Kepler-68 is a Sun-like

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

star. It is known to have at least three planets orbiting around it. The outermost planet has a mass similar to Jupiter but orbits within the habitable zone. High resolution imaging observations of Kepler-68 carried out with the lucky imaging instrument AstraLux on the 2.2m telescope at

Calar Alto Observatory The Calar Alto Observatory (Centro Astronómico Hispano en Andalucía or "Spanish Astronomical Centre in Andalusia") is an astronomical observatory located in Almería province in Spain on Calar Alto, a mountain in the Sierra de Los Filabres ra ...

detected a wide companion candidate approximately 11 arcseconds away. Comparing these observations to the

2MASS The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and ...

positions shows that the companions

proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...

is consistent with it being bound to the Kepler-68 system, but further observations are needed to confirm this conclusion. Eleven arcseconds at the distance of Kepler-68 leads to a sky projected separation of approximately 1600 Astronomical units. A circular orbit at that distance would have a period of roughly 50,000 years.

Planetary system

Currently, three planets have been discovered to orbit around Kepler-68. Two of the innermost planets were discovered by the planetary transit method. Follow-up Doppler measurements helped to determine the mass of Kepler-68b and helped to discover Kepler-68d. There is an additional signal present in the

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

measurements indicating another body in the system at a period of greater than 10 years. The mass of this object is unknown and it could be either another planet or a stellar companion.

References

{{Stars of Cygnus Cygnus (constellation) Planetary transit variables

246 __NOTOC__ Year 246 ( CCXLVI) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar, the 246th Year of the Common Era ( CE) and Anno Domini ( AD) designations, the 246th year of the 1st millennium, th ...

Planetary systems with three confirmed planets G-type main-sequence stars BD+48 2893 J19240775+4902249