The spectroscopic signature of hot Jupiters in FU Orionis objects

We show that if FU Orionis objects harbour hot Jupiters embedded in their discs, the resulting non-axisymmetric dissipation profile in the disc would be manifest as time-dependent distortions in the absorption-line profiles of these objects. In order to affect the infrared line profiles, planets must lie within ∼0.5 au of the central star, whereas only planets within ∼0.1 au would influence the optical line profiles. The time-scale for modulation of the line profiles is relatively short (months) in each case, so that the effect could not have been discovered from published spectra (which combine data taken in different observing seasons). The detection of hot Jupiters in FU Orionis objects would be in line with the expectations of tidal migration theories (which predict a high incidence of close planets around young stars), and would also lend support to models that link the triggering of rapid-rise FU Orionis events to the existence of a close massive planet.