Resurrecting KOI-5 as TOI 1241: Confirmation of Kepler’s Second Planetary Candidate — a sub-Saturn Planet in a Triple Stellar System

Kepler’s second planetary candidate, KOI 5, was never confirmed. Early on in the Kepler follow-up observation program, it was found to be a spectroscopic binary and then later to be a triple star. Now that TESS has observed portions of the Kepler field, TESS has rediscovered KOI 5 as TOI 1241. Combining high resolution imaging and radial velocity data from both the Kepler and TESS follow-up observation programs spanning more than a decade of observation, we demonstrate that not only is KOI 5 (TOI 1241) a bound triple star system but the primary star hosts a sub-Saturn mass planet, confirming a Kepler’s second planetary candidate, resurrected by TESS, as a true planetary system.