What is the first star to appear at night? What is the brightest star?

Sirius

The brightest star in the night sky, with a visual magnitude of -1.45. It is a double star in the constellation Canis Major. The leonon star in the binary star is a blue-white star that is 23 times brighter than the sun. Its volume is slightly larger than the sun, and its temperature is much higher than the sun. It is about 8.6 light-years from the solar system, only twice the distance of the nearest star other than the sun. The ancient Egyptians recognized that the star rose with the Sun, which meant that the annual flooding of the Nile Delta began just before the sun rose. Moreover, they discovered that the time interval between Sirius rising with the sun was not 365 days in the Egyptian calendar year but 365.25 days. In 1844, the German astronomer Bessel inferred that Sirius was a binary star based on the wave pattern appearing in its moving path. Because the star moved along a wave-shaped trajectory in nearby space, he concluded that it had a companion star and orbited it. The conclusion is that the cycle is about 50 years. This companion star was first seen by American astronomer A. Clark in 1862 using his self-made 4.7m refractor telescope, which was the largest at the time. Sirius and its companion stars revolve around each other in highly eccentric orbits, with an average distance of about 20 times the distance between the sun and the earth. Although the bright star shines brightly, it is not difficult to see the 7th magnitude companion star with a large telescope. The companion star is about the same mass as the sun and much denser than the sun. It is the first white dwarf star to be discovered.

Sirius is Alpha Canis Major and is the brightest star in the sky. Sirius is a visual double star composed of two stars, A and B. Star A is the brightest star in the sky and is a blue dwarf star on the main sequence. Star B is generally called the Sirius companion star. It is a white dwarf star with a mass slightly larger than the sun and a smaller radius than the earth. Its material is mainly in a degenerate state, with an average density of about 3.8×106/cubic centimeter. The orbital period of 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 from us. Whether Sirius is a close binary star is related to the evolution of the Sirius binary star. It was recorded in ancient times that Sirius was red, which provides us with research clues. X-rays from Sirius were discovered in 1975. Some people think that this may be thermal radiation from the deep atmosphere of the almost pure hydrogen atmosphere of Star B. Some people think that it may be generated by the high-temperature corona of Star A or Star B. This is still going on today. Research. According to data from 1980, the High Energy Observatory Satellite No. 2 measured the X-rays in the 0.15-3.0 kiloelectronvolt band of Star A and Star B respectively, and found that the X-rays of Star B were much stronger than those of Star A

Winter Starry sky, looking to the southeast from the three stars of Orion, one of the brightest stars in the sky is shining there. It is the Alpha Canis Major star, which was also called Sirius in ancient my country. Sirius has an apparent magnitude of -1.45m and is only 8.6 light-years away from us.

In ancient Egypt, every time Sirius rose from the eastern horizon at dawn (this phenomenon is called "sunrise" in astronomy), it was the time when the Nile River flooded once a year. The flooding of the Nile River irrigated large areas of fertile land on both sides, so the Egyptians began farming again. Since the appearance of Sirius was closely related to 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.

We know that the pyramids were conceived and built from the perspective of astronomy. Since ancient Egyptian astronomy is not well-known, doesn’t this opinion seem a bit forced? Sirius is one of the few planets related to the pyramids. However, it is precisely this kind of attention to Sirius that makes people feel quite strange. Because when people want to observe Sirius from the city of Memphis, they can only see it in the vast morning light close to the horizon when the Nile River floods. There is a book in Egypt The detailed almanac - from 421 BC, is enough to make people feel confused! This almanac is based on the rising of Sirius (first appearance is July 19), and determines the annual cycle as more than 32,000 years.

We admit that ancient astronomers did not have time to observe the sun, moon and celestial bodies for eternity. Finally, they reached a consensus and believed that all celestial bodies would settle in the same place after about 365 days of movement. However, from then on Isn't it ridiculous that the first almanac was derived from Sirius data? Completely ridiculous! Because it was much easier for them to deal with the sun and moon, and they could get more accurate results. The "Sirian Almanac" seems completely It is a product of pure assumption, a calculation of probability, because it has indeed never been able to predict the appearance of a planet: the flooding of the Nile and the associated phenomenon, the appearance of Sirius on the dawn-shrouded horizon, were purely accidental. The Nile was not It floods every year, and the Nile does not always flood on the same day. Why on earth did a "Sirius Almanac" appear? An ancient document also appeared in this regard? Was it carefully hidden as a secret by ancient priests? What about the scriptural information or promises? We have no way of knowing.

In the constellation Canis Major, Sirius is the brightest star among them

Sirius’s companion star, β, was the first discovered by humans. White dwarf. It is very small in size, about the same size as the Earth, and invisible to the naked eye; but extremely dense, 30,000 times larger than Mercury, and about the same mass as the sun. This star was observed by astronomers using a telescope in 1862, and was only identified in 1915 Its identity as a "white dwarf" has attracted great attention from the astronomical community. However, at least 1,200 years ago, the Dogan tribe in Mali, Africa, began to worship this star and knew its volume, density, and orbital shape. (ellipse) and its period around Sirius (forty-nine Earth years), these are recorded on the woodcuts, murals and textiles of this primitive tribe.

It is said that a man named "Nomo" "The god who imparted the knowledge about Sirius Beta to the Dogan people. The Dogan people preserved a painting. The picture shows the god they believe in riding a large spaceship dragging flames, descending from the sky and arriving at the Dogan tribe. . Therefore, people speculated that the "Nomo" might be an alien who came to the earth from the Sirius β star (or a star related to it).

When it comes to the Sirius companion star β, we have to Tell the story that happened from it, because many major discoveries often start from some small "deviations".

In the eighth century BC, an astronomer from the Tang Dynasty of China and his party made his observations Comparing it with ancient records, it was found that the positions of the stars had changed. More than a thousand years later, in the 18th century, the British Halley also independently saw the same phenomenon. It turns out that the so-called immobile and unchanging "stars", Wrong call. The stars in the sky are moving and changing.

In 1844, astronomer Bessel noticed that Sirius, the brightest star in the sky, was moving strangely and its path was undulating. , unlike ordinary stars that always move evenly along a straight line. The astronomer thus concluded that Sirius is not a star, but a binary star system, and the other star is an "invisible" companion star; Wave The undulating course is the result of Sirius moving and rotating. Later, some astronomers studied the movement of Sirius and predicted the position of Sirius based on the law of universal gravitation. Twenty-eight years later, in 1862 In 2006, the "invisible" companion star of Sirius was finally found in the telescope. Compared with Sirius, this "invisible" companion star is too faint. In the telescope, it looks like it is caused by the defect of the telescope. The illusion is the same. But when observing other objects, this "flaw" disappeared, and everyone believed that they had found Sirius's "invisible" companion star.

The two stars that form a binary star are called binary stars. The brighter one is called the main star; the dimmer one is called the companion star. Some of the brightness differences between the main star and the companion star are not much different, and some are very different. There are many double stars, which are very far apart from each other. Even with the largest modern telescopes, it is impossible to distinguish their two sub-stars. However, astronomers can find that they are composed of two stars using spectra obtained by spectroscopic methods. Such binary stars are called spectroscopic binary stars. Therefore, the above-mentioned double stars whose two sub-stars can be distinguished with a telescope are accordingly called visual double stars.

Some double stars will have a solar eclipse-like event when they orbit each other. phenomenon, which causes the brightness of this type of binary star to change periodically. Such a binary star is called an eclipsing binary star or an eclipsing variable star. Eclipsing binary stars are generally spectroscopic binary stars. There are also binary stars that are not only very close to each other, but also have matter from them. One sub-star flows to another sub-star. Such a binary star is called a close binary star. Some close binary stars emit X-rays when matter flows, which is called an X-ray binary star.

In the Milky Way Galaxy , the number of binary stars is very large, and it is estimated that it is no less than single stars. Studying binary stars is not only important for understanding the diversity of star formation and evolution processes, but is also an indispensable aspect for understanding the formation and evolution of the Milky Way.< /p>