摘要：Context.The formation of planets in compact or highly eccentric binaries and the migration of hot Jupiters are two outstanding problems in planet formation. Detailed characterisation of known systems is important for informing and testing models. The hot JupiterτBoo Ab orbits the primary star in the long-period (P≳ 1000 yr), highly eccentric (e~ 0.9) double star systemτBoötis. Due to the long orbital period, the orbit of the stellar binary is poorly constrained.Aims.Here we aim to constrain the orbit of the stellar binaryτBoo AB in order to investigate the formation and migration history of the system. The mutual orbital inclination of the stellar companion and the hot Jupiter has important implications for planet migration. The binary eccentricity and periastron distance are important for understanding the conditions under whichτBoo Ab formed.Methods.We combine more than 150 yr of astrometric data with twenty-five years of high-precision radial velocities. The combination of sky-projected and line-of-sight measurements places tight constraints on the orbital inclination, eccentricity, and periastron distance ofτBoo AB.Results.We determine the orbit ofτBoo B and find an orbital inclination of 47.2−3.7+2.7°, a periastron distance of 28.3−3.0+2.3au, and an eccentricity of 0.87−0.03+0.04. We find that the orbital inclinations ofτBoo Ab andτBoo B, as well as the stellar spin-axis ofτBoo A coincide at ~45°, a result consistent with the assumption of a well-aligned, coplanar system.Conclusions.The likely aligned, coplanar configuration suggests planetary migration within a well-aligned protoplanetary disc. Due to the high eccentricity and small periastron distance ofτBoo B, the protoplanetary disc was tidally truncated at ≈6 au. We suggest thatτBoo Ab formed near the edge of the truncated disc and migrated inwards with high eccentricity due to spiral waves generated by the stellar companion.
关键词：Key wordsenstars: individual: τ Boötisplanetary systemsplanet-disk interactionsastrometrytechniques: radial velocitiesplanets and satellites: dynamical evolution and stability
