Explosion of supernovae - Crab Nebula

According to a Chinese history book "Weak Meeting", on the morning of July 4, 1054, near the constellation Meteorite (Heavenly Gate) of the constellation Taurus appears "crystal guest" very bright . In the first 23 days its brightness exceeded Venus, still visible in the middle of the day. Later this star faded away, until April 6, 1056 completely shut down. This is the first meticulously recorded thing in the world about the big bang of the supernova. The crab nebula is the vestige of this big explosion of supernovae.

In the West, the crab nebula was discovered by astronomers in England in 1731. In 1884, Lord Ross (England) discovered that the shape of the nebula was like a large crab crawling across the sky, should be named Crab Nebula . That stubborn name exists today.

Crab Nebula (Photo: astroa.physics)

After the discovery of the Crab Nebula always caught the attention of astronomers. In 1921, Dunken - an American astronomer compared two nebula images taken 12 years apart, finding that the nebula is always expanding. In 1928, American astronomers measured the expansion rate of the Crab Nebula at 1,100km / sec. Many astronomers later confirmed that the Crab Nebula is the gaseous cloud created by the supernova explosion in July 1054.

The temperature of the Crab Nebula is not as hot as the Sun, but its radiation is very strong, in which the source of X-rays, radio waves, visible light and gamma rays are very strong. It is really a large capacity "Space Radio" . Where does this radiant energy come from? In 1968 astronomers removed from the "big belly" of the Crab nebula a peculiar "pearl" bead, the neutron star. This star is less than 20km in diameter but its weight is equivalent to the Sun. It has a very strong magnetic field, the surface temperature reaches 10 million degrees Celsius, the internal temperature is up to several hundred million degrees Celsius. The rotation speed is 30 revolutions per second. The pulse circuit is cyclic, in the Earth it can obtain its "molasses" . So neutron stars are also called stars Pulse circuits.

X rays in the Crab Nebula (Photo: chandra.harvard)