Proxima Centauri. Red dwarfs. Alpha Centauri System

Proxima Centauri is the star that is closest to the Earth. The name she received from the Latin word proxima, which means "nearest". The distance from it to the Sun is 4.22 light years. However, in spite of the fact that the star is closer to us than the Sun, it can be seen only through a telescope. It is so small that nothing existed about its existence until 1915. The discoverer of the star was Robert Innes, an astronomer from Scotland.

Star System Alpha Centauri

Proxima is part of the Alpha Centauri system. In addition to it, it also includes two more stars: Alpha Centaurus A and Alpha Centaurus B. They are much brighter and more visible than Proxima. So, star A, the brightest in this constellation, is at a distance of 4.33 light years from the Sun. It is called Rigel Centauri, which translates as "Centaur's Leg". This star is something like our Sun. Probably because of its brightness. Unlike Centauri's Proxima, it has been known since ancient times, as it is very noticeable in the night sky.

Alpha Centauri V is also not inferior to the "sister" in brightness. Together they are a tight double system. Proxima Centauri is far enough away from them. Between the stars - a distance of thirteen thousand astronomical units (this is farther than from the Sun to the planet Neptune in as many as four hundred times!).

All the stars of the Centaurus system rotate in orbit around their common center of mass. Only Proxima moves very slowly: the period of its circulation takes millions of years. Therefore, this star will remain very close to the Earth for a very long time.

Very small

The Proxima Centauri star is not only closest to all of the constellation to us, but is also the smallest. Its mass is so meager that it is barely enough to support the processes of formation of helium from hydrogen, necessary for existence. The star is dimly lit. Proxima is much lighter than the Sun, about seven times. And the temperature on its surface is much lower: "only" three thousand degrees. By brightness, Proxima yields to the Sun a hundred and fifty times.

Red dwarfs

The small star of Proxima refers to the spectral class M with very low luminosity. Another name for celestial bodies of this class is widely known: red dwarfs. Stars with such a small mass are interesting objects. Their internal arrangement is somewhat similar to the structure of giant planets, such as Jupiter. The substance of red dwarfs is in an exotic state. In addition, there are suggestions that planets that are located near such stars can be livable.

Red dwarfs live very long, much longer than any other stars. They are very slowly evolving. Any nuclear reactions within them begin to emerge only a few billion years after their inception. The lifetime of a red dwarf is longer than the lifetime of an entire universe! So, in the far-distant future, when not one star of the Sun type will go out, the red dwarf Proxima Centauri will all also dimly shine in the darkness of the cosmos.

In general, red dwarfs are the most frequent stars in our galaxy. More than 80% of all the star bodies of the Milky Way are exactly them. And here is the paradox: they are completely invisible! Do not notice any of them with the naked eye.

Measurement

Until now, the ability to accurately measure the size of such small stars as red dwarfs, because of their weak luminosity, simply was not possible. But today this problem is solved with a special VLT-interferometer (VLT - short for English Very Large Telescope). This device, which operates on the basis of two large 8.2-meter VLT-telescopes located at the Paranal Astronomical Observatory (ESO). These two huge telescopes, separated by 102.4 meters, allow us to measure the celestial bodies with such precision, which simply is beyond the power of other devices. So the astronomers of the Geneva Observatory for the first time received the exact dimensions of such a small star.

The Changing Centauri

In size, Proxima Centauri borders on a real star, a planet and a brown dwarf. And yet it's a star. Its mass and diameter make up one seventh of the mass, and also the diameter of the sun, respectively. The star is massive than the planet Jupiter, a hundred and fifty times, but weighs one and a half times less. If Proxima Centauri weighed even less, it would simply not be able to become a star: there would not be enough hydrogen in its bowels to radiate light. In this case, it would be an ordinary brown dwarf (ie, dead), and not a real star.

Proxima itself is a very dull celestial body. In the ordinary state, its luminosity reaches no more than 11m. Bright it looks only on pictures taken by huge telescopes, such as, for example, "Hubble". However, sometimes the brilliance of a star sharply and significantly increases. Scientists explain this fact by the fact that Proxima Centauri belongs to the class of so-called changeable, or flashing, stars. This is due to strong flares on its surface, which are the results of violent convection processes. They are somewhat similar to those that occur on the surface of the Sun, only much stronger, which leads even to a change in the brightness of the star.

Still quite a child

These turbulent processes and outbreaks suggest that the nuclear reactions taking place in the depths of Centauri's Proxima have not yet stabilized. Conclusions of scientists: this is still quite a young star by the standards of space. Although its age is quite comparable with the age of our Sun. But Proxima is a red dwarf, so they can not even be compared. After all, like other "red cousins," it will very slowly and economically burn its nuclear fuel, and therefore it will shine very, very long - about three hundred times longer than our entire universe! What is there to talk about the sun ...

Many science fiction writers believe that Proxima Centauri is the most suitable star for space exploration and adventure. Some believe that in its Universe there are hidden planets on which other civilizations can be found. Maybe it is, but only the distance from Earth to Proxima Centauri is more than four light years. So, although it is the nearest, but still is far away.