Constraints on a planetary origin for the gap in GM Aurigae's protoplanetary disc

Abstract

The unusual spectral energy distribution (SED) of the classical T Tauri star GM Aurigae provides evidence for the presence of an inner disc hole extending to several au. Using a combination of hydrodynamical simulations and Monte Carlo radiative transport, we investigate whether the observed SED is consistent with the inner hole being created and maintained by an orbiting planet. We show that an ~ 2 M_Jupiter planet, orbiting at 2.5 au in a disc with mass 0.047 M_sun and radius 300 au, provides a good match both to the SED and to CO observations which constrain the velocity field in the disc. A range of planet masses is allowed by current data, but could in principle be distinguished with further observations between 3 and ~ 20 microns. Future high precision astrometric instruments should also be able to detect the motion of the central star due to an orbiting Jupiter mass planet. We argue that the small number of T Tauri stars with SEDs resembling that of GM Aur is broadly consistent with the expected statistics of embedded migrating planets.