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The nearest exoplanet to us, Proxima b may have the ocean, and her star his activity reminds us of the Sun. About the latest scientific discoveries from the vicinity of alpha Centauri — in the material “Газеты.Ru”.
In the last two months nearest to the Sun star — Proxima Centauri — is increasingly becoming the subject of scientific news. After discovering she earth-like planetit has interested many scientists from around the world. Constantly go all the new scientific articles, clarifying the parameters of the star system and the possible physical conditions on the planet’s surface. But the main question — whether at Proxima b to exist life, or the conditions are too extreme — remains unanswered.
The star Proxima Centauri belongs to the system of alpha Centauri. It is a triple star system, two components of which (alpha Centauri A and alpha Centauri B) clearly visible to the naked eye as one star, but for the third (Proxima) need a telescope. Alpha Centauri A and B stars of the main sequence, that is, their physical characteristics similar to the sun. They revolve around a common center of mass at a fairly eccentric orbit with a period 79,91. The age of the star system is estimated at 6 billion years, slightly more than age of the Sun, which is about 4.6 billion
Thus, according to many researchers, if there are planets in the habitable zone,they could theoretically support life.
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Perhaps that is why the alpha Centauri system is so popular in works of fiction. For example, it is the satellite of the gas giant Polyphemus Pandora was inhabited by the blue men na’vi in James Cameron’s “Avatar”. By the way, in 2012, astronomers at the European southern Observatory announced the discovery of a planet in orbit around alpha Centauri B with a mass close to the earth. The period of its revolution around the star is just over three days, so that area of life that this planet does not fall.
Unlike part A and B, Proxima Centauri is a red dwarf. Star just 1.5 times the size of Jupiter and is 150 times heavier. It is removed from the other two component to the distance of 15000.e. (astronomical unit — distance from Earth to the Sun). According to astronomers, the period of its revolution around a common center of mass of the system is more than 500 thousand years.
Proxima is now located at a distance of 4.22 St year, making it the nearest to the Sun star.
Perhaps the most significant event during the study of Proxima Centauri was the discovery of her planet. 24 August 2016 European southern Observatory announced the discovery of nearby stars for earth-like planets. And this planet is in the habitable zone, and thus on the surface the possible existence of liquid water. Astronomers could and hope the planet with favorable conditions for life can be located so “close” from the Solar system. However, many researchers caution against premature expectations. The orbital period of the recently discovered around Proxima Centauri planets only 11 earth hours.
And there is a very high probability that the planet has experienced tidal capture and facing the star on one side. You can often hear the opinion, what is the position of the planet leads
by freeze drying of the atmosphere on the night side due to a very low temperature and to heat up the day side.
However, modeling of planetary atmospheres is a very complex task that requires very high computational power and complex mathematical calculations. So to answer, what will be the weather conditions, constantly facing the star the planet is now difficult.
The second problem of the habitability of Proxima Centauri b is the star. Due to the specific structure of red dwarfs is very active stars. On the surface much more spots than in the Sun, and the flash is also similar to the sun, much more powerful and occur more often.
Powerful x-ray flares and ejections of substance from the surface of the star are a serious threat to a hypothetical biosphere. From the negative effects from red dwarf might partly protect a powerful magnetic field or in the deepest ocean, but yet we know nothing about these factors. But in any case the star and the planet and now deserve the most attention.
However, a recent study of astronomers from the Harvard-Smithsonian center for astrophysics shows that Proxima Centauri which is more like the Sun than previously thought.
It turned out that stars exist activity cycles similar to the sun.
In the years of minimum of solar activity on the disk is almost not observed stains, and in the peak years of their number may reach several hundred. At this time, the spots can summarily close a fraction of a percent of the area of the solar surface. But during one cycle the Sun changes not only the number of spots, but the level of radio, ultraviolet and x-ray radiation.
Examining long-term data of observations of Proxima Centauri in the optical, ultraviolet and x-rays, scientists have discovered that the nearest star to the Sun also has cycles and their period is approximately seven years. But unlike the Sun,
at Proxima in the years of maximum activity spot can close about 20% of the surface of the star.
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The size of these spots is also much larger than the sun. Previously, astronomers believed that the “boiling” of the outer layers of such stars is so rapidly that activity should vary randomly and not cycles. The study has been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society.
Earlier astronomers from the University of AIX-Marseille tried to simulate on the newly opened planet ocean. The main problem was that the radius of the planet remains unknown, but scholars know only its lower limit on the mass. With such meager knowledge about the planet to build its accurate model is impossible. However, by combining different parameters of radius and mass, scientists showed that under certain combinations of ocean on the planet could exist. A study accepted for publication in the journal The Astrophysical Journal Letters.
By the way, to alpha Centauri is planned to send the spacecraft with a speed of 60 thousand km/s in the framework of the project of Yuri Milner and Stephen Hawking Breakthrough Starshot. The project is expected to disperse satellites weighing 1 gram with a system of powerful lasers. Theoretically, such a satellite must attain a speed of 20% of the speed of light
and fly to the stars for 20-30 years.
Now, after the discovery of the planet from Proxima Centauri, the satellites could be directed to a new target. But not all scientists believe in the possibility of implementing such a project. The famous Russian physicist and chief editor of the newspaper “Troitsky variant” Boris Shtern cites in his article many of the arguments against the feasibility of Breakthrough Starshot. Among the main problems of the project physicist highlights the problem of dispersal of the laser beam.
After a sail will get the radiation flux at 50 gigawatts, he’ll be gone regardless of the material from which were made, the scientist believes.
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Well, if somehow one gram gold companion get to another star system, he will not be able to send a signal that you can catch from the Ground.
Anyway, recently a couple of scholars, including Abraham Loeb, a famous astrophysicist from Harvard University,showedthat the most stable during the flight to the nearest star will behave Parus spherical shape.
Much more a real project yet offers a group of researchers from the private non-profit BoldlyGo Institute (USA). They are going to launcha small private telescope the size of a washing machine, which is designed to search for and explore possible planets orbiting Proxima Centauri. The construction of the telescope will cost $25-50 million, which is planned to collect the crowdfunding.
