Dynamical Architectures of S-type Transiting Planets in Binaries I: Target Selection Using Hipparcos and Gaia Proper Motion Anomalies

The effect of stellar multiplicity on planetary architecture and orbitaldynamics provides an important context for exoplanet demographics. We present avolume-limited catalog up to 300 pc of 66 stars hosting planets and planetcandidates from Kepler, K2 and TESS with significant Hipparcos-Gaia propermotion anomalies, which indicate the presence of companions. We assess thereliability of each transiting planet candidate using ground-based follow-upobservations, and find that the TESS Objects of Interest (TOIs) withsignificant proper motion anomalies show nearly four times more false positivesdue to Eclipsing Binaries compared to TOIs with marginal proper motionanomalies. In addition, we find tentative evidence that orbital periods ofplanets orbiting TOIs with significant proper motion anomalies are shorter thanthose orbiting TOIs without significant proper motion anomalies, consistentwith the scenario that stellar companions can truncate planet-forming disks.Furthermore, TOIs with significant proper motion anomalies exhibit lower Gaiadifferential velocities in comparison to field stars with significant propermotion anomalies, suggesting that planets are more likely to form in binarysystems with low-mass substellar companions or stellar companions at widerseparation. Finally, we characterize the three-dimensional architecture of LTT1445 ABC using radial velocities, absolute astrometry from Gaia and Hipparcos,and relative astrometry from imaging. Our analysis reveals that LTT 1445 is anearly flat system, with a mutual inclination of 2.88 deg between the orbit ofBC around A and that of C around B. The coplanarity may explain why multipleplanets around LTT 1445 A survive in the dynamically hostile environment ofthis system.