypeMap(DbType.Time, size: null, precision: null);

                template.ShouldBe("DATETIME");
            }

            [Test]
            public void ItMapsDateToDatetime()
            {
                var template = TypeMap.GetTypeMap(DbType.Date, size: null, precision: null);

                template.ShouldBe("DATETIME");
            }

            [Test]
            public void ItMapsDatetimeToDatetime()
            {
                var template = TypeMap.GetTypeMap(DbType.DateTime, size: null, precision: null);

                template.ShouldBe("DATETIME");
            }
        }
    }
}

redpajama_set_name: RedPajamaGithub


text:
Chapter 6 Socio Cultural Music Branding
DOI: 10.23912/978-1-908999-52-8-2266
Component type: chapter
Published in: Music, Markets and Consumption
Parent DOI: 10.23912/978-1-908999-52-8-2009
10.23912/978-1-908999-52-8-2266
All of the issues in the preceding chapter come under the heading of meaning. Although there is some acknowledgement within the marketing discipline of the notion of brand meanings, relatively little attention has been paid to an underlying theory of cultural meaning. In order to deal with this, it is helpful to turn to cultural studies and a socio-cultural approach to branding. In this chapter, a framework is proposed for how music brands are created. Branding discourse is not good at understanding the meaning of arts and entertainment offerings. Because branding terminology has been largely developed by business academics, practitioners and intermediaries, it is a very blunt instrument in the cultural arena. By framing something or someone as a brand, the speaker invokes a particular way of speaking, a discursive repertoire, or a lens, which focuses on certain features of a phenomenon and pushes others out of focus. In fact, a serious failure of mainstream branding theory as applied by commercial marketers is its failure, relatively speaking, to handle the cultural dimensions of arts brands. It is unhelpful to apply commercial branding terminology to arts and entertainment brands without carefully considering the cultural context, the social interaction between all of the stakeholders, what meanings are generated and understood around the specific musical project or scene, what art-generic conventions apply, and what ideologies and values inform production and consumption practices in the project in question.
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Dr Daragh O'Reilly, University of Sheffield (Author)
Dr Gretchen Larsen, King's College London (Author)
Dr Krzysztof Kubacki, Griffith University (Author)
For the source title:
O'Reilly, Larsen & Kubacki, 2013
O'Reilly, D.D., Larsen, D.G. & Kubacki, D.K. (2013) "Chapter 6 Socio Cultural Music Branding" In: O'Reilly, D.D., Larsen, D.G. & Kubacki, D.K. (ed) . Oxford: Goodfellow Publishers http://dx.doi.org/10.23912/978-1-908999-52-8-2266
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redpajama_set_name: RedPajamaCommonCrawl