Earth twin in our neighborhood

Potentially life-friendly Super Earth Gliese 832c is only 16 light-years away

The super-earth Gliese 832c might look like that, and the Red Dwarf Gliese 832 can be seen to the left of it. © PHL / University of Puerto Rica, Arecibo
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Only 16 light-years away from us exists a potentially habitable super-earth. The planet Gliese 832c is orbiting a red dwarf on a track, which probably gives it similar temperatures as on Earth. At the moment Gliese 832c is one of the three Earth-like exoplanets known so far - and he is very close to us, as the international team of astronomers reports.

The Red Dwarf Gliese 832, which is only 16 light-years away from Earth, is no unknown astronomer. As early as 2009, researchers had discovered a gas giant orbiting in its orbit. The planet Gliese 832b, takes nine years to orbit and is considered a "cold" Jupiter. Because a red dwarf radiates much less energy than the sun, the habitable zone - the zone where temperatures allow liquid water - lies further inward than in our solar system.

Mini version of the solar system

Astronomers around Robert Wittenmyer of the University of New South Wales have now discovered a second planet around this dwarf star. This was achieved with the help of the Anglo-Australian Telescope and the 3.6 meter telescope of the European Southern Observatory, which captured the slight tumbling of the star due to the gravitational influence of the planet. He circles around Gliese 832 and only needs 16 days to complete one revolution.

With five times the mass of the earth, it belongs to the super-earth - Gliese 832c is thus a rock planet. "With an outer gas giant and an inner rock planet, one could think of this planetary system as a miniature version of our solar system, " says co-author Chris Tinney of the University of New South Wales.

Gliese 832c vs. Earth © PHL / University of Puerto Rica, Arecibo

Life-friendly conditions?

Because the red dwarf is weaker than the sun, the new super-earth, in spite of its narrow orbit, receives about as much radiant energy as the earth from the sun, as the astronomers explain. Therefore, the temperature on its surface could correspond approximately to that of the earth liquid water would be possible. However, the oblique axis of rotation of the planet ensures that extreme seasons differences exist on it. display

If Gliese 832c had an atmosphere similar to that of the earth, life would be quite possible on it, say the astronomers. However: "In view of the large mass of the planet, it could also have a denser atmosphere, which absorbs heat and makes it a kind of super-Venus too hot for life, "says Tinney. How the gas-well of Super-Earth actually is, is not yet clear.

Rank 3 on the Earth Similarity Index

However, as the researchers report, Gliese 832c still ranks third in the Earth Similarity Index (ESI), a scale that describes the earthiness of exoplanets. The closer a planet comes to the value 1 for the earth, the more similar it is. The exoplanet on this scale is 0.84 Gliese 667C c, a super-Earth that is about 23 light-years away. It is followed by Kepler-62e with a value of 0.83, which, however, with 1.200 light years distance is not exactly in the neighborhood. Then follows the new planet Gliese 832c with a value of 0.81. (Astrophysical Journal, in press; arXiv: 1406.5587)

(University of New South Wales, 01.07.2014 - NPO)