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The mystery of the bright stars: Why are there only 22 stars shining in the night sky?
When we look up at the night sky, those twinkling stars always inspire wonder and awe. However, for those celestial bodies that live around the solar system, a puzzling question is: among our cosmic neighbors 20 light-years away, why are only 22 stars able to show their light within the range of naked human eyes? This issue has attracted widespread attention from astronomers and astronomy enthusiasts.
Around our solar system, 131 known stars have been discovered, including white dwarfs, brown dwarfs and sub-brown dwarfs, but only 22 stars are bright enough to shine in the dark night sky.
According to current observational data, these 131 objects are distributed in 94 star systems, of which 103 are main sequence stars, including 80 red dwarfs and 23 more massive stars. In addition, astronomers also discovered 6 white dwarfs, 21 brown dwarfs, and 1 sub-brown dwarf WISE 0855−0714, which may be a rogue planet. Among them, the closest star system to us is Alpha Centauri, which is only 4.2465 light-years away from the Earth. Proxima Star in its system is the closest star.
Brightness and distance of stars
Stars that can shine within the range visible to the naked eye must have a visual magnitude of visible light intensity reaching or exceeding 6.5. According to the latest detection results, the brightest of these 22 stars is Sirius A. It is not only the brightest star in the earth's night sky, but also one of the most massive and bright stars among many observation objects. Its white dwarf companion Sirius B is the hottest of these objects, showing the huge differences in light and heat between these stars.
For astronomers, observing these stars shining in the night sky not only increases our understanding of the universe, but also triggers thinking about the evolution of the universe. How exactly do these stars change over time?
Basics of astronomy: parallax and normal motion
Astronomers usually measure the distance from a star to the sun through parallax. Parallax is a measure of the movement of stars between background objects as the Earth orbits it. For stars within 5 parsecs of the Sun, the parallax is usually greater than 0.2 arc seconds. Understanding the motion of these stars involves not only parallax, but also their normal motion, that is, their actual motion relative to the sun. This data is important because it helps astronomers predict how stars will change over the next few million years, and how stars may move closer or farther away over time.
Future proximity and past events
As the stars move, their distance from the Sun will change over time. According to the latest research, it is expected that about 694 stars will approach the solar system in the next 15 million years, and 26 of them have a good probability of entering within 1.0 parsecs. This means that in the next few million years, the surrounding environment of the solar system will usher in new celestial bodies, which may have an impact on the currently stable starry sky.
If these stars are really close to us, they will cause significant interference to the Oort cloud of the solar system, which makes people think: How subtle is the distance between us and these stars?
Conclusion
In the near future, scientists will also use more technologies to conduct deeper interstellar exploration. All these developments will continue to enrich our understanding of the universe, especially the stars that shine quietly in the night sky. These stars are not just brilliant points of light, but the bearers of countless stories and unsolved mysteries. Will we be able to uncover the secrets of these stars and understand their significance and influence in our daily lives?
