FORWARD MODELLING OF CORONAL FUNNELS

摘要

We propose a forward modeling approach of coronal funnelsrnto investigate the role of the outer layers of the solarrnatmosphere in the thermodynamical and spectral propertiesrnof the transition region. We first investigate thernstationary plasma flow out of funnels with a new 2DrnMHD time dependent model including the solar atmospherernall the way from the chromosphere to the corona.rnThe plasma in the funnel is treated with single-fluidMHDrnequations including radiative losses, thermal conduction,rnand a parameterized heating. We adjust the parametersrnto the quantities measured in the lower solar corona. Wernobtained 2D plasma properties (e.g. density, temperature,rnflow speed) within the funnel. From the results of thernMHD calculation we derive spectral profiles of variousrnemission lines formed in the transition region and the lowrncorona. This allows us e.g. to study the Doppler shifts atrnvarious temperatures across the funnel and thus enablesrna detailed comparison of the model results with observations.rnWe present here results for the Ne VIII (770.4 A)rnlow coronal line. These results indicate a systematic variationrnof the Doppler shifts in lines formed in the lowrncorona. The line shift above the magnetic field concentrationrnin the network is stronger than in the inter-network,rnhowever, the maximum blue-shift is not to be found inrnthe very center of the network but in the vicinity of therncenter.