Oral Presentation

Reveal the structure and kinematics of circumstellar disks in star formation with sub-millimeter light

Author(s): Ya-Wen Tang (ASIAA)

Presenter: Ya-Wen Tang (ASIAA)

More and more circumstellar discs around pre-main-sequence stars are found to have complex structures, such as great cavities seen in thermal dust emission and spiral-like features seen in the optical near-infrared images. Among them, AB Aurigae exhibits a spectacular spiral pattern. One popular formation mechanism often invoked for these two structures is the gravitational perturbation created by embedded companion/brown dwarf in the disks. However, the explanations of the spiral formations are purely based on the morphologies due to the lack of the kinematic information.
In this talk, I will present our study of the AB Aurigae system with high sensitivity and high angular resolution to trace the
kinematics of the spirals using CO lines with the Submillimeter Array, the Plateau de Bure Inteferometer and the 30-m. Using the 12CO 2-1 images with 0.5" resolution of AB Aurigae, we found the "spiral" like features appear counter-rotating with respect to the circumstellar disc. Late accretion from the envelope above and below the disc plane is the simplest mechanism to form these molecular spirals. Beside the spirals, the dense disk of AB Aurigae is resolved into an inner disk, an outer ring and a dust gap with a width of 50 AU using the 1.3 mm continuum (dust) emission. This suggests that there is an undetected companion with a mass of 0.03 M$_{\sun}$ at a radius of 45 AU.