New “Super Earth” Found At Right Distance For Life

A new planet—probably a rocky super-Earth—has been found squarely within its star's habitable zone, making it one of the best candidates yet to support life, its discoverers say.

The planet, dubbed GJ 667Cc, orbits a red dwarf star 22 light-years from Earth, in the constellation Scorpio. A binary pair of orange dwarf stars are part of the same system.

(Related: "'Tatooine' Planet With Two Suns Could Host Habitable Moon?")

The new planet has a mass 4.5 times that of Earth and orbits its host star every 28 days.

The red dwarf is relatively dim, so the planet receives slightly less light from its star than Earth does from the sun. But most of the star's light is infrared, so the planet should absorb more of its incoming energy than Earth does from sunlight.

That means if the planet has a rocky surface—which is predicted for planets less than ten times Earth's mass—and an atmosphere, it could support liquid water and maybe life, said co-discoverer Guillem Anglada-Escudé, who conducted the work while at the Carnegie Institution for Science in Washington, D.C.

"If it has an atmosphere, it's probably reddish all the time, because the star is really red," Anglada-Escudé said. "It would be like being evening all the time."

For any hypothetical observers on the surface, the binary stars in the distance would be "very prominent in the sky, and it would be an exotic thing."

(Relaed: "New Planet May Be Among Most Earthlike—Weather Permitting.")

Rocky Planet Around Unexpected Star

Anglada-Escudé and colleagues found the new planet using public data from the European Southern Observatory, which hosts telescopes that can measure wobbles in a star's orbit caused by a planet's gravitational tug.

The new super-Earth was somewhat unexpected, because some planetary-formation models say that metal-poor stars such as GJ 667C shouldn't have terrestrial planets around them.

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