In the nearest to the Earth star system finally discovered planet earth. Just don't say that for you, it's a surprise!

The surroundings orange star alpha of Centaurus B in the area of the planet in the view of the artist. Not shown certainly visible in this area, the red dwarf Proxima Centauri. (Here and below illustrate ESO / DSS 2, Davide De Martin.)

The discovery was made using the receiver HARPS the 3.6-meter optical telescope at the European southern Observatory, located at the Observatory in La Silla (Chile). Out of the ordinary planet is not only because of it until the Earth just 4,36 light years, but also because of its size: it is the smallest of all exoplanets detected at a sun-like stars. Its mass - 113% from the earth.

Alpha Centauri is one of the brightest objects in the southern sky. She is nearest to the Sun star system; the distance to it is 4.3 light years. The system is a triple star: two adjacent component, alpha of Centaurus A (class G2V the Sun ) and II Centauri B (K1V, orange) - sun-like stars, rotating around a common center of gravity, and the more remote and weaker red component, invisible to the naked eye red dwarf, known as Proxima Centauri (M5,5Ve):

Since the XIX century astronomers build assumptions about planets revolving around these stars is perhaps closest to us foci of life outside the Solar system, but the search is still to nothing lead, despite increasing the accuracy of measurements. Up to now. "Our observations with HARPS instrument, which lasted more than four years, has revealed a very weak but real signal from a planet orbiting alpha of Centaurus B with a period of 3.2 days, " says Xavier Domus from the Geneva Observatory (Switzerland) and Astrophysical center of the University of Porto (Portugal), lead author of the study. - This extraordinary discovery made at the limit accuracy of our methods!"

To discover the planet, had long and hard to measure tiny variations in the motion alpha of Centauri B, caused by the gravitational attraction of a rotating in orbit of the body. As a planet near the star is almost weightless, its gravity leaves truly microscopic mark on the trajectory of the light: periodic oscillations in one and the other side with a speed not exceeding 51 centimetres per second (about 1.8 km/h!), close to the speed of crawling on all fours baby (true, energetic). This is the highest accuracy, ever achieved such measurement technology, and it bore fruit.

alpha of Centauri B, around which revolves the newly discovered planet is very similar to the Sun - just a little bit less and not so bright. The above method of determining fluctuations radial velocities astronomers can reliably assess only the minimal mass of the planet; evaluation depends on the unknown inclination of the orbital plane of the planet to a beam of view. But usually this minimum mass is close to a real mass of the planet. The exoplanet is nearest to us star system at the lowest mass slightly heavier than Earth, but, alas, revolving in its orbit, separated from a parent star in just 0.04 A. E. (about 6 million km)that in 5-7 times less than the distance from mercury to the Sun. Although from the second brightest star system, alpha of Centaurus A, the planet hundreds of times on, the roof of her mouth alpha of Centaurus A is the brightest object, comparable with the Sun in the area of the satellites of Jupiter. Visible from her and Proxima Centauri.

The first exoplanet in sun-like stars was found by the same group of researchers in 1995. Since made more than 800 confirmed discoveries of this type, but this is mainly a body about the size of Jupiter, and more. That is why it is so important to find nearby Solar system extrasolar planets with masses comparable to the earth, the orbit of which lie within the "habitats" around the parent stars. With this discovery process seems to have gone.

"This is the first planet with a mass close to the Earth, found in sun-like stars. Its orbit is very close to the parent star, and on its surface must be too hot for life in the form in which we know it, " says Stefan Oudry of the Geneva Observatory, co-author of the article and one of the members of the research team. - It is possible that this is only one of several planets in the system. And the results of our measurements with HARPS, and new findings "Kepler" clearly show that the majority of low-mass planets are that [is] in such systems". Indeed, the surface of the planet has a temperature of not less than 1 500 K. But if she kept looking at shining one party of the regions terminator will show a very different meaning.

"This is a huge step to finding the twin Earth in the immediate vicinity of the Sun. We live in a great time!" - enthuses Xavier Domus. Reasonable enthusiasm. And time is truly remarkable: the radial-velocity method, the easiest way to find the planet, located in a few million kilometres from the star; something 150 million km, but the same mass HARPS technically we can not find. But it is clear that the emergence of sensitive devices is not far off.



The star of the newly discovered planet from close range in the view of the artist. Although alpha of Centaurus B has 90.7 percent of the mass of the Sun, its luminosity is only 50.0% from the level of our star.

But for a second abstract from Paphos. Or, more precisely, will betray him even stronger. If future studies confirm another earth-a planet in the habitable zone in the nearest system, stars which are older than we are about 1.5 billion years, it will not acquire whether the Fermi paradox very very frightening mystery? If you think we're running too far ahead - well, maybe. To quote only one sentence from the article published by scientists in connection with the opening: "the Observed poluamiid [half of the peak-to-peak amplitude] radial velocity equivalent called the planet with minimal weight in four of the earth, located in the habitable zone of the star (the circulation period of 200 days)".



Their research appears in the online edition of the journal Nature on October 17, 2012, and with its Preprint available here.

Based on the materials of the European southern Observatory.