16 Cygni or 16 Cyg is a triple star system approximately 69 light-years away from Earth in the constellation of Cygnus.

The system was within the field of view of the original mission of the Kepler spacecraft, which collected extremely precise photometric data of the stars.

[11] The angular diameters together with the asteroseismology models were used to calculate radii of 1.229 and 1.116 times the solar radius for components A and B respectively.

[4] Despite having the same age and presumably the same primordial composition, observations show a small difference in the metallicity of the two 16 Cygni stars.

[14] It has been hypothesized that the accretion of about 1 Earth mass of metals by 16 Cygni B soon after the system's formation may have destroyed the lithium in the star's atmosphere.

[14] Another proposed scenario is the engulfment of a Jupiter-mass planet by 16 Cygni A, which increased the amount of lithium in the star's outer atmosphere.

In particular, simulations show the planet's eccentricity oscillates between low and high values in timescales of tens of millions of years.

[20][21] Like the majority of extrasolar planets detectable from Earth, 16 Cygni Bb was deduced from the radial velocity of its parent star.

[22] In a computer simulation, only particles inside approximately 0.3 AU remained stable within a million years of formation, leaving open the possibility of short-period planets.