In 1676, Edmund Halley spent a year on the island of St. Helena in the southern Atlantic Ocean to study the stars in the Southern Hemisphere. Some 40 years later, in 1718, after comparing his astrometric measurements with Ptolemy's Almagest Astronomical, he discovered the self-motion of stars that had been considered "fixed" for a long time. Both Arcturus and Sirius moved significantly, with Sirius moving 30 minutes south (about the diameter of the Moon) in 1800 years.

In 1868, Sirius became the first star to have its orbital rate measured. William · Sir Huggins carefully examined Sirius' spectrum and observed a significant redshift. He therefore concluded that Sirius was moving away from the solar system at a speed of about 40 km/s. Although it is a large difference from the 7.6 km/s velocity value measured in recent times, this measurement began the study of the radial velocity of the celestial body.

However, the latest observations suggest that Sirius is approaching the solar system, and that its apparent magnitude will peak in about 6 × 10^4 years, when Sirius will become very bright. After that it will gradually move away from the solar system, but for 2.1 × 10^5 years after that, it will remain the brightest star in the sky after the Sun.

Sirius Observation MethodEdit Sirius has an apparent magnitude of about -1.46, making it the brightest star in the night sky and almost twice as bright as the second brightest old star. However, it is still not as bright as the Moon, Venus, or Jupiter. Mercury and Mars are also occasionally brighter than Sirius. Sirius can be observed from almost any manned place on Earth, except for people who live north of 73°N. However, some cities on the north side of the Earth do not see Sirius rising very high, such as St. Petersburg, where Sirius rises only 13° above the horizon. Since Sirius has an declination of about -17°, it is an arch star from 73° south latitude. Sirius can be seen from the Southern Hemisphere in early July as it goes down after the sun goes down and rises again just before the sun rises. Under the right environmental conditions, Sirius can even be seen by the naked eye when there is a sun. Of course, the sky must be very clear, the altitude of the observation site must be high, the sun must be low on the horizon, and Sirius must be overhead, which is very rare.

Based on the orbit of the Sirius binary star system, the two stars have a minimum distance of 3 arc seconds and a maximum distance of 11 arc seconds. When they were closest to each other, it was difficult to separate the two stars in the observation, because the white dwarf Sirius B was next to Sirius A, which was so close to it but much brighter than it. To clearly separate them, an astronomical telescope with an aperture of at least 300 mm is required, except in ideal weather. In 1994, the two stars reached their apron, and from that time on, the pair of binaries began to move away from each other, and it was easier to separate them with an astronomical telescope. At a distance of 8.6 ly from Earth, Sirius A and Sirius B occupy two of the eight closest stars to the Solar System, and the fifth closest star system to the Solar System.

Although Sirius is only 25.4 times brighter than the Sun, its proximity is what makes Sirius so bright. Other similar stars include the dim South Gate II, compared to distant but extremely bright supergiants such as Old Man, Betelgeuse or Betelgeuse. The closest large star to Sirius is the South River Tri at a distance of about 5.24 ly. The Voyager 2 spacecraft, launched in 1977, is expected to reach Sirius 8.6 miles away in about 2.96 × 10^5 years after completing its mission to study four Jupiteroids.

Sirius AEdit Sirius A is a blue dwarf star with a radius of about 1.711 R⊙. The radius of the star was measured by an optical interferometer and the estimated angular diameter was 5.936 ± 0.016 mas. It rotates at a speed of about 16 km/s, so it does not effectively flatten the star into an ellipse. Vega rotates at a higher speed of 274 km/s, making it an oblate sphere.

Celestial models indicate that Sirius A was formed during the collapse of a molecular cloud, and by 10^7 years later, its energy generation was entirely provided by nuclear fusion. Its core becomes the troposphere, which uses the C-N-O cycle to produce energy. It is predicted that Sirius A will run out of hydrogen stored in its core within 1.76 × 10^9 years after its formation. At this point, it goes through the red giant phase, when Sirius A will have a great increase in luminosity. Then it will moderate down and become a white dwarf.

The spectrum of Sirius A has deep metallic lines that show enhancements of some elements heavier than helium (such as iron), so it is also classified as an Am star. Compared to the Sun, Sirius A's atmosphere contains Fe/H = 0.5 in relation to hydrogen, which is also equal to 100.5, meaning that the iron content in its atmosphere is 316% that of the Sun. It is unlikely that the entire star is rich in metals, which may be suspended in a thin troposphere on the surface.

Sirius BEdit Sirius B has a mass greater than the mass of the Sun and is one of the most massive white dwarfs known. It has almost 1.1 M⊙. Yet so much matter is compressed to about the size of the Earth. Its surface temperature is 25000 ± 200 K. However, since there is no energy generated inside, the remaining heat will radiate out of outer space, and Sirius B will eventually cool down, which will take more than 2 × 10^8 years.

A star does not become a white dwarf until it passes through the main-sequence and red giant phases. About 1.2 × 10^8 years ago, Sirius B may have been a more luminous blue dwarf with a spectrum between B4-B5 and a mass of about 5M⊙. When Sirius B becomes a red giant, it may have increased the amount of metal in its companion planet, Sirius A.

Sirius B was originally composed of carbon and oxygen, which were produced by the fusion of helium nuclei in the dead star that formed Sirius B. These elements are covered by lighter elements and layered according to mass, as Sirius B has a high surface gravity. As a result, Sirius B's outer atmosphere is almost pure hydrogen, the lightest element in the universe, and nothing else can be found in the spectrum.

Sirius Cluster of SiriusEditor in 1909 Eichner Herzplon was the first to propose that Sirius is one of the moving asterisms in the constellation Ursa Major, and he came to this conclusion after observing the path of the Sirius system in the sky.

The Ursa Major moving cluster is made up of 220 stars and has the same path of movement in space. It was first formed as part of an open cluster and has since been gradually detached from gravitational traction. However, analyses made in 2003 and 2005 suggest that Sirius may not belong to this cluster. The Ursa Major moving cluster is estimated to be 4 × 10^8 ~ 6 × 10^8 years, while Sirius has a similar amount of metal to that of the Sun, so it may only be 2 × 10^8 years old, which is too young for this cluster.

Sirius may belong to a proposed "Sirius cluster", and other scattered stars that may belong to this cluster are β Auriga, α Corona, β Giant, β and Serpenti β. This cluster is one of three star clusters within 500 light-years of the Sun. The other two are the Pleiades and the Pleiades, each with hundreds of stars.

Sirius Constellation CultureEdit Origin of the name Sirius

Sirius's western name Sirius, derived from the Greek Σείριος, has the meaning of "burned", its first sun rises after the summer heat comes, the ancients believed that Sirius and the sun rose at the same time when it was summer, Sirius's light and the sun's light together, is the reason for the hot summer weather, so the Sirius was called Sirius. The ancient Greeks called summer "dog day" because only dogs would run out like crazy in such hot weather, so this star is also called "dog star".

Sirius astronomical coordinates The ancient Egyptians called Sirius Sothis, which means "star on the water." Sirius's formal name in English comes from the Latin Sīrius and the ancient Greek ∑εριο (Seirios means "hot" or "hot weather"), but it is also possible that the Greek word developed somewhere before the Greek Archaic period. The earliest discovery of the use of the name dates back to the 7th century BC in Hesiod's poem Work and Time.

Sirius has more than 50 other numbers and names. In Arabic, Sirius is called "ㄆ" (pinyin: al-椁'rā or al-shira, Chinese: "chief"), from which the English name Aschere derives. In Sanskrit, Sirius is Mrgavyadha ("deer hunter") or Lubdhaka ("hunter"). Sirius represents Rudra (Shiva) when it is called Mrgavyadha, and in Scandinavia, Sirius is considered Lokabrenna ("Rocky's fire" or "Rocky's torch") and in Japanese language it is called Aoboshi. In medieval astrology, Sirius was a Behenian fixed star.

Sirius Poetry Records

From the first year of Song Renzong Tiansheng to the fourth year of Song Shenzong Yuanfeng was the "Chengping" period of the Northern Song Dynasty, and it was also the "Chengping" period of Su Dongpo. Although Su Dongpo has been wandering in the sea since he left Shu, and has served in Fengxiang, Hangzhou, Mizhou, Xuzhou, and Huzhou, Su Dongpo has not lost hope in the Northern Song Dynasty court during this period, and still expects to be reused by the court and show his political ambitions. This kind of political enthusiasm and life ideals are not uncommon in his poems.

Among the several Jiangchengzi poems filled by Su Dongpo, two of them are influential, "Jiangchengzi · "Hunting in Michigan" is a more typical song. Said typical because this poem can be regarded as Su Dongpo's first bold words, after writing he himself is also very proud of his work, a few days later he wrote to his friend Xian Yu Zijun in the letter said: "Recently, but quite a small word, although there is no Liu Qilang flavor, it is also a family, hehe." A few days ago, I hunted in the suburbs and caught a lot. Make a bang, so that the strong men of Dongzhou stand up to the palm and sing, play the flute and beat the drum as a festival, quite spectacular!"

Looking northwest, shooting the wolf, the old man chatted about the youthful madness, the left led the yellow, and the right Qingcang.

Brocade hat mink fur, thousands of horses roll flat gang.

In order to repay the city, follow the Taishou, shoot the tiger in person, and watch Sun Lang.

The wine is still open, and the temples are slightly frosty, so what's the matter!

In the clouds, when will Feng Tang be sent?

Will hold the bow like a full moon, look northwest, and shoot the wolf.

("Jiang Chengzi · Michigan Hunting)

This word was made by Su Dongpo when he was appointed as the Taishou of Mizhou, although he was already old and standing, he was not considered old. But why do you call yourself an "old man"? Su Dongpo later made a statement in Huangzhou: "If you are amorous, you should laugh at me, and you will be born early." ("Nian Nujiao · Chibi Nostalgia ") may be the reason why Dongpo calls himself an "old man". Regardless of the reason for Su Dongpo's "old man" words, and look at his ambition and feelings of serving the country. "Look northwest and shoot the wolf. It refers to the Western Xia regime located in the northwest of the Northern Song Dynasty during the Northern Song Dynasty. The Northern Song Dynasty signed a peace treaty with the Western Xia after the alliance of the Yuanyuan, sending 72,000 taels of silver, 153,000 horses of silk, and 30,000 catties of tea to the Western Xia every year, which caused the Northern Song Dynasty to be poor and weak for a long time. The people with lofty ideals in the Northern Song Dynasty were even more ambitious, hoping to pacify the Western Xia as soon as possible and change the situation of poverty and weakness.

The whole word is magnificent, and through the entertainment activity of going out of the city to hunt, it shows the lofty ambition of a literati who is determined to resist the enemy and serve the country and pacify the country.

The last sentence "look northwest, shoot the wolf" is worth scrutinizing, if you think that it is "looking northwest" from the geographical location where Su Shi was at the time, it would be wrong. Because Sirius is located in the Southern Hemisphere, it will never be located in the northwest from the Northern Hemisphere of the Earth. "Justice": "The arc of nine stars, in the southeast of the wolf, the bow of the sky also." "History of the Song Dynasty · Astronomical Chronicles: "The nine stars of the arc are in the southeast of Wolf Star, and the heavenly bow is also. That is, Sirius is in the northwest of the arc. Therefore, Su Shi used "looking northwest", which was said from the position of the nine stars of the arc.

Similarly, "Chu Ci · Nine Songs · There is a sentence in "Dongjun" "Qingyun is dressed in white clothes, and he shoots the wolf with a long arrow". It was Qu Yuan who used Sirius to allude to Qiang Qin, who was in the northwest of Chu at that time.

Su Shi's poems expressing a similar mood of "looking northwest, shooting the wolf" also include:

No one knows the warriors in Hexi, and the sunset Jinting has read the boat.

Passers-by felt that the horse was thin, and they did not know that the iron lance was as big as a rafter.

Because he said that the West had not fought for a long time, he was willing to be the first to be the first of ten thousand horsemen.

I should rely on Shi and fable to watch Jun Fei Yaji collect the blanket.

(Guo Lun)

The chaotic mountains surround the ancient capital, and the city is easy to bring the barbarians.

There is little spring ploughing in the thin ridge, and the night dew in the lonely city.

There was a police officer on the side, and there was no return to the horse.

Since Conghua, the years have also been closed.

He is quite greedy for Han cloth, but he has not taken off the gold rod.

He is strong and weak, and my people are all beautiful.

(Rongzhou)

Sirius Ancient Egyptian Culture

In ancient Egypt, when Sirius rose over the eastern horizon at dawn (a phenomenon known in astronomy as "rising with the sun"), it was the annual time of the Nile flood, which irrigated large tracts of fertile land on both sides, and the Egyptians began their cultivation again. The ancient Egyptians recognized that the Nile Delta began its annual flooding as the star rose and the sun rose. And they found that the time interval between the two sunrises of Sirius was not 365 days in the Egyptian calendar year, but 365.25 days. Ancient Egypt identified the day Sirius rose in the east before dawn as the year head. It can be said that the predecessor of the "Gregorian calendar" that we use was first born in ancient Egypt.

Sirius (rendering) We know that the pyramids were conceived and built from an astronomical point of view. Sirius is one of the few planets associated with the pyramids, but it is precisely this focus on Sirius that makes people feel rather strange. For, when one were to observe Sirius from the city of Memphis, it could only be seen in the faint morning light near the horizon at the beginning of the Nile flooding. There is a detailed almanac in Egypt from 421 B.C., which is confusing enough! This almanac is based on the rising of Sirius (the first appearance is July 19) and has a year period of about 3.2 × 10^4 years. (Controversy: The Sirius Almanac appears to be entirely a product of pure hypothesis, a calculation of probability, for it is true that it has never been able to predict the flooding of the Nile and the associated phenomena associated with it, i.e., the appearance of Sirius on the horizon shrouded in the morning light, purely by chance.) The Nile does not flood every year, and the Nile does not always flood on the same day. Why is there a Sirius almanac? There is also an ancient source of material in this regard? Is there any scriptural material or promise that was carefully concealed by the ancient priests as a secret? We have no way of knowing). In Egypt, almost all religious buildings and funerary buildings are oriented to astronomical significance. One of the celestial bodies that was aligned by the Egyptians with a collimator was Sirius. Many temples face this star (e.g. the Temple of Hator in Dandra).

Sirius is the brightest star in the night sky and is easy to find. However, this feature alone is not enough to explain the whole story. The architects have kept in mind this exact location: the position of Sirius in the sky near July 15. In ancient Egypt, Sirius returned to the sky at this time of year. We don't need to study astronomy to understand this: the Earth's orbit around the Sun and the Earth's rotation cause the stars in the night sky to change from night to night. When night falls, some of the stars rise later until they disappear from the night sky for several weeks, and then return to the sky. The fact is that every year in mid-July, after 70 days of "escape", Sirius "reappears". Before sunrise, it appeared in the faint morning light, shining in the Egyptian sky. However, as it happens, the annual Nile high tide - an important event that is indispensable in the life of Egyptians also takes place at this time. Every year in mid-July, when Sirius rises in the east before dawn, the Nile River begins to flood. Some of the silt overflows the riverbed with the water, moistening the surrounding land. When the tide recedes, farmers begin to sow seeds on the fertile soil. All agricultural production in Egypt is closely related to the ebb and flow of the Nile. As a result, the Egyptians worshipped Sirius as a god, and even built temples in the same direction as Sirius rose.

There is also a related puzzle, which is related to Sirius. The ancient Egyptians loved to associate Sirius with Isis. Isis is the sister and spouse of Osiris and the mother of Horus. There is a passage in the pyramid verse that is written precisely about Osiris:

Your sister Isis is here, you are happy, you love. You put her on top of you...... Because of the child, Isis grew up, like Sept (referring to Sirius). Horus · Horus Sept was born in the name of the inhabitants of Septus.

Perhaps we could interpret this text in a variety of ways. But the most interesting thing is obviously the hint of her "dual identity" from "Isis has grown up because of having children". Not only that, but after the child was born, Horos did not leave, but stayed and became a "resident of Sept".

An unusual star, Sirius shines exceptionally brightly on winter nights in the Northern Hemisphere. As the pyramid verse indicates, it has a dual planetary system identity: what we see is Sirius A. Sirius B surrounds Sirius A, but it's just too small and too low to be visible to the naked eye. American astronomer Alvin Alvin Clark didn't discover it until 1862, using the largest and newest celestial telescope at the time. It was also the first time the world had seen Sirius B. However, how did the writers of the pyramid verses learn that Sirius is a two-star system?

Both the ancient Egyptians and the "gods" must have spent a lot of time observing celestial phenomena, especially Sirius. Ancient Egypt had a very convenient concept of the Sirius cycle calendar, which they believed to be given by the gods (the ancient Egyptian calendar had a cycle of 1460 years and the solar calendar had a cycle of 1461 years).

The so-called Sirius cycle is "the cycle in which Sirius rises again in the same place as the Sun". During the regular season, Sirius disappears from the sky and then rises again from the eastern sky before the sun rises to dawn. In terms of time, if you divide the mantissa of the decimal point, the period is 365.25 days. What is particularly surprising is that of the 2,000 stars we can discern with the naked eye, only one star rises at the same time as the Sun on an exact 365.25-day cycle, which is also the result of Sirius's "propermotion" (the speed at which the planet moves in the universe) and precession. At the same time, in the ancient Egyptian calendar, the day when Sirius rose before the sun was specially designated as New Year's Day. Previously, in Heliopolis, the place where the pyramid verses were written, the ancient Egyptians had calculated the coming of New Year's Day and informed all the temples on the Nile.