Astronomers at the Carnegie Institution of Washington and the University of California at Santa Cruz have published a paper in Astrophysical Journal Letters announcing the exciting discovery of a planet designated GJ667Cc.
GJ667Cc is considered a Super-Earth, which means that it is larger than the Earth in terms of diameter, and mass, and even though it is at least 4.5 times the mass of Earth, GJ667Cc is in the lower range for exoplanets, being relatively small for all the exoplanets being discovered by the Kepler Space Telescope. At that mass, GJ667Cc is almost certainly made of very similar material to the Earth, so primarily rocky in composition. It isn’t massive enough to form a gas giant, and is much to close to its parent star to retain an extremely extensive atmosphere like Saturn or Neptune. This newfound planet orbits the barycenter, or gravitational center, of the system every 28.15 days, which is amazingly fast. Mercury, the fastest orbiting planet in our solar system, orbits the Sun every 88 days, and GJ667Cc is even closer to it’s sun than Mercury is to ours. Now, if GJ667Cc’s parent star was similar to the Sun, GJ667Cc would be a barren, heat blasted hellscape, but the star is a much more amiable red dwarf, so the planet is smack dab in the middle of the habitable zone.
Of supreme interest is the fact that GJ667Cc orbits in a solar system that orbits as part of a solar system. Yes, slightly confusing, but extremely interesting. GJ667Cc is in orbit around a red dwarf, which is in orbit around a binary system composed of two Sun-like stars. The red dwarf is about as distant from the binary system as Pluto is from our Sun, and Pluto has an orbit of 248 years, so the system is quite far away. The binary system would appear as two very bright stars in the night sky of GJ 667Cc, but otherwise won’t have any significant effect on GJ667Cc.
In addition to GJ667Cc, the red dwarf is orbited by two more rocky planets with a 7.2 day and 75 day orbit, respectively. The system also possibly contains a gas giant farther out, but its existence has yet to be confirmed. The planets in this system have such short orbital periods because the mass of their star is greatly reduced compared to the Sun, so they must be closer to be captured, or the accretion disk that they formed from was much smaller than the one that made our solar system. Curiously, a system of planets such as these shouldn’t be able to form around a red dwarf, according to current solar system formation theory. The stars in the system have very low levels of the heavy elements present needed to form planets, but this could be a fluke or the beginning of a sting of examples that lead to a revision in solar system formation theory revision.
The third exciting fact about GJ667Cc is that it is a mere 22 light-years, making it an amazing candidate for colonization in the far future. Being relatively close to Earth, in the habitable zone and similar in composition to the Earth, it may have life, because it could very well have a dense atmosphere and liquid water. The reasons it might be good for out colonization are the same reasons life is very possible on GJ667Cc.
All in all, quite a fascinating find that hopefully will be a new home for humanity sometime in the near-ish future. Oh, and those hoping for intelligent life on GJ667Cc, don’t get your hopes up. Since it’s on 22 light years away, the civilization will have discovered radio 22 years ago in the best possible scenario. It doesn’t look too hopeful.