Jingwen Zhang (UCSB): "Studying the three-dimensional architecture of transiting planets and their outer companions in the era of Gaia"

Stellar and substellar companions are thought to play a crucial role in shaping the formation and migration of the inner planets. However, the three-dimensional orbital architecture of these systems, including the mutual inclination between inner planets and outer companions, are largely unexplored. In this talk, I will describe our survey of planetary and stellar companions to transiting planet hosts with significant Hipparcos-Gaia astrometric acceleration. First, I will highlight discoveries of distant giant planets whose three-dimensional orbits are well constrained using RVs and astrometry. These systems offer key insights into how outer giants can drive the inward migration of hot Jupiters or perturb the orbits of inner small planets. Second, I will share results on stellar companions, where we measured the mutual inclinations between planetary orbits and binary companions. Our analysis shows strong evidence favoring a two-population model: one group with nearly aligned planet-binary orbits and another with a broader mutual inclination distribution. This observed dichotomy likely reflects distinct dynamical histories shaping the planet formation in binary systems. I will also discuss the prospects for discovering more giant planets with the upcoming Gaia DR4 release, and how these findings will complement future opportunities with JWST and the Roman Coronagraph.