Spectro-polarimetric simulations of the solar limb: absorption-emission FeI $6301.5\mathrmÅ$ and $6302.5\mathrmÅ$ line profiles and torsional flows in the intergranular magnetic flux concentrations

S. Shelyag

Published 2015-01-05Version 1

Using radiative magneto-hydrodynamic simulations of the magnetised solar photosphere and detailed spectro-polarimetric diagnostics with the FeI $6301.5\mathrm{\AA}$ and $6302.5\mathrm{\AA}$ photospheric lines in the local thermodynamic equilibrium approximation, we model active solar granulation as if it was observed at the solar limb. We analyse general properties of the radiation across the solar limb, such as the continuum and the line core limb darkening and the granulation contrast. We demonstrate the presence of profiles with both emission and absorption features at the simulated solar limb, and pure emission profiles above the limb. These profiles are associated with the regions of strong linear polarisation of the emergent radiation, indicating the influence of the intergranular magnetic fields on the line formation. We analyse physical origins of the emission wings in the Stokes profiles at the limb, and demonstrate that these features are produced by localised heating and torsional motions in the intergranular magnetic flux concentrations.