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Kepler-31
Observation data; Epoch J2000 Equinox J2000
Constellation	[corvus]
Right ascension	19h 36m 05.5270s
Declination	+45° 51′ 11.108″
Apparent magnitude (V)	14.0
Characteristics
Spectral type	G5
Astrometry
Proper motion (μ)	RA: −1.007(25) mas/yr ; Dec.: −7.439(23) mas/yr
Parallax (π)	0.6013 ± 0.0200 mas
Distance	5,400 ± 200 ly ; (1,660 ± 60 pc)
Details
Mass	1.21 ± 0.17 M☉
Radius	1.22 ± 0.24 R☉
Luminosity	0.79 ± 0.04 L☉
Temperature	6340 ± 200 K
Metallicity [Fe/H]	–0.076 ± 0.400 dex
Other designations
	KOI-935, KIC 9347899, 2MASS J19360552+4551110, Gaia DR2 2128013019361703936
Database references
SIMBAD	data
KIC	data

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.

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 $R$ _J
b	<6.8 $M$ _J	0.16	20.8613	—	—	0.38±0.07 $R$ _J
c	<4.7 $M$ _J	0.26	42.6318	—	—	0.38±0.07 $R$ _J
d	—	0.39	87.648901±0.000801	—	—	0.407±0.099 $R$ _J

References

^ "Cygnus – constellation boundary", The Constellations, International Astronomical Union, retrieved 2011-12-15
^ ^a ^b ^c ^d ^e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ ^a ^b ^c ^d ^e ^f ^g Kepler-31b, NASA Ames Research Center, archived from the original on 2012-05-03, retrieved 2011-12-06
^ ^a ^b Schneider, Jean, "Star: Kepler-23", Extrasolar Planets Encyclopaedia, archived from the original on 2012-05-05, retrieved 2011-12-06
^ Lissauer, Jack J.; Ragozzine, Darin; Fabrycky, Daniel C.; Steffen, Jason H.; Ford, Eric B.; Jenkins, Jon M.; Shporer, Avi; Holman, Matthew J.; Rowe, Jason F.; Quintana, Elisa V.; Batalha, Natalie M.; Borucki, William J.; Bryson, Stephen T.; Caldwell, Douglas A.; Carter, Joshua A.; Ciardi, David; Dunham, Edward W.; Fortney, Jonathan J.; Gautier, Iii, Thomas N.; Howell, Steve B.; Koch, David G.; Latham, David W.; Marcy, Geoffrey W.; Morehead, Robert C.; Sasselov, Dimitar (2011), "Architecture and Dynamics of Kepler 'S Candidate Multiple Transiting Planet Systems", The Astrophysical Journal Supplement Series, 197 (1): 8, arXiv:1102.0543, Bibcode:2011ApJS..197....8L, doi:10.1088/0067-0049/197/1/8, S2CID 43095783
^ Transit Timing Observations from Kepler: IV. Confirmation of 4 Multiple Planet Systems by Simple Physical Models
^ Pichierri, Gabriele; Batygin, Konstantin; Morbidelli, Alessandro (2019), "The role of dissipative evolution for three-planet, near-resonant extrasolar systems", Astronomy & Astrophysics, 625: A7, arXiv:1903.09474, Bibcode:2019A&A...625A...7P, doi:10.1051/0004-6361/201935259, S2CID 85459759
^ Planet Kepler-31 d at exoplanets.eu