Artistic representation of the star system consisting of three dwarf stars. Right now the discovered Super-Earth GJ667Cc, which orbits the middle dwarf star. Image: University of Göttingen
Reading Astronomers have tracked down a planet that could harbor life and is in an exotic constellation: it orbits a so-called red dwarf, which in turn belongs to a system of three stars. According to the researchers, this triple system is poor in heavy elements, which is why astronomers have previously considered the existence of rocky planets rather unlikely. The current discovery contradicts this assumption, suggesting that earth-like planets in the universe may be much more common than previously thought. The discoverers consider the planet named GJ667Cc the best candidate for life-friendly conditions: according to data analysis, it has 4.5 times the mass of the earth and orbits its star in an orbit that allows temperatures at which water would be liquid. This is considered a basic requirement for life, as we know it. Compared to Earth, GJ667Cc is much closer to its central star, but the surface temperature is probably comparable, say the researchers. For the planet, according to the calculations, gets about the same energy as the earth, because it orbits a dwarf star of the M-class, which radiates much weaker than our sun. The other two stars of the triple system of GJ667 are also dwarf stars. Due to their greater distance, they only form two weak additional light sources in the firmament of GJ667Cc.

Super earth in cosmic neighborhood

Astronomically speaking, the highly interesting celestial body is located right in front of our cosmic door: it is only 22 light-years from Earth, which is equivalent to about 209 billion kilometers. Astronomers place it in the category of the so-called "super-earths"? to. This term refers to distant planets (exoplanets), which are slightly larger than the earth and made of rock. This delimits them from Jupiter-like celestial bodies? gigantic gas giants, which, according to current theory, hardly offer development opportunities for life. In total, planet hunters have spotted more than 750 exoplanets, including some super-Earths. The planet Kepler-22b was previously considered the most promising candidate for living-friendly conditions. But compared to GJ667Cc it is much further away from us: its distance from Earth is 600 light-years.

Researchers around Guillem Anglada-Escudé of the Carnegie Institution in Washington discovered GJ667Cc by analyzing data from the European Southern Observatory (ESO) and the Magellan II telescope in Chile, as well as the Keck Observatory in Hawaii. The planet betrayed itself by the regular tiny humming and tumbling of its parent star, which arises when the gravity of his companion tugs at him. This results in weak light changes (more precisely, periodic shifts in the speckle lines) that provide information about the properties of planets. According to the researchers, GJ667Cc also has neighbors: another super-earth, but too hot for life to develop as it circles the central star too close, and probably another rock planet in an outer orbit, though only offers icy conditions. display

According to analyzes of the wavelengths of light that emanate from the three stars of the GJ667 system, there are few heavy elements in the Earth compared to our solar system, of which the Earth is largely composed. Researchers have previously assumed that these are poor starting conditions for the formation of rocky planets. "Our discovery shows that potentially life-friendly planets can emerge in more diverse environments than previously thought, " says Anglada-Escudé. "With a new generation of measuring instruments, scientists could now systematically study dwarf stars for planets and, in turn, search for spectroscopic signs of life, " adds the astronomer, who now works at the University of Göttingen.

Communication from the Carnegie Institution and the University of Göttingen © wissenschaft.de? Martin Vieweg

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