Where is Sirius? What is it like?

When Orion, the representative of the winter constellation, climbs to the highest peak of zenith, a bunch of bright stars can be seen at the lower left, shining above the horizon in the southeast. This pile of bright stars are hounds, dogs and dogs, and Orion is nearby when hunting outside. You should find this big dog easily, because Sirius, the brightest star in the night sky, is located in Canis major.

Sirius is the brightest star seen by the naked eye except the sun. Its Latin name is Sirius, which comes from the Greek word "brilliant". The brightness of Sirius is-1.6, which is almost ten times that of the so-called first-class star. Even the famous Summer Triangle is only a quarter as bright as Sirius, so Sirius has how bright. Sirius is so bright, not only because its diameter is 1.76 times that of the sun, but also because its light quantity reaches 30 times that of the sun.

When we watch Sirius, the brightest star in the winter night sky, we will find that it emits strong blue-white light, which indicates that its surface temperature exceeds 10000 degrees. Astronomers analyze the spectrum of Sirius and discuss its physical state. They think Sirius was born about 500 million years ago. Compared with our sun born 4.6 billion years ago, Sirius can only be regarded as a "kindergarten student".

1844, the famous German astronomer Bessel compared the trajectory of Sirius from 1755 to 1843, and found that it was not in the usual linear motion, but actually appeared in the form of "wave curve". Basing on celestial mechanics, Bessel finally concluded that Sirius has an "invisible" star with a period of 50 years. 1862, Clark, a famous American telescope manufacturer, observed Sirius to test its optical effect when he finished polishing the largest 18 inch (45 cm) refractor at that time. As a result, a small light spot was found next to Sirius. At that time, he thought it was the optical defect caused by unsuccessful lens polishing, and he was quite annoyed. It was not until later that this light spot with one-ninth brightness was discovered, that is, one hundred years ago. According to the displacement of Sirius, astronomers calculated that the companion star should have a large mass, but its brightness is very small. It seems that something is wrong. Later, by analyzing its spectrum, we suddenly realized that it is actually an abnormal star with a very small diameter and a very high density. Further research on this companion star shows that its mass is a little larger than our sun, which is 1.05 times!