10 June 2015

Daniel Evans
Friends of Hot Jupiters II: No correspondence between hot-Jupiter spin-orbit misalignment and the incidence of directly imaged stellar companions

Ngo, Knutson et al. present the results of a 3-year search for stellar companions to transiting exoplanet systems, using the Keck AO system. Of the 50 systems they observed (mainly WASP and HAT systems), 7 new bound companions were discovered by the survey, in addition to 10 previously discovered companions that were re-observed in order to confirm common proper motion. Consideration of their survey's completeness indicates that 49% of Hot Jupiters have an outer stellar companion in a 50-2000 au orbit, far in excess of the field star multiplicity rate in the same range (approximately 20%). By including the results of a separate radial velocity search of the same targets, which probes a different part of the companion population, it is suggested that 72% of Hot Jupiters have an outer planetary or stellar companion.