User:Kepler-1229b/Gliese 581 f

Gliese 581 f or Gl 581 f is a nonexistent exoplanet in the Gliese 581 system, located 20 light years (about 120 trillion miles) from Earth. It was the fifth planet claimed in the system and the sixth in order from the star. Its discovery was announced September 29, 2010.

Overview
The planet was detected using radial velocity measurements combining the data from the HIRES instrument of the Keck 1 telescope and the HARPS instrument of ESO's 3.6m telescope at La Silla Observatory.

The planet had a minimum mass of 7.0 Earth masses, suggesting that it may be either a large terrestrial planet (super earth) or a gaseous planet similar to Neptune. It orbits at a distance from its star of 0.758 AU, slightly more than Venus's distance from our Sun, but it is likely to be far too cold at its surface for liquid water.

Existence
The existence of Gliese 581 f is controversial. Follow-up studies incorporating updated data from HARPS have not confirmed its existence,  and it appears the radial velocity variations at this period may instead be associated with the stellar activity cycle of Gliese 581 itself rather than any orbiting planet.