Oral title: Circumstellar disks of the most vigorously accreting young stars

Oral abstract: We imaged a sample of unusually actively accreting young stellar objects 
(YSOs), namely the FU Orionis objects, with extremely high contrast and resolution,  using 
the Subaru 8.2 m Telescope. These observations unveiled large-scale gas  arms and arcs 
surrounding the protostars. They are smoking guns of chaotic gravitational interactions 
between protostars and protoplanetary disks