Tracing the Influence of Distant companions on Exoplanetary Systems (TIDES) I. Highly Eccentric and Misaligned Binary Companions to Hot Jupiters

Abstract

The origin of hot Jupiters remains an open question. A significant fraction reside in binary or multiple star systems, suggesting that stellar companions may play an important role in shaping their present-day architectures. However, the orbits of the vast majority of these stellar companions remain poorly constrained, leaving their role in hot Jupiter evolution an open question. We present the Tracing the Influence of Distant companions on Exoplanetary Systems (TIDES) survey, a campaign to map the orbits of stellar companions in systems hosting hot Jupiters to assess the extent to which binaries play a role in hot Jupiter formation and migration. Here, we introduce our survey design and new orbital fits for the first six systems in our sample---$τ$ Boo, WASP-2, WASP-11, WASP-76, HAT-P-14, and HAT-P-16---by combining previous observations of the stellar companions together with new Keck/NIRC2 imaging and Keck/KPIC relative radial velocities. Among these six systems, the four with the most precisely constrained orbits exhibit high eccentricities ($e \geq 0.8$), and three of these systems also display significant planet--binary misalignments ($Δi \geq 20^\circ$). This suggests the orbital properties of stellar companions to hot Jupiter host stars are qualitatively different than field binaries and binaries hosting inner transiting small planets. These orbital architectures are consistent with stellar companions shaping the evolution of hot Jupiters, either through high-eccentricity migration or by participating in an earlier episode of dynamical evolution that ultimately led to hot Jupiter formation. Continued orbital monitoring of the full sample will reveal whether outer stellar companions play a causal role in the evolution of hot Jupiters.