Analysis of the solar coronal green line profiles from eclipse observations

Abstract

Analysis of the solar coronal green line profiles reveals information regarding the physical conditions of the solar corona like temperature, density, Doppler velocity, non-thermal velocity etc. It provides insights to the unresolved problems like the coronal heating and the acceleration of the solar winds. Recent studies have reported excess blueshifts in the coronal line profiles and are interpreted as due to nanoflare heating, type II spicules and nascent solar wind flow. We have analyzed a time series of Fabry-Perot interferograms of the solar corona obtained during the total solar eclipse of 2001 June 21 from Lusaka, Zambia. The spatial behavior of the coronal green line profiles were examined and variations in intensity, linewidth, Doppler velocity and line asymmetry were obtained. Several line profiles showed asymmetry indicating the presence of multicomponents. Such line profiles were fitted with double Gaussian curves. It has been found that 42% of the line profiles were single components, 34% were blueshifted, and 24% were red shifted. The secondary component of a typical line profile with blue asymmetry is found to have a relative intensity about 0.26, Doppler velocity around -30 km/s and a halfwidth about 0.65Å.