Solar Wind Modelling: MHD And Kinetic Treatments with Kappa Distributions for the Electrons

Abstract:

We want to constrain a kinetic solar wind model with Kappa-distributed electrons using observation-driven magnetohydrodynamics (MHD) modelling and in-situ data.
Solar wind modelling efforts are presented using MHD - based modelling as well as a kinetic approach. In the fluid approach, photospheric magnetograms serve as observational input in semi-empirical coronal models that are used for estimating the plasma characteristics up to a heliocentric distance of 0.1AU. From there on a full MHD model which computes the three-dimensional time-dependent evolution of the macroscopic variables of the solar wind up to the orbit of the Earth is recruited. In the kinetic approach, an exospheric kinetic solar wind model based on the assumption of Maxwell and Kappa velocity distributions functions for protons and electrons respectively is used to determine appropriate boundary conditions to obtain the best comparison with available observations at the Earth's orbit. This will provide insight on more physically detailed processes, such as coronal heating and solar wind acceleration, that naturally arise by inclusion of suprathermal electrons in the model. We are interested in the profile of the solar wind speed and density at 1 AU, in characterising the slow and fast source regions of the wind and in comparing the features of that with results of exospheric models in similar conditions. We start from similar boundary conditions at the exobase and propagate the solution up to 1AU to compare MHD and kinetic treatments with observations.