Kepler-223

Kepler-223 (KOI-730, KIC 10227020) is a G8 star with an extrasolar planetary system discovered by the Kepler mission. Studies indicate that the Kepler-223 star system consists of 4 planets orbiting the star.^[9][10]

Kepler-223

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cygnus[1]
Right ascension	19h 53m 16.4202s[2]
Declination	+47° 16′ 46.308″[2]
Apparent magnitude (V)	15.3[3]
Characteristics
Evolutionary stage	subgiant[2]
Spectral type	G8[3]
Apparent magnitude (g)	15.903[4]
Apparent magnitude (r)	15.301[4]
Apparent magnitude (i)	15.105[4]
Apparent magnitude (z)	14.963[4]
Apparent magnitude (D51)	15.667[4]
Apparent magnitude (J)	14.095[4]
Apparent magnitude (H)	13.727[4]
Apparent magnitude (K)	13.632[4]
J−K color index	0.463[4]
Astrometry
Proper motion (μ)	RA: −4.227(25) mas/yr[2] Dec.: −11.094(24) mas/yr[2]
Parallax (π)	0.5005±0.0215 mas[2]
Distance	6,500 ± 300 ly (2,000 ± 90 pc)
Details
Mass	1.04[5] M☉
Radius	1.52[5] R☉
Surface gravity (log g)	4.09[5] cgs
Temperature	5,803[5] K
Metallicity [Fe/H]	−0.211[4] dex
Rotation	17.82 days[6]
Rotational velocity (v sin i)	2.4[7] km/s
Age	3.7[7] Gyr
Other designations
KOI-730, KIC 10227020, 2MASS J195316.40+471646.1[8]
Database references
SIMBAD	data
KIC	data

Planetary system

The Kepler-223 planetary system

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	—	—	7.3845	—	—	3 R🜨
c	—	—	9.8456	—	—	3.4 R🜨
d	—	—	14.7887	—	—	5.2 R🜨
e	—	—	19.7257	—	—	4.6 R🜨

The confirmed planetary system was first detected by the Kepler mission, and contains four planets.^[11] This system was initially believed to contain two co-orbital planets orbiting the star at approximately the same orbital distance every 9.8 days, with one permanently locked 60° behind the other in one of the two Trojan Lagrangian points.^[12] The two co-orbital planets were thought to be locked in mean motion resonances with the other two planets, creating an overall 6:4:4:3 resonance.^[13] This would have been the first known example of co-orbital planets.

However, follow-up study of the system revealed that an alternative configuration, with the four planets having orbital periods in the ratio 8:6:4:3 is better supported by the data. This configuration does not contain co-orbital planets,^[14] and has been confirmed by further observations.^[10] It represents the first confirmed 4-body orbital resonance.^[11]

The radii are 3.0, 3.4, 5.2, and 4.6 Earth radii, and the orbital periods are 7.3845, 9.8456, 14.7887 and 19.7257 days, respectively.^[10]

• 
  Kepler-223 6:4:4:3 orbital ratios
• 
  Kepler-223 8:6:4:3 orbital ratios