Kepler-223 (KOI-730, KIC 10227020) is a G8 star with an extrasolar

planetary system A planetary system is a set of gravity, gravitationally bound non-stellar Astronomical object, bodies in or out of orbit around a star or star system. Generally speaking, systems with one or more planets constitute a planetary system, although ...

discovered by the Kepler mission. Studies indicate that the Kepler-223

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravity, gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally calle ...

consists of 4

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

ing the

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

Planetary system

The confirmed planetary system was first detected by the Kepler mission, and contains four planets. 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 point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium (mechanics), equilibrium for small-mass objects under the gravity, gravitational influence of two massive orbit, orbiting b ...

s. 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. 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, and has been confirmed by further observations. It represents the first confirmed 4-body

orbital resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...

. 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.

References

External links

"Planetary System KOI-730 Exhibiting a Pair of Co-Orbital Planets"
(this site requires a browser with support for

WebGL WebGL (short for Web Graphics Library) is a JavaScript Application programming interface, API for rendering interactive 2D and 3D graphics within any compatible web browser without the use of plug-in (computing), plug-ins. WebGL is fully integra ...

) * 2MASS Catalo
Retrieval
{{Stars of Cygnus Planetary systems with four confirmed planets G-type subgiants 730 Cygnus (constellation) J195316.40+471646.1 Planetary transit variables