Kepler-31 is a star in the northern constellation of Cygnus, the swan. It is orbited by three known exoplanets. It is located at the celestial coordinates: Right Ascension 19h 36m 05.5270s, Declination +45° 51′ 11.108″. With an apparent visual magnitude of 14.0, this star is too faint to be seen with the naked eye.

Planetary system

The three gas giant planets orbiting Kepler-31 were discovered in early 2011, albeit with large false alarm probability, and were confirmed in 2012. The planets form a resonant chain, with orbital periods ratio 1:2:4, although 20% probability exists that these period ratios may be coincidental.

The Kepler-31 planetary system
Companion (in order from star)MassSemimajor axis (AU)Orbital period (days)EccentricityInclinationRadius
.04(unconfirmed)0.09379.61730282±3.35e-50.173 RJ
b<6.8 MJ0.1620.86130.38±0.07 RJ
c<4.7 MJ0.2642.63180.38±0.07 RJ
d0.3987.648901±0.0008010.407±0.099 RJ