مشخصات پژوهش

Recent research on the exoplanets caused a particular focus on the protoplanetary disks (PPDs). The time evolution of a PPD gives us new insight on the planetary system around the central objects. Although the time dependency of a quasi-spherical disk has been considered in detail by many theoretical works, the time dependency of a PPD has not yet been fully understood. In this study, we consider the time evolution of the inner regions of a polytropic PPD with a toroidal magnetic field in the non-ideal magnetohydrodynamic regime. In this regime, we consider a magnetic Prandtl number for this disk that is the ratio of magnetic diffusivity to the viscosity. Also, we use a selfsimilar formalism to study the dynamical behavior of a PPD. Two variables, i.e., the independent self-similar variable (x) and dimensionless polytropic index (a), are mainly considered in the formulation of the problem. Therefore, we are able to consider both polytropic and isothermal cases in a unit formulation. The problem is solvable for small x in the isothermal case, where we obtain a new perspective on the dynamics of a PPD. Furthermore, we investigate the magnetic dissipation originated from the magnetic diffusivity, which is dependent on the magnetic Prandtl number, in the PPDs. The importance of this study is in the angular momentum transport and formation of planetesimal in a PPD.