Presentation #338.08 in the session Exoplanet Formation of Planets and Protoplanetary Disks II.
One third of solar-type stars in the solar neighborhood have at least one companion, and thus the effects of stellar multiplicity on planetary architecture and orbital dynamics provide crucial context for exoplanet demographics. However, the difficulty of identifying planets in binary systems has left the role of stellar multiplicity uncertain. We present a volume-limited catalog to 300 pc of 50 stellar companions that are gravitationally bound to stars that host transiting planet candidates, based on cross-matching planet candidates from TESS, Kepler and K2 with the Hipparcos-Gaia Catalog of Accelerations (HGCA, Brandt et al. 2021). We are confirming the companions using Keck/NIRC2 AO imaging and characterize the three dimensional orbits of the companions using radial velocities (RVs) from Keck/HIRES, absolute astrometry from Gaia and Hipparcos, and relative astrometry from imaging. We have combined these techniques for the TOI-1684 system, in which we discovered a K dwarf companion orbiting around a red giant primary with a separation of ~6.5 AU and an inclination of ~45 deg. Our analysis demonstrates that the transiting planet candidate, a hot Jupiter, orbits the secondary. TOI-1684 system is one of the closest binaries with a transiting S-type planet known to date and offers an important testbed to explore the dynamic influence from companions on planet formation and evolution.