Looking up at the night sky, when the weather is good, you can see the sky full of stars, in fact, there are only more than 6,000 stars that can be observed with the naked eye on the earth, these stars have been named by astronomers, except for the five naked-eye visible planets and the moon, the stars in the night sky are all stars, because only stars in the universe will emit light, and the brightness of stars depends on the luminous ability of these stars themselves and the distance from the earth.
Although all the stars are named, but most of the stars are very low in popularity, we are familiar with the stars are only so few, "Big Dipper seven stars" should be the most well-known seven stars, so what do the seven stars that make up the Big Dipper look like, how far away are they from us, how big is the size?
The Big Dipper seven stars occupy an important position in China's ancient astronomical culture, we often say "Wenqu Star", "Wuqu Star", "Greedy Wolf Star" and "Broken Army Star" are one of the members of the Big Dipper Seven Stars, these four also have a less well-known "Lian Zhen Star", "Lu Cun Star" and "Giant Gate Star".
These seven stars are located in the "Ursa Major Galaxy", the Ursa Major Galaxy is the most important and easiest to observe galaxy in the night sky north of the Earth, the seven bright stars in the constellation Ursa Major are what we often call the Big Dipper, when observing Ursa Major, the spoon shape composed of the seven stars of the Big Dipper is more eye-catching than the constellation Ursa Major itself.
There is no doubt that the Big Dipper are "stars", and far away from us, the stars that can be observed by us with the naked eye are larger and hotter than the sun, in fact, there are far more stars in the universe than we see with the naked eye, but most of the stars are not bright enough for us to see with the naked eye, let's take a look at the specific data of the Big Dipper.
<h1 class="pgc-h-arrow-right" data-track="6" >01 celestial hub</h1>
Celestial Hub, also known as "Wolf Star", its number is "Ursa Major α Star A", in the Big Dipper, The Celestial Hub is the farthest star from Earth, on the contrary, it is the closest to the North Star. Compared to the other six stars, celestial hubs belong to a "giant star" that is a product of the late stages of star evolution.
The celestial hub is about 123 light-years away from The Earth, the mass is 4.25 times, the brightness is 316 times that of the Sun, is the second brightest star in the Big Dipper, although the Celestial Hub is large and bright, but its temperature and density are not high, the surface temperature is lower than the Sun, which is a common feature of giant stars, because the stars will begin to expand continuously in the final stage of their own lives, accelerating the consumption of mass in the core will cause the stars to become brighter and brighter, and all stars will become brighter and brighter over time.
<h1 class="pgc-h-arrow-right" data-track="35" >02 Celestial Star</h1>
Tianxuan star is also known as giant star, its number is β Ursa Major, it is also a giant star at the end of the evolution of stars, but not as large as the celestial hub, can only be regarded as a "sub-giant star", scientists speculate that the hydrogen element in the core of Tianxuan has been completely consumed, and the hydrogen element in the core shell is currently being consumed to release heat.
Located about 80 light-years from Earth, Tianxuan is 2.7 times more massive than the Sun, has a radius of 2.84 times that of the Sun, and is about 63 times brighter than the Sun, and is slowly cooling.
<h1 class="pgc-h-arrow-right" data-track="36" >03 Celestial Star</h1>
The star A, numbered γ ursa major, is 83.2 light-years away from Earth, and unlike the previous two stars, A. A. is a "main sequence star" that, like the Sun, is still in the young adult period of the star's lifetime, which is about 3 billion years old, younger than the Sun, and at the same time massive and larger, and brighter than the Sun, such stars are rare.
Asterus has a mass of 2.94 times that of the Sun and a radius of 3.04 times that of the Sun, and is also a binary system, with its companion star γ Ursa Major B, which is a little less massive than the Sun, and is about 8 light-years away from it
<h1 class="pgc-h-arrow-right" data-track="37" >04 Celestial Power</h1>
Celestial Power, the δ star in the constellation Ursa Major, which is also commonly known as the "Wenqu Star", is the darkest star in the Big Dipper, 80.5 light-years away from the Sun, and is also a main sequence star in its prime.
The mass of The Star is 1.63 times that of the Sun, the radius is 1.4 times that of the Sun, and the brightness is 14 times that of the Sun, although the Star is larger and brighter than the Sun, but because it is far enough away from us, it is the faintest one when we observe.
<h1 class="pgc-h-arrow-right" data-track="38" >05 Yuhengxing</h1>
Yuheng Star is the brightest of the seven stars of the Big Dipper, 82.6 light-years away from the earth, he is one of the brightest stars in the sky, the ancients used it as a navigation star when sailing, it is a main sequence star, but also a "pulsating variable star", numbered Ursa Major ε.
Yuheng Star has a mass of 2.91 times that of the Sun and a radius of 4.14 times that of the Sun, because the strong magnetic field inside makes the star's spectrum show a certain degree of fluctuation, and its magnetic field is about 100 times that of Earth!
<h1 class="pgc-h-arrow-right" data-track="39" >06</h1>
Kaiyang Star, we often say Wuqu Star, numbered Ursa Major ζ, 78.2 light years away from the Earth, Kaiyang Star is a typical binary star system, its companion star is "Kaiyang Zengyi", numbered 80 Ursa Major, the two stars are very close, only about a quarter of the light years, so this binary star system is very recognizable, is the first human observed binary star system.
In follow-up studies, scientists have found that Kaiyang star actually belongs to a "four-star system", which and another pair of binary star systems orbit each other.
<h1 class="pgc-h-arrow-right" data-track="41" >07 Yaoguang star</h1>
Yaoguang Star, often said to be the Broken Army Star, numbered Ursa Major η, the Shaking Star is the youngest star in the Big Dipper, it is only 10 million years old, far from other stars, that is to say, in the era of active dinosaurs, there was no star in the sky!
The mass of the shaken light is 6 times that of the Sun, the radius is 3.4 times that of the Sun, and the brightness is as high as 594 times that of the Sun! It is a blue-and-white main sequence star.
There are countless stars in the universe, humans can only see a small part of the Milky Way, there are many stars that are not bright enough to be observed by our naked eyes, perhaps from the perspective of other civilizations in the universe, the sun is just a faint star.