What is the Neutron Star? | Properties, Magnetic Field, Pulsar Sounds…


The neutron star is a star residue left behind by the supernova explosion when massive stars have no more fuel left to burn.

They arise as a result of the collapse of the nuclei of stars with masses between 10 and 29 solar masses. They are the most intense stars known and observed throughout the universe. Due to their high density, they are extremely compact (compact), so their dimensions are also quite small. The size of a typical neutron star, expressed in 10 kilometers, has masses between 1.4 and 2.16 solar masses.

Unlike standard stars, the neutron star does not generate heat and cools down over time (its heat loses its energy through its radiation). Therefore, even if the evolutionary processes are not expected under normal conditions, if the material in their circumference takes place, if the mass transfer is made with the help of the accretion disk, evolution can be made. This situation is usually encountered in binary or multiple systems.

The massive star produces an explosive supernova explosion and leaves a neutron star, but the associated star has not yet completed its evolution. Since the neutron star is a very compact object, the transfer of matter from the star to the neutron star may occur. The transfer of this substance may have started before the supernova explosion or may have started after various disturbances.

Most of the models made predict that neutron stars consist entirely of neutrons wherever they are. The nucleus, which gets stuck during the supernova explosion, creates neutrons by forcing the electron and proton in the atom to join together. The disappearance of the device space between the electron and the proton makes the neutron star such a compact body. Of course, this happens within the range allowed by neutrons, and neutron stars are not encountered above a certain mass limit. In a more specific expression, neutron stars exist thanks to the hydrostatic range provided by the neutron pressure of the neutron.

Neutron Star Formations

In order for a neutron star to form, the mass of the star must be more than 8 solar masses on the main sequence. Such a star can burn the glass up to the bottom of the center and creates a deliberately rich nucleus. After the excessive accumulation of the nucleus in the center, the nuclear reactions decrease. This results in a drop in pressure, now the pressure that keeps the star alive is the pressure.

However, in this case, the nucleated combustion reactions in the shell continue. If these combustion reactions cause the star’s nucleus to exceed the Chandrasekhar limit (if there is a sufficient mass), the nucleus will continue to collapse further (the declination-electron pressure drops). With the further compression of the bean, the temperature in the macaroni rises to 5 billion degrees. The gamma rays produced at these temperatures decompose the iron in the core into alpha particles by photopartitioning.

Following the rise in temperature, the electron and the proton combine (via electron capture) to form a nucleus from the neutron. During this reaction, serious neutrino release occurs in the environment. In fact, this neutrino oscillation emits the outer layers of the star towards space, forming a supernova. The remaining material will be held by the neutron pressure, causing a neutron star to remain. If the mass of the star is greater, the neutron pressure of the neutron will also cause the formation of a unique low black hole. This situation occurs when the residue formed after supernova is more than about 3 solar masses.

Pulsar (Pulsar)

Pulsars, as the name suggests, are neutron stars with a higher high magnetic field that pulsate at certain time intervals (sometimes white dwarfs may also be pulsars, but we will exclude this from the category for now). Each pulsar is a neutron star, but a neutron star is not a pulsar. So pulsars are a specific subset of neutron stars.

We call our observers pulsars that emit various electromagnetic waves (light) from neutron stars, including the radio wavelength. Since this light emerges from the magnetic axis and there is an angle between the spin axis of the neutron star and the magnetic axis, the light of the neutron star does not seem to blink at us as it rotates. It appears to be flashing at certain intervals, just like a boat.

Simulation of a pulsar

Neutron stars can rotate so fast around their axes that the duration of these pulses falls down to 1 in 700 of a second (it takes 700 rotations around the axis in one second). The fastest pulsar that could be observed is the PSR J1748-2446ad, which takes 716 rotations per second (716 Hz).

Pulsars as High Precision Watches

These pulses are extremely periodic and do not change within a short time interval. In other words, a pulsar whose frequency is measured as 100 Hz today will be measured as 100 Hz again 1 year later. Thanks to the therapeutic calculations, it is possible to calculate how long the pulsar will slow down in what time. Thus, the change in frequency can be predicted and compared with the observers. Because of their precision, they can be rivals to atomic clocks. Because the time between each pulse is the same throughout our observation range wherever it is.

Some Special Pulsars

The first radio pulsar of the eyes is “CP 1919” (or PSR B1919 + 21), with a period of 1.337 seconds, the pulse duration is 0.04 seconds. bright millisecond pulsar PSR J0437-4715. The first X-ray pulsar of the eye, Cеn X-3. The millisecond X-ray pulse with the first accretion disc in the eye SAX J1808.4-3658. Pulsar system PSR j0737-3039Pulse with the shortest period of the eyes (with the highest frequency), PSR J1748-2446ad with 1.4 milliseconds (716 rounds per second) .Scorp with 118.2 seconds. It is also an example of a white dwarf. The neutron star pulsar with the longest period of the eye, PSR J2144-3933, with 8.51 seconds. Pulsar with the most stable period PSR J0437-4715PSR J1841-0500 a pulse that stops firing for exactly 580 days. It is one of the two pulsars known to stay longer than a few minutes. PSR B1931 + 24 pulsar with a cycle. It pulses for a week and then stops pulsing for about a month. The second pulsar is known to last longer than five minutes.1

Pulsar Words

If we convert the pulsations of pulsars to sеs file, we hear that they make pulses as in the video below. You have paid attention to how sensitive the measurements are made.

Physical Properties

The mass of a neutron star can be between 1.1 and 3 solar masses. But in general, stars below 1.4 solar mass are white dwarfs, and the most massive neutron star ever to be observed has a solar mass of 2.01. General densities vary between 3.7 × 1017 and 5.9 × 1017 kg / m3. This value is more than the atomic nucleus. In other words, a teaspoon of neutron stars is 900 times heavier than the Giza pyramids. The pressure varies from 3.2 × 1031 to 1.6 × 1034 Pa4. The pressure we experience at your sea level is only 101325 Pa.

The temperature inside a newly formed neutron star is between 100 billion and 1 trillion kennings. But with the massive amount of neutrinos it broadcasts, it drops to 1 million degrees within a few years.3 A neutron star at this temperature makes most of its radiation in the X-ray region (see Star Astrophysics: Black Body Radiation). Neutron stars are also famous for their enormous magnetic field. The magnetic field strength on its surface can range from 104 Tеsla to 1011 Tеsla5. As a simple comparison, the MR devices we use are at the level of only a few Tеsla. So that, with a magnetic field of 16 Tеsla, a frog could be kept in the air by diamagnetic stimulation6.

Such a compact object has a very strong gravitational area on its surface, although not as much as black holes. Thus, this gravity on its surface is on average 1012 m / s2. This value is 100 billion times higher than the earth gravity of the Earth and the gravity we experience. It may be expected that such an object will cause micro-speckle like black holes. If the radius of a shape is round, a photon can also be trapped in an orbit. However, there are various concerns, such that the trajectories of the photons in a photon sphere will change.

If the gravitational field is too severe, it will cause time drift and spagitization, which are other factors we see in black holes. A typical neutron star will have 4 years on its surface and 5 years on Earth (assuming it does not rotate so that it will make a difference when it spins very fast in reality) 7.


Neutron stars rotate at an extremely rapid rate due to the conservation of the angular momentum during their formation. Such that one revolution varies between seconds and milliseconds. In addition to this, the rotation period may slow down due to various factors over time and may accelerate. In the case of its deceleration, it is spin down (spin down) and in the case of its acceleration, spin up.

Spin Down

Neutron stars slow down due to the radiation they make over time (both photon and neutrino), as their rotating magnetic fields lose their energy. However, this slowdown can be interpreted as it does not change at all in a short period of time, since it is quite small in the time we think. Theoretically, this slowdown can be calculated as follows.

As a result, knowing the luminosity of the nebula, as we observe it, gives an idea about how much it will slow down. The Well Known Nebulae