Winds and Alfvén waves in angular momentum transport in protostellar accretion disks

Abstract

The angular momentum transport in accretion disks associated to young stellar objects is a key mechanism in understanding and describing the evolution of stars -and planetary systems- in their early stages. Currently, there are two important mechanisms used to describe the angular momentum transport in accretion disks of T Tauri stars: the Magnetorotational Instability (MRI) and the magnetocentrifugal winds. Both mechanisms are deeply affected by the non-ideal MHD effects (Ohmic resistivity, ambipolar diffusion and the Hall effect), which, in turn, are associated to the ionization degree of the disk's particles. In the literature, there are several indications that the damping of Alfvén waves could increase the disk's ionization fraction significantly. Therefore, this project aims to study, considering recombination/ionization processes and the damping of Alfvén waves, the angular momentum transport in these disks, assuming that both MRI and magnetocentrifugal winds are present in these systems. The effects of external ionization sources, besides other kinds of winds (both thermal disk winds and protostellar winds), will be considered. We intend to use a tridimensional MHD code to evaluate the temporal evolution of the star-disk system, under these effects, including the consequences for planetesimal formation. (AU)