Effects of Metal Poor Environments on the Episodic Accretion in Protoplanetary Disks

A young star inevitably accretes through a surrounding disk due to the conservation of angular momentum of the parent molecular cloud. Such a protoplanetary disk typically forms a magnetically dead zone at the distance of a few au from the central protostar, where the turbulence resulting from magnetorotational instability (MRI) is suppressed. The dead zone results in a bottleneck in the angular momentum transport and as a consequence, a large amount of mass may accumulate in the inner disk. Accretion through such a layered disk is not steady but intrinsically unstable and can exhibit powerful outbursts known as FUor and EXor events. In this talk, I will present the results of the first investigation into the effects of low metallicity environment on the structure of the dead zone as well as outbursting behavior of the protoplanetary disk. A metal poor disk accumulates much more mass in the innermost regions, as compared to its solar metallicity counterpart. The duration of the burst phase is also reduced significantly at low metallicities and is confined mostly to the early, embedded stages. In conclusion, metallicity of a protoplanetary disk can have profound effects on both its structure and evolution in terms of episodic accretion.