Kepler-31

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 19^h 36^m 05.5270^s, Declination +45° 51′ 11.108″.^[2] With an apparent visual magnitude of 14.0,^[3] this star is too faint to be seen with the naked eye.

Kepler-31

Observation data Epoch J2000      Equinox J2000
Constellation	[corvus][1]
Right ascension	19h 36m 05.5270s[2]
Declination	+45° 51′ 11.108″[2]
Apparent magnitude (V)	14.0[3]
Characteristics
Spectral type	G5[4]
Astrometry
Proper motion (μ)	RA: −1.007(25) mas/yr[2] Dec.: −7.439(23) mas/yr[2]
Parallax (π)	0.6013±0.0200 mas[2]
Distance	5,400 ± 200 ly (1,660 ± 60 pc)
Details
Mass	1.21 ± 0.17[3] M☉
Radius	1.22 ± 0.24[3] R☉
Luminosity	0.79 ± 0.04[3] L☉
Temperature	6340 ± 200[3] K
Metallicity [Fe/H]	–0.076 ± 0.400[3] dex
Other designations
KOI-935, KIC 9347899, 2MASS J19360552+4551110, Gaia DR2 2128013019361703936
Database references
SIMBAD	data
KIC	data

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.^[5][6] The planets form a resonant chain, with orbital periods ratio 1:2:4, although 20% probability exists that these period ratios may be coincidental.^[7]

The Kepler-31 planetary system^[4][8]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
.04(unconfirmed)	—	0.0937	9.61730282±3.35e-5	—	—	0.173 RJ
b	<6.8 MJ	0.16	20.8613	—	—	0.38±0.07 RJ
c	<4.7 MJ	0.26	42.6318	—	—	0.38±0.07 RJ
d	—	0.39	87.648901±0.000801	—	—	0.407±0.099 RJ