Where is Canis Canis in the starry sky?

Canis Canis is one of the constellations in the southern sky in winter, which is located in the southeast of Orion and just east of Scorpio. Sirius, the brightest star in the whole day, is very easy to identify.

Canis major is a small constellation 1 in the southern sky, but it is very eye-catching because of Sirius, the brightest star in the whole day. The whole constellation, like 1 a galloping hound, is pouncing on the celestial constellation on its west side. Sirius is located on the nose of the hound, and the big dog ε star (China called Sagittarius VII) is as bright as 1, just in the abdomen of the hound, while the big dog β star (Juncheng I) is located on 1 foot of the hound. Although the whole constellation is small, it is very bright. Canis major has 122 stars of magnitude 6 or above.

According to ancient Greek myths and legends, after the hunter Oliver was killed by his lover Al themis, his hound Cyrus was very sad. It hasn't eaten all day and cried sadly. Finally starved to death in the master's house. This touched Zeus, who lifted him to the sky and became Canis major. Canis Canis followed closely by Orion, indicating Ju Lushi's loyalty to his master.

It is said that Zeus raised 1 cunning rabbit into the sky to keep Orion and his hounds hunting in the sky, becoming a rabbit constellation. In the traditional star official system in China, Canis Canis is equivalent to a military city and a part of the arrow. For example, Canis major is called Jun Shiyi, Canis major δ is called Arrow One, Canis major η is called Arrow Two, Canis major ε is called Arrow Seven, and so on. At 8: 00 pm on February 26th every year, Canis Canis reaches the zenith.

Alpha Canis is called Sirius in China. In ancient times, people regarded it as an evil star which was the main symbol of aggression. The great patriotic poet Qu Yuan wrote in Dong Jun: "If you raise your long arrow, you will shoot at Sirius, but if you hold the remaining arrow, you will fall down." Comparing Sirius to the powerful Qin State, I hope I can "shoot Sirius" and kill people. There is such a record in Historical Records: "There is a big star (Betelgeuse) in the east of it, named Wolf. Wolf horns change color, and there are many thieves. " "Jin Shu Tian Wenzhi" records: "The wolf is in the east of Tokyo. The wolf is a wild general and invades. " Li Bai, a famous poet in the Tang Dynasty, wrote such a poem: "Who is the famous Bing Gu? It's a pity that the soldiers are exhausted. Sirius died, and the father and son were at ease "("Humaksong in Youzhou "), comparing Sirius to Xiongnu who often committed border invasions.

Canis major. The Spanish name is Sirius, which comes from Greek and means "burnt". Ancient people may think that Sirius is called Sirius because it is summer when Sirius and the sun rise from the east almost at the same time (this phenomenon is called rising together), and the combination of Sirius's light and sunlight is the reason for the hot weather in summer. The ancient Egyptians called Sirius Sothis, which means "the star on the water". In Egypt, it is also the season and festival when the Saucisse rises from the east from summer to around every year. Sotheby's was regarded as a god and worshipped by the Egyptians because he could predict the flood of the Nile. The main entrance of many temples faces the rising direction of Sirius. The ancient Egyptians also set the rising period of Sirius as 1 year, and set the day before dawn when Sirius rose from the east as the beginning of the year. The ancient Romans called Sirius the dog star, and called July 3rd (the date of Sirius sunrise) to August 1 1 as dog day.

Sirius is the brightest star in the sky with an apparent magnitude of-146. This is not only because of its strong luminous ability (absolute magnitude is 142 and so on). And the luminosity is 2 1 times that of the sun), and because it is close to the earth, it ranks 15 among the stars close to the earth, with a distance of 865 light years. It is a white A 1 main sequence star (AW) with a surface temperature of 9970 degrees Celsius and a diameter of 16 times that of the sun. Because of its great motion, it moves1"328 on the celestial sphere every year, which makes the British astronomer Harley discover the motion of the star itself and break the concept that the star is eternal for the first time in the history of human understanding. 17 18, Harley compared the coordinates of the stars he measured on the island of St. Helena in the South Atlantic with the catalog of the ancient Greek astronomer Hippocrates, and found that the coordinates of Sirius (as well as arcturus and Bi Su Wu) were quite different from those measured by ancient Greek astronomers. After further comparative study between Harley and other catalogues, it is concluded that the star well is not eternal, but also moves in space. People call the angular distance of a star's annual displacement on the celestial sphere automaticity. It is the projection of the space motion of stars on the celestial sphere.

1844, German astronomer Bessel carefully measured the position change of Sirius star and found that it moved along a wavy curve with a period of 50 years. Obviously, Sirius should move in a straight line without the influence of other celestial bodies. What caused Sirius to vacillate? Before Bethel died, he made a scientific judgment: Sirius must be a binary system with 1 weak companion. The center of mass of the binary star walks in a straight line, and Sirius rotates around the center of mass of the binary star, so its trajectory is wavy. Since Bessel proposed that Sirius had a companion star, many observatories began to observe the movement of Sirius. KP Peters of pulkovo observatory, Russia, calculated the orbit of Sirius companion star according to the observation data, and estimated its relative position with Sirius main star in advance. 1862, Clark, an American telescope manufacturer, aimed the telescope at Sirius when testing the objective lens of the telescope with a diameter of 508 cm, and found 1 dark star of about magnitude 8 next to Sirius. The position of this constant star is almost identical to the position of Sirius companion estimated by Peters in 1862, thus confirming Bessel's prediction. To this end, Clark Jr. won the medal of the French Academy of Sciences. By the way, Clark and his son are geniuses in grinding lenses. At that time, many famous observatories in the world, such as the Washington Naval Observatory, the American Lick Observatory, the Lowell Observatory, the Yekeshi Observatory, and the Russian pulkovo observatory's Large Refractive Telescope, were founded by their father and son.

Since Sirius's companion star was observed by telescope, people have calculated the sum of the masses of two stars (34 times the mass of the sun), the mass of each star (25 solar masses of the main star and 095 solar masses of the companion star) and the orbit of the companion star around the main star (the average distance between the two stars is 20 astronomical units) according to the observed data and the distance R of Sirius. In addition, the absolute magnitude m of the companion star is calculated from its apparent magnitude m (87, etc.). ) (use the formula m: m+5-5 1gr). The results show that the absolute magnitude m of Sirius companion is 1 15, etc. That is to say, the luminosity of Sirius's main star is about 10000 times that of Sirius's companion star! Under the cover of bright Sirius, it is difficult to see Sirius's companion star;

We know that the luminosity (absolute magnitude) of a star mainly depends on two factors. One factor is its surface temperature. The higher the surface temperature, the greater the luminosity. Another factor is the surface area of the star. The bigger the star, the greater the luminosity. Sirius's companion is a white A star (A5). In other words, its surface temperature is almost the same as that of Sirius's main star. So the difference of luminosity between them mainly depends on the difference of surface area. At the same surface temperature, the same area can emit the same light. The brightness of Sirius' companion star is only one tenth of that of Sirius, which means that the surface area of Sirius' companion star is only one tenth of that of 65438+ Sirius. In other words, the radius of the companion star is only 1% of the radius of the main star. It is known that the radius of Sirius is 16 times the radius of the sun, that is, 16×696000 km, so the radius of Sirius' companion star is about 1 1000 km. As mentioned earlier, the companion star mass of Sirius is 095 solar mass, and the mass of 095 solar mass is compressed into a ball with a radius of 1 1000 km, and the density is almost several million times that of water! The result seems incredible, but every step of our calculation is beyond doubt. When a strange conclusion is reached in science, people often ask whether there is any other way to confirm this seemingly incredible result. Einstein's theory of relativity points out that when photons leave the surface of the star, they will lose some energy when they leave the gravitational control of the star. As a result, the wavelength of photons will become longer, that is, the spectral lines of the star spectrum will move to the red end. This phenomenon is called gravitational redshift. Redshift is proportional to the mass of the star and inversely proportional to the radius of the star. The actual measurement of the gravitational redshift of Sirius companion proves that the mass and size of Sirius companion are almost the result of the above calculation. This makes people have no doubt that Sirius's companion star is indeed two dense celestial bodies.

Because of the color (white), weak luminosity and small radius of Sirius companion star, people call this kind of star a white dwarf. Hundreds have been found near the sun, so it is inferred that there are many white dwarfs in the Milky Way.