What are Pulsars ? One of The Most Extreme Objects in Space ! скачать в хорошем качестве

What are Pulsars ? One of The Most Extreme Objects in Space !

A pulsar is a rapidly spinning neutron star. It is extremely dense, composed almost entirely of neutrons, and has a diameter of less than 20 km (12 miles). In most cases, pulsars have a mass that is 1.35 times the mass of the Sun. Their mass ranges between 1.18 and 1.97 times the mass of the Sun. When the core of a violently exploding star collapses inward and becomes compressed, a neutron star is formed. A star's surface is covered with neutrons decaying into protons and electrons. A magnetic field of 1012 Gauss surrounds the star and rotates alongside it as charged particles are released from the surface. By accelerating to speeds approaching that of light, the particles emit electromagnetic radiation. A pulsar's magnetic poles release this radiation as intense beams. Even though all known pulsars exhibit similar behavior, their periods, or the intervals between successive pulses, vary considerably. So far, the slowest pulsar observed has a period of about 11.8 seconds. PSR J 1939+2134 was the fastest pulsar ever observed for more than two decades. This star was discovered in 1982 and spins 642 times each second, which is equivalent to 0.00155 seconds. In 2006 an even faster one was reported: known as J 1748−2446 A D, it has a period of 1.396 milliseconds, which corresponds to a spin rate of 716 times per second. These fast pulsars are referred to as millisecond pulsars. Like slower-rotating pulsars, they are formed by supernovae. However, millisecond pulsars are often found in binary star systems. During the supernova, the neutron star accretes matter from its companion, causing the pulsar to spin more rapidly. Observations of radio pulsars show that they are slowing down very gradually at a rate of about a millionth of a second per year. An indication of the age of a pulsar can be found in the ratio of its present period to its average slowdown rate. It is common for the characteristic age to be much closer to the actual age than its timing age. It took the Crab Pulsar 1,240 years to form during a supernova explosion observed in 1054 CE. Despite slowing down so gradually, pulsars make excellent clocks. It is possible to test theories about gravity using this accuracy since pulsars also have strong gravitational fields. Pulsars also undergo much more drastic period changes, called glitches, in which the period increases suddenly and then decreases gradually. Starquakes, or sudden cracks in a star's iron crust, can cause glitches. There are others that are caused by the interaction between the crust and the fluid interior. #space #science #neutronstar #galaxy #pulsar #fastest