High resolution imaging of the GG Tauri system at 267 GHz

Context. Studying circumbinary disks is critical to understanding the formation mechanisms of binary stars. While optical or mid-infrared images reveal the scattered emission, millimeter observations provide direct measurements of the dust thermal emission. Aims. We study the properties of the circumbinary disk around the well-known, multiple young stellar object GG Tau with the highest possible sensitivity and spatial resolution. Methods. We mapped the continuum emission of GG Tau at 267 GHz using the IRAM Plateau de Bure interferometer equipped with upgraded receivers and LO systems. An angular resolution of 0.45 '' x 0.25 '' was achieved, corresponding to a linear resolution of 65 x 35 AU. Results. The GG Tau A circumbinary disk is observed as an extremely clearly defined narrow ring. The width of the ring is not resolved. Emission from the central binary is detected and clearly separated from the ring: it coincides with the GG Tau Aa position and may therefore trace a circumstellar disk around this star. The mass ratio of the circumbinary to circumprimary material is similar to 80.