Impact of Heavy Ions on the Structure of Current Sheets in the Gravity Field of Exoplanets and Stars

Boundary current sheets (CSs) can be formed in collisionless space plasmas in the environment of exoplanets and cold stars. Usually they represent curved surfaces carrying the electric current analogous to the well-known planetary ionospheres, magnetopauses, or stellar coronas surrounding celestial bodies. At smaller local scales, some of them can be imagined as planar current layers of a finite scale located parallel to the surface of a celestial object and, correspondingly, perpendicular to the direction of the gravitational force. In some cases, this force crossed with magnetic field can influence the dynamics of charged particles in CSs and substantially change the structure of both the current layer and the magnetic field. We have generalized our prior model, taking into account a multi-ion plasma composition and a magnetic field configuration with a shear. It is shown that, due to the drift motion of plasma particles in the crossed gravitational and magnetic fields, the structure of CSs becomes more complex, accruing asymmetric and shifted profiles of the current and plasma densities that depend on dominating current carriers and the characteristics of the magnetic shear. We discuss possible applications of the results to the interpretation of observations of boundary layers in different space plasmas.

Automated summary

Boundary current sheets (CSs) can form in collisionless space plasmas around exoplanets and cold stars. These CSs are curved surfaces carrying electric current, similar to planetary ionospheres, magnetopauses, or stellar coronas. At smaller scales, some CSs can be imagined as planar current layers of finite scale parallel to a celestial object's surface. The combination of gravitational and magnetic fields can influence the dynamics of charged particles in the CSs and alter the structure of both the current layer and magnetic field. This study presents a generalized model that considers a multi-ion plasma composition and a magnetic field configuration with shear. The results show that the structure of CSs becomes more complex due to the drift motion of plasma particles in the crossed gravitational and magnetic fields.