On the vertical shear instability in magnetized protoplanetary discs

ABSTRACT The vertical shear instability (VSI) is a robust phenomenon in irradiated protoplanetary discs (PPDs). While there extensive literature on the VSI hydrodynamic limit, PPDs are expected to be magnetized and their extremely low ionization fractions imply that non-ideal magnetohydrodynamic effects should properly considered. To this end, we present linear analyses of with Ohmic resistivity. We primarily consider toroidal magnetic fields, which likely dominate field geometry PPDs. perform vertically global radially local capture characteristic modes extended structures. focus effect magnetism, locally isothermal equation state employed. find magnetism provides stabilizing dampen VSI, surface modes, rather than body being first vanish increasing magnetization. Subdued can revived by resistivity, where sufficient diffusion overcomes stabilization, results recovered. also briefly poloidal fields account for magnetorotational (MRI), may develop towards layers outer regions MRI grows efficiently at small radial wavenumbers, contrast VSI. When resistivity considered, dominates over Elsässer numbers ?0.09 plasma beta parameter ?Z ? 104.