Kepler-68 is a Sun-likemain sequence star located 471light-years (144parsecs) away in the constellationCygnus. It is known to have at least four planets orbiting around it.[6] The third planet has a mass similar toJupiter but orbits within thehabitable zone.[4]
High resolution imaging observations of Kepler-68 carried out with thelucky imaging instrument AstraLux on the 2.2m telescope atCalar Alto Observatory detected a wide companion candidate approximately 11arcseconds away. Comparing these observations to the2MASS positions showed that the companion'sproper motion appeared consistent with it being bound to the Kepler-68 system, but further observations were needed to confirm this conclusion.[10] In 2019 this was found to be an unrelated background star usingGaia DR2 astrometry.[11]
Currently, four planets have been discovered to orbit around Kepler-68. The two innermost planets were discovered by theplanetary transit method. Follow-up Doppler measurements helped to determine the mass of Kepler-68b and helped to discover Kepler-68d.[4][12] There is an additional signal present in theradial 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.[13] In 2023, this fourth planet was confirmed, with aminimum mass about that ofSaturn.[6]
^Grieves, N.; Ge, J.; Thomas, N.; Willis, K.; Ma, B.; Lorenzo-Oliveira, D.; Queiroz, A. B. A.; Ghezzi, L.; Chiappini, C.; Anders, F.; Dutra-Ferreira, L.; Porto De Mello, G. F.; Santiago, B. X.; Da Costa, L. N.; Ogando, R. L. C.; Del Peloso, E. F.; Tan, J. C.; Schneider, D. P.; Pepper, J.; Stassun, K. G.; Zhao, B.; Bizyaev, D.; Pan, K. (2018)."Chemo-kinematics of the Milky Way from the SDSS-III MARVELS survey".Monthly Notices of the Royal Astronomical Society.481 (3): 3244.arXiv:1803.11538.Bibcode:2018MNRAS.481.3244G.doi:10.1093/mnras/sty2431.
^Buchhave, Lars A.; Latham, David W.; Johansen, Anders; Bizzarro, Martin; Torres, Guillermo; Rowe, Jason F.; Batalha, Natalie M.; Borucki, William J.; Brugamyer, Erik; Caldwell, Caroline; Bryson, Stephen T.; Ciardi, David R.; Cochran, William D.; Endl, Michael; Esquerdo, Gilbert A.; Ford, Eric B.; Geary, John C.; Gilliland, Ronald L.; Hansen, Terese; Isaacson, Howard; Laird, John B.; Lucas, Philip W.; Marcy, Geoffrey W.; Morse, Jon A.; Robertson, Paul; Shporer, Avi; Stefanik, Robert P.; Still, Martin; Quinn, Samuel N. (2012). "An abundance of small exoplanets around stars with a wide range of metallicities".Nature.486 (7403):375–377.Bibcode:2012Natur.486..375B.doi:10.1038/nature11121.PMID22722196.
