CI Tau: A Controlled Experiment in Disk–Planet Interaction

CI Tau is a young (~2 Myr) T Tauri system with a substantial near-infrared excess in its SED, indicating that the protoplanetary disk extends very close to its star. This is seemingly at odds with the radial-velocity discovery of CI Tau b, a ~12 M_J companion at ~0.1 au, which would be expected to carve a wide, deep cavity in the innermost disk. To investigate this apparent contradiction, we run 2D hydrodynamics simulations to study the effect of the planet on the disk, then post-process the results with radiative transfer to obtain an SED. We find that at ~0.1 au, even such a massive companion has little impact on the near-infrared excess, a result that holds regardless of planetary eccentricity and dust size distribution. This bolsters the case for CI Tau b's existence, and encourages investigation into the early formation of hot Jupiters by mechanisms such as disk migration and \textit{in-situ} formation. As our simulations uncover, transition-disk signatures in SEDs are more likely to be signposts of nascent "warm" Jupiters, located at around 1 AU in the future habitable zones of their host stars.