Seek the myth about Sirius.

In ancient Rome, in July every year, when the dog star first appeared from the horizon in the morning, people always offered red-haired dogs as their sacrifices. Their poets wrote, "Mars sparkles with mild red light, but the red of the dog star is stronger than it." Many famous classical writers described the light of the dog star as red. Even before 1 BC, Babylonians also used their cuneiform characters to record the color of this star as red.

This dog star is what we call Sirius today. Sirius is located in Canis Canis, and its scientific name is Canis Canis. 2. It is the brightest star in the night sky and one of the closest stars, less than 9 light years away from us. But the Sirius we observed today is not red, but white. Are ancient astronomers wrong?

Some scientists think that Sirius was observed by ancient astronomers when it was close to the horizon, and just like the sunset, Sirius was also red because of the refraction of the earth's atmosphere.

However, the astronomer Schlossa of the Federal Republic of Germany and the historian Bergevin disagreed. They think that Sirius observed by ancient astronomers was really red until the sixth century. The two scholars jointly published an article in Nature. They studied the chronicles made by Bishop Gregory of Dull in the early Middle Ages in 577 AD. In order to provide correct morning prayers for monasteries at that time, Bishop Gregory listed the moments when some constellations rose from the horizon every month in his volume. After studying the rising times of these stars in the chronicles and the moments when they disappeared in the morning light, I recognized that one of the stars was Sirius. Bishop Gregory called this star "Rubiola", which means "red" or "rust color". They pointed out that Gregory did not have a traditional star name, probably because he was not familiar with the astrological knowledge of ancient Greece and Rome. Therefore, the two federal German scientists came to the conclusion that Sirius was still red before 14. However, about 4 years later, In the catalog made by Arabian astronomer Al Sufi, Sirius was not included in the category of red stars, so Sirius changed its color in about 4 years.

In the 19th century, astronomers discovered that Sirius was originally a binary star. It had a companion star called Sirius B. Because Sirius B was too dark, we couldn't see it with the naked eye. It was a white dwarf. It's a dying planet.

Astronomers believe that an old planet will cool and expand into a red giant before it becomes a white dwarf. The two Federal German astronomers said that what ancient astronomers observed was Sirius B. Because ancient astronomers observed it with the naked eye, they could not distinguish Sirius A from Sirius B's dazzling red light during the day. Because the light of the two stars was added, So Sirius was particularly bright at that time. The cuneiform writing of the ancient Babylonians recorded that Sirius could be seen from the daytime sky.

The evolution of Sirius B into a white dwarf can be gradual or sudden, depending on the original mass of Sirius B. Most astronomers believe that it takes about 1, years for a red giant to gradually evolve into a white dwarf. So if Sirius B gradually evolves into a white dwarf within 4 years, This period of time is surprisingly short. If Sirius B suddenly collapsed, then this process should be accompanied by a big explosion of Sirius B and throw most of its stellar matter into space. But we can't observe any clues of this explosion. For example, we should observe an outward expanding gas cloud ring around Sirius B. Moreover, The outbreak of Sirius B will definitely cause Sirius to suddenly become very dazzling in a few weeks or months, which will leave a deep impression on people on earth. But so far, we have not found any written records about this outbreak.

There is a clue that may be pursued. The spectral analysis of Sirius A shows that the metal content of Sirius A is higher than the normal content of similar planets. Scientists point out that, This extra metal composition may have been sprayed on Sirius A when Sirius B broke out and absorbed by Sirius A. Anyway, Shloxia said, "Because of the study of Sirius, we may have to rewrite the theory of celestial evolution."