Kepler-68

Kepler-68 is a Sun-like main sequence star located away in the constellation Cygnus. It is known to have at least four planets orbiting around it. The third 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 detected a wide companion candidate approximately 11 arcseconds away. Comparing these observations to the 2MASS positions showed that the companion's proper motion appeared consistent with it being bound to the Kepler-68 system, but further observations were needed to confirm this conclusion. In 2019 this was found to be an unrelated background star using Gaia DR2 astrometry.

Planetary system

Currently, four planets have been discovered to orbit around Kepler-68. The two 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 measurements indicating another body in the system at a period of greater than 10 years. The mass of this object was initially unknown and it could be either another planet or a stellar companion. In 2023, this fourth planet was confirmed, with a minimum mass about that of Saturn.