What is a pulsar?
Pulsars are cosmic sources of radio, optical, X-ray and / or gamma radiation coming to Earth in the form of periodic bursts (pulses).
A pulsar is a small spinning star. There is a section on the surface of a star that emits a narrow beam of radio waves into space. Our radio telescopes receive this radiation when the source is turned towards the Earth. The star rotates and the radiation flow ceases. The next revolution of the star - and we again receive her radio message.
How does a pulsar work?
The beacon with a rotating lamp also functions. From a distance we perceive its light as pulsating. The same thing happens with the pulsar. We perceive its radiation as a source of radio wave radiation pulsating with a certain frequency. Pulsars belong to the family of neutron stars. A neutron star is a star that remains after a catastrophic explosion of a giant star.
Pulsar - a neutron star
A medium-sized star, such as the Sun, is a million times larger than a planet like Earth. Giant stars across 10, and sometimes 1000 times the size of the Sun. A neutron star is a giant star, squeezed to the size of a large city. This circumstance makes the behavior of a neutron star very strange. Each such star is equal in mass to a giant star, but this mass is squeezed in an extremely small volume. One teaspoon of neutron star matter weighs a billion tons.
How are pulsars formed?
Here's how it goes.After the star explodes, its remnants are compressed by gravitational forces. Scientists call this process the collapse of a star. As the collapse develops, the force of gravity grows, and the atoms of the material of the star are pressed more and more closely together. In a normal state, atoms are at a considerable distance from each other, because the electron clouds of atoms are mutually repulsive. But after the explosion of a giant star, the atoms are pressed so tightly and compressed that the electrons are literally pressed into the nuclei of the atoms.
The nucleus of an atom consists of protons and neutrons. Electrons squeezed into the nucleus react with protons, and neutrons are formed as a result. Over time, all the material of the star becomes a giant ball of compressed neutrons. A neutron star is born.
When did pulsars occur?
Scientists believe that star pulsars have existed since time immemorial. In any case, they were long before they were opened. The first evidence of their existence was obtained in November 1967, when several radio telescopes in England found a previously unknown source of radiation in the sky. There are many sources of radio waves in space. For example, water and ammonium molecules drifting in interstellar space emit radio waves. These waves are captured by the dish antennas of radio telescopes.
The new source of radio waves, however, was not like the others. Senior student Joslyn Bell studied the radio waves recorded by the recorders of the radio telescope.She drew attention to regularly recurring bursts of electromagnetic radiation, which arrived at the telescope antenna with an interval of 1.33733 seconds.
When the news of the discovery of Bell became public, some scholars decided that Bell accepted the message of a foreign civilization. A few months later another source of pulsating radio emission was recorded. Scientists abandoned the idea of their artificial origin. It was decided that these sources are superdense stars. They were called pulsars because of the pulsating nature of the radiation. Pulsars turned out to be the very neutron stars that scientists have long been hunting for. Since then, hundreds of such stars have been discovered.
Why are pulsars throbbing?
Scientists believe that the reason is their rapid rotation. All stars, like planets, rotate around its axis. For example, the sun makes one revolution in one month. As the size of a rotating body decreases, it begins to rotate faster. Imagine a skater spinning on ice. When he presses his hands to his body, the rotation accelerates sharply. The same thing happens with superdense stars. A Los Angeles-sized pulsar rotates at one revolution per second. Other pulsars can spin even faster. Pulsars can rotate at speeds up to 1000 revolutions per second
In this rotation lies the cause of the pulsating radiation. Pulsars are surrounded by a strong magnetic field. Protons and electrons move along the lines of force of this magnetic field.As you know, the strength of the magnetic field increases at the north and south magnetic poles. At these points, the velocity of protons and electrons becomes very large. With this acceleration, particles emit energy quanta in the range from x-rays to radio waves. Since the pulsar rotates, and the radiation source rotates with it, we perceive the radiation of the pulsar only at the moment when the source is turned towards the Earth. In the same way, we perceive the light of a lighthouse with a rotating lamp.
