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A diagram of the Kepler-31 System, compared to our Inner Solar System.
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus[1]
Right ascension 19h 36m 05.523s
Declination +45° 51′ 11.09″
Apparent magnitude (V) [2]
Spectral type G5[3]
Distance 15237[3] ly
Mass 1,21±017[2] M
Radius 1.22±0.24[2] R
Luminosity 0.79 ± 0.04[2] L
Temperature 6340±200[2] K
Metallicity [Fe/H] –0.076±0.400[2] dex
Rotational velocity (v sin i) [2] km/s
Other designations

Kepler-31 is a star in the northern constellation of Cygnus, the swan, that is orbited by a planet found to be unequivocally within the star's habitable zone. It is located at the celestial coordinates: Right Ascension 19h 36m 05.523s}, Declination +45° 51′ 11.09″.[4] With an apparent visual magnitude of 14.0,[2] this star is too faint to be seen with the naked eye.

The Kepler-31 planetary system[3]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b 6.8 MJ 0.16 20.8613 4.1 R
c 4.7 MJ 0.26 42.6318 4.1 R


  1. ^ "Cygnus – constellation boundary", The Constellations, International Astronomical Union, retrieved 2011-12-15 
  2. ^ a b c d e f g h Kepler-31b, NASA Ames Research Center, retrieved 2011-12-06 
  3. ^ a b c Schneider, Jean, "Star: Kepler-23", Extrasolar Planets Encyclopaedia, Paris Observatory, retrieved 2011-12-06 
  4. ^ "Kepler Discoveries". 2011-12-05. 

Coordinates: Sky map 19h 36m 05.523s, +45° 51′ 11.09″