Kepler-89 is a star with four confirmed planets. Kepler-89 is a possible wide binary star.

Planetary system

The discovery of four planets orbiting the star was announced October 2012 by analyzing data gathered by

Kepler space telescope The Kepler space telescope is a defunct space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orb ...

. Follow-up radial velocity measurements confirmed the existence of

Kepler-89d Kepler-89 is a star with four confirmed planets. Kepler-89 is a possible wide binary star. Planetary system The discovery of four planets orbiting the star was announced October 2012 by analyzing data gathered by Kepler (spacecraft), Kepl ...

, indicating that Kepler-89d is slightly larger and more massive than

Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...

. In October 2013, other three planets were confirmed with

Kepler-89c Kepler-89 is a star with four confirmed planets. Kepler-89 is a possible wide binary star. Planetary system The discovery of four planets orbiting the star was announced October 2012 by analyzing data gathered by Kepler space telescope. F ...

and

Kepler-89e Kepler-89e, also known as KOI-94e, is an exoplanet in the constellation of Cygnus. It orbits Kepler-89. Physical properties It is classed as a type III planet, making it cloudless and blue, and giving it the appearance of a larger version of Ur ...

getting reasonable mass constraints. Transit-timing variations of the outermost planet suggest that additional planets or minor bodies are present in the system. In 2012, a partial transit of the second outermost planet by the outermost planet was reported. This was the first time a planet-planet transit in front of the star was detected. This allowed to determine the mutual inclination of the planets d and e to be 1.15°. Stephen R. Kane did a dynamical analysis of the Kepler-89 system that demonstrated that planets c and d, although close to the 2:1 secular

resonance Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ...

, are not permanently in a 2:1 resonance configuration.

References

{{2012 in space Planetary systems with four confirmed planets 94 Cygnus (constellation) F-type main-sequence stars J19491993+4153280 Planetary transit variables