GJ 667 C g is a proposed cold super-Earth, the outermost of up to seven planets reported in 2013 around GJ 667 C, a red dwarf about 24 light-years away that orbits a pair of other stars, GJ 667 A and B. In that model it circles GJ 667 C every 256 days or so, far beyond the star's habitable zone, and has a minimum mass of about 4.6 Earth masses.
It came from a study led by Guillem Anglada-Escudé that combined measurements from the HARPS, PFS and HIRES spectrographs and used the radial velocity method, which detects the slight back-and-forth motion a planet's gravity gives its star. The team found that six signals described the data better than the two planets already known, b and c. Among them was a cold super-Earth on a roughly 260-day orbit, which became GJ 667 C g. They placed three of the other candidates, c, f and e, in the habitable zone, the range of distances where liquid water could last on a surface. At its distance, g would receive only about a twentieth of the light Earth gets from the Sun, according to the NASA Exoplanet Archive.
Like the system's other extra candidates, it has not been confirmed. In 2014 a team led by Paul Robertson corrected the measurements for the star's magnetic activity, which can produce signals that look like planets. They confirmed planets b and c, attributed a 90-day signal to the star's rotation, and could not confirm the other periods described in 2013, including g's. GJ 667 C g remains a candidate until new observations settle it. It has never been seen passing in front of its star.