When we go camping in the wilderness and look up at the stars outside the tent, we will always see a familiar scene, that is, the seven stars of the Big Dipper.
If you're not an astronomy enthusiast, the Big Dipper may be the only astronomical landscape you can name when you look up at the stars. The Big Dipper is made up of seven bright stars, which makes it look particularly conspicuous in the night sky.
The Big Dipper is part of a constellation, the sign of Ursa Major, and of course, not everyone knows the sign of Ursa Major, but almost everyone knows the Big Dipper, because these seven stars are too obvious, so they appear more striking than the sign of Ursa Major itself. It is precisely because of this that since ancient times, there have been many legends about the seven stars of the Big Dipper in the land of China. So what were these seven stars called in ancient Chinese astrological culture? The Big Dipper is a distinct spoon shape, so let's start with the spoon handle.
The star at the tip of the spoon handle is the "Broken Army Star", and next to it is the "Wuqu Star", which was often compared to the Wuqu Star in ancient times. Next to the Wuqu Star is the "Lian Zhen Star", and next to it is the "Wenqu Star", which is the same as the Wu Zhuangyuan, and the ancients believed that the Wenqu Xing was the Wenqu Star under the mortal.
The next three stars are "Lu Cun Star", "Giant Gate Star" and "Wolf Star". Because the stars of the Big Dipper are so conspicuous, they have been artificially given a lot of special meaning, but in fact they are just seven ordinary stars in the universe, and they have no relationship with each other. In fact, the Big Dipper, like other stars visible in the night sky, is a star very far away from us. Let's get to know each other now, or start with the spoon handle. The first is the Broken Army Star, which is the youngest star among the seven stars of the Big Dipper, the current age is about 10 million years old, and our sun is already 5 billion years old, which shows that as a star, it is indeed only a descendant.
Although it is much younger than the Sun, it is much larger than the Sun, its mass is about 6 times that of the Sun, its volume is 3.4 times that of the Sun, and its brightness is as high as 594 times that of the Sun, but due to the distance, it seems that it is only a small bright spot.
The Wuqu Star next to the Broken Army Star is a very special star, which is about 78.2 light-years away from Earth. It is said to be special, not because of its size, but because it is a "four-star system". What is a four-star system? Wuqu star itself is a binary star system that orbits each other with another star, and next to them, there is another binary star system, and these two binary star systems orbit each other under the action of gravity, so they form a four-star system, it seems that Wuqu star is really lively. Next up is Lianzhen Star, which has a mass of 2.91 times that of the Sun and is about 82.6 light-years away from Earth, a star with an extremely strong internal magnetic field, which we call a "pulsating variable star".
Due to its characteristics, it is extremely bright and easy to identify in the night sky, so ancient navigators liked to use it as a navigation star.
Next is the Wenqu Star, the ancient literati are usually humble, low-key, and wenqu star also has similar characteristics, in the composition of the seven stars of the Big Dipper, Wenqu Star is the lowest brightness, in the night sky appears the dimmest, it and the Earth's distance is about 80.5 light years, the size is similar to the Sun, the mass is only 1.63 times that of the Sun.
Lu Cunxing next to Wenqu Star is a star about 3 billion years old, which has some similarities with Wuqu Star and is also a binary star system, with a mass of 2.94 times that of the Sun and about 83.2 light-years away from Earth. The next giant star is different from the previous five stars, which is a star that has already ended the main sequence star stage, that is, it has expanded into a giant star.
When a star's main sequence phase ends, the hydrogen fusion inside it will turn into helium fusion and continue to push toward heavier elements, and when its temperature and pressure are not enough to ignite the fusion of heavier elements, it will collapse into a white dwarf, and then enter a long cooling phase.
That is to say, in the future, the giant gate star will disappear from the night sky, and the Big Dipper will no longer be complete. The star that has ended the main sequence star stage is not only a giant star, but also the wolf star has already entered the end of its life. Coyote is a star farther away from Earth , it is about 123 light-years away from The Earth , but the expansion makes it brighter and brighter, reaching 316 times the brightness of the Sun , so the Star is still very obvious in the night sky. In the future, after the wolf star and the giant gate star have disappeared, the big dipper will also become the big dipper five stars, and the regular spoon will also become a curved line segment, when our descendants look up at the starry sky again, they may not even be able to call out the name of a star.