Dead zones and extrasolar planetary properties

Most low-mass protostellar discs evolve in clustered environments where they are affected by external radiation fields, while others evolve in more isolated star-forming regions. Assuming that the magnetorotational instability (MRI) is the main source of viscosity, we calculate the size of a poorly ionized, MRI inactive and hence low viscosity region — the ‘dead zone’-in these protostellar discs. We include disc ionization by X-rays, cosmic …