Sirius (Sirius)
The visual magnitude of the brightest star in the night sky is-1.5, etc. It is a binary star in the constellation Canis. Liangzi is a blue and white binary star, and its brightness is 23 times that of the sun. Its volume is slightly larger than the sun, but its temperature is much higher than the sun. It is about 8.6 light-years away from the solar system, only twice as far as the nearest star except the sun. The ancient Egyptians realized that the star pool rose with the sun, that is, the Nile Delta began to flood every year before the sun rose. Moreover, they found that the time interval between Sirius's two rises was 365.25 days, not 365 days in Egypt. German astronomers reported in 1844 that Sirius is a binary star, because it moves along a wavy trajectory in the nearby space, thus inferring that it has a companion star with an orbital period of about 50 years. This companion star was first seen by American astronomers in 1862. Sirius and its companion star revolve around each other in orbits with large eccentricity, and the average distance is about 20 times that of the sun and the earth. Although the bright star shines brightly, it is not difficult to see the companion star with a large telescope. The companion star is similar in mass to the sun, but much denser than the sun. This is the first white dwarf discovered.
Sirius is Alpha Canis, the brightest star in the whole day. Sirius is a visual binary star consisting of A and B. Star A is the first bright star in the whole day and belongs to the main sequence blue dwarf. Star B, commonly known as Sirius companion, is a white dwarf star with a slightly larger mass than the sun and a smaller radius than the earth. Its substance is mainly in degenerate state, and its average density is about 3.8× 106/ cubic centimeter. The orbital period of satellites A and B is 50.090 0.056 years and the orbital eccentricity is 0.5923 0.0019. Sirius is 8.65 0.09 light years away. Whether Sirius is a near binary is related to the evolution of Sirius binary. It was recorded in ancient times that Sirius was red, which provided us with research clues. X-rays of Sirius were discovered in 1975. Some people think that it may be the thermal radiation in the deep atmosphere of almost pure hydrogen of Star B, while others think that it may be caused by the high temperature corona of Star A or Star B, which is still under study. According to the data of 1980, the X-rays of A and B in the band of 0. 15 ~ 3.0 kV were measured by the High Energy Observatory-2 satellite, and it was found that the X-rays of B were much stronger than that of A..
In the winter sky, from Orion to the southeast, one of the brightest stars in the whole day shines there. It is Alpha Canis, also known as Sirius in ancient China. Sirius's apparent magnitude is-1.45 m, which is only 8.6 light years away from us.
In ancient Egypt, whenever Sirius rose from the eastern horizon at dawn (this phenomenon is called "rising together" in astronomy), it was the annual flood of the Nile, which irrigated large areas of fertile land on both sides of the river, so the Egyptians began farming again. Because the appearance of Sirius was closely related to the agricultural production in ancient Egypt, people at that time regarded it as a god, and determined the day when Sirius rose in the east before dawn as the beginning of the year. It can be said that the Gregorian calendar we use now was first born in ancient Egypt.
As we all know, the pyramids were conceived and built from the perspective of astronomy. Because astronomy in ancient Egypt is not well known, is this view a bit reluctant? Sirius is one of the few planets associated with the pyramids. However, it is this concern for Sirius that makes people feel quite strange. Because when people want to observe Sirius from Memphis, they can only see it in the morning light of the Nile, which is close to the horizon. Egypt has a detailed almanac-42 BC1,which is confusing enough! This kind of almanac was embarrassed by the rise of Sirius (first appeared in July of 19), and the annual cycle was determined to be more than 32,000 years.
We admit that ancient astronomers did not have time to observe the sun, moon and celestial bodies forever. Finally, they agreed that all the celestial bodies were in the same place after running for about 365 days. But isn't it ridiculous to deduce the first almanac from Sirius' data? Totally ridiculous! Because it is much easier for them to deal with the sun and the moon, they can get more accurate results. Sirius Almanac seems to be a product of pure hypothesis, a probability calculation, because it has never been able to predict the appearance of planets: the Nile flood and related phenomena, that is, Sirius appeared on the horizon shrouded in morning light, by accident. The Nile does not flood every year, nor does it always flood on the same day. Why on earth did a copy of Sirius appear? There are ancient documents on this subject again? Are there any scriptures or promises carefully hidden by ancient priests as secrets? We have no way of knowing.
Sirius is the brightest star in Canis.
Sirius's companion star β is the earliest white dwarf discovered by human beings. It is so small that it is almost invisible to the naked eye. But its density is extremely high, 30,000 times larger than water, and its mass is similar to that of the sun. This star was observed by astronomers with a telescope in 1862, and was identified as a "white dwarf" in 19 15, which attracted great attention from the astronomical community. However, at least 1200 years ago, many tribes in Mali, Africa began to worship this star.
It is said that a god named Noam taught many people about Sirius Beta. Many people kept pictures of the gods they believed in and descended from the sky in a big spaceship with flames and came to many tribes. So people suspect that "Nome" may be an alien who came to earth from Sirius Beta (or a star related to it).
When it comes to Sirius companion β, we have to tell its story, because many important discoveries often start with some small "deviations".
In the 8th century BC, astronomers in the Tang Dynasty in China compared their observations with ancient records and found that the positions of the stars had changed. More than a thousand years later, in the18th century, the same phenomenon appeared independently in Harley, England. It turns out that the so-called "star" is called wrong. The stars in the sky are moving and changing.
1834, an astronomer noticed that Sirius, the brightest star in the sky, was moving strangely, and its trajectory was wavy, unlike ordinary stars, which always moved at a constant speed along a straight line. The astronomer therefore asserted that Sirius is not a star, but a binary star system, and the other star is an "invisible" companion star. The undulating course of the waves is the result of Sirius wandering while moving. Later, some astronomers studied the motion of Sirius and predicted the position of Sirius according to the law of universal gravitation. Twenty-eight years later, this "invisible" Sirius companion was finally found in the telescope. Compared with Sirius, this "invisible" companion star is too dark. In the telescope, it seems that the illusion is caused by the defect of the telescope. However, when observing other celestial bodies, this "defect" is gone, and everyone believes that they have found Sirius's "invisible" companion.
The two stars that make up a binary star are both called children of the binary star. The brighter one is called the main star. The darker one is called a companion star. There is little difference in brightness between the main star and the companion star, and some are very different. There are many binaries, which are very close to each other. Even with the largest telescope in modern times, their two sub-stars are inseparable. But astronomers can find that they are made up of two stars by spectral methods. Such binary stars are called spectral binary stars. Therefore, the above binary stars can be separated by telescopes.
Some binary stars will appear similar to solar eclipse when they orbit each other, which makes the brightness of such binary stars change periodically. This binary star is called eclipsing binary star or eclipsing binary star. Eclipse binaries are generally spectral binaries. Other binary stars are not only close to each other, but also matter flows from one sub-star to another. This binary star is called near binary star. Some nearby binaries emit X-rays when matter flows, which are called X-ray binaries.
In the Milky Way, there are many binary stars, which are estimated to be no less than a single star. Studying binary stars is not only of great significance to understand the diversity of star formation and evolution, but also an indispensable aspect to understand the formation and evolution of the Milky Way.