Observations of the Corona at the Eclipse of 1983 June 11. I. Temperature and Rotation of the Corona from 5303A and 6374A profiles

Abstract

During the total solar eclipse of 1983 June 11, coronal spectra were obtained in the 5303A (Fe XIV) line using the multislit spectrograph at a dispersion of 2.17A mm-1 . The line profiles measured at 113 locations from 1.04 to 1.24 R have half widths ranging from 0.6A to 1.4A. The most frequent width of 0.9A corresponds to a temperature of 3.1 x 106 K. Since according to the ionization equilibrium calculations a temperature of 2 x 106 K is typical of regions emitting 5303A radiation, we ascribe the difference between our observed and the latter temperature to random turbulent velocities of 18.4 Km s-1 derived from the 1980 eclipse, it appears that the random turbulent velocity may be cycle dependent. The line of sight velocities on most locations are within ± 5 Km s-1 indicating that the corona is quite. We had set up of another experiment with a second multislit spectrograph for the 6374A line spectra and the coronal rotation velocities derived from these profiles have a mean value of 3.5 Km s-1. These observations confirm the findings of the 1980 eclipse by the Institute’s team that the corona does not show any localized differential mass motions and that it corotates with the Photospheric layers.