About seven thousand years ago, a star suddenly exploded in a remote corner of outer space, dropping the outer layers of matter. A relatively large and massive star suddenly ran into a serious energy problem – its physical integrity was in jeopardy. When the boundary of stability was passed, an exciting, extremely powerful one of the most catastrophic explosions in the entire Universe broke out, giving rise to a supernova.
For six thousand years, light from this star from the constellation Taurus raced through outer space and finally reached Earth. It happened in 1054. In Europe, science was then slumbering, and among the Arabs it was experiencing a period of stagnation, but in another part of the Earth, observers noticed an object glistening majestically in the sky before sunrise.
Fourth of July 1054 Chinese astronomers, peering into the sky, saw a luminous celestial object, which was much brighter than Venus. He was observed in Beijing and Kaifeng and was called the “guest star.” It was the brightest object in the sky after the Sun. For 23 days, until July 27, 1054, it was visible even in the afternoon. Gradually, the object became weaker, but still remained visible to the naked eye for another 627 days and finally disappeared on April 17, 1056. It was the brightest of all registered supernovae – it shone like 500 million suns. If she could find us at such a distance as the closest star Alpha Centauri, then even on the darkest night in her light, we could freely read the newspaper – it would shine much brighter than the full moon.
In European chronicles of those years there is no mention of this event, but we should not forget that something was the years of the Middle Ages, when the light of science on the European continent almost died out.
One interesting moment in the history of the discovery of this star. In 1955 William Miller and Helmut Abt of Mount Wilson and Mount Palomar Observatories discovered prehistoric pictograms on the wall of a cave in the rock of Navajo Canyon in Arizona. In the canyon, the image was carved on stone, and in the cave – painted with a piece of hematite – red iron ore. Both figures show a circle and a crescent. Miller interprets these figures as an image of a lunar sickle and star; in his opinion, they probably reflect the appearance of a supernova in 1054. There are two reasons for this conclusion: firstly, in 1054, when the supernova broke out, the moon phase and its location relative to the supernova were exactly as shown in the figure.
Secondly, according to clay shards found in those places, it was established that Indians lived in this area about a thousand years ago. Thus, the drawings are apparently an artistic depiction of a supernova made by the ancient Indians.
After photographing and thoroughly investigating the area of the sky where the supernova was located, it was discovered that the remnants of the supernova form a complex chaotic expanding gaseous envelope containing several stars. This entire complex of gas and stars was called the Crab Nebula. The source of the material of the nebula is one of the central stars, the same one that exploded seven thousand years ago. This is a neutron star. It has a temperature of 6-7 million K and an extremely small diameter. From photographs and spectrograms, one can determine the physical characteristics of a star.
As a result of the study, it turned out that in the Crab nebula two types of radiating regions are distinguished. Firstly, it is a fibrous network consisting of a gas heated to several tens of thousands of degrees and ionized under the influence of intense ultraviolet radiation from a central star; gas includes hydrogen, helium, oxygen, neon, sulfur. And, secondly, a large luminous amorphous region, against which we see gas fibers.
From photographs taken about twelve years ago, it was found that some of the fibers of the nebula move from its center to the outside. Knowing the angular dimensions, as well as approximately the distance and speed of expansion, scientists determined that about nine centuries ago there was a point source at the site of the nebula. Thus, it was possible to establish a direct relationship between the crab nebula and that supernova explosion that was observed almost a thousand years ago by Chinese and Japanese astronomers.
The question of the causes of supernova explosions is still the subject of discussion and serves as an occasion for putting forward conflicting hypotheses.
A star with a mass exceeding the solar by about 20% can become unstable over time. This was shown in his brilliant theoretical study, made at the end of the 30s of our century, by the astronomer Chandrasekar. He found that such stars on the slope of life sometimes undergo catastrophic changes, as a result of which a certain equilibrium state is achieved, allowing the star to adequately complete its life path. Many astronomers have studied the last stages of stellar evolution and the dependence of the evolution of a star on its mass.